2002 - B.S., Physics, Drohobych State University, Ukraine
2004 - M.S., Physics, Minnesota State University, Mankato, MN
2008 - Ph.D., Applied Physics, University of South Florida (H. Lee Moffitt Cancer Center and Research Institute), Tampa, FL
2010 - Medical Physics Residency, Mayo Clinic, Rochester, MN

Academic Appointments:
2010 - 2015 - Instructor, Harvard Medical School, Massachusetts General Hospital/Boston Medical Center, Department of Radiation Oncology, Boston, MA
2015 - 2019 - Clinical Assistant Professor, Stanford University, Department of Radiation Oncology, Stanford, CA
2019 - present - Clinical Associate Professor, Stanford University, Department of Radiation Oncology, Stanford, CA
2019 - present - Adjunct Associate Professor, MD Anderson Cancer Center/University of Texas, Houston, TX

Academic Appointments

Honors & Awards

  • Parliament of Ukraine Certificate of Merit for the Service to the People of Ukraine, Parliament of Ukraine (Verkhovna Rada Ukrainy) (2023)
  • Keith Boddy best SCOPE article award for ”Fighting on Two Fronts: War and Cancer in Ukraine”, SCOPE (2023)
  • Richard Hoppe Leadership Award, Radiation Oncology Department, Stanford, Stanford (2022)
  • Medical Physics Teaching Award, Radiation Oncology Department, Stanford, Stanford (2021)
  • Medical Physics Teaching Award, Radiation Oncology Department, Stanford, Stanford (2017)
  • ARRO Educator of the Year Award by Harvard Radiation Oncology Residency Program, ARRO (2014)
  • Quality Improvement Award at Boston Medical Center, Boston Medical Center (2013)
  • Resident Travel Grant Award for the 2009 American Brachytherapy Society (ABS) Annual Meeting, ABS (2009)
  • Boutzoukas Radiology Research Award, H. Lee Moffitt, Moffitt Cancer Center (2006)
  • Midwestern Association of Graduate Schools Distinguished Thesis Competition Award, MAGS (2005)
  • MSU Best Thesis of the Year Award, MSU (2004)

Boards, Advisory Committees, Professional Organizations

  • Physics Chair, NRG CC013 (2023 - Present)
  • American Board of Radiology, Therapy Oral Exam (Part 3), examiner (2021 - Present)
  • Physics Co-Chair, NRG HN006 (2019 - Present)
  • Physics Chair, NRG HN005 (2018 - Present)
  • NRG Physics HN committee, liaison (2018 - Present)
  • COG Workgroup on pediatric TBI, member (2018 - Present)
  • AAPM MP3.0 Committee, member (2018 - Present)
  • COG Physics Committee, member (2017 - Present)
  • NRG Physics Committee, member (2017 - Present)
  • ASTRO, member (2010 - Present)
  • AAPM, member (2008 - Present)

Community and International Work

  • Founder of Help Ukraine Group (HUG)

    Ongoing Project


    Opportunities for Student Involvement


Clinical Trials

  • Comparing Sentinel Lymph Node (SLN) Biopsy With Standard Neck Dissection for Patients With Early-Stage Oral Cavity Cancer Recruiting

    This phase II/III trial studies how well sentinel lymph node biopsy works and compares sentinel lymph node biopsy surgery to standard neck dissection as part of the treatment for early-stage oral cavity cancer. Sentinel lymph node biopsy surgery is a procedure that removes a smaller number of lymph nodes from your neck because it uses an imaging agent to see which lymph nodes are most likely to have cancer. Standard neck dissection, such as elective neck dissection, removes many of the lymph nodes in your neck. Using sentinel lymph node biopsy surgery may work better in treating patients with early-stage oral cavity cancer compared to standard elective neck dissection.

    View full details

  • De-intensified Radiation Therapy With Chemotherapy (Cisplatin) or Immunotherapy (Nivolumab) in Treating Patients With Early-Stage, HPV-Positive, Non-Smoking Associated Oropharyngeal Cancer Recruiting

    This phase II/III trial studies how well a reduced dose of radiation therapy works with nivolumab compared to cisplatin in treating patients with human papillomavirus (HPV)-positive oropharyngeal cancer that is early in its growth and may not have spread to other parts of the body (early-stage), and is not associated with smoking. Radiation therapy uses high-energy x-rays to kill tumor cells and shrink tumors. Chemotherapy drugs, such as cisplatin, work in different ways to stop the growth of tumor cells, either by killing the cells, by stopping them from dividing, or by stopping them from spreading. Immunotherapy with monoclonal antibodies, such as nivolumab, may help the body's immune system attack the cancer, and may interfere with the ability of tumor cells to grow and spread. This trial is being done to see if a reduced dose of radiation therapy and nivolumab works as well as standard dose radiation therapy and cisplatin in treating patients with oropharyngeal cancer.

    View full details

  • Mismatched Related Donor Versus Matched Unrelated Donor Stem Cell Transplantation for Children, Adolescents, and Young Adults With Acute Leukemia or Myelodysplastic Syndrome Recruiting

    This phase III trial compares hematopoietic (stem) cell transplantation (HCT) using mismatched related donors (haploidentical [haplo]) versus matched unrelated donors (MUD) in treating children, adolescents, and young adults with acute leukemia or myelodysplastic syndrome (MDS). HCT is considered standard of care treatment for patients with high-risk acute leukemia and MDS. In HCT, patients are given very high doses of chemotherapy and/or radiation therapy, which is intended to kill cancer cells that may be resistant to more standard doses of chemotherapy; unfortunately, this also destroys the normal cells in the bone marrow, including stem cells. After the treatment, patients must have a healthy supply of stem cells reintroduced or transplanted. The transplanted cells then reestablish the blood cell production process in the bone marrow. The healthy stem cells may come from the blood or bone marrow of a related or unrelated donor. If patients do not have a matched related donor, doctors do not know what the next best donor choice is. This trial may help researchers understand whether a haplo related donor or a MUD HCT for children with acute leukemia or MDS is better or if there is no difference at all.

    View full details

All Publications

  • Radiation Therapy Under the Falling Bombs: A Tale of 2 Ukrainian Cancer Centers. Advances in radiation oncology Kovalchuk, N., Zelinskyi, R., Hanych, A., Severyn, Y., Bachynska, B., Beznosenko, A., Duda, O., Kowalchuk, R., Iakovenko, V., Melnitchouk, N., Suchowerska, N. 2022; 7 (6): 101027

    View details for DOI 10.1016/j.adro.2022.101027

    View details for PubMedID 36072756

  • Treatment planning system commissioning of the first clinical biology-guided radiotherapy machine. Journal of applied clinical medical physics Simiele, E., Capaldi, D., Breitkreutz, D., Han, B., Yeung, T., White, J., Zaks, D., Owens, M., Maganti, S., Xing, L., Surucu, M., Kovalchuk, N. 2022: e13638


    PURPOSE: The RefleXion X1 is a novel radiotherapy machine designed for image-guided radiotherapy (IGRT) and biology-guided radiotherapy (BgRT). Its treatment planning system (TPS) generates IMRT and SBRT plans for a 6MV-FFF beam delivered axially via 50 firing positions with the couch advancing every 2.1mm. The purpose of this work is to report the TPS commissioning results for the first clinical installation of RefleXion X1.METHODS: CT images of multiple phantoms were imported into the RefleXion TPS to evaluate the accuracy of data transfer, anatomical modeling, plan evaluation, and dose calculation. Comparisons were made between the X1, Eclipse, and MIM. Dosimetric parameters for open static fields were evaluated in water and heterogeneous slab phantoms. Representative clinical IMRT and SBRT cases were planned and verified with ion chamber, film, and ArcCHECK@ measurements. The agreement between TPS and measurements for various clinical plans was evaluated using Gamma analysis with a criterion of 3%/2mm for ArcCHECK@ and film. End-to-end (E2E) testing was performed using anthropomorphic head and lung phantoms.RESULTS: The average difference between the TPS-reported and known HU values was -1.4 ± 6.0 HU. For static fields, the agreements between the TPS-calculated and measured PDD10 , crossline profiles, and inline profiles (FWHM) were within 1.5%, 1.3%, and 0.5mm, respectively. Measured output factors agreed with the TPS within 1.3%. Measured and calculated dose for static fields in heterogeneous phantoms agreed within 2.5%. The ArcCHECK@ mean absolute Gamma passing rate was 96.4% ± 3.4% for TG 119 and TG 244 plans and 97.8% ± 3.6% for the 21 clinical plans. E2E film analysis showed 0.8mm total targeting error for isocentric and 1.1mm for off-axis treatments.CONCLUSIONS: The TPS commissioning results of the RefleXion X1 TPS were within the tolerances specified by AAPM TG 53, MPPG 5.a, TG 119, and TG 148. A subset of the commissioning tests has been identified as baseline data for an ongoing QA program.

    View details for DOI 10.1002/acm2.13638

    View details for PubMedID 35644039

  • Volumetric modulated arc therapy total body irradiation in pediatric and adolescent/young adult patients undergoing stem cell transplantation: Early outcomes and toxicities. Pediatric blood & cancer Marquez, C., Hui, C., Simiele, E., Blomain, E., Oh, J., Bertaina, A., Klein, O., Shyr, D., Jiang, A., Hoppe, R. T., Kovalchuk, N., Hiniker, S. M. 2022: e29689


    INTRODUCTION: Total body irradiation (TBI) is an important component of many conditioning regimens for hematopoietic stem cell transplantation (HSCT), most commonly used in pediatric and adolescent/young adult (AYA) patients. We aimed to evaluate outcomes and toxicities among pediatric and AYA patients treated with TBI utilizing volumetric modulated arc therapy total body irradiation (VMAT-TBI).METHODS: We reviewed pediatric and AYA patients treated with VMAT-TBI at our institution from 2019 to 2021. Data on patient and disease characteristics, treatment details, outcomes and toxicities were collected. Overall survival (OS) and relapse-free survival (RFS) were analyzed using the Kaplan-Meier method.RESULTS: Among 38 patients, 16 (42.1%) were treated with myeloablative regimens and 22 (57.9%) with nonmyeloablative regimens. Median age was 7.2 years (range: 1-27) and median follow-up was 8.7 months (range: 1-21). Lungs Dmean was 7.3 ± 0.3Gy for myeloablative regimens (range: 6.8-7.8). Kidneys were spared to average mean dose of 71.4 ± 4.8% of prescription dose. Gonadal sparing was achieved for patients treated for nonmalignant diseases to Dmean of 0.7 ± 0.1Gy. No patient experienced primary graft failure; one (2.6%) experienced secondary graft failure. The most common grade 1-2 acute toxicities were nausea (68.4%) and fatigue (55.3%). Mucositis was the most common grade 3-4 acute toxicity, affecting 39.5% of patients. There were no cases of pneumonitis or nephrotoxicity attributable to TBI.CONCLUSION: VMAT-TBI offers increased ability to spare organs at risk in pediatric and AYA patients undergoing HSCT, with a favorable acute/subacute toxicity profile and excellent disease control.

    View details for DOI 10.1002/pbc.29689

    View details for PubMedID 35373904

  • While Ukrainian soldiers are fearlessly defending their country, Ukrainian oncologists are bravely battling cancer Advances in Radiation Oncology Kovalchuk, N., Beznosenko, A., Kowalchuk, R., Ryzhkova, J., Iakovenko, V., Kacharian, A. 2022
  • The Stanford VMAT TBI Technique Practical Radiation Oncology Kovalchuk, N., Simiele, E., Skinner, L., Yang, Y., Howell, N., Lewis, J., Hui, C., Blomain, E., Hoppe, R. T., Hiniker, S. M. 2022
  • A time- and space-saving Monte Carlo simulation method using post-collimation generative adversarial network for dose calculation of an O-ring gantry Linac. Physica medica : PM : an international journal devoted to the applications of physics to medicine and biology : official journal of the Italian Association of Biomedical Physics (AIFB) Shi, M., Cui, S., Chuang, C., Oderinde, O., Kovalchuk, N., Surucu, M., Xing, L., Han, B. 2024; 119: 103318


    This study explores the feasibility of employing Generative Adversarial Networks (GANs) to model the RefleXion X1 Linac. The aim is to investigate the accuracy of dose simulation and assess the potential computational benefits.The X1 Linac is a new radiotherapy machine with a binary multi-leaf collimation (MLC) system, facilitating innovative biology-guided radiotherapy. A total of 34 GAN generators, each representing a desired MLC aperture, were developed. Each generator was trained using a phase space file generated underneath the corresponding aperture, enabling the generation of particles and serving as a beam source for Monte Carlo simulation. Dose distributions in water were simulated for each aperture using both the GAN and phase space sources. The agreement between dose distributions was evaluated. The computational time reduction from bypassing the collimation simulation and storage space savings were estimated.The percentage depth dose at 10 cm, penumbra, and full-width half maximum of the GAN simulation agree with the phase space simulation, with differences of 0.4 % ± 0.2 %, 0.32 ± 0.66 mm, and 0.26 ± 0.44 mm, respectively. The gamma passing rate (1 %/1mm) for the planar dose exceeded 90 % for all apertures. The estimated time-saving for simulating an plan using 5766 beamlets was 530 CPU hours. The storage usage was reduced by a factor of 102.The utilization of the GAN in simulating the X1 Linac demonstrated remarkable accuracy and efficiency. The reductions in both computational time and storage requirements make this approach highly valuable for future dosimetry studies and beam modeling.

    View details for DOI 10.1016/j.ejmp.2024.103318

    View details for PubMedID 38382210

  • First-Year Experience of Stereotactic Body Radiation Therapy/Intensity Modulated Radiation Therapy Treatment Using a Novel Biology-Guided Radiation Therapy Machine. Advances in radiation oncology Shi, M., Simiele, E., Han, B., Pham, D., Palomares, P., Aguirre, M., Gensheimer, M., Vitzthum, L., Le, Q., Surucu, M., Kovalchuk, N. 2024; 9 (1): 101300


    Purpose: The aim of this study was to present the first-year experience of treating patients using intensity modulated radiation therapy (IMRT) and stereotactic body radiation therapy (SBRT) with a biology-guided radiation therapy machine, the RefleXion X1 system, installed in a clinical setting.Methods and Materials: A total of 78 patients were treated on the X1 system using IMRT and SBRT from May 2021 to May 2022. Clinical and technical data including treatment sites, number of pretreatment kilovoltage computed tomography (kVCT) scans, beam-on time, patient setup time, and imaging time were collected and analyzed. Machine quality assurance (QA) results, machine performance, and user satisfactory survey were also collected and reported.Results: The most commonly treated site was the head and neck (63%), followed by the pelvis (23%), abdomen (8%), and thorax (6%). Except for 5 patients (6%) who received SBRT treatments for bony metastases in the pelvis, all treatments were conventionally fractionated IMRT. The number of kVCT scans per fraction was 1.2 ± 0.5 (mean ± standard deviation). The beam-on time was 9.2 ± 3.5 minutes. The patient setup time and imaging time per kVCT was 4.8 ± 2.6 minutes and 4.6 ± 1.5 minutes, respectively. The daily machine output deviation was 0.4 ± 1.2% from the baseline. The patient QA had a passing rate of 97.4 ± 2.8% at 3%/2 mm gamma criteria. The machine uptime was 92% of the total treatment time. The daily QA and kVCT image quality received the highest level of satisfaction. The treatment workflow for therapists received the lowest level of satisfaction.Conclusions: One year after the installation, 78 patients were successfully treated with the X1 system using IMRT and/or SBRT. With the recent Food and Drug Administration clearance of biology-guided radiation therapy, our department is preparing to treat patients using positron emission tomography-guidance via a new product release, which will address deficiencies in the current image-guided radiation therapy workflow.

    View details for DOI 10.1016/j.adro.2023.101300

    View details for PubMedID 38260216

  • BIOGUIDE-X: A First-in-Human Study of the Performance of Positron Emission Tomography-Guided Radiotherapy. International journal of radiation oncology, biology, physics Vitzthum, L. K., Surucu, M., Gensheimer, M. F., Kovalchuk, N., Han, B., Pham, D., Chang, D., Shirvani, S. M., Aksoy, D., Maniyedath, A., Narayanan, M., Da Silva, A. J., Mazin, S., Feghali, K. A., Iyengar, P., Dan, T., Pompos, A., Timmerman, R., Öz, O., Cai, B., Garant, A. 2023


    SCINTIX® Biology-guided radiotherapy (BgRT) is a novel tracked dose delivery modality that uses real-time positron emission tomography (PET) to guide radiotherapy beamlets. The BIOGUIDE-X study was performed with sequential cohorts of participants to (1) identify the fluorodeoxyglucose (FDG) dose for SCINTIX therapy and (2) confirm that the emulated dose distribution was consistent with a physician-approved radiotherapy plan.This prospective study included participants with at least 1 FDG-avid targetable primary or metastatic tumor (≥2cm and ≤5cm) in the lung or bone. For Cohort I, a modified 3 + 3 design was used to determine the FDG dose that would result in adequate signal for SCINTIX therapy. For Cohort II, PET imaging data were collected on the X1 system before the first and last fractions among patients undergoing conventional stereotactic body radiotherapy. SCINTIX therapy dose distributions were modeled on the patient's CT anatomy using the collected PET data at each fraction as input to an "emulated delivery" and compared to the physician-approved plan.Cohort I demonstrated adequate FDG activity in 6/6 (100.0%) evaluable participants with the first injected dose level of 15 mCi FDG. In Cohort II, 4 patients with lung tumors and 5 with bone tumors were enrolled, and evaluable emulated delivery data points were collected for 17 treatment fractions. Sixteen of the 17 emulated deliveries resulted in SCINTIX dose distributions that were accurate with respect to the approved SCINTIX therapy plan. The 17th data point was just below the 95% threshold for accuracy (DVH Score = 94.6%). All emulated fluences were physically deliverable. No toxicities were attributed to multiple FDG administrations.SCINTIX therapy is a novel radiotherapy modality in which a radiolabeled tumor can act as its own fiducial for radiotherapy targeting. Emulated SCINTIX therapy dose distributions calculated from continuously acquired real-time PET data were accurate and machine-deliverable in tumors that were 2-5 cm in size with adequate FDG signal characteristics.

    View details for DOI 10.1016/j.ijrobp.2023.12.019

    View details for PubMedID 38147912

  • Automating the Treatment Planning Process for Volumetric Modulated Arc Therapy Craniospinal Irradiation (VMAT-CSI). Practical radiation oncology Romero, I. O., Simiele, E. A., Lozko, Y., Severyn, Y., Skinner, L. B., Yang, Y., Wang, J. Y., Xing, L., Gibbs, I., Hiniker, S. M., Kovalchuk, N. 2023


    The purpose of this work is to develop a method to automate the treatment planning process of craniospinal irradiation (CSI) using volumetric modulated arc therapy (VMAT).Two scripts were developed using the Eclipse Scripting Application Programming Interface (ESAPI) to perform auto-plan preparation and optimization. Ten patients (age, 5-44 years) previously treated at our institution with low dose VMAT-CSI (prescription of 12 Gy) prior to total body irradiation were selected to evaluate the efficacy of the proposed auto-planning process. Paired t-tests compared the dosimetric indices of the auto-plans to the manually generated clinical plans. All plans were normalized to 95% of PTV coverage with the prescription dose. Two physicians and one physicist were asked to evaluate the manual plans and auto-plans of each patient in a blinded retrospective review and to indicate clinical acceptability and which plans were preferred for treatment.Compared to the manual CSI plans, the auto plans obtained significant reductions in Dmean to the parotids, submandibular glands, larynx, thyroid, and significant reduction in the plan PTV Dmax and D0.03cc. The standard deviation range of the dosimetric parameters was greatly reduced for auto plans (range, 0.1-1.3 Gy) relative to manual plans (range, 0.4-5.9 Gy) indicating better plan consistency. Among the ten patients, the auto-plans were preferred over the manual plans 90% of the time by the reviewing experts. The required time for auto-planning was approximately 1 hour compared to estimated 4 or more hours for manual planning.Reductions in planning time without sacrifices in plan quality were obtained using the auto-planning process compared with manual planning. Variation in plan quality was also reduced. The auto-planning scripts will be made freely available to other institutions and clinics.

    View details for DOI 10.1016/j.prro.2023.11.014

    View details for PubMedID 38048988

  • Patient Selection and Outcomes for Hypofractionated Accelerated Radiation and Concurrent Chemotherapy for Non-Small-Cell Lung Cancer. Clinical lung cancer Hui, C., Marquez, C., Lau, B., Das, M., Myall, N. J., Roy, M., Wakelee, H. A., Neal, J. W., Kovalchuk, N., Chin, A., Diehn, M., Loo, B. W., Xiang, M., Vitzthum, L. K. 2023


    Adoption of hypofractionated accelerated radiation therapy (HART) with concurrent chemotherapy has been limited by toxicity concerns. We aimed to describe outcomes of patients treated with HART and concurrent chemotherapy and to evaluate dosimetry to organs at risk to guide patient selection.We evaluated a retrospective cohort of NSCLC patients treated with concurrent chemotherapy with HART (>2.2 Gy per fraction) or standard fractionated radiation therapy (SFRT; 2-2.2 Gy fractions). Dosimetric parameters to key organs at risk were compared, and toxicity, patterns of recurrence and survival were calculated for the cohorts.Fifty-three patients treated with HART were compared with 100 patients treated with SFRT. Median dose per fraction for the HART cohort was 2.75 Gy (range 2.4-3 Gy). HART patients had significantly lower doses to the lung, heart, and esophagus due to patient selection. The HART group and had rates of grade 2+ pneumonitis (9.4 vs. 19%, P = .16) and grade 2+ esophagitis (20.8 vs. 45%, P < .01) that compared favorably to SFRT. Cumulative incidence of in-field recurrence trended lower in the HART cohort (7.6% vs. 23.1%, P = .058). Among the HART group, 88.7% (47/53) met the newly proposed lung constraints based on the degree of hypofractionation CONCLUSION: In select patients with favorable dosimetry to organs at risk, definitive HART with concurrent chemotherapy achieved excellent local control with low toxicity. These results are being used to inform a prospective study on the safety and efficacy of HART with concurrent chemotherapy for select NSCLC patients.

    View details for DOI 10.1016/j.cllc.2023.11.008

    View details for PubMedID 38065707

  • Personalized Accelerated ChEmoRadiation (PACER) for Lung Cancer: Protocol for a Bayesian Optimal Phase I/II Trial. Clinical lung cancer Hui, C., Brown, E., Wong, S., Das, M., Wakelee, H., Neal, J., Ramchandran, K., Myall, N. J., Pham, D., Xing, L., Yang, Y., Kovalchuk, N., Yuan, Y., Lu, Y., Xiang, M., Chin, A., Diehn, M., Loo, B. W., Vitzthum, L. K. 2023


    Prior attempts to escalate radiation dose for non-small cell lung cancer (NSCLC) have not improved survival. Given the high risk for cardiopulmonary toxicity with treatment and heterogenous presentation of locally advanced NSCLC, it is unlikely that a single dose regimen is optimal for all patients. This phase I/II trial aims to evaluate a novel treatment approach where the level of accelerated hypofractionation is determined by the predicted toxicity from dose to organs at risk (OARs).Patients ≥ 18 years old with lung cancer planned for fractionated radiotherapy to the lung with concurrent chemotherapy will be eligible. Radiation therapy (RT) will be delivered to a total dose of 60 to 66 Gy in 30, 25, or 20 fractions depending on the ability to meet constraints to key organs at risk including the lungs, heart, and esophagus. The primary endpoint is high grade pulmonary, esophageal, or cardiac toxicity. A Bayesian optimized design is used to determine stopping boundaries and evaluate the primary endpoint.PACER will evaluate the safety and feasibility of personalized accelerated chemoradiotherapy for lung cancer.

    View details for DOI 10.1016/j.cllc.2023.11.004

    View details for PubMedID 38040540

  • Improved organ sparing using auto-planned Stanford volumetric modulated arc therapy for total body irradiation technique. Pediatric blood & cancer Ngo, N., Blomain, E. S., Simiele, E., Romero, I., Hoppe, R. T., Hiniker, S. M., Kovalchuk, N. 2023: e30589


    To evaluate dosimetric differences between auto-planned volumetric modulated arc therapy (VMAT) total body irradiation (TBI) technique and two-dimensional radiotherapy using anterior-posterial/posterio-anterial beams (2D AP/PA) TBI technique.Ten pediatric patients treated with VMAT-TBI on Varian c-arm linac were included in this study. VMAT-TBI plans were generated using our in-house developed and publicly shared auto-planning scripts. For each VMAT-TBI plan, a 2D AP/PA plan was created replicating the institution's clinical setup with the patient positioned at extended source to skin distance (SSD) with a compensator to account for differences in patient thickness, 50% transmission daily lung blocks, and electron chest wall boosts prescribed to 50% of the photon prescription. Clinically relevant metrics were analyzed and compared between the VMAT and 2D plans.All VMAT-TBI plans achieved planned target volume (PTV) D90% ≥ 100% of prescription. VMAT-TBI PTV D90% significantly increased (7.1% ± 2.9%, p < .001) compared to the 2D technique, whereas no differences were observed in global Dmax (p < .2) and PTV V110% (p < .4). Compared to the 2D plans, significant decreases in the Dmean to the lungs (-25.6% ± 11.5%, p < .001) and lungs-1 cm (-34.1% ± 10.1%, p < .001) were observed with the VMAT plans. The VMAT technique also enabled decrease of dose to other organs: kidneys Dmean (-32.5% ± 5.0%, p < .001) and lenses Dmax (-5.3% ± 8.1%, p = .03); and in addition, for 2 Gy prescription: testes/ovaries Dmean (-41.5% ± 11.5%, p < .001), brain Dmean (-22.6% ± 5.4%, p = .002), and thyroid Dmean (-18.2% ± 16.0%, p = .03).Superior lung sparing with improved target coverage and similar global Dmax were observed with the VMAT plans as compared to 2D plans. In addition, VMAT-TBI plans provided greater dose reductions in gonads, kidneys, brain, thyroid, and lenses.

    View details for DOI 10.1002/pbc.30589

    View details for PubMedID 37486149

  • Adaptive Region-Specific Loss for Improved Medical Image Segmentation. IEEE transactions on pattern analysis and machine intelligence Chen, Y., Yu, L., Wang, J., Panjwani, N., Obeid, J., Liu, W., Liu, L., Kovalchuk, N., Gensheimer, M. F., Vitzthum, L. K., Beadle, B. M., Chang, D. T., Le, Q., Han, B., Xing, L. 2023; PP


    Defining the loss function is an important part of neural network design and critically determines the success of deep learning modeling. A significant shortcoming of the conventional loss functions is that they weight all regions in the input image volume equally, despite the fact that the system is known to be heterogeneous (i.e., some regions can achieve high prediction performance more easily than others). Here, we introduce a region-specific loss to lift the implicit assumption of homogeneous weighting for better learning. We divide the entire volume into multiple sub-regions, each with an individualized loss constructed for optimal local performance. Effectively, this scheme imposes higher weightings on the sub-regions that are more difficult to segment, and vice versa. Furthermore, the regional false positive and false negative errors are computed for each input image during a training step and the regional penalty is adjusted accordingly to enhance the overall accuracy of the prediction. Using different public and in-house medical image datasets, we demonstrate that the proposed regionally adaptive loss paradigm outperforms conventional methods in the multi-organ segmentations, without any modification to the neural network architecture or additional data preparation.

    View details for DOI 10.1109/TPAMI.2023.3289667

    View details for PubMedID 37363838

  • Patient-specific Auto-segmentation on Daily kVCT Images for Adaptive Radiotherapy. International journal of radiation oncology, biology, physics Chen, Y., Gensheimer, M. F., Bagshaw, H. P., Butler, S., Yu, L., Zhou, Y., Shen, L., Kovalchuk, N., Surucu, M., Chang, D. T., Xing, L., Han, B. 2023


    This study explored deep learning-based patient-specific auto-segmentation using transfer learning on daily kVCT images to facilitate adaptive radiotherapy, based on data from the first group of patients treated with the innovative RefleXion system.For head and neck (HaN) site and pelvic site, a deep convolutional segmentation network was initially trained on a population dataset, which contained 67 and 56 patient cases respectively. Then the pre-trained population network was adapted to the specific RefleXion patient by fine-tuning the network weights with a transfer learning method. For each of the 6 collected RefleXion HaN cases and 4 pelvic cases, initial planning CT and 5-26 sets of daily RefleXion kVCT were used for the patient-specific learning and evaluation separately. The performance of the patient-specific network was compared with the population network and the clinical rigid registration method and evaluated by the Dice similarity coefficient (DSC) with manual contours being the reference. The corresponding dosimetric impacts resulting from different auto-segmentation and registration methods were also investigated.The proposed patient-specific network achieved mean DSC results of 0.88 for three HaN organs at risk (OARs) of interest and 0.90 for eight pelvic target and OARs, outperforming the population network (0.70 and 0.63) and the registration method (0.72 and 0.72). The DSC of the patient-specific network gradually increased with the increment of longitudinal training cases and approached saturation with more than 6 training cases. Compared with using the registration contour, the target and OAR mean doses and dose-volume histograms obtained using the patient-specific auto-segmentation were closer to the results using the manual contour.Auto-segmentation of RefleXion kVCT images based on the patient-specific transfer learning could achieve higher accuracy, outperforming a common population network and clinical registration-based method. This approach shows promise in improving dose evaluation accuracy in RefleXion adaptive radiotherapy.

    View details for DOI 10.1016/j.ijrobp.2023.04.026

    View details for PubMedID 37141982

  • Stratified assessment of an FDA-cleared deep learning algorithm for automated detection and contouring of metastatic brain tumors in stereotactic radiosurgery. Radiation oncology (London, England) Wang, J. Y., Qu, V., Hui, C., Sandhu, N., Mendoza, M. G., Panjwani, N., Chang, Y. C., Liang, C. H., Lu, J. T., Wang, L., Kovalchuk, N., Gensheimer, M. F., Soltys, S. G., Pollom, E. L. 2023; 18 (1): 61


    Artificial intelligence-based tools can be leveraged to improve detection and segmentation of brain metastases for stereotactic radiosurgery (SRS). VBrain by Vysioneer Inc. is a deep learning algorithm with recent FDA clearance to assist in brain tumor contouring. We aimed to assess the performance of this tool by various demographic and clinical characteristics among patients with brain metastases treated with SRS.We randomly selected 100 patients with brain metastases who underwent initial SRS on the CyberKnife from 2017 to 2020 at a single institution. Cases with resection cavities were excluded from the analysis. Computed tomography (CT) and axial T1-weighted post-contrast magnetic resonance (MR) image data were extracted for each patient and uploaded to VBrain. A brain metastasis was considered "detected" when the VBrain- "predicted" contours overlapped with the corresponding physician contours ("ground-truth" contours). We evaluated performance of VBrain against ground-truth contours using the following metrics: lesion-wise Dice similarity coefficient (DSC), lesion-wise average Hausdorff distance (AVD), false positive count (FP), and lesion-wise sensitivity (%). Kruskal-Wallis tests were performed to assess the relationships between patient characteristics including sex, race, primary histology, age, and size and number of brain metastases, and performance metrics such as DSC, AVD, FP, and sensitivity.We analyzed 100 patients with 435 intact brain metastases treated with SRS. Our cohort consisted of patients with a median number of 2 brain metastases (range: 1 to 52), median age of 69 (range: 19 to 91), and 50% male and 50% female patients. The primary site breakdown was 56% lung, 10% melanoma, 9% breast, 8% gynecological, 5% renal, 4% gastrointestinal, 2% sarcoma, and 6% other, while the race breakdown was 60% White, 18% Asian, 3% Black/African American, 2% Native Hawaiian or other Pacific Islander, and 17% other/unknown/not reported. The median tumor size was 0.112 c.c. (range: 0.010-26.475 c.c.). We found mean lesion-wise DSC to be 0.723, mean lesion-wise AVD to be 7.34% of lesion size (0.704 mm), mean FP count to be 0.72 tumors per case, and lesion-wise sensitivity to be 89.30% for all lesions. Moreover, mean sensitivity was found to be 99.07%, 97.59%, and 96.23% for lesions with diameter equal to and greater than 10 mm, 7.5 mm, and 5 mm, respectively. No other significant differences in performance metrics were observed across demographic or clinical characteristic groups.In this study, a commercial deep learning algorithm showed promising results in segmenting brain metastases, with 96.23% sensitivity for metastases with diameters of 5 mm or higher. As the software is an assistive AI, future work of VBrain integration into the clinical workflow can provide further clinical and research insights.

    View details for DOI 10.1186/s13014-023-02246-z

    View details for PubMedID 37016416

    View details for PubMedCentralID 7174761

  • Mitigation of IMRT/SBRT treatment planning errors on the RefleXion X1 system using FMEA within Six Sigma framework Advances in Radiation Oncology Simiele, E., Han, B., Skinner, L., Pham, D., Lewis, J., Gensheimer, M., Vitzthum, L., Chang, D., Surucu, M., Kovalchuk, N. 2023
  • Personalized Accelerated ChEmoRadiation (PACER) for Lung Cancer: Protocol for a Bayesian Optimal Phase I/II Trial Clin Lung Cancer Hui, C., Brown, E., Das, M., Wakalee, H., Neal, J., Ramchandran, K., Myall, N., Pham, D., Xing, L., Yang, Y., Kovalchuk, N., Yuan, Y., Xiang, M., Chin, A., Diehn, M., Loo, B. W., Vitzthum, L. K. 2023
  • Clinical Implementation of an Automated IMRT/VMAT Treatment Planning Tool Yang, Y., Wang, J., Dong, P., Kovachuk, N., Gensheimer, M., Beadle, B., Bagshaw, H., Buyyounouski, M., Le, Q., Xing, L. 2023
  • Improved Medical Image Auto-Segmentation with Adaptive Region-Specific Loss Scheme ASTRO Chen, Y., Yu, L., Wang, J., Panjwani, N., Obeid, J., Liu, W., Kovalchuk, N., Gensheimer, M., Vitzthum, L., Beadle, B., Le, Q., Han, B., Xing, L. 2023
  • Reinforcement Learning Powered Station Parameter Optimized Radiation Therapy (SPORT): a novel treatment planning and beam delivery technique ASTRO Dai, X., Yang, Y., Liu, W., Niedermayr, T., Kovalchuk, N., Gensheimer, M., Beadle, B., Le, Q., Xing, L. 2023
  • Stratified assessment of a commercial deep learning algorithm for automated detection and contouring of metastatic brain tumors in stereotactic radiosurgery ASTRO Wang, J., Hui, C., Sandhu, N., Mendoza, M., Panjawani, N., Lin, J., Chang, Y., Liang, C., Lu, J., Wang, L., Kovalchuk, N., Gensheimer, M., Soltys, S., Pollom, E. 2023
  • Dosimetric Accuracy of Multi-target Biology-guided Radiotherapy Treatments in a Single Session ASTRO Schmall, J., Bal, G., Xu, S., Voronenko, Y., Shi, L., Mitra, A., Groll, A., Sharma, S., Ramos, K., Shao, L., Narayanan, M., Olcott, P., Kuduvalli, G., Han, B., Kovalchuk, N., Surucu, M. 2023
  • Intrafraction Dosimetric Evaluation of Biology-guided Radiotherapy to a Target Under Respiratory Motion ASTRO Bal, G., Schmall, J., Voronenko, Y., Bailey, T., Xu, S., Shi, L., Groll, A., Sharma, S., Ramos, K., Shao, L., Narayanan, M., Kuduvalli, G., Han, B., Surucu, M. 2023
  • Characterization of Biology-guided Radiotherapy accuracy as a function of PET Tracer Uptake ASTRO Han, B., Schmall, J., Khan, S., Xu, S., Voronenko, Y., Shi, L., Mitra, A., Groll, A., Sharma, S., Ramos, K., Shao, L., Olcott, P., Kuduvalli, G., Kovalchuk, N., Surucu, M. 2023
  • Image-mode performance characterization of a positron emission tomography subsystem designed for Biology-guided radiotherapy (BgRT). The British journal of radiology Hu, Z., Bieniosek, M., Ferri, V., Iagaru, A., Kovalchuk, N., Han, B., Xing, L., Vitzthum, L., Olcott, P., Narayanan, M., Laurence, T., Ren, Y., Oderinde, O. M., Shirvani, S. M., Chang, D., Surucu, M. 2022: 20220387


    OBJECTIVES: In this study, we characterize the imaging-mode performance of the positron emission tomography (PET) subsystem of the RefleXion X1 machine using the NEMA NU-2 2018 standard.METHODS: The X1 machine consists of two symmetrically opposing 900 arcs of PET detectors incorporated into the architecture of a ring-gantry linear accelerator rotating up to 60RPM. PET emissions from a tumor are detected by the PET detectors and used to guide the delivery of radiation beam. Imaging performance of the PET subsystem on X1 machine was evaluated based on1 sensitivity of the PET detectors,2 spatial resolution,3 count-loss performance,4 Image quality, and daily system performance check.RESULTS: PET subsystem sensitivity was measured as 0.183 and 0.161 cps/kBq at the center and off-center positions, respectively. Spatial resolution: average FWHM values of 4.3, 5.1, and 6.7mm for the point sources at 1, 10, and 20cm off center, respectively were recorded. For count loss, max NECR: 2.63 kcps, max true coincidence rate: 5.56 kcps, and scatter fraction: 39.8%. The 10mm sphere was not visible. Image-quality contrast values were: 29.6%, 64.9%, 66.5%, 81.8%, 81.2%, and background variability: 14.8%, 12.4%, 10.3%, 8.8%, 8.3%, for the 13, 17, 22, 28, 37mm sphere sizes, respectively.CONCLUSIONS: When operating in an imaging mode, the spatial resolution and image contrast of the X1 PET subsystem were comparable to those of typical diagnostic imaging systems for large spheres, while the sensitivity and count rate were lower due to the significantly smaller PET detector area in the X1 system. Clinical efficacy when used in BgRT remains to be validated.ADVANCES IN KNOWLEDGE: This is the first performance evaluation of the PET subsystem on the novel BgRT machine. The dual arcs rotating PET subsystem on RefleXion X1 machine performance is comparable to those of the typical diagnostic PET system based on the spatial resolution and image contrast for larger spheres.

    View details for DOI 10.1259/bjr.20220387

    View details for PubMedID 36317922

  • Diagnostic CT Planning for Palliative Inpatient Treatments: A Cost-savings and Clinical Analysis of a Pilot Program to Reduce the Need for CT Simulation Scans Blomain, E., Alnajjar, N., Chin, A., Lewis, J., Kovalchuk, N., Horst, K. LIPPINCOTT WILLIAMS & WILKINS. 2022: S55
  • Radiologists staunchly support patient safety and autonomy, in opposition to the SCOTUS decision to overturn Roe v Wade. Clinical imaging Karandikar, A., Solberg, A., Fung, A., Lee, A. Y., Farooq, A., Taylor, A. C., Oliveira, A., Narayan, A., Senter, A., Majid, A., Tong, A., McGrath, A. L., Malik, A., Brown, A. L., Roberts, A., Fleischer, A., Vettiyil, B., Zigmund, B., Park, B., Curran, B., Henry, C., Jaimes, C., Connolly, C., Robson, C., Meltzer, C. C., Phillips, C. H., Dove, C., Glastonbury, C., Pomeranz, C., Kirsch, C. F., Burgan, C. M., Scher, C., Tomblinson, C., Fuss, C., Santillan, C., Daye, D., Brown, D. B., Young, D. J., Kopans, D., Vargas, D., Martin, D., Thompson, D., Jordan, D. W., Shatzkes, D., Sun, D., Mastrodicasa, D., Smith, E., Korngold, E., Dibble, E. H., Arleo, E. K., Hecht, E. M., Morris, E., Maltin, E. P., Cooke, E. A., Schwartz, E. S., Lehrman, E., Sodagari, F., Shah, F., Doo, F. X., Rigiroli, F., Vilanilam, G. K., Landinez, G., Kim, G. G., Rahbar, H., Choi, H., Bandesha, H., Ojeda-Fournier, H., Ikuta, I., Dragojevic, I., Schroeder, J. L., Ivanidze, J., Katzen, J. T., Chiang, J., Nguyen, J., Robinson, J. D., Broder, J. C., Kemp, J., Weaver, J. S., Conyers, J. M., Robbins, J. B., Leschied, J. R., Wen, J., Park, J., Mongan, J., Perchik, J., Barbero, J. P., Jacob, J., Ledbetter, K., Macura, K. J., Maturen, K. E., Frederick-Dyer, K., Dodelzon, K., Cort, K., Kisling, K., Babagbemi, K., McGill, K. C., Chang, K. J., Feigin, K., Winsor, K. S., Seifert, K., Patel, K., Porter, K. K., Foley, K. M., Patel-Lippmann, K., McIntosh, L. J., Padilla, L., Groner, L., Harry, L. M., Ladd, L. M., Wang, L., Spalluto, L. B., Mahesh, M., Marx, M. V., Sugi, M. D., Sammer, M. B., Sun, M., Barkovich, M. J., Miller, M. J., Vella, M., Davis, M. A., Englander, M. J., Durst, M., Oumano, M., Wood, M. J., McBee, M. P., Fischbein, N. J., Kovalchuk, N., Lall, N., Eclov, N., Madhuripan, N., Ariaratnam, N. S., Vincoff, N. S., Kothary, N., Yahyavi-Firouz-Abadi, N., Brook, O. R., Glenn, O. A., Woodard, P. K., Mazaheri, P., Rhyner, P., Eby, P. R., Raghu, P., Gerson, R. F., Patel, R., Gutierrez, R. L., Gebhard, R., Andreotti, R. F., Masum, R., Woods, R., Mandava, S., Harrington, S. G., Parikh, S., Chu, S., Arora, S. S., Meyers, S. M., Prabhu, S., Shams, S., Pittman, S., Patel, S. N., Payne, S., Hetts, S. W., Hijaz, T. A., Chapman, T., Loehfelm, T. W., Juang, T., Clark, T. J., Potigailo, V., Shah, V., Planz, V., Kalia, V., DeMartini, W., Dillon, W. P., Gupta, Y., Koethe, Y., Hartley-Blossom, Z., Wang, Z. J., McGinty, G., Haramati, A., Allen, L. M., Germaine, P. 2022

    View details for DOI 10.1016/j.clinimag.2022.07.011

    View details for PubMedID 36064645

  • Help Ukraine. Advances in radiation oncology Kovalchuk, N. 2022; 7 (4): 100955

    View details for DOI 10.1016/j.adro.2022.100955

    View details for PubMedID 35865374

  • Beam commissioning of the first clinical biology-guided radiotherapy system. Journal of applied clinical medical physics Han, B., Capaldi, D., Kovalchuk, N., Simiele, E., White, J., Zaks, D., Xing, L., Surucu, M. 2022: e13607


    This study reports the beam commissioning results for the first clinical RefleXion Linac.METHODS: The X1 produces a 6MV photon beam and the maximum clinical field size is 40*2cm2 at source-to-axis distance of 85cm. Treatment fields are collimated by a binary multileaf collimator (MLC) system with 64 leaves with width of 0.625cm and y-jaw pairs to provide either a 1 or 2cm opening. The mechanical alignment of the radiation source, the y-jaw, and MLC were checked with film and ion chambers. The beam parameters were characterized using a diode detector in a compact water tank. In-air lateral profiles and in-water percentage depth dose (PDD) were measured for beam modeling of the treatment planning system (TPS). The lateral profiles, PDDs, and output factors were acquired for field sizes from 1.25*1 to 40*2cm2 field to verify the beam modeling. The rotational output variation and synchronicity were tested to check the gantry angle, couch motion, and gantry rotation.RESULTS: The source misalignments were 0.049mm in y-direction, 0.66% out-of-focus in x-direction. The divergence of the beam axis was 0.36mm with a y-jaw twist of 0.03°. Clinical off-axis treatment fields shared a common center in y-direction were within 0.03mm. The MLC misalignment and twist were 0.57mm and 0.15°. For all measured fields ranging from the size from 1.25*1 to 40*2cm2 , the mean difference between measured and TPS modeled PDD at 10cm depth was -0.3%. The mean transverse profile difference in the field core was -0.3%±1.1%. The full-width half maximum (FWHM) modeling was within 0.5mm. The measured output factors agreed with TPS within 0.8%.CONCLUSIONS: This study summarizes our specific experience commissioning the first novel RefleXion linac, which may assist future users of this technology when implementing it into their own clinics.

    View details for DOI 10.1002/acm2.13607

    View details for PubMedID 35482018

  • The Stanford VMAT TBI Technique. Practical radiation oncology Kovalchuk, N., Simiele, E., Skinner, L., Yang, Y., Howell, N., Lewis, J., Hui, C., Blomain, E. S., Hoppe, R. T., Hiniker, S. M. 2022


    In this work, we describe the technical aspects of the XXX VMAT TBI technique, compare it to other VMAT TBI techniques, and share our initial experience.From September 2019 to August 2021, 35 patients were treated with VMAT TBI at our institution. Treatment planning was performed using in-house developed automated planning scripts. Organ sparing depended on the regimen: myeloablative (lungs, kidneys, and lenses); non-myeloablative with benign disease (lungs, kidneys, lenses, gonads, brain, and thyroid). Quality assurance was performed using EPID portal dosimetry and Mobius3D. Robustness was evaluated for the first ten patients by performing local and global isocenter shifts of 5 mm. Treatment was delivered using IGRT for every isocenter and every fraction. In-vivo measurements were performed on the matchline between the VMAT and AP/PA fields and on the testes for the first fraction.The lungs, lungs-1cm, and kidneys Dmean were consistently spared to 57.6±4.4%, 40.7±5.5%, and 70.0±9.9% of the prescription dose, respectively. Gonadal sparing (Dmean=0.69±0.13 Gy) was performed for all patients with benign disease. The average PTV D1cc was 120.7±6.4% for all patients. The average Gamma passing rate for the VMAT plans was 98.1±1.6% (criteria of 3%/2mm). Minimal differences were observed between Mobius3D- and EclipseAAA-calculated PTV Dmean (0.0±0.3%) and lungs Dmean (-2.5±1.2%). Robustness evaluation showed that the PTV Dmax and lungs Dmean are insensitive to small positioning deviations between the VMAT isocenters (1.1±2.4% and 1.2±1.0%, respectively). The average matchline dose measurement indicated patient setup was reproducible (96.1±4.5% relative to prescription dose). Treatment time, including patient setup and beam-on, was 47.5±9.5 min.The XXX VMAT TBI technique, from simulation to treatment delivery, was presented and compared to other VMAT TBI techniques. Together with publicly shared autoplanning scripts, our technique may provide the gateway for wider adaptation of this technology and the possibility of multi-institutional studies in the cooperative group setting.

    View details for DOI 10.1016/j.prro.2021.12.007

    View details for PubMedID 35182803

  • Evaluation of Treatment Interruptions and Recovery During Biology-guided Radiotherapy Delivery ASTRO Bal, G., Xu, S., Shi, L., Voronenko, Y., Narayanan, M., Shao, L., Kuduvalli, G., Han, B., Kovalchuk, N., Surucu, M. 2022
  • Stratified Assessment of a Commercial Deep Learning Algorithm for Automated Detection and Contouring of Metastatic Brain Tumors in Stereotactic Radiosurgery ASTRO Wang, J., Qu, V., Hui, C., Sandhu, N., Mendoza, M., Panjwani, N., Lin, J., Chang, Y., Liang, C., Lu, J., Wang, L., Kovalchuk, N., Gensheimer, M., Soltys, S., Pollom, E. 2022
  • IMRT and SBRT Treatment Planning Study for the First Clinical Biology-Guided Radiotherapy System ASTRO Pham, D., Breitkreutz, D., Simiele, E., Capaldi, D., Ngo, N., Han, B., Surucu, M., Xing, L., Vitzthum, L., Gensheimer, M., Bagshaw, H., Chang, D., Kovalchuk, N. 2022
  • VMAT TBI Technique Based on Automated Treatment Planning ASTRO Kovalchuk, N., Simiele, E., Skinner, L., Yang, Y., Howell, N., Lewis, J., Blomain, E., Hui, C., Hoppe, R., Hiniker, S. 2022
  • Volumetric Modulated Arc Therapy Total Body Irradiation (VMAT-TBI) in Pediatric and Adolescent/Young Adult Patients Undergoing Stem Cell Transplantation: Early Outcomes and Toxicities. ASTRO Hui, C., Marquez, C., Simiele, E., Blomain, E., Oh, J., Bertaina, A., Klein, O., Shyr, D., Jiang, A., Hoppe, R., Hiniker, S., Kovalchuk, N. 2022
  • Stanford VMAT TBI Technique Kovalchuk, N., Simiele, E., Skinner, L., Yang, Y., Howell, N., Lewis, J., Hui, C., Blomain, E., Hoppe, R., Hiniker, S. 2022
  • Biology-Guided Radiotherapy (BgRT) Treatment Planning Feasibility Study for Head-And-Neck, Abdomen, and Pelvis AAPM Kovalchuk, N. 2022
  • IMRT and SBRT Treatment Planning Study for the First Clinical Installation of Biology-Guided Radiotherapy System AAPM Pham, D. 2022
  • A Treatment Planning Feasability Study for Cranio-Spinal Irradiation (CSI) using RefleXion X1 AAPM Pham, D. 2022
  • Systematic Study of Patient-Specific Organs at Risk Auto-Segmentation on Daily kVCT Images for Adaptive Head and Neck Radiotherapy ASTRO Chen, Y., Gensheimer, M., Bagshaw, H., Butler, S., Yu, L., Zhou, Y., Shen, L., Kovalchuk, N., Surucu, M., Chang, D., Xing, L., Han, B. 2022
  • Help Ukraine Advances in Radiation Oncology Kovalchuk, N. 2022
  • IMRT and SBRT treatment planning study for the first clinical Biology-guided Radiotherapy System Technology in Cancer Research and Treatment Pham, D., Simiele, E., Breitkreutz, D., Capaldi, D., Han, B., Surucu, M., Oderinde, S., Vitzthum, L., Gensheimer, M., Bagshaw, H., Chin, A., Xing, L., Chang, D., Kovalchuk, N. 2022
  • Treatment planning system commissioning of the first clinical biology-guided radiotherapy machine Journal of Applied Clinical Medical Physics Simiele, E., Capaldi, D., Breitkreutz, D., Han, B., Yeung, T., White, J., Zaks, D., Owens, M., Maganti, S., Xing, L., Surucu, M., Kovalchuk, N. 2022
  • CyberKnife® in Abdominal Stereotactic Body Radiosurgery Principles and Practice of Image-Guided Abdominal Radiation Therapy Wang, L., Kovalchuk, N., Pollom, E. Institute of Physics (IOP) Publishing. 2022
  • Small field measurement and monte carlo model validation of a novel image-guided radiotherapy system. Medical physics Shi, M., Chuang, C. F., Kovalchuk, N., Bush, K. K., Zaks, D., Xing, L., Surucu, M., Han, B. 2021


    PURPOSE: The RefleXionTM X1 is a novel radiotherapy system that is designed for image-guided radiotherapy and, eventually, biology-guided radiotherapy (BgRT). BgRT is a treatment paradigm that tracks tumor motion using real-time positron emission signals. This study reports the small field measurement results and the validation of a Monte Carlo (MC) model of the first clinical RefleXion unit.METHODS: The RefleXion linear accelerator (linac) produces a 6 MV flattening filter free (FFF) photon beam and consists of a binary multi-leaf collimator (MLC) system with 64 leaves and two pairs of y-jaws. The maximum clinical field size achievable is 400 * 20 mm2 . The y-jaws provide either a 10 mm or 20 mm opening at source-to-axis distance (SAD) of 850 mm. The width of each MLC leaf at SAD is 6.25 mm. Percentage depth doses (PDDs) and relative beam profiles were acquired using an Edge diode detector in a water tank for field sizes from 12.5 * 10 mm2 to 100 * 20 mm2 . Beam profiles were also measured using films. Output factors of fields ranging from 6.25 * 10 mm2 to 100 * 20 mm2 were measured using W2 scintillator detector, Edge detector, and films. Output correction factors k of the Edge detector for RefleXion were calculated. A MC model of the linac including pre-MLC beam sources and detailed structures of MLC and lower y-jaws was validated against the measurements. Simulation codes BEAMnrc and GATE were utilized.RESULTS: The diode measured PDD at 10 cm depth (PDD10) increases from 53.6% to 56.9% as the field opens from 12.5 * 10 mm2 to 100 * 20 mm2 . The W2-measured output factor increases from 0.706 to 1 as the field opens from 6.25 * 10 mm2 to 100 * 20 mm2 (reference field size). The output factors acquired by diode and film differ from the W2 results by 1.65% (std = 1.49%) and 2.09% (std = 1.41%) on average, respectively. The profile penumbra and full width half maximum (FWHM) measured by diode agree well with the film results with a deviation of 0.60 mm and 0.73% on average, respectively. The averaged beam profile consistency calculated between the diode and film measured profiles among different depths is within 1.72%. By taking the W2 measurements as the ground truth, the output correction factors k for Edge detector ranging from 0.958 to 1 were reported. For the MC model validation, the simulated PDD10 agreed within 0.6% to the diode measurement. The MC simulated output factor differed from the W2 results by 2.3% on average (std = 3.7%) while the MC simulated beam penumbra differed from the diode results by 0.67 mm on average (std = 0.42 mm). The MC FWHM agreed with the diode results to within 1.40% on average. The averaged beam profile consistency calculated between the diode and MC profiles among different depths is less than 1.29%.CONCLUSIONS: This study represents the first small field dosimetry of a clinical RefleXion system. A complete and accurate MC model of the RefleXion linac has been validated. This article is protected by copyright. All rights reserved.

    View details for DOI 10.1002/mp.15273

    View details for PubMedID 34628666

  • IMRT Treatment Planning Study for the First Clinical Biology-guided Radiotherapy System Kovalchuk, N., Pham, D., Breitkreutz, D., Simiele, E., Capaldi, D., Vitzthum, L., Chang, D. LIPPINCOTT WILLIAMS & WILKINS. 2021: S137-S138
  • NRG Oncology HN006: Randomized phase II/III trial of sentinel lymph node biopsy versus elective neck dissection for early-stage oral cavity cancer. Lai, S., Torres-Saavedra, P. A., Dunlap, N. E., Beadle, B., Chang, S. S., Subramaniam, R. M., Yu, J., Lowe, V. J., Khan, S. A., Truong, M., Bell, D., Liu, C. Z., Kovalchuk, N., Rong, Y., Abazeed, M. E., Kappadath, S., Harris, J., Le, Q. LIPPINCOTT WILLIAMS & WILKINS. 2021
  • A Step Toward Making VMAT TBI More Prevalent: Automating the Treatment Planning Process. Practical radiation oncology Simiele, E., Skinner, L., Yang, Y., Blomain, E. S., Hoppe, R. T., Hiniker, S. M., Kovalchuk, N. 2021


    Our purpose was to automate the treatment planning process for total body irradiation (TBI) with volumetric modulated arc therapy (VMAT).Two scripts were developed to facilitate autoplanning: the binary plug-in script automating the creation of optimization structures, plan generation, beam placement, and setting of the optimization constraints and the stand-alone executable performing successive optimizations. Ten patients previously treated in our clinic with VMAT TBI were used to evaluate the efficacy of the proposed autoplanning process. Paired t tests were used to compare the dosimetric indices of the produced auto plans to the manually generated clinical plans. In addition, 3 physicians were asked to evaluate the manual and autoplans for each patient in a blinded retrospective review.No significant differences were observed between the manual and autoplan global Dmax (P < .893), planning target volume V110% (P < .734), kidneys Dmean (P < .351), and bowel Dmax (P < .473). Significant decreases in the Dmean to the lungs and lungs-1cm (ie, lungs with 1-cm inner margin) volumes of 5.4% ± 6.4% (P < .024) and 6.8% ± 7.4% (P < .017), respectively, were obtained with the autoplans compared with the manual plans. The autoplans were selected 77% of the time by the reviewing physicians as equivalent or superior to the manual plans. The required time for treatment planning was estimated to be 2 to 3 days for the manual plans compared with approximately 3 to 5 hours for the autoplans.Large reductions in planning time without sacrificing plan quality were obtained using the developed autoplanning process compared with manual planning, thus reducing the required effort of the treatment planning team. Superior lung sparing with the same target coverage and similar global Dmax were observed with the autoplans as compared with the manual treatment plans. The developed scripts have been made open-source to improve access to VMAT TBI at other institutions and clinics.

    View details for DOI 10.1016/j.prro.2021.02.010

    View details for PubMedID 33711488

  • Practice patterns of pediatric total body irradiation techniques: A Children's Oncology Group survey. International journal of radiation oncology, biology, physics Rassiah, P., Esiashvili, N., Olch, A. J., Hua, C. H., Ulin, K., Molineu, A., Marcus, K., Gopalakrishnan, M., Pillai, S., Kovalchuk, N., Liu, A., Niyazov, G., Peñagarícano, J. A., Cheung, F., Olson, A. C., Wu, C. C., Malhotra, H., MacEwan, I. J., Faught, J., Breneman, J. C., Followill, D. S., FitzGerald, T. J., Kalapurakal, J. A. 2021


    The aim of this study was to examine current practice patterns in pediatric total body irradiation (TBI) techniques among xxx member institutions.Between Nov 2019 and Feb 2020 a questionnaire, containing 52 questions related to the technical aspects of TBI was sent to medical physicists at 152 xxx institutions. The questions were designed to obtain technical information on commonly used TBI treatment techniques. Another set of 9 questions related to the clinical management of patients undergoing TBI was sent to 152 xxx member radiation oncologists at the same institutions.Twelve institutions were excluded because TBI was not performed in their institutions. A total of 88 physicists from 88 institutions (63% response rate) and 96 radiation oncologists from 96 institutions responded (69% response rate). The AP/PA technique was the most common (49 institutions - 56%); 44 institutions (50%) used the lateral technique and 14 institutions (16%) used volumetric modulated arc therapy (VMAT)/Tomotherapy. Mid-plane dose rates of 6-15 cGy/min were most commonly used. The most common specification for lung dose was the mid lung dose for both AP/PA (71%) and lateral (63%) techniques. All physician responders agreed with the need to refine current TBI techniques and 79% supported the investigation of new TBI techniques to further lower the lung dose.There is no consistency in the practice patterns, methods for dose measurement and reporting of TBI doses among xxx institutions. The lack of a standardization precludes meaningful correlation between TBI doses and clinical outcomes including disease control and normal tissue toxicity. The xxx radiation oncology discipline is currently undertaking several steps to standardize the practice and dose reporting of pediatric TBI using detailed questionnaires and phantom-based credentialing for all xxx centers.

    View details for DOI 10.1016/j.ijrobp.2021.07.1715

    View details for PubMedID 34352289

  • Retrospective Tuning of MRI Contrast From a Single T1-Weighted Image ASTRO Wu, Y. 2021
  • SBRT Treatment Planning Study for the First Clinical Biology-Guided Radiotherapy System ASTRO Pham, D. 2021
  • The kVCT System Commissioning of a Novel Medical Linear Accelerator Designed for Biology-Guided Radiotherapy ASTRO Han, B. 2021
  • Improved Organ Sparing with Autoplanned VMAT TBI ASTRO Ngo, N. 2021
  • A motion phantom study on RefleXion X1: the dosimetric impacts of stereotactic radiation therapy delivery technique and motion AAPM Capaldi, D. 2021
  • IMRT Treatment Planning Study for the First Clinical Biology-guided Radiotherapy System AAPM Pham, D. 2021
  • Improving workflow efficiency and safety for RefleXion X1 treatment planning process via Eclipse API scripting AAPM Simiele, E. 2021
  • Preliminary Treatment Planning System Commissioning Results for the First Clinical Biology-guided Radiotherapy Machine AAPM Kovalchuk, N. 2021
  • A Step Towards Making VMAT TBI More Prevalent: Automating the Treatment Planning Process ASTRO Simiele, E. 2021
  • Importance of a Culture Committee for Boosting Morale and Maintaining a Healthy Work Environment in Radiation Oncology. Advances in radiation oncology Gutkin, P. M., Minneci, M. O., Valenton, J. n., Kovalchuk, N. n., Chang, D. T., Horst, K. C. 2020


    During the unprecedented workplace disruption from the corona virus disease 2019 (COVID-19) pandemic, health care workers have been particularly vulnerable to increased work-related stress and anxiety. This may have a negative effect on job performance and personal well-being. Personal safety, job security, and childcare needs are essential concerns that must be addressed by health care organizations to ensure stability of its workforce. In addition, workplace morale is also damaged by the many daily changes brought about by social distancing. Thus, opportunities exist for departments to address the loss of social bonding and cohesiveness needed for successful team building. In this report, we describe the efforts of our departmental workplace culture committee during this pandemic.

    View details for DOI 10.1016/j.adro.2020.07.002

    View details for PubMedID 32838068

    View details for PubMedCentralID PMC7368646

  • Evaluation of a Knowledge-Guided Automated Treatment Planning Tool ASTRO Yang, Y. 2020
  • Improved Lung and Gonadal Sparing During Total Body Irradiation Using a VMAT Technique: Preliminary Single-institutional Experience AAPM Kovalchuk, N. 2020
  • Six Sigma-driven Automated Plan Check (APC) Tool Enhances Safety and Efficiency in External Beam Radiation Therapy ASTRO Kovalchuk, N. 2020
  • A preliminary report of gonadal-sparing TBI using a VMAT technique. Practical radiation oncology Blomain, E. S., Kovalchuk, N. n., Neilsen, E. n., Skinner, L. n., Hoppe, R. T., Hiniker, S. M. 2020


    Reproductive toxicity is common following total body irradiation and has major quality of life implications for patients. In that context, this is the first report of gonadal-sparing VMAT TBI, successfully delivered in a boy and a girl with aplastic anemia. Both patients' VMAT TBI plans demonstrated improved gonadal sparing versus simulated conventional 2D approach (mean testes dose 0.45 Gy VMAT versus 0.72 Gy 2D; mean ovary dose 0.64 Gy VMAT versus 1.47 Gy 2D). PTV coverage was also improved for both cases with the VMAT plan versus conventional 2D plan (2 Gy D90% versus 1.9 Gy D90%, respectively). Given these dosimetric advantages, the present study can serve as a proof-of-concept for further prospective studies evaluating this technique for wider applications in populations receiving TBI.

    View details for DOI 10.1016/j.prro.2020.07.006

    View details for PubMedID 32795616

  • Successful Full-term Pregnancies After High-dose Pelvic Radiotherapy for Ewing Sarcoma: A Case Report. Journal of pediatric hematology/oncology Gutkin, P. M., Chen, E. L., Miller, C. J., Donaldson, S. S., Kovalchuk, N., Callejas, M. J., Hiniker, S. M. 2019


    Survivors of childhood cancer are at risk of long-term sequelae that arise as a consequence of cancer treatment. Radiation and chemotherapy treatment in pediatric female patients can have detrimental impacts on fertility, particularly in those with pelvic tumor involvement. We report 2 successful natural full-term pregnancies with vaginal delivery in a woman 12 years after biopsy, irradiation (55.5Gy), and multi-agent chemotherapy for treatment of pelvic Ewing sarcoma. Both children were born healthy, with no complications in pregnancy or delivery. Fertility preservation and risk assessment following chemotherapy/radiation therapy is evolving, providing new data to effectively counsel and treat young women.

    View details for DOI 10.1097/MPH.0000000000001581

    View details for PubMedID 31415018

  • Incorporating dosimetric features into the prediction of 3D VMAT dose distributions using deep convolutional neural network PHYSICS IN MEDICINE AND BIOLOGY Ma, M., Kovalchuk, N., Buyyounouski, M. K., Xing, L., Yang, Y. 2019; 64 (12)
  • Incorporating dosimetric features into the prediction of 3D VMAT dose distributions using deep convolutional neural network. Physics in medicine and biology Ma, M., Kovalchuk, N., Buyyounouski, M. K., Xing, L., Yang, Y. 2019


    An accurate prediction of achievable dose distribution on a patient specific basis would greatly improve IMRT/VMAT planning in both efficiency and quality. Recently machine learning techniques have been proposed for IMRT dose prediction based on patient's contour information from planning CT. In these existing prediction models geometric/anatomic features were learned for building the dose prediction models and few features that characterize the dosimetric properties of the patients were utilized. In this study we propose a method to incorporate the dosimetric features in the construction of a more reliable dose prediction model based on the deep convolutional neural network (CNN). In addition to the contour information, the dose distribution from a PTV-only plan (i.e., the plan with the best PTV coverage by sacrificing the OARs sparing) is also employed as the model input to build a deep learning based dose prediction model. A database of 60 volumetric modulated arc therapy (VMAT) plans for the prostate cancer patients was used for training. The trained prediction model was then tested on a cohort of 10 cases. Dose difference maps, DVHs, dosimetric endpoints and statistical analysis of the sum of absolute residuals (SARs) were used to evaluate the proposed method. Our results showed that the mean SARs for the PTV, bladder and rectum using our method were 0.007±0.003, 0.035±0.032 and 0.067±0.037 respectively, lower than the SARs obtained with the contours-based method, indicating the potential of the proposed approach in accurately predicting dose distribution.

    View details for PubMedID 31082805

  • Attention-aware fully convolutional neural network with convolutional long short-term memory network for ultrasound-based motion tracking MEDICAL PHYSICS Huang, P., Yu, G., Lu, H., Liu, D., Xing, L., Yin, Y., Kovalchuk, N., Xing, L., Li, D. 2019; 46 (5): 2275–85

    View details for DOI 10.1002/mp.13510

    View details for Web of Science ID 000467556800032

  • Attention-aware Fully Convolutional Neural Network with Convolutional Long Short-Term Memory Network for Ultrasound-Based Motion Tracking. Medical physics Huang, P., Yu, G., Lu, H., Liu, D., Xing, L., Yin, Y., Kovalchuk, N., Xing, L., Li, D. 2019


    PURPOSE: One of the promising options for motion management in radiation therapy (RT) is the use of Linac-compatible robotic-arm-mounted ultrasound imaging system due to its high soft tissue contrast, real-time capability, absence of ionizing radiation and low cost. The purpose of this work is to develop a novel deep learning-based real-time motion tracking strategy for ultrasound image-guided RT.METHODS: The proposed tracker combined the attention-aware Fully Convolutional Neural Network (FCNN) and the Convolutional Long Short-Term Memory network (CLSTM) that is end-to-end trainable. The glimpse sensor module was built inside the attention-aware FCNN to discard majority of background by focusing on a region containing the object of interest. FCNN extracted discriminating spatial features of glimpse to facilitate temporal modeling for CLSTM. The saliency mask computed from CLSTM refined the features particular to the tracked landmarks. Moreover, the multi-task loss strategy including bounding box loss, localization loss, saliency loss, and adaptive loss weighting term was utilized to facilitate training convergence and avoid over/under-fitting. The tracker was tested on the databases provided by MICCAI 2015 challenges, and the ground truth data was obtained with the help of brute force-based template matching technology.RESULTS: The mean tracking error of 0.97 ± 0.52 mm and maximum tracking error of 1.94 mm were observed for 85 point-landmarks across 39 ultrasound cases compared to the ground truth annotations. The tracking speed per frame per landmark with the GPU implementation ranged from 66 and 101 frames per second, which largely exceeded the ultrasound imaging rate.CONCLUSION: The results demonstrated the robustness and accuracy of the proposed deep learning-based motion estimation, despite of the existence of some known shortcomings of ultrasound imaging such as speckle noise. The tracking speed of the system was found to be remarkable, sufficiently fast for real-time applications in RT environment. The approach provides a valuable tool to guide RT treatment with beam gating or multi leaf collimator (MLC) tracking in real time. This article is protected by copyright. All rights reserved.

    View details for PubMedID 30912590

  • Dosimetric features-driven machine learning model for DVH prediction in VMAT treatment planning MEDICAL PHYSICS Ma, M., Kovalchuk, N., Buyyounouski, M. K., Xing, L., Yang, Y. 2019; 46 (2): 857–67

    View details for DOI 10.1002/mp.13334

    View details for Web of Science ID 000459616200041

  • Optimizing efficiency and safety in external beam radiotherapy using automated plan check (APC) tool and six sigma methodology. Journal of applied clinical medical physics Liu, S. n., Bush, K. K., Bertini, J. n., Fu, Y. n., Lewis, J. M., Pham, D. J., Yang, Y. n., Niedermayr, T. R., Skinner, L. n., Xing, L. n., Beadle, B. M., Hsu, A. n., Kovalchuk, N. n. 2019; 20 (8): 56–64


    To develop and implement an automated plan check (APC) tool using a Six Sigma methodology with the aim of improving safety and efficiency in external beam radiotherapy.The Six Sigma define-measure-analyze-improve-control (DMAIC) framework was used by measuring defects stemming from treatment planning that were reported to the departmental incidence learning system (ILS). The common error pathways observed in the reported data were combined with our departmental physics plan check list, and AAPM TG-275 identified items. Prioritized by risk priority number (RPN) and severity values, the check items were added to the APC tool developed using Varian Eclipse Scripting Application Programming Interface (ESAPI). At 9 months post-APC implementation, the tool encompassed 89 check items, and its effectiveness was evaluated by comparing RPN values and rates of reported errors. To test the efficiency gains, physics plan check time and reported error rate were prospectively compared for 20 treatment plans.The APC tool was successfully implemented for external beam plan checking. FMEA RPN ranking re-evaluation at 9 months post-APC demonstrated a statistically significant average decrease in RPN values from 129.2 to 83.7 (P < .05). After the introduction of APC, the average frequency of reported treatment-planning errors was reduced from 16.1% to 4.1%. For high-severity errors, the reduction was 82.7% for prescription/plan mismatches and 84.4% for incorrect shift note. The process shifted from 4σ to 5σ quality for isocenter-shift errors. The efficiency study showed a statistically significant decrease in plan check time (10.1 ± 7.3 min, P = .005) and decrease in errors propagating to physics plan check (80%).Incorporation of APC tool has significantly reduced the error rate. The DMAIC framework can provide an iterative and robust workflow to improve the efficiency and quality of treatment planning procedure enabling a safer radiotherapy process.

    View details for DOI 10.1002/acm2.12678

    View details for PubMedID 31423729

  • Dosimetric Features-Driven Machine Learning Model for DVHs Prediction in VMAT Treatment Planning. Medical physics Ma, M., Kovalchuk, N., Buyyounouski, M. K., Xing, L., Yang, Y. 2018


    PURPOSE: Few features characterizing the dosimetric properties of the patients are included in currently available dose-volume histogram (DVH) prediction models, making it intractable to build a correlative relationship between the input and output parameters. Here we use PTV-only treatment plans of the patients (i.e., the achievable dose distribution in the absence of organs-at-risks (OARs) constraints) to estimate the potentially achievable quality of treatment plans and establish a machine learning-based DVH prediction framework with the use of the dosimetric metric as model input parameters.METHODS: A support vector regression (SVR) approach was used as the backbone of our machine learning model. A database containing volumetric modulated arc therapy (VMAT) plans of 63 prostate cancer patients were used. For each patient, the PTV-only plan was generated first. A correlative relationship between the OAR DVH of the PTV-only plan (model input) and the corresponding DVH of the clinical treatment plan (CTP) (model output) was then established with the 53 training cases. The prediction model was tested by the validation cohort of 10 cases.RESULTS: For the training cohort, the checks of dosimetric endpoints (DEs) indicated that 52 out of 53 plans (98%) were within 10% error bound for bladder, and 45 out of 53 plans (85%) were within 10% error bound for rectum. In the validation tests, 92% and 96% of the DEs were within the 10% error bounds for bladder and rectum respectively, and 8 out of 10 validation plans (80%) were within 10% error bound for both bladder and rectum. The sum of absolute residuals (SAR) achieved mean 0.034 ± 0.028 and 0.046 ± 0.021 for the bladder and rectum, respectively.CONCLUSIONS: A novel dosimetric features-driven machine learning model with the use of PTV-only plan has been established for DVH prediction. The framework is capable of efficiently generating best achievable DVHs for VMAT planning. This article is protected by copyright. All rights reserved.

    View details for PubMedID 30536442

  • Liver Stereotactic Radiosurgery and Stereotactic Body Radiation Therapy Qian, Y., Weiner , J., Moding, E., Kovalchuk, N., Koong, A., Hong, T., Chang, D. Demos Medical. 2018
  • Deep learning-driven target volume delineation for prostate cancer radiation therapy AAPM Wu, Y. 2018
  • Machine Learning Applications in Medical Dosimetry Recent Advancements and Applications in Dosimetry Kovalchuk, N., Xing, L. Nova Publishers. 2018
  • Dosimetry and Physics Quality Assurance Gastrointestinal Malignancies: A Practical Guide on Treatment Techniques Kovalchuk, N., Niedermayr, T., Russo, S., Chang, D. Springer. 2018
  • Stereotactic body radiotherapy for pediatric hepatocellular carcinoma with central biliary obstruction PEDIATRIC BLOOD & CANCER Hiniker, S. M., Rangaswami, A., Lungren, M. P., Thakor, A. S., Concepcion, W., Balazy, K. E., Kovalchuk, N., Donaldson, S. S. 2017; 64 (6)


    Here, we present the case of a pediatric patient with newly diagnosed hepatocellular carcinoma causing central biliary obstruction and persistently elevated bilirubin of 3.0-4.3 mg/dl despite placement of bilateral internal-external biliary drains. The tumor was not resectable, and the patient was not a candidate for liver transplant due to nodal disease, for chemotherapy due to hyperbilirubinemia, or for local therapies aside from stereotactic body radiotherapy (SBRT). In this report, we discuss the successful use of SBRT in the management of this patient, and its role in allowing the patient to become a candidate for additional therapies.

    View details for DOI 10.1002/pbc.26330

    View details for PubMedID 28436210

  • Stereotactic body radiotherapy for pediatric hepatocellular carcinoma with central biliary obstruction PEDIATRIC BLOOD & CANCER Hiniker, S. M., Rangaswami, A., Lungren, M. P., Thakor, A. S., Concepcion, W., Balazy, K. E., Kovalchuk, N., Donaldson, S. S. 2017; 64 (6)

    View details for DOI 10.1002/pbc.26330

    View details for Web of Science ID 000400616500005

  • Postmastectomy Radiotherapy with and without Reconstruction Radiation Therapy Techniques and Treatment Planning for Breast Cancer. Horst, K., Kovalchuk, N., Marquez, C. Springer. 2016
  • Optimizing efficiency and safety in a radiation oncology department through the use of ARIA 11 Visual Care Path PRACTICAL RADIATION ONCOLOGY Kovalchuk, N., Russo, G. A., Shin, J. Y., Kachnic, L. A. 2015; 5 (5): 295–303


    Visual Care Path (VCP) is a workflow tool within the ARIA 11 Record and Verify System. The purpose of this study was to quantify the impact of VCP implementation on the metrics of efficiency, safety, and staff satisfaction.Our multidisciplinary quality improvement team reviewed the entire process of patient care and constructed VCP modules to chart serial and parallel events from consultation to treatment completion. A failure mode and effects analysis was performed to identify high-risk tasks within existing patient care workflow. Data on timeliness of task completion were collected for 612 patients (6560 tasks) in 3 time phases: pre-VCP, transition, and post-VCP. Errors detected during a physics plan check were also monitored. A survey about the VCP was distributed to all staff to evaluate the impact of the VCP on the department. Descriptive statistics were calculated for the metrics of efficiency, safety, and staff satisfaction.Notable improvements in efficiency and safety were observed. Radiation oncologists' compliance with timely completion of the Simulation Preparation VCP tasks increased from 45.9% ± 14.3% during the pre-VCP phase to 85.8% ± 10.9% during the post-VCP phase. Compliance with Treatment Planning VCP tasks also increased from 52.6% ± 9.9% during the pre-VCP phase to 76.0% ± 9.7% during the post-VCP phase. The monthly defect rate (ratio of plans with errors to the total number of plans checked by a physicist) decreased from 19.1% ± 1.3% during the pre-VCP phase to 5.2% ± 4.1% during the post-VCP phase. Ninety-four percent of staff members responded to the VCP survey; more than 80% of respondents found the VCP to have a favorable impact.Implementation of the VCP in our department improved workflow efficiency, reduced the number of errors, and was very well received within the department.

    View details for DOI 10.1016/j.prro.2015.05.001

    View details for Web of Science ID 000422360300012

    View details for PubMedID 26127009

  • Clinical and treatment factors associated with vaginal stenosis after definitive chemoradiation for anal canal cancer PRACTICAL RADIATION ONCOLOGY Mirabeau-Beale, K., Hong, T. S., Niemierko, A., Ancukiewicz, M., Blaszkowsky, L. S., Crowley, E. M., Cusack, J. C., Drapek, L. C., Kovalchuk, N., Markowski, M., Napolitano, B., Nyamwanda, J., Ryan, D. P., Wolfgang, J., Kachnic, L. A., Wo, J. Y. 2015; 5 (3): E113–E118


    We sought to evaluate the incidence of vaginal stenosis (VS) and identify clinical and treatment factors that predict for VS in female patients with anal cancer treated with definitive chemoradiation.The cohort included 95 consecutive women receiving definitive chemoradiation between 2003 and 2012. All but 1 received intensity modulated radiation therapy; median primary tumor dose 50.4 Gy (range, 41.4-60). A modified National Cancer Institute Common Terminology Criteria for Adverse Events version 4 was used to score VS based on the medical record description of dyspareunia, pain with dilator use, vaginal dryness, or difficult pelvic examination. Ordered logistic regression was performed to assess VS predictors.Median age was 60.4 years (range, 19-97). With median follow-up of 2.5 years, 70 women (74%) had adequate information to assess VS. Of these, VS grade distribution was 21.4% grade 0, 14.3% grade 1, 27.1% grade 2, and 37.1% grade 3. By multivariable ordered logistic regression, younger age (P = .02), higher tumor dose (P = .06), and earlier treatment year (P = .04) were associated with higher grade of VS.VS is a common late complication in women treated definitively with chemoradiation for anal canal cancer. Younger age, higher tumor dose, and earlier year of treatment were associated with a higher grade of stenosis. Prospective investigation into patient reported outcomes is warranted, including sexual function and VS prevention strategies to better understand its effect on long-term survivorship.

    View details for DOI 10.1016/j.prro.2014.09.003

    View details for Web of Science ID 000422354000002

    View details for PubMedID 25424587

  • Radiotherapy Planning PET CLINICS Minh Tam Truong, Kovalchuk, N. 2015; 10 (2): 279–96


    Incorporation of PET/computed tomography (CT) in radiotherapy planning plays a critical role in assisting gross tumor volume delineation for radiotherapy planning and delivery. As radiotherapy techniques evolve to become more conformal with the increasing use of intensity-modulated radiotherapy and stereotactic body radiotherapy, whereby sharp dose gradients exist between the target and adjacent normal tissue, accurate contouring of tumor targets is vital for the success of radiotherapy to achieve cure and locoregional control. This article outlines the integration of PET/CT into radiotherapy planning for head and neck, lung, and other solid tumors.

    View details for DOI 10.1016/j.cpet.2014.12.010

    View details for Web of Science ID 000422075500011

    View details for PubMedID 25829092

  • Volumetric tumor burden and its effect on brachial plexus dosimetry in head and neck intensity-modulated radiotherapy MEDICAL DOSIMETRY Romesser, P. B., Qureshi, M. M., Kovalchuk, N., Minh Tam Truong 2014; 39 (2): 169–73


    To determine the effect of gross tumor volume of the primary (GTV-P) and nodal (GTV-N) disease on planned radiation dose to the brachial plexus (BP) in head and neck intensity-modulated radiotherapy (IMRT). Overall, 75 patients underwent definitive IMRT to a median total dose of 69.96Gy in 33 fractions. The right BP and left BP were prospectively contoured as separate organs at risk. The GTV was related to BP dose using the unpaired t-test. Receiver operating characteristics curves were constructed to determine optimized volumetric thresholds of GTV-P and GTV-N corresponding to a maximum BP dose cutoff of > 66Gy. Multivariate analyses were performed to account for factors associated with a higher maximal BP dose. A higher maximum BP dose (> 66 vs ≤ 66Gy) correlated with a greater mean GTV-P (79.5 vs 30.8cc; p = 0.001) and ipsilateral GTV-N (60.6 vs 19.8cc; p = 0.014). When dichotomized by the optimized nodal volume, patients with an ipsilateral GTV-N ≥ 4.9 vs < 4.9cc had a significant difference in maximum BP dose (64.2 vs 59.4Gy; p = 0.001). Multivariate analysis confirmed that an ipsilateral GTV-N ≥ 4.9cc was an independent predictor for the BP to receive a maximal dose of > 66Gy when adjusted individually for BP volume, GTV-P, the use of a low anterior neck field technique, total planned radiation dose, and tumor category. Although both the primary and the nodal tumor volumes affected the BP maximal dose, the ipsilateral nodal tumor volume (GTV-N ≥ 4.9cc) was an independent predictor for high maximal BP dose constraints in head and neck IMRT.

    View details for DOI 10.1016/j.meddos.2013.12.004

    View details for Web of Science ID 000336465900009

    View details for PubMedID 24480376

    View details for PubMedCentralID PMC5018050

  • Correlating planned radiation dose to the cochlea with primary site and tumor stage in patients with head and neck cancer treated with intensity-modulated radiation therapy MEDICAL DOSIMETRY Zhang, J., Qureshi, M. M., Kovalchuk, N., Truong, M. 2014; 39 (1): 88–92


    The aim of the study was to determine tumor characteristics that predict higher planned radiation (RT) dose to the cochlea in patients with head and neck cancer (HNC) treated with intensity-modulated radiotherapy (IMRT). From 2004 to 2012, 99 patients with HNC underwent definitive IMRT to a median dose of 69.96Gy in 33 fractions, with the right and left cochlea-vestibular apparatus contoured for IMRT optimization as avoidance structures. If disease involvement was adjacent to the cochlea, preference was given to tumor coverage by prescription dose. Descriptive statistics were calculated for dose-volume histogram planning data, and mean planning dose to the cochlea (from left or right cochlea, receiving the greater amount of RT dose) was correlated to primary site and tumor stage. Mean (standard deviation) cochlear volume was 1.0 (0.60)cm(3) with maximum and mean planned doses of 31.9 (17.5)Gy and 22.1 (13.7)Gy, respectively. Mean planned dose (Gy) to cochlea by tumor site was as follows: oral cavity (18.6, 14.4), oropharynx (21.7, 9.1), nasopharynx (36.3, 10.4), hypopharynx (14.9, 7.1), larynx (2.1, 0.62), others including the parotid gland, temporal bone, and paranasal sinus (33.6, 24.0), and unknown primary (25.6, 6.7). Average mean planned dose (Gy) to the cochlea in T0-T2 and T3-T4 disease was 22.0 and 29.2Gy, respectively (p = 0.019). By site, a significant difference was noted for nasopharynx and others (31.6 and 50.7, p = 0.012) but not for oropharynx, oral cavity, and hypopharynx. Advanced T category predicted for higher mean cochlear dose, particularly for nasopharyngeal, parotid gland, temporal bone, and paranasal sinus HNC sites.

    View details for DOI 10.1016/j.meddos.2013.10.004

    View details for Web of Science ID 000330927800017

    View details for PubMedID 24485054

  • A quantitative assessment of volumetric and anatomic changes of the parotid gland during intensity-modulated radiotherapy for head and neck cancer using serial computed tomography MEDICAL DOSIMETRY Ajani, A. A., Qureshi, M. M., Kovalchuk, N., Orlina, L., Sakai, O., Minh Tam Truong 2013; 38 (3): 238–42


    To evaluate the change in volume and movement of the parotid gland measured by serial contrast-enhanced computed tomography scans in patients with head and neck cancer treated with parotid-sparing intensity-modulated radiotherapy (IMRT). A prospective study was performed on 13 patients with head and neck cancer undergoing dose-painted IMRT to 69.96Gy in 33 fractions. Serial computed tomography scans were performed at baseline, weeks 2, 4, and 6 of radiotherapy (RT), and at 6 weeks post-RT. The parotid volume was contoured at each scan, and the movement of the medial and lateral borders was measured. The patient's body weight was recorded at each corresponding week during RT. Regression analyses were performed to ascertain the rate of change during treatment as a percent change per fraction in parotid volume and distance relative to baseline. The mean parotid volume decreased by 37.3% from baseline to week 6 of RT. The overall rate of change in parotid volume during RT was-1.30% per fraction (-1.67% and-0.91% per fraction in≥31Gy and<31Gy mean planned parotid dose groups, respectively, p = 0.0004). The movement of parotid borders was greater in the≥31Gy mean parotid dose group compared with the<31Gy group (0.22% per fraction and 0.14% per fraction for the lateral border and 0.19% per fraction and 0.06% per fraction for the medial border, respectively). The median change in body weight was-7.4% (range, 0.75% to-17.5%) during RT. A positive correlation was noted between change in body weight and parotid volume during the course of RT (Spearman correlation coefficient, r = 0.66, p<0.01). Head and neck IMRT results in a volume loss of the parotid gland, which is related to the planned parotid dose, and the patient's weight loss during RT.

    View details for DOI 10.1016/j.meddos.2013.01.007

    View details for Web of Science ID 000323025000003

    View details for PubMedID 23558146

  • Cone-beam computed tomography image guided therapy to evaluate lumpectomy cavity variation before and during breast radiotherapy JOURNAL OF APPLIED CLINICAL MEDICAL PHYSICS Minh Tam Truong, Hirsch, A. E., Kovalchuk, N., Qureshi, M. M., Damato, A., Schuller, B., Vassilakis, N., Stone, M., Gierga, D., Willins, J., Kachnic, L. A. 2013; 14 (2): 209–19
  • Correlation between Long-Term Outcome and Volumetric Changes in Primary and Nodal Tumors during Intensity Modulated Radiotherapy for Head and Neck Cancer ASTRO Kovalchuk, N. 2013
  • Radiosurgery and Radiotherapy for Benign and Malignant Anterior Skull Base Lesions Rhinology and Endoscopic Skull Base Surgery Romesser, P., Kovalchuk, N., Nawaz, A., Truong, M. Springer. 2013
  • Rectal and Anal Cancer Decision Tools for Radiation Oncology Chin, J., Kovalchuk, N., Kachnic, L. Springer. 2013
  • PET/CT of Cancer Patients: Part 2, Deformable Registration Imaging Before and After Chemotherapy for Radiation Treatment Planning in Head and Neck Cancer AMERICAN JOURNAL OF ROENTGENOLOGY Schoenfeld, J. D., Kovalchuk, N., Subramaniam, R. M., Minh Tam Truong 2012; 199 (5): 968–74


    The purpose of this perspective is to discuss the use of deformable registration as a tool for image fusion to integrate information from PET/CT scans obtained before and after chemotherapy to assist definition of radiation targets in the management of head and neck cancer.The consistent method for target delineation described capitalizes on the capability of deformable registration to compensate for changes in position and accurately represent evolving spatial relationships between normal anatomy and areas at risk of disease.

    View details for DOI 10.2214/AJR.12.8562

    View details for Web of Science ID 000310593000027

    View details for PubMedID 23096167

  • Deformable Registration of Preoperative PET/CT with Postoperative Radiation Therapy Planning CT in Head and Neck Cancer RADIOGRAPHICS Kovalchuk, N., Jalisi, S., Subramaniam, R. M., Truong, M. T. 2012; 32 (5): 1329–41


    In intensity-modulated radiation therapy (IMRT), precise target delineation is important to avoid underdosing areas at risk for recurrence and overdosing adjacent normal tissue. In postoperative radiation therapy of patients with head and neck cancer (HNC), surgical extirpation of tumor, anatomic changes resulting from tissue removal, and surgical reconstruction often obscure anatomic detail and may make it difficult to identify high-risk target volumes at postoperative planning computed tomography (CT). Positron emission tomography (PET)/CT can significantly affect CT-based tumor contours by providing information on both biologic and metabolic features of cancer. To incorporate diagnostic PET/CT into target delineation at postoperative CT, an advanced image registration method is required to overcome significant differences in patient position and anatomy between the imaging studies. Rigid registration can account for only linear or uniform transformation between the imaging datasets within six degrees of freedom (three rotations and three translations). However, deformable registration can account for significant temporal and anatomic changes between the corresponding images by computing nonlinear and nonuniform relationships between the volume elements across the imaging datasets. Use of deformable registration to integrate preoperative PET/CT with postoperative treatment planning CT is a powerful tool for target volume delineation in HNC patients undergoing postoperative IMRT.

    View details for DOI 10.1148/rg.325125008

    View details for Web of Science ID 000308632900011

    View details for PubMedID 22977021

  • Radiation dose to the brachial plexus in head-and-neck intensity-modulated radiation therapy and its relationship to tumor and nodal stage. International journal of radiation oncology, biology, physics Truong, M. T., Romesser, P. B., Qureshi, M. M., Kovalchuk, N. n., Orlina, L. n., Willins, J. n. 2012; 84 (1): 158–64


    The purpose of this retrospective study was to determine tumor factors contributing to brachial plexus (BP) dose in head-and-neck cancer (HNC) patients treated with intensity-modulated radiotherapy (IMRT) when the BP is routinely contoured as an organ at risk (OAR) for IMRT optimization.From 2004 to 2011, a total of 114 HNC patients underwent IMRT to a total dose of 69.96 Gy in 33 fractions, with the right and left BP prospectively contoured as separate OARs in 111 patients and the ipsilateral BP contoured in 3 patients (total, 225 BP). Staging category T4 and N2/3 disease were present in 34 (29.8%) and 74 (64.9%) patients, respectively. During IMRT optimization, the intent was to keep the maximum BP dose to ≤60 Gy, but prioritizing tumor coverage over achieving the BP constraints. BP dose parameters were compared with tumor and nodal stage.With a median follow-up of 16.2 months, 43 (37.7%) patients had ≥24 months of follow-up with no brachial plexopathy reported. Mean BP volume was 8.2 ± 4.5 cm(3). Mean BP maximum dose was 58.1 ± 12.2 Gy, and BP mean dose was 42.2 ± 11.3 Gy. The BP maximum dose was ≤60, ≤66, and ≤70 Gy in 122 (54.2%), 185 (82.2%), and 203 (90.2%) BP, respectively. For oropharynx, hypopharynx, and larynx sites, the mean BP maximum dose was 58.4 Gy and 63.4 Gy in T0-3 and T4 disease, respectively (p = 0.002). Mean BP maximum dose with N0/1 and N2/3 disease was 52.8 Gy and 60.9 Gy, respectively (p < 0.0001).In head-and-neck IMRT, dose constraints for the BP are difficult to achieve to ≤60 to 66 Gy with T4 disease of the larynx, hypopharynx, and oropharynx or N2/3 disease. The risk of brachial plexopathy is likely very small in HNC patients undergoing IMRT, although longer follow-up is required.

    View details for DOI 10.1016/j.ijrobp.2011.10.079

    View details for PubMedID 22300574

    View details for PubMedCentralID PMC5014352

  • Correlating Planned Radiation Dose to Cochlea with Tumor Stage in Head and Neck Patients Treated with Intensity Modulated Radiotherapy ASTRO Zhang, J. 2012
  • Iris Melanoma Brachytherapy Treatment Using Modified COMS Plaque Kovalchuk, N. 2009
  • High Dose-Rate (HDR) Brachytherapy as Monotherapy for Localized Prostate Cancer: Correlation of Early Adverse Events (AEs) and Dose RSNA Call, J. 2009
  • Dosimetric Effect of Interfractional Catheter Displacement in Prostate High-Dose-Rate Brachytherapy Kovalchuk, N., Furutani, K., MacDonald, O., Pisansky, T. 2009
  • Statistical Learning Theory Paradigms Adapted to Breast Cancer Diagnosis / Classification Using Image and Non-Image Clinical Data. Int J Funct Inform Personal Med Land, W., Heine, J., Mizaku, A., Raway, T., Kovalchuk, N., Yang, J. 2008
  • Advancements in Automated Diagnostic Mammography. Land, W. 2007
  • Advancements in Automated Diagnostic Mammography Using K-PLS Nonlinear Mappings. Land, W. 2007
  • Three-dimensional Representation of Breast Cancer Using X-ray Imaging Emerging Technologies in Breast Imaging and Mammography Kallergi, M., Manohar, A., Kovalchuk, N. American Scientific Publishers. 2006
  • Magnetic Resonance Electrical Impedance Mammography: A Pilot Study Kallergi, M. 2006
  • Magnetic Resonance Electrical Impedance Mammography: A Feasibility Study Kovalchuk, N. 2006
  • Magnetic Resonance Electrical Impedance Mammography: A Pilot Study Kallergi, M. 2006