Honors & Awards

  • 25th Christoph-Schmelzer-Award for outstanding PhD theses related to tumor therapy with ion beams, GSI Helmholtz Centre for Heavy Ion Research (Nov 2023)
  • Best PhD award in Medical Physics 2023, German Society of Medical Physics (DGMP) (Sep 2023)
  • Best PhD award in Applied Physics 2023, Swiss Physical Society (Sep 2023)
  • Varian Recognition Award 2022 for best research paper in medical physics, Swiss Society of Radiation Biology and Medical Physics (SSRMP) (Oct 2022)
  • PTCOG 2022 Travel Fellowship, PTCOG (June 2022)
  • European Student Grant for IPAC 2022, European Physical Society (June 2022)
  • Best Poster Award, 4D treatment workshop on particle therapy, Delft, The Netherlands (Nov 2021)
  • European Student Grant for IPAC 2021, European Physical Society (June 2021)
  • Nuclear Innovation Scholarship, IMT foundation (July 2017)
  • IMT Challenge 2017 Airbus Award (for Best Start-up Idea), École Nationale Supérieure des Mines, France (June 2017)
  • Travel Grant to participate in ICTP/IAEA Nuclear Energy Management School, International Atomic Energy Agency (IAEA) (Oct 2016)
  • J. N. Tata Scholar (Scholarship for master studies), J. N. Tata Foundation (Sep 2016)
  • Excellence Scholarship, IMT Atlantique, Nantes, France (Sep 2016)
  • Nuclear Olympiad 2015, Third Rank, IAEA, Vienna, Austria, World Nuclear Association (Sep 2015)
  • Robert J. Sorenson Scholarship 2014 (Best Student Member of the Year 2014), Institute of Nuclear Materials Management, Atlanta, USA (July 2014)
  • Partnership for Nuclear Security Scholarship for an exchange program with Texas A&M University, USA, US Department of State (May 2014)
  • Travel Grant to participate in IAEA-ICTP School on Nuclear Security, International Atomic Energy Agency (IAEA) funding (April 2024)
  • Partnership for Nuclear Security Scholarship to participate in School on Radiation Technology, US Department of State (March 2014)
  • Travel Scholarship to participate in American Nuclear Society Winter Meeting, US Department of State (Nov 2013)
  • Travel Scholarship for PATRAM 2013 annual meeting, US Department of State (Sep 2013)
  • Young Scientist Scholarship, Science and Engineering Research Board (SERB), Government of India. (April 2013)
  • Graduate Aptitude Test in Engineering Scholarship, Government of India (July 2012)

Professional Education

  • Doctor of Science, ETH Zurich, Physics (2023)


  • Vivek Maradia. " Patent EP21173019 Compact beam transport system for multi-room particle therapy facility", May 12, 2022
  • Vivek Maradia. " Patent EP21163081 A particle beam transport system for the delivery of particle beam therapy", Mar 18, 2022
  • Vivek Maradia. " Patent EP21185726 Optimized matching of beam emittance and collimation system to maximize transmission through beamline", Jul 15, 2021

Current Research and Scholarly Interests

My current focus lies in the simulation and experimental implementation of ultra-high dose rate delivery utilizing proton, x-ray, and electron beams for FLASH preclinical studies, with potential applications in clinical research.

Within this domain, I am deeply engaged in exploring the dynamic interplay between various parameters such as beam energy, dose rate, and biological response. Through a combination of computational modeling and hands-on experimentation, I endeavor to unravel the underlying mechanisms governing the efficacy and safety of ultra-high dose rate delivery systems.

By delving into the intricacies of FLASH preclinical studies, my efforts are directed towards unlocking transformative insights that could revolutionize the landscape of cancer therapy. These endeavors pave the way for the development of innovative treatment modalities with the potential to redefine standards of care and enhance patient outcomes in the realm of oncology.

Additionally, drawing upon the valuable insights garnered from the beamline upgrade at PSI's PROScan facility, I am spearheading the design of a compact cyclotron-based proton therapy infrastructure. This innovative design is envisioned to be versatile enough to accommodate conventional radiation therapy bunkers or multi-room facilities akin to tennis courts.

All Publications

  • Demonstration of momentum cooling to enhance the potential of cancer treatment with proton therapy NATURE PHYSICS Maradia, V., Meer, D., Doelling, R., Weber, D. C., Lomax, A. J., Psoroulas, S. 2023
  • Momentum cooling can improve transmission rates for proton therapy NATURE PHYSICS Maradia, V., Psoroulas, S. 2023
  • A novel method of emittance matching to increase beam transmission for cyclotron-based proton therapy facilities: simulation study Journal of Physics: Conference Series Maradia, V., Meer, D., Lomax, A. J., Schippers, J. M., Psoroulas, S. 2023
  • A novel intensity compensation method to achieve energy independent beam intensity at the patient location for cyclotron based proton therapy facilities Journal of Physics: Conference Series Maradia, V., Meer, D., Lomax, A. J., Psoroulas, S. 2023; 2420 (1)
  • Universal and dynamic ridge filter for pencil beam scanning particle therapy: a novel concept for ultra-fast treatment delivery. Physics in medicine and biology Maradia, V., Colizzi, I., Meer, D., Weber, D. C., Lomax, A. J., Actis, O., Psoroulas, S. 2022; 67 (22)


    Objective.In pencil beam scanning particle therapy, a short treatment delivery time is paramount for the efficient treatment of moving targets with motion mitigation techniques (such as breath-hold, rescanning, and gating). Energy and spot position change time are limiting factors in reducing treatment time. In this study, we designed a universal and dynamic energy modulator (ridge filter, RF) to broaden the Bragg peak, to reduce the number of energies and spots required to cover the target volume, thus lowering the treatment time.Approach. Our RF unit comprises two identical RFs placed just before the isocenter. Both RFs move relative to each other, changing the Bragg peak's characteristics dynamically. We simulated different Bragg peak shapes with the RF in Monte Carlo simulation code (TOPAS) and validated them experimentally. We then delivered single-field plans with 1 Gy/fraction to different geometrical targets in water, to measure the dose delivery time using the RF and compare it with the clinical settings.Main results.Aligning the RFs in different positions produces different broadening in the Bragg peak; we achieved a maximum broadening of 2.5 cm. With RF we reduced the number of energies in a field by more than 60%, and the dose delivery time by 50%, for all geometrical targets investigated, without compromising the dose distribution transverse and distal fall-off.Significance. Our novel universal and dynamic RF allows for the adaptation of the Bragg peak broadening for a spot and/or energy layer based on the requirement of dose shaping in the target volume. It significantly reduces the number of energy layers and spots to cover the target volume, and thus the treatment time. This RF design is ideal for ultra-fast treatment delivery within a single breath-hold (5-10 s), efficient delivery of motion mitigation techniques, and small animal irradiation with ultra-high dose rates (FLASH).

    View details for DOI 10.1088/1361-6560/ac9d1f

    View details for PubMedID 36279860

  • Ultra-fast pencil beam scanning proton therapy for locally advanced non-small-cell lung cancers: Field delivery within a single breath-hold. Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology Maradia, V., van de Water, S., Meer, D., Weber, D. C., Lomax, A. J., Psoroulas, S. 2022; 174: 23-29


    The use of motion mitigation techniques such as breath-hold can reduce the dosimetric uncertainty of lung cancer proton therapy. We studied the feasibility of pencil beam scanning (PBS) proton therapy field delivery within a single breath-hold at PSI's Gantry 2.In PBS proton therapy, the delivery time for a field is determined by the beam-on time and the dead time between proton spots (the time required to change the energy and/or lateral position). We studied ways to reduce beam-on and lateral scanning time, without sacrificing dosimetric plan quality, aiming at a single field delivery time of 15 seconds at maximum. We tested this approach on 10 lung cases with varying target volumes. To reduce the beam-on time, we increased the beam current at the isocenter by developing new beam optics for PSI's PROSCAN beamline and Gantry 2. To reduce the dead time between the spots, we used spot-reduced plan optimization.We found that it is possible to achieve conventional fractionated (2 Gy(RBE)/fraction) and hypofractionated (6 Gy(RBE)/fraction) field delivery times within a single breath-hold (<15 sec) for a variety non-small-cell lung cancer cases.In summary, the combination of spot reduction and improved beam line transmission is a promising approach for the treatment of mobile tumours within clinically achievable breath-hold durations.

    View details for DOI 10.1016/j.radonc.2022.06.018

    View details for PubMedID 35788354

  • Application of a scattering foil to increase beam transmission for cyclotron based proton therapy facilities FRONTIERS IN PHYSICS Maradia, V., Meer, D., Weber, D., Lomax, A., Schippers, J., Psoroulas, S. 2022; 10
  • Increase of the transmission and emittance acceptance through a cyclotron-based proton therapy gantry. Medical physics Maradia, V., Giovannelli, A. C., Meer, D., Weber, D. C., Lomax, A. J., Schippers, J. M., Psoroulas, S. 2022; 49 (4): 2183-2192


    In proton therapy, the gantry, as the final part of the beamline, has a major effect on beam intensity and beam size at the isocenter. Most of the conventional beam optics of cyclotron-based proton gantries have been designed with an imaging factor between 1 and 2 from the coupling point (CP) at the gantry entrance to the isocenter (patient location) meaning that to achieve a clinically desirable (small) beam size at isocenter, a small beam size is also required at the CP. Here we will show that such imaging factors are limiting the emittance which can be transported through the gantry. We, therefore, propose the use of large beam size and low divergence beam at the CP along with an imaging factor of 0.5 (2:1) in a new design of gantry beam optics to achieve substantial improvements in transmission and thus increase beam intensity at the isocenter.The beam optics of our gantry have been re-designed to transport higher emittance without the need of any mechanical modifications to the gantry beamline. The beam optics has been designed using TRANSPORT, with the resulting transmissions being calculated using Monte Carlo simulations (BDSIM code). Finally, the new beam optics have been tested with measurements performed on our Gantry 2 at PSI.With the new beam optics, we could maximize transmission through the gantry for a fixed emittance value. Additionally, we could transport almost four times higher emittance through the gantry compared to conventional optics, whilst achieving good transmissions through the gantry (>50%) with no increased losses in the gantry. As such, the overall transmission (cyclotron to isocenter) can be increased by almost a factor of 6 for low energies. Additionally, the point-to-point imaging inherent to the optics allows adjustment of the beam size at the isocenter by simply changing the beam size at the CP.We have developed a new gantry beam optics which, by selecting a large beam size and low divergence at the gantry entrance and using an imaging factor of 0.5 (2:1), increases the emittance acceptance of the gantry, leading to a substantial increase in beam intensity at low energies. We expect that this approach could easily be adapted for most types of existing gantries.

    View details for DOI 10.1002/mp.15505

    View details for PubMedID 35099067

    View details for PubMedCentralID PMC9303721

  • Beam properties within the momentum acceptance of a clinical gantry beamline for proton therapy. Medical physics Giovannelli, A. C., Maradia, V., Meer, D., Safai, S., Psoroulas, S., Togno, M., Bula, C., Weber, D. C., Lomax, A. J., Fattori, G. 2022; 49 (3): 1417-1431


    Energy changes in pencil beam scanning proton therapy can be a limiting factor in delivery time, hence, limiting patient throughput and the effectiveness of motion mitigation techniques requiring fast irradiation. In this study, we investigate the feasibility of performing fast and continuous energy modulation within the momentum acceptance of a clinical beamline for proton therapy.The alternative use of a local beam degrader at the gantry coupling point has been compared with a more common upstream regulation. Focusing on clinically relevant parameters, a complete beam properties characterization has been carried out. In particular, the acquired empirical data allowed to model and parametrize the errors in range and beam current to deliver clinical treatment plans.For both options, the local and upstream degrader, depth-dose curves measured in water for off-momentum beams were only marginally distorted (γ(1%, 1 mm) > 90%) and the errors in the spot position were within the clinical tolerance, even though increasing at the boundaries of the investigated scan range. The impact on the beam size was limited for the upstream degrader, while dedicated strategies could be required to tackle the beam broadening through the local degrader. Range correction models were investigated for the upstream regulation. The impaired beam transport required a dedicated strategy for fine range control and compensation of beam intensity losses. Our current parameterization based on empirical data allowed energy modulation within acceptance with range errors (median 0.05 mm) and transmission (median -14%) compatible with clinical operation and remarkably low average 27 ms dead time for small energy changes. The technique, tested for the delivery of a skull glioma treatment, resulted in high gamma pass rates at 1%, 1 mm compared to conventional deliveries in experimental measurements with about 45% reduction of the energy switching time when regulation could be performed within acceptance.Fast energy modulation within beamline acceptance has potential for clinical applications and, when realized with an upstream degrader, does not require modification in the beamline hardware, therefore, being potentially applicable in any running facility. Centers with slow energy switching time can particularly profit from such a technique for reducing dead time during treatment delivery.

    View details for DOI 10.1002/mp.15449

    View details for PubMedID 35041207

    View details for PubMedCentralID PMC10234452

  • Different Methods to Increase the Transmission in Cyclotron-Based Proton Therapy Facilities CYCLOTRONS 2022 Maradia, V., Meer, D., Lomax, A. J., Schippers, M., Psoroulas, S. 2022
  • Upgrade of a Clinical Facility to Achieve a High Transmission and Gantry Angle-Independent Flash Tune Proc. 23rd Int. Conf. Cyclotrons Appl. (CYCLOTRONS'22) Colizzi, I., Maradia, V., Kuenzi, R., Gabard, A., Baumgarten, C., Lomax, A. J., Meer, D., Psoroulas, S. 2022
  • A new emittance selection system to maximize beam transmission for low-energy beams in cyclotron-based proton therapy facilities with gantry. Medical physics Maradia, V., Meer, D., Weber, D. C., Lomax, A. J., Schippers, J. M., Psoroulas, S. 2021; 48 (12): 7613-7622


    In proton therapy, the potential of using high-dose rates in the cancer treatment is being explored. High-dose rates could improve efficiency and throughput in standard clinical practice, allow efficient utilization of motion mitigation techniques for moving targets, and potentially enhance normal tissue sparing due to the so-called FLASH effect. However, high-dose rates are difficult to reach when lower energy beams are applied in cyclotron-based proton therapy facilities, because they result in large beam sizes and divergences downstream of the degrader, incurring large losses from the cyclotron to the patient position (isocenter). In current facilities, the emittance after the degrader is reduced using circular collimators; however, this does not provide an optimal matching to the acceptance of the following beamline, causing a low transmission for these energies. We, therefore, propose to use a collimation system, asymmetric in both beam size and divergence, resulting in symmetric emittance in both beam transverse planes as required for a gantry system. This new emittance selection, together with a new optics design for the following beamline and gantry, allows a better matching to the beamline acceptance and an improvement of the transmission.We implemented a custom method to design the collimator sizes and shape required to select high emittance, to be transported by the following beamline using new beam optics (designed with TRANSPORT) to maximize acceptance matching. For predicting the transmission in the new configuration (new collimators + optics), we used Monte Carlo simulations implemented in BDSIM, implementing a model of PSI Gantry 2 which we benchmarked against measurements taken in the current clinical scenario (circular collimators + clinical optics).From the BDSIM simulations, we found that the new collimator system and matching beam optics results in an overall transmission from the cyclotron to the isocenter for a 70 MeV beam of 0.72%. This is an improvement of almost a factor of 6 over the current clinical performance (0.13% transmission). The new optics satisfies clinical beam requirements at the isocenter.We developed a new emittance collimation system for PSI's PROSCAN beamline which, by carefully selecting beam size and divergence asymmetrically, increases the beam transmission for low-energy beams in current state-of-the-art cyclotron-based proton therapy gantries. With these improvements, we could predict almost 1% transmission for low-energy beams at PSI's Gantry 2. Such a system could easily be implemented in facilities interested in increasing dose rates for efficient motion mitigation and FLASH experiments alike.

    View details for DOI 10.1002/mp.15278

    View details for PubMedID 34655083

    View details for PubMedCentralID PMC9298197

  • A Novel Beam Optics Concept to Maximize the Transmission Through Cyclotron-based Proton Therapy Gantries IPAC 2021 Maradia, V., Meer, D., Lomax, A., Schippers, M., Psoroulas, S. 2021