FLASH radiotherapy with carbon ion beams

Weber, Uli; Scifoni, E.; Durante, Marco

doi:10.1002/mp.15135

Cited by 58 publications

(64 citation statements)

References 119 publications

(275 reference statements)

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“…A number of CPT facilities have been able to modify their accelerators (mostly isochronous cyclotrons and synchrocyclotrons) for FLASH with proton beams (171), and photon beams have been studied at large scale synchrotron research facilities (172). FLASH with different ions such as carbon and helium is also being examined (173)(174)(175).…”

Section: Flashmentioning

confidence: 99%

Future Developments in Charged Particle Therapy: Improving Beam Delivery for Efficiency and Efficacy

2021

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The physical and clinical benefits of charged particle therapy (CPT) are well recognized. However, the availability of CPT and complete exploitation of dosimetric advantages are still limited by high facility costs and technological challenges. There are extensive ongoing efforts to improve upon these, which will lead to greater accessibility, superior delivery, and therefore better treatment outcomes. Yet, the issue of cost remains a primary hurdle as utility of CPT is largely driven by the affordability, complexity and performance of current technology. Modern delivery techniques are necessary but limited by extended treatment times. Several of these aspects can be addressed by developments in the beam delivery system (BDS) which determines the overall shaping and timing capabilities enabling high quality treatments. The energy layer switching time (ELST) is a limiting constraint of the BDS and a determinant of the beam delivery time (BDT), along with the accelerator and other factors. This review evaluates the delivery process in detail, presenting the limitations and developments for the BDS and related accelerator technology, toward decreasing the BDT. As extended BDT impacts motion and has dosimetric implications for treatment, we discuss avenues to minimize the ELST and overview the clinical benefits and feasibility of a large energy acceptance BDS. These developments support the possibility of advanced modalities and faster delivery for a greater range of treatment indications which could also further reduce costs. Further work to realize methodologies such as volumetric rescanning, FLASH, arc, multi-ion and online image guided therapies are discussed. In this review we examine how increased treatment efficiency and efficacy could be achieved with improvements in beam delivery and how this could lead to faster and higher quality treatments for the future of CPT.

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Section: Flashmentioning

confidence: 99%

Future Developments in Charged Particle Therapy: Improving Beam Delivery for Efficiency and Efficacy

2021

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“…By incorporating biological models, the application of the current method could be extended to heavier particles, such as carbon ions ( 15 ).…”

Section: Discussionmentioning

confidence: 99%

Conformal Dose Modulator for Proton Beam Therapy Part 1: A Simulation Study

et al. 2022

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PurposeConformal dose deliveries in proton therapy utilize either a passive scattering system with a modulator or a pencil beam scanning (PBS) system. Efforts have been made to achieve conformal dose delivery by scanning a single energy layer of pencil beams through a 3D conformal modulator (3DCM), which combines a spread-out Bragg peak (SOBP) modulator consisting of a micro-pyramid array and a range compensator. The current published approach of designing such 3DCM relies on forward calculation methods to determine the geometry of the modulator. This study presents an alternative designing algorithm that inversely generates the geometry of a 3DCM paired with a corresponding fluence map, customized to patient-specific clinical indications.MethodsCritical spacing governing the size and separation between neighboring micro-pyramids was first determined, under which the dose homogeneity at desired depths could be achieved. We designed an adaptive ring optimization method using a modified gradient descent algorithm to inversely calculate the geometry of the 3DCM. This method includes several stages that progressively optimize both target coverage and dose conformity. The output contains the geometry of the 3DCM and its corresponding proton fluence map. Monte Carlo (MC) simulation was used to validate the results.ResultsThe critical size and spacing of Lucite pyramids was determined to be 0.5 cm for a 184-MeV pristine proton beam. Using MATLAB (R2020a), the inverse designing algorithm generated an optimized 3DCM geometry and a fluence distribution achieving 100% target coverage with the 90% isodose surface and a corresponding conformity index of 1.057 on a spherical target. The resulting geometry was pruned to accommodate the MC simulation software and a currently accessible 3D printing service. The pruned geometry gave 95% target coverage by 90% isodose surface with a conformity index of 1.09 by ray-tracing dose computation. The MC simulation validated the 3DCM with 95% target coverage by 87% isodose surface and a conformity index of 1.12.ConclusionWe have demonstrated the feasibility of using a novel inverse optimization algorithm to generate 3DCM geometry and its corresponding proton beam fluence/intensity map, which could deliver highly conformal dose distribution with pencil beam scanning system using a single energy layer.

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“…In addition, proton linear accelerators (linacs) are being developed that are expected to deliver very high dose rates 29–31 . The specific issues related with Flash and carbon ions are discussed in a dedicated paper in this issue (reference to the paper by Weber et al) 32 . For the purpose of this paper, we defined a set of properties for two proton therapy systems, one based on an isochronous cyclotron and one based on a linac, both coupled with a PBS delivery system (Table 1).…”

Section: Beam Production and Deliverymentioning

confidence: 99%

Treatment planning for Flash radiotherapy: General aspects and applications to proton beams

et al. 2022

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The increased radioresistence of healthy tissues when irradiated at very high dose rates (known as the Flash effect) is a radiobiological mechanism that is currently investigated to increase the therapeutic ratio of radiotherapy treatments. To maximize the benefits of the clinical application of Flash, a patient‐specific balance between different properties of the dose distribution should be found, that is, Flash needs to be one of the variables considered in treatment planning. We investigated the Flash potential of three proton therapy planning and beam delivery techniques, each on a different anatomical region. Based on a set of beam delivery parameters, on hypotheses on the dose and dose rate thresholds needed for the Flash effect to occur, and on two definitions of Flash dose rate, we generated exemplary illustrations of the capabilities of current proton therapy equipment to generate Flash dose distributions. All techniques investigated could both produce dose distributions comparable with a conventional proton plan and reach the Flash regime, to an extent that was strongly dependent on the dose per fraction and the Flash dose threshold. The beam current, Flash dose rate threshold, and dose rate definition typically had a more moderate effect on the amount of Flash dose in normal tissue. A systematic estimation of the impact of Flash on different patient anatomies and treatment protocols is possible only if Flash‐specific treatment planning features become readily available. Planning evaluation tools such as a voxel‐based dose delivery time structure, and the inclusion in the optimization cost function of parameters directly associated with Flash (e.g., beam current, spot delivery sequence, and scanning speed), are needed to generate treatment plans that are taking full advantage of the potential benefits of the Flash effect.

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FLASH radiotherapy with carbon ion beams

Abstract: This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as

Cited by 58 publications

References 119 publications

Future Developments in Charged Particle Therapy: Improving Beam Delivery for Efficiency and Efficacy

Future Developments in Charged Particle Therapy: Improving Beam Delivery for Efficiency and Efficacy

Conformal Dose Modulator for Proton Beam Therapy Part 1: A Simulation Study

Treatment planning for Flash radiotherapy: General aspects and applications to proton beams

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