Pitfalls of tungsten multileaf collimator in proton beam therapy

Moskvin, V.; Cheng, Chee Wai; Das, Indra J.

doi:10.1118/1.3658655

Cited by 19 publications

(18 citation statements)

References 83 publications

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“…Radiation levels from radionuclides in the treatment nozzle must be assessed during commissioning and checked annually by monitoring radiation levels at appropriate locations near the treatment nozzle . Although the location of measurement should be an institutional adopted policy to protect the staff, we point out that the maximum distance of measurement should not exceed 30 cm from the surface MLC based on the NCRP 151 report .…”

Section: Annual Quality Assurance Proceduresmentioning

confidence: 99%

AAPM task group 224: Comprehensive proton therapy machine quality assurance

et al. 2019

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Purpose: Task Group (TG) 224 was established by the American Association of Physicists in Medicine's Science Council under the Radiation Therapy Committee and Work Group on Particle Beams. The group was charged with developing comprehensive quality assurance (QA) guidelines and recommendations for the three commonly employed proton therapy techniques for beam delivery: scattering, uniform scanning, and pencil beam scanning. This report supplements established QA guidelines for therapy machine performance for other widely used modalities, such as photons and electrons (TG 142, TG 40, TG 24, TG 22, TG 179, and Medical Physics Practice Guideline 2a) and shares their aims of ensuring the safe, accurate, and consistent delivery of radiation therapy dose distributions to patients. Methods: To provide a basis from which machine‐specific QA procedures can be developed, the report first describes the different delivery techniques and highlights the salient components of the related machine hardware. Depending on the particular machine hardware, certain procedures may be more or less important, and each institution should investigate its own situation. Results: In lieu of such investigations, this report identifies common beam parameters that are typically checked, along with the typical frequencies of those checks (daily, weekly, monthly, or annually). The rationale for choosing these checks and their frequencies is briefly described. Short descriptions of suggested tools and procedures for completing some of the periodic QA checks are also presented. Conclusion: Recommended tolerance limits for each of the recommended QA checks are tabulated, and are based on the literature and on consensus data from the clinical proton experience of the task group members. We hope that this and other reports will serve as a reference for clinical physicists wishing either to establish a proton therapy QA program or to evaluate an existing one.

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Section: Annual Quality Assurance Proceduresmentioning

confidence: 99%

AAPM task group 224: Comprehensive proton therapy machine quality assurance

et al. 2019

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“…The implementation of a multi-leaf collimator (MLC) will reduce this cost, improve the workflow and eliminate the waiting time for hardware fabrication. However, an MLC made from tungsten (27), conventionally used in megavoltage photon therapy, may not be an optimal option for proton therapy (28). Also additional caution with beam penumbra with such devices should be evaluated (29).…”

Section: Discussionmentioning

confidence: 99%

Proton Therapy Facility Planning From a Clinical and Operational Model

Das

Moskvin

Zhao

et al. 2014

Technol Cancer Res Treat

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This paper provides a model for planning a new proton therapy center based on clinical data, referral pattern, beam utilization and technical considerations. The patient-specific data for the depth of targets from skin in each beam angle were reviewed at our center providing megavoltage photon external beam and proton beam therapy respectively.Further, data on insurance providers, disease sites, treatment depths, snout size and the beam angle utilization from the patients treated at our proton facility were collected and analyzed for their utilization and their impact on the facility cost. The most common disease sites treated at our center are head and neck, brain, sarcoma and pediatric malignancies. From this analysis, it is shown that the tumor depth from skin surface has a bimodal distribution (peak at 12 and 26 cm) that has significant impact on the maximum

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“…Ironically, the spot size (in air) increases with decreasing proton energy, and the use of collimators in the beam line may be needed to sharpen the beam boundaries, which some vendors are planning to achieve with MLCs. However, the use of conventional MLCs for proton therapy is not pragmatic in most cases and has not been successful so far [60, 61]. This is, presumably, due to their large bulk and slow speed to adapt dynamically to changes in aperture to achieve three-dimensional conformation.…”

Section: Treatment Delivery Related Challenges and Potential Solutmentioning

confidence: 99%

“…For both MLC and DCS systems, consideration needs to be given to the radioactivity induced in the device components by the secondary neutrons [61] and to the trade-off between improved PT dose conformality and the increased neutron and activation dose to the patient and the healthcare providers.…”

Section: Treatment Delivery Related Challenges and Potential Solutmentioning

confidence: 99%

Empowering Intensity Modulated Proton Therapy Through Physics and Technology: An Overview

Mohan

Das

Ling

2017

International Journal of Radiation Oncology*Biology*Physics

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Considering the clinical potential of protons attributable to their physical characteristics, interest in proton therapy has increased greatly in this century as has the number of proton therapy installations. Until recently, passively scattered proton therapy (PSPT) was used almost entirely. Notably, overall clinical results to date have not shown convincing benefit protons over photons. A rapid transition is now occurring with the implementation of the most advanced form of proton therapy, the intensity-modulated proton therapy (IMPT). IMPT is superior to PSPT and IMRT dosimetrically. However, numerous limitations exist in the present IMPT methods. In particular, compared to IMRT, IMPT is highly vulnerable to various uncertainties. In this overview we identify three major areas of current limitations of IMPT: treatment planning, treatment delivery, and motion management, and discuss current and future efforts for improvement. For treatment planning, we need to reduce uncertainties in proton range and in computed dose distributions, improve robust planning and optimization, enhance adaptive treatment planning and delivery, and consider how to exploit the variability in the relative biological effectiveness (RBE) of protons for clinical benefit. The quality of proton therapy also depends on the characteristics of the IMPT delivery systems and image-guidance. Efforts are needed to optimize the beamlet spot size for both improved dose conformality and faster delivery. For the latter, faster energy switching time and increased dose-rate are also needed. Real-time in-room volumetric imaging for guiding IMPT is in its early stages with CBCT and CT-on-rails, and continued improvements are anticipated. In addition, imaging of the proton beams themselves using, for instance, prompt gamma emissions, is being developed to determine the proton range and to reduce range uncertainty. With the realization of the advances described above, we posit that IMPT, thus empowered, will lead to substantially improved clinical results.

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Pitfalls of tungsten multileaf collimator in proton beam therapy

Cited by 19 publications

References 83 publications

AAPM task group 224: Comprehensive proton therapy machine quality assurance

AAPM task group 224: Comprehensive proton therapy machine quality assurance

Proton Therapy Facility Planning From a Clinical and Operational Model

Empowering Intensity Modulated Proton Therapy Through Physics and Technology: An Overview

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