Theoretical Benefits of Dynamic Collimation in Pencil Beam Scanning Proton Therapy for Brain Tumors: Dosimetric and Radiobiological Metrics

Moignier, A.; Gelover, Edgar; Wang, Dongxu; Smith, Blake; Flynn, R; Kirk, Maura; Lin, Liyong; Solberg, Timothy D.; Lin, Alexander; Hyer, Daniel E.

doi:10.1016/j.ijrobp.2015.08.030

Cited by 42 publications

(67 citation statements)

References 32 publications

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“…However, PBS can result in larger lateral dose fall‐off due to the width of the incoming beam . This may be reduced with the use of smaller spot sizes and patient‐specific apertures or collimation at the nozzle . Dosimetric studies have demonstrated improved sparing of OARs using PBS‐PT as compared to DS‐PT using these modifications …”

Section: Discussionmentioning

confidence: 99%

Proton therapy for pediatric head and neck malignancies

Vogel

Both

Kirk

et al. 2017

Pediatric Blood & Cancer

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Section: Discussionmentioning

confidence: 99%

Proton therapy for pediatric head and neck malignancies

Vogel

Both

Kirk

et al. 2017

Pediatric Blood & Cancer

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“…Plan‐specific film response correction factors were determined for a set of three brain treatments previously studied in the works of Smith and Moignier . A single radiological depth near the center of the PTV was chosen as the candidate depth in which a representative lateral dose profile of the treatment plan could be benchmarked.…”

Section: Methodsmentioning

confidence: 99%

“…Plan-specific film response correction factors were determined for a set of three brain treatments previously studied in the works of Smith 29 and Moignier. [30][31][32] A single radiological depth near the center of the PTV was chosen as the candidate depth in which a representative lateral dose profile of the treatment plan could be benchmarked. About this depth, a series of SOBP profiles, which were characteristic of the energy ranges experienced by the film dosimeter at the plane of measurement, were created and optimized using the Raystation treatment planning system (Raysearch Labs, Sweden) and exported as a PLD file.…”

Section: B2 Spread-out Bragg Peak Irradiationsmentioning

confidence: 99%

LET response variability of Gafchromic EBT3 film from a Co calibration in clinical proton beam qualities

et al. 2019

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Purpose To establish a method of accurate dosimetry required to quantify the expected linear energy transfer (LET) quenching effect of EBT3 film used to benchmark the dose distribution for a given treatment field and specified measurement depth. In order to facilitate this technique, a full analysis of film calibration which considers LET variability at the plane of measurement and as a function of proton beam quality is demonstrated. Additionally, the corresponding uncertainty from the process was quantified for several measurement scenarios. Materials and methods The net change in optical density (OD) from a single version of GafchromicTM EBT3 film was measured using an Epson flatbed scanner and NIST‐traceable OD filters. Film OD response was characterized with respect to the known dose to water at the point of measurement for both a NIST‐traceable 60Co beam at the UWADCL and several clinical single‐energy and spread‐out Bragg peak (SOBP) proton beam qualities at the Northwestern Medicine Chicago Proton Center. Increasing proton LET environments were acquired by placing film at increasing depths of Gammex HE Solid Water® whose water‐equivalent thickness was characterized prior to measurement. Results A strong LET dependence was observed near the Bragg peak (BP) consistent with previous studies performed with earlier versions of EBT3 film. The influence of range straggling on the film's LET response appears to have a uniform effect toward the BP regardless of the nominal beam energy. Proximal to this depth, the film's response decreased with decreasing energy at the same dose‐average LET. The opposite trend was observed for depths past the BP. Changes in the SOBP energy modulation showed a linear relationship between the film's relative response and dose‐averaged LET. Relative effectiveness factors (RE) were observed to range between 2%–7% depending on the width of the SOBP and depth of the film. Using the field‐specific calibration technique, a total k = 1 uncertainty in the absorbed dose to water was estimated to range from 4.68%–5.21%. Conclusion While EBT3 film's strong LET dependence is a common problem in proton beam dosimetry, this work has shown that the LET dependence can be taken into account by carefully considering the depth and energy modulation across the film using field‐specific corrections. RE factors were determined with a combined k = 1 uncertainty of 3.57% for SOBP environments and between 3.17%–4.69% for uniform, monoenergetic fields proximal to the distal 80% of the BP.

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“…The potential clinical delivery improvement by spot trimming was reported in a retrospective study of five intracranial cases . A representative result is presented in Fig.…”

Section: New Horizons: Beam Delivery Systemsmentioning

confidence: 82%

“…Comparison of dose distribution between Untrimmed and Trimmed plans using an in‐house treatment planning system capable of including the beam trimmer ( RDX ) …”

Section: New Horizons: Beam Delivery Systemsmentioning

confidence: 99%

New horizons in particle therapy systems

Farr¹,

Flanz

Gerbershagen

et al. 2018

Medical Physics

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Particle therapy is rapidly expanding and claiming its position as the treatment modality of choice in teletherapy. However, the rate of expansion continues to be restricted by the size and cost of the associated particle therapy systems and their operation. Additional technical limitations such as dose delivery rate, treatment process efficiency, and achievement of superior dose conformity potentially hinder the complete fulfillment of the promise of particle therapy. These topics are explored in this review considering the current state of particle therapy systems and what improvements are required to overcome the current challenges. Beam production systems (accelerators), beam transport systems including gantries and beam delivery systems are addressed explicitly in these regards.

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Theoretical Benefits of Dynamic Collimation in Pencil Beam Scanning Proton Therapy for Brain Tumors: Dosimetric and Radiobiological Metrics

Cited by 42 publications

References 32 publications

Proton therapy for pediatric head and neck malignancies

Proton therapy for pediatric head and neck malignancies

LET response variability of Gafchromic EBT3 film from a Co calibration in clinical proton beam qualities

New horizons in particle therapy systems

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