The role of a microDiamond detector in the dosimetry of proton pencil beams

Gomà, Carles; Marinelli, M.; Safai, Sairos; Verona-Rinati, G.; Würfel, Jan

doi:10.1016/j.zemedi.2015.08.003

Cited by 22 publications

(24 citation statements)

References 16 publications

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“…Diamond detectors can be produced in small sizes (compared to standard dosimeters, such as cylindrical or plane-parallel ionization chambers), so they can be easily placed in different experimental setups and anatomical structures of irradiated phantoms, as well as be deployed for in vivo dosimetery [48]. Diamond detectors have already been used in dosimetry of proton pencil beams [49]. They have also been employed in FLASH experiments, and no significant dose-rate dependency has been found for dose rates up to 40 Gy/s [9].…”

Section: Active Detectorsmentioning

confidence: 99%

FLASH Irradiation with Proton Beams: Beam Characteristics and Their Implications for Beam Diagnostics

Nesteruk

Psoroulas

2021

Applied Sciences

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FLASH irradiations use dose-rates orders of magnitude higher than commonly used in patient treatments. Such irradiations have shown interesting normal tissue sparing in cell and animal experiments, and, as such, their potential application to clinical practice is being investigated. Clinical accelerators used in proton therapy facilities can potentially provide FLASH beams; therefore, the topic is of high interest in this field. However, a clear FLASH effect has so far been observed in presence of high dose rates (>40 Gy/s), high delivered dose (tens of Gy), and very short irradiation times (<300 ms). Fulfilling these requirements poses a serious challenge to the beam diagnostics system of clinical facilities. We will review the status and proposed solutions, from the point of view of the beam definitions for FLASH and their implications for beam diagnostics. We will devote particular attention to the topics of beam monitoring and control, as well as absolute dose measurements, since finding viable solutions in these two aspects will be of utmost importance to guarantee that the technique can be adopted quickly and safely in clinical practice.

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Section: Active Detectorsmentioning

confidence: 99%

FLASH Irradiation with Proton Beams: Beam Characteristics and Their Implications for Beam Diagnostics

Nesteruk

Psoroulas

2021

Applied Sciences

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“…The observed decrease in R Q =R Q 0 at the effective photon energy of 13.9 keV (25 kV beam spectrum) could be due to detector under-response when the linear energy transfer (LET) of secondary electrons increases. An under-response of a microDiamond was reported in high-LET carbon and oxygen beams, 7 but in proton beams the reported results were inconclusive indicating either no significant LET dependence 7,8 or under-response. 6 The R Q =R Q 0 values are higher only at the lowest energies and approach unity with increasing energy.…”

Section: A2 MC Simulations Of Effects Associated With Detector Dementioning

confidence: 99%

“…Commercially available synthetic diamond detectors microDiamond (PTW 60019, Freiburg, Germany) have been used in small-field dosimetry of high-energy photon and electron beams, [1][2][3][4] as well as in proton and carbon beams. [5][6][7][8] These studies showed that the detectors have low absorbed-dose energy dependence, negligible dose-rate dependence and do not require high pre-irradiation doses (up to 2 Gy). These characteristics shown in high-energy beams combined with the closeness of the effective atomic numbers of water and carbon prompted a question about diamond detector's applicability in low-energy photon beams, such as BT and diagnostic x-ray fields.…”

Section: Introductionmentioning

confidence: 98%

“…Recently, diamond detectors have regained interest because the current manufacturing technology allows for reproducible high‐purity crystal growth. Commercially available synthetic diamond detectors microDiamond (PTW 60019, Freiburg, Germany) have been used in small‐field dosimetry of high‐energy photon and electron beams, as well as in proton and carbon beams . These studies showed that the detectors have low absorbed‐dose energy dependence, negligible dose‐rate dependence and do not require high pre‐irradiation doses (up to 2 Gy).…”

Section: Introductionmentioning

confidence: 99%

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Investigation of a synthetic diamond detector response in kilovoltage photon beams

et al. 2020

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Purpose An important characteristic of radiation dosimetry detectors is their energy response which consists of absorbed‐dose and intrinsic energy responses. The former can be characterized using Monte Carlo (MC) simulations, whereas the latter (i.e., detector signal per absorbed dose to detector) is extracted from experimental data. Such a characterization is especially relevant when detectors are used in nonrelative measurements at a beam quality that differs from the calibration beam quality. Having in mind the possible application of synthetic diamond detectors (microDiamond PTW 60019, Freiburg, Germany) for nonrelative dosimetry of low‐energy brachytherapy (BT) beams, we determined their intrinsic and absorbed‐dose energy responses in 25–250 kV beams relative to a 60Co beam, which is usually the reference beam quality for detector calibration in radiotherapy. Material and Methods Three microDiamond detectors and, for comparison, two silicon diodes (PTW 60017) were calibrated in terms of air‐kerma free in air in six x‐ray beam qualities (from 25 to 250 kV) and in terms of absorbed dose to water in a 60Co beam at the national metrology laboratory in Sweden. The PENELOPE/penEasy MC radiation transport code was used to calculate the absorbed‐dose energy response of the detectors (modeled based on blueprints) relative to air and water depending on calibration conditions. The MC results were used to extract the relative intrinsic energy response of the detectors from the overall energy response. Measurements using an independent setup with a single ophthalmic BEBIG I25.S16 125I BT seed (effective photon energy of 28 keV) were used as a qualitative check of the extracted intrinsic energy response correction factors. Additionally, the impact of the thickness of the active volume as well as the presence of extra‐cameral components on the absorbed‐dose energy response of a microDiamond detector was studied using MC simulations. Results The relative intrinsic energy response of the microDiamond detectors was higher by a factor of 2 in 25 and 50 kV beams compared to the 60Co beam. The variation in the relative intrinsic energy response of silicon diodes was within 10% over the investigated photon energy range. The use of relative intrinsic energy response correction factors improved the agreement among the absorbed dose to water values determined using microDiamond detectors and silicon diodes, as well as with the TG‐43 formalism‐based calculations for the 125I seed. MC study of microDiamond detector design features provided a possible explanation for inter‐detector response variation at low‐energy photon beams by differences in the effective thickness of the active volume. Conclusions MicroDiamond detectors had a non‐negligible variation in the relative intrinsic energy response (factor of 2) which was comparable to that in the absorbed‐dose energy response relative to water at low‐energy photon beams. Silicon diodes, in contrast, had an absorbed‐dose energy dependence on photon energy that varied by a factor of 6, whe...

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“…Beddar et al [ 7 , 8 ] demonstrated that characteristics such as water equivalence, fast response time, and dose-rate responses of plastic scintillators qualify them for external beam radiation therapy. At the CPT, the response of several detectors has been tested and characterized to understand their suitability for proton dosimetry [ 9 , 10 , 11 ]. Different types of scintillating fibers generally have different light emission spectra, light outputs, and levels of quenching.…”

Section: Introductionmentioning

confidence: 99%

Characterization of a Low-Cost Plastic Fiber Array Detector for Proton Beam Dosimetry

Loch

Eichenberger

Togno

et al. 2020

Sensors

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The Pencil Beam Scanning (PBS) technique in proton therapy uses fast magnets to scan the tumor volume rapidly. Changing the proton energy allows changing to layers in the third dimension, hence scanning the same volume several times. The PBS approach permits adapting the speed and/or current to modulate the delivered dose. We built a simple prototype that measures the dose distribution in a single step. The active detection material consists of a single layer of scintillating fibers (i.e., 1D) with an active length of 100 mm, a width of 18.25 mm, and an insignificant space (20 μm) between them. A commercial CMOS-based camera detects the scintillation light. Short exposure times allow running the camera at high frame rates, thus, monitoring the beam motion. A simple image processing method extracts the dose information from each fiber of the array. The prototype would allow scaling the concept to multiple layers read out by the same camera, such that the costs do not scale with the dimensions of the fiber array. Presented here are the characteristics of the prototype, studied under two modalities: spatial resolution, linearity, and energy dependence, characterized at the Center for Proton Therapy (Paul Scherrer Institute); the dose rate response, measured at an electron accelerator (Swiss Federal Institute of Metrology).

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The role of a microDiamond detector in the dosimetry of proton pencil beams

Cited by 22 publications

References 16 publications

FLASH Irradiation with Proton Beams: Beam Characteristics and Their Implications for Beam Diagnostics

FLASH Irradiation with Proton Beams: Beam Characteristics and Their Implications for Beam Diagnostics

Investigation of a synthetic diamond detector response in kilovoltage photon beams

Characterization of a Low-Cost Plastic Fiber Array Detector for Proton Beam Dosimetry

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