Dosimetric characteristics of four PTW microDiamond detectors in high-energy proton beams

Marsolat, Fanny; Marzi, Ludovic De; Patriarca, Annalisa; Nauraye, C.; Moignier, Cyril; Pomorski, M.; Moignau, F.; Heinrich, Sophie; Tromson, D.; Mazal, A.

doi:10.1088/0031-9155/61/17/6413

Cited by 20 publications

(37 citation statements)

References 36 publications

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“…In Ref. , the evaluation of four microDiamonds indicates that the microDiamond detectors are not reproducible and presented differences in terms of stability, sensitivity, and LET dependence. The LET dependence is in contrast with other studies .…”

Section: Resultsmentioning

confidence: 99%

“…In some cases, quenching effects may occur in regions with increased LET and therefore solid detectors must be used carefully. Diamond detectors are tissue equivalent and therefore could be of high interest in future . The microDiamond TM60019 (PTW, Freiburg), which offers an effective thickness of 1 μ m, a radius of 1.1 mm and a volume of 0.004 mm 3 , has been used for reference transverse profile acquisitions in water for TPS commissioning.…”

Section: Methodsmentioning

confidence: 99%

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Implementation of dosimetry equipment and phantoms at the MedAustron light ion beam therapy facility

et al. 2017

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Purpose: To describe the implementation of dosimetry equipment and phantoms into clinical practice of light ion beam therapy facilities. This work covers not only standard dosimetry equipment such as computerized water scanners, films, 2D-array, thimble, and plane parallel ionization chambers, but also dosimetry equipment specifically devoted to the pencil beam scanning delivery technique such as water columns, scintillating screens or multilayer ionization chambers. Method: Advanced acceptance testing procedures developed at MedAustron and complementary to the standard acceptance procedures proposed by the manufacturer are presented. Detailed commissioning plans have been implemented for each piece of dosimetry equipment and include an estimate of the overall uncertainty budget for the range of clinical use of each device. Some standard dosimetry equipment used in many facilities was evaluated in detail: for instance, the recombination of a 2D-array or the potential use of a microdiamond detector to measure reference transverse dose profiles in water in the core of the primary pencil beams and in the low-dose nuclear halo (over four orders of magnitude in dose). Results: The implementation of dosimetry equipment as described in this work allowed determining absolute spot sizes and spot positions with an uncertainty better than 0.3 mm. Absolute ranges are determined with an uncertainty comprised of 0.2-0.6 mm, depending on the measured range and were reproduced with a maximum difference of 0.3 mm over a period of 12 months using three different devices. Conclusion: The detailed evaluation procedures of dosimetry equipment and phantoms proposed in this work could serve as a guidance for other medical physicists in ion beam therapy facilities and also in conventional radiation therapy.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Implementation of dosimetry equipment and phantoms at the MedAustron light ion beam therapy facility

et al. 2017

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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, but in proton beams the reported results were inconclusive indicating either no significant LET dependence or under‐response …”

Section: Discussionmentioning

confidence: 99%

“…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%

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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“…Also in protons, most dosimetry studies conclude that the response of the PTW‐60019 microDiamond detector exhibits no LET dependence nor quenching effect (Mandapaka et al, Marinelli et al, Yuichi et al, Rossomme et al, Akino et al). In, which is based on an intercomparison of four microDiamond detectors in a clinical 138 MeV proton beam, authors reported a nonreproducibility between devices in terms of stability, sensitivity, and LET dependence. The response of the PTW‐60019 microDiamond detector has been little investigated in carbon ion beams.…”

Section: Introductionmentioning

confidence: 99%

Response of synthetic diamond detectors in proton, carbon, and oxygen ion beams

Rossomme

Marinelli²,

Verona-Rinati³

et al. 2017

Medical Physics

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Due to the high LET value, a LET dependence of the response of the synthetic diamond detector was observed in the case of carbon and oxygen beams. The effect was found to be negligible in proton beams, due to the low LET value. The under-response of the synthetic diamond detector may result from the recombination of electron/hole in the thin synthetic diamond layer, due to the high LET-values. More investigations are required to confirm this assumption.

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Dosimetric characteristics of four PTW microDiamond detectors in high-energy proton beams

Cited by 20 publications

References 36 publications

Implementation of dosimetry equipment and phantoms at the MedAustron light ion beam therapy facility

Implementation of dosimetry equipment and phantoms at the MedAustron light ion beam therapy facility

Investigation of a synthetic diamond detector response in kilovoltage photon beams

Response of synthetic diamond detectors in proton, carbon, and oxygen ion beams

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