Dose rate dependence of the PTW 60019 microDiamond detector in high dose-per-pulse pulsed beams

Brualla-González, L.; Gómez, F.; Pombar, M.; Pardo-Montero, Juan

doi:10.1088/0031-9155/61/1/n11

Cited by 19 publications

(22 citation statements)

References 40 publications

(50 reference statements)

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…While the response of the Diode E changes by up to 3% in the DPP range of 0.13 mGy/pulse to 0.86 mGy/pulse, the microSilicon exhibits a lower DPP dependence comparable to that of the microDiamond, where the detector’s response changes by less than 1%. The DPP dependence of the microDiamond detector agrees with the results published by Brualla‐González et al For the axial orientation, the EPOM of the microSilicon was found to lie 0.7 ± 0.2 mm below the detector’s outer front surface, which is comparable to the manufacturer’s specification of 0.8 mm.…”

Section: Discussionsupporting

confidence: 89%

Technical Note: Characterization of the new microSilicon diode detector

Schönfeld

Poppinga²,

Kranzer³

et al. 2019

Medical Physics

View full text Add to dashboard Cite

PurposeDosimetric properties of the new microSilicon diode detector (60023) have been studied with focus on application in small‐field dosimetry. The influences of the dimensions of the sensitive volume and the density of the epoxy layer surrounding the silicon chip of microSilicon have been quantified and compared to its predecessor (Diode E 60017) and the microDiamond (60019, all PTW‐Freiburg, Germany).MethodsDose linearity has been studied in the range from 0.01 to 8.55 Gy and dose‐per‐pulse dependence from 0.13 to 0.86 mGy/pulse. The effective point of measurement (EPOM) was determined by comparing measured percentage depth dose curves with a reference curve (Roos chamber). Output ratios were measured for nominal field sizes from 0.5 × 0.5 cm2 to 4 × 4 cm2. The corresponding small‐field output correction factors, k, were derived with a plastic scintillation detector as reference. The lateral dose–response function, K(x), was determined using a slit beam geometry.ResultsMicroSilicon shows linear dose response (R 2 = 1.000) in both low and high dose range up to 8.55 Gy with deviations of only up to 1% within the dose‐per‐pulse values investigated. The EPOM was found to lie (0.7 ± 0.2) mm below the front detector’s surface. The derived k for microSilicon (0.960 at s eff = 0.55 cm) is similar to that of microDiamond (0.956), while Diode E requires larger corrections (0.929). This improved behavior of microSilicon in small‐fields is reflected in the slightly wider K(x) compared to Diode E. Furthermore, the amplitude of the negative values in K(x) at the borders of the sensitive volume has been reduced.ConclusionsCompared to its predecessor, microSilicon shows improved dosimetric behavior with higher sensitivity and smaller dose‐per‐pulse dependence. Profile measurements demonstrated that microSilicon causes less perturbation in off‐axis measurements. It is especially suitable for the applications in small‐field output factors and profile measurements.

show abstract

Section: Discussionsupporting

confidence: 89%

Technical Note: Characterization of the new microSilicon diode detector

Schönfeld

Poppinga²,

Kranzer³

et al. 2019

Medical Physics

View full text Add to dashboard Cite

show abstract

“…The dose‐rate in beam quality Q was in this range, and no dose‐rate corrections were applied to detector readings in in‐phantom measurements in HDR 192 Ir beams. It is known that the level of impurities and defects in a crystal affects the signal of a diamond detector, and their presence can be assessed indirectly in terms of dose‐rate dependence and preirradiation dose . The nearly identical responses of all microDiamonds in short‐term stability measurements suggest that the detectors used in the present study do not differ in terms of their crystal properties that might influence dose‐rate dependence and stabilization of a detector.…”

Section: Resultsmentioning

confidence: 82%

“…A detailed description of its structure and detection properties can be found elsewhere . Characterization in high‐energy photon beams showed that it has linear response to dose from 0.5 to 15 Gy, good stability, negligible dose‐rate dependence, uniform energy response (including low‐energy scattered photons) and low angular and temperature dependences . Since dosimetry of HDR 192 Ir BT sources is similar to that of small photon fields in terms of high dose gradients and high dose rates, these findings, coupled with near water‐equivalence of carbon, direct readout and convenience of use, suggest that the microDiamond would be suitable for the determination of absorbed dose to water in HDR 192 Ir beams.…”

Section: Introductionmentioning

confidence: 92%

See 1 more Smart Citation

Suitability of microDiamond detectors for the determination of absorbed dose to water around high‐dose‐rate ¹⁹²Ir brachytherapy sources

et al. 2017

View full text Add to dashboard Cite

Purpose: Experimental dosimetry of high-dose-rate (HDR) 192 Ir brachytherapy (BT) sources is complicated due to high dose and dose-rate gradients, and softening of photon energy spectrum with depth. A single crystal synthetic diamond detector microDiamond (PTW 60019, Freiburg, Germany) has a small active volume, high sensitivity, direct readout, and nearly water-equivalent active volume. The purpose of this study was to evaluate the suitability of microDiamond detectors for the determination of absorbed dose to water around HDR 192 Ir BT sources. Three microDiamond detectors were used, allowing for the comparison of their properties. Methods: In-phantom measurements were performed using microSelectron and VariSource iX HDR 192 Ir BT treatment units. Their treatment planning systems (TPSs), Oncentra (v. 4.3) and BrachyVision (v. 13.6), respectively, were used to create irradiation plans for a cubic PMMA phantom with the microDiamond positioned at one of three source-to-detector distances (SDDs) (1.5, 2.5, and 5.5 cm) at a time. The source was stepped in increments of 0.5 cm over a total length of 6 cm to yield absorbed dose of 2 Gy at the nominal reference-point of the detector. Detectors were calibrated in 60 Co beam in terms of absorbed dose to water, and Monte Carlo (MC) calculated beam quality correction factors were applied to account for absorbed-dose energy dependence. Phantom correction factors were applied to account for differences in dimensions between the measurement phantom and a water phantom used for absorbed dose calculations made with a TPS. The same measurements were made with all three of the detectors. Additionally, dose-rate dependence and stability of the detectors were evaluated in 60 Co beam. Results: The percentage differences between experimentally determined and TPS-calculated absorbed doses to water were from À1.3% to +2.9%. The values agreed to within experimental uncertainties, which were from 1.9% to 4.3% (k = 2) depending on the detector, SDD and treatment delivery unit. No dose-rate or intrinsic energy dependence corrections were applied. All microDiamonds were comparable in terms of preirradiation dose, stability of the readings and energy response, and showed a good agreement. Conclusions:The results indicate that the microDiamond is potentially suitable for the determination of absorbed dose to water around HDR 192 Ir BT sources and may be used for independent verification of TPS's calculations, as well as for QA measurements of HDR 192 Ir BT treatment delivery units at clinical sites.

show abstract

“…Our results hence do not contradict findings in high-energy photon and electron beams reporting negligible beam quality dependence. 1,38,39 Furthermore, no significant relative intrinsic energy dependence was observed in our previous study 9 of microDiamond detectors in 192 Ir beam which had an effective photon energy close to 300 keV.…”

Section: A2 MC Simulations Of Effects Associated With Detector Dementioning

confidence: 71%

Investigation of a synthetic diamond detector response in kilovoltage photon beams

et al. 2020

View full text Add to dashboard Cite

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...

show abstract

Dose rate dependence of the PTW 60019 microDiamond detector in high dose-per-pulse pulsed beams

Cited by 19 publications

References 40 publications

Technical Note: Characterization of the new microSilicon diode detector

Technical Note: Characterization of the new microSilicon diode detector

Suitability of microDiamond detectors for the determination of absorbed dose to water around high‐dose‐rate ¹⁹²Ir brachytherapy sources

Investigation of a synthetic diamond detector response in kilovoltage photon beams

Contact Info

Product

Resources

About

Dose rate dependence of the PTW 60019 microDiamond detector in high dose-per-pulse pulsed beams

Cited by 19 publications

References 40 publications

Technical Note: Characterization of the new microSilicon diode detector

Technical Note: Characterization of the new microSilicon diode detector

Suitability of microDiamond detectors for the determination of absorbed dose to water around high‐dose‐rate 192Ir brachytherapy sources

Investigation of a synthetic diamond detector response in kilovoltage photon beams

Contact Info

Product

Resources

About

Suitability of microDiamond detectors for the determination of absorbed dose to water around high‐dose‐rate ¹⁹²Ir brachytherapy sources