Energy and dose rate dependence of a diamond detector in the dosimetry of 4–25 MV photon beams

Laub, Wolfram; Kaulich, Theodor W.; Nüsslin, Fridtjof

doi:10.1118/1.597902

Cited by 74 publications

(56 citation statements)

References 8 publications

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“…Exponent values reported in the literature lie in the range 0.92-1 for PTW diamond detectors [24][25][26][27][28][29], 0.86-1.035 for CVD diamond [24,25,[30][31][32], and 0.49-0.97 for HPHT diamond [13,14]. The values observed for the devices fabricated on Diamond Materials and Element Six diamond films are close to one and hence compare well to the literature.…”

Section: Primed Responsesupporting

confidence: 71%

“…Specific sensitivities values reported in the literature have been measured using a variety of x-ray (250 kV, and 6, 10, and 25 MV) and electron (4-25 MeV) energies from linear accelerators, as well as other radiation sources such as 60 Co and 90 Sr. For PTW natural diamond detectors the specific sensitivities lie in the range 50-140 nC·Gy -1 ·mm -3 [8,24,26,27,33]. A wide range of specific sensitivities have been reported for CVD diamond-based detectors, ranging from a few to over a thousand nC·Gy -1 ·mm -3 ; generally, the lower values (of up to ~100 nC·Gy -1 ·mm -3 ) appear to be reported for polycrystalline material grown in-house by the researchers [8,9,25,30,34], whereas the higher values were obtained using commercial CVD diamond, some of which was described as 'detector grade' [10,24,31,34,35].…”

Section: Primed Responsementioning

confidence: 99%

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Investigation of the suitability of commercially available CVD diamond for megavoltage X-ray dosimetry

Lansley

Betzel

Baluti

et al. 2009

Nuclear Instruments and Methods in Physics Research Section A:

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Sandwich-type x-ray detectors were fabricated on commercially-available chemical vapour deposition diamond sourced from three manufacturers: Diamond Materials GmbH, Diamonex, and Element Six. These devices were investigated using Raman spectroscopy and 6 megavolt photons from a clinical linear accelerator. Parameters such as the level of the dark (leakage) and photo-currents, necessary priming dose, linearity of photocurrent with dose rate, and device sensitivity were considered. Device characteristics vary considerably. Devices fabricated using Diamonex material required high priming doses, and displayed high dark currents, low photocurrents (and hence low x-ray sensitivity), and non-linear dose-rate responses. In contrast, devices fabricated from Diamond Materials and Element Six material required lower priming doses, and displayed 'zero' dark currents (beyond the detection limit), higher photocurrents and linear dose-rate responses. In addition, the Element Six devices exhibited less variation in response when irradiated at different angles of incidence.

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Section: Primed Responsesupporting

confidence: 71%

Section: Primed Responsementioning

confidence: 99%

Investigation of the suitability of commercially available CVD diamond for megavoltage X-ray dosimetry

Lansley

Betzel

Baluti

et al. 2009

Nuclear Instruments and Methods in Physics Research Section A:

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“…The dose rate dependency of the diamond detector sensitivity is explained by Fowler (10) who introduced an expression for the dose rate dependency of the detector linearity, which was quoted by other researchers 5 , 11 . The detector signal (S) versus the dose rate

false(\overset{falseˇ}{D} false)

is expressed by the equation

i = R . {false(\overset{ˇ}{D} false)}^{Δ} + i_{d a r k}

\overset{falseˇ}{D} = 1

, the relationship is linear; R is a detector‐specific constant, and

i_{d a r k}

is the signal due to the dark current of the detector.…”

Section: Methodsmentioning

confidence: 99%

Diamond detector in absorbed dose measurements in high‐energy linear accelerator photon and electron beams

Ravichandran

Binukumar

Amri

et al. 2016

J Applied Clin Med Phys

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Diamond detectors (DD) are preferred in small field dosimetry of radiation beams because of small dose profile penumbras, better spatial resolution, and tissue‐equivalent properties. We investigated a commercially available ‘microdiamond’ detector in realizing absorbed dose from first principles. A microdiamond detector, type TM 60019 with tandem electrometer is used to measure absorbed doses in water, nylon, and PMMA phantoms. With sensitive volume 0.004 mm3, radius 1.1 mm, thickness 1×10−3mm, the nominal response is 1 nC/Gy. It is assumed that the diamond detector could collect total electric charge (nC) developed during irradiation at 0 V bias. We found that dose rate effect is less than 0.7% for changing dose rate by 500 MU/min. The reproducibility in obtaining readings with diamond detector is found to be ±0.17% (1 SD) false(n=11false). The measured absorbed doses for 6 MV and 15 MV photons arrived at using mass energy absorption coefficients and stopping power ratios compared well with Nd, water calibrated ion chamber measured absorbed doses within 3% in water, PMMA, and nylon media. The calibration factor obtained for diamond detector confirmed response variation is due to sensitivity due to difference in manufacturing process. For electron beams, we had to apply ratio of electron densities of water to carbon. Our results qualify diamond dosimeter as a transfer standard, based on long‐term stability and reproducibility. Based on micro‐dimensions, we recommend these detectors for pretreatment dose verifications in small field irradiations like stereotactic treatments with image guidance.PACS number(s): 87.56.Da

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“…The dependence on natural diamond resulted in a detector series with variations in response reflective of the variation in the composition of diamonds available. In addition, relative dose measurements often have to be corrected to account for dose‐rate dependence of the first commercial detectors 4 , 13 …”

Section: Introductionmentioning

confidence: 99%

Clinical radiation therapy measurements with a new commercial synthetic single crystal diamond detector

Laub

Crilly

2014

J Applied Clin Med Phys

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A commercial version of a synthetic single crystal diamond detector (SCDD) in a Schottky diode configuration was recently released as the new type 60019 microDiamond detector (PTW‐Freiburg, Germany). In this study we investigate the dosimetric properties of this detector to independently confirm that findings from the developing group of the SCDDs still hold true for the commercial version of the SCDDs. We further explore if the use of the microDiamond detector can be expanded to high‐energy photon beams of up to 15 MV and to large field measurements. Measurements were performed with an Elekta Synergy linear accelerator delivering 6, 10, and 15 MV X‐rays, as well as 6, 9, 12, 15, and 20 MeV electron beams. The dependence of the microdiamond detector response on absorbed dose after connecting the detector was investigated. Furthermore, the dark current of the diamond detector was observed after irradiation. Results are compared to similar results from measurements with a diamond detector type 60003. Energy dependency was investigated, as well. Photon depth‐dose curves were measured for field sizes 3×3,10×10, and 30×30.15emcm2. PDDs were measured with the Semiflex type 31010 detector, microLion type 31018 detector, P Diode type 60016, SRS Diode type 60018, and the microDiamond type 60019 detector (all PTW‐Freiburg). Photon profiles were measured at a depth of 10 cm. Electron depth‐dose curves normalized to the dose maximum were measured with the 14×14.15emcm2 electron cone. PDDs were measured with a Markus chamber type 23343, an E Diode type 60017 and the microDiamond type 60019 detector (all PTW‐Freiburg). Profiles were measured with the E Diode and microDiamond at half of D90,D90,D70, and D50 depths and for electron cone sizes of 6×6.15emcm2, 14×14.15emcm2, and 20×20.15emcm2. Within a tolerance of 0.5% detector response of the investigated detector was stable without any preirradiation. After preirradition with approximately 250 cGy the detector response was stable within 0.1%. A dark current after irradiation was not observed. The microDiamond detector shows no energy dependence in high energy photon or electron dosimetry. Electron PDD measurements with the E Diode and microDiamond are in good agreement. However, compared to E Diode measurements, dose values in the bremsstrahlungs region are about 0.5% lower when measured with the microDiamond detector. Markus detector measurements agree with E Diode measurements in the bremsstrahlungs region. For depths larger than dmax, depth‐dose curves of photon beams measured with the microDiamond detector are in close agreement to those measured with the microLion detector for small fields and with those measured with a Semiflex 0.125 cc ionization chamber for large fields. Differences are in the range of 0.25% and less. For profile measurements, microDiamond detector measurements agree well with microLion and P Diode measurements in the high‐dose region of the profile and the penumbra region. For areas outside the open field, P Diode measurements are about 0.5%–1.0% highe...

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Energy and dose rate dependence of a diamond detector in the dosimetry of 4–25 MV photon beams

Cited by 74 publications

References 8 publications

Investigation of the suitability of commercially available CVD diamond for megavoltage X-ray dosimetry

Investigation of the suitability of commercially available CVD diamond for megavoltage X-ray dosimetry

Diamond detector in absorbed dose measurements in high‐energy linear accelerator photon and electron beams

Clinical radiation therapy measurements with a new commercial synthetic single crystal diamond detector

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