Evaluation of a PTW diamond detector for electron beam measurements

Heydarian, M.; Hoban, Peter; Beckham, Wayne; Borchardt, I M; Beddoe, A H

doi:10.1088/0031-9155/38/8/002

Cited by 57 publications

(64 citation statements)

References 6 publications

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“…[2][3][4] In addition, spatial averaging effects due to the finite size of ionization chambers make them not suitable when high spatial resolution is required. 5 Although being not tissue-equivalent, silicon diodes (p-type) have been well established in clinical electron dosimetry due to their small sensitive volume, high sensitivity, and high spatial resolution. [6][7][8] The silicon to water stopping power ratio is fairly constant for electron energies between 5 and 25 MeV and, once calibrated against an ionization chamber, the diode response is assumed to represent the dose with no need of depth-dependent correction factors.…”

Section: Introductionmentioning

confidence: 99%

“…[11][12][13][14][15][16][17] Moreover, the carbon to water stopping power ratio stays nearly constant over an electron energy range 1-20 MeV; thus, allowing direct measurement of dose distributions in tissue equivalent medium. 1,5 Furthermore, unlike silicon diodes, the same diamond detector is expected to be suitable for both electron and photon dosimetry. 5 Most studies on diamond application for megavoltage electron and photon radiotherapy beam dosimetry have been performed using PTW natural diamond detectors and are reported as comparative investigations with respect to reference detectors, i.e., ionization chambers and silicon diodes.…”

Section: Introductionmentioning

confidence: 99%

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Characterization of a synthetic single crystal diamond Schottky diode for radiotherapy electron beam dosimetry

Venanzio

Marinelli²,

Milani³

et al. 2013

Med. Phys.

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Purpose: To investigate the dosimetric properties of synthetic single crystal diamond based Schottky diodes under irradiation with therapeutic electron beams from linear accelerators. Methods: A single crystal diamond detector was fabricated and tested under 6, 8, 10, 12, and 15 MeV electron beams. The detector performances were evaluated using three types of commercial detectors as reference dosimeters: an Advanced Markus plane parallel ionization chamber, a Semiflex cylindrical ionization chamber, and a p-type silicon detector. Preirradiation, linearity with dose, dose rate dependence, output factors, lateral field profiles, and percentage depth dose profiles were investigated and discussed. Results: During preirradiation the diamond detector signal shows a weak decrease within 0.7% with respect to the plateau value and a final signal stability of 0.1% (1σ ) is observed after about 5 Gy. A good linear behavior of the detector response as a function of the delivered dose is observed with deviations below ±0.3% in the dose range from 0.02 to 10 Gy. In addition, the detector response is dose rate independent, with deviations below 0.3% in the investigated dose rate range from 0.17 to 5.45 Gy/min. Percentage depth dose curves obtained from the diamond detector are in good agreement with the ones from the reference dosimeters. Lateral beam profile measurements show an overall good agreement among detectors, taking into account their respective geometrical features. The spatial resolution of solid state detectors is confirmed to be better than that of ionization chambers, being the one from the diamond detector comparable to that of the silicon diode. A good agreement within experimental uncertainties was also found in terms of output factor measurements between the diamond detector and reference dosimeters. Conclusions: The observed dosimetric properties indicate that the tested diamond detector is a suitable candidate for clinical electron beam dosimetry.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Characterization of a synthetic single crystal diamond Schottky diode for radiotherapy electron beam dosimetry

Venanzio

Marinelli²,

Milani³

et al. 2013

Med. Phys.

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“…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%

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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“…The central electrode of the pinpoint chamber is 1.6 mm from the outer surface and the position of the sensitive volume in the diamond detector is 1 mm from the surface. 8 Unlike the pinpoint chamber, the diamond detector does not require temperature and pressure corrections and has very little energy dependence. 8,9 Phantom materials This study investigated the properties of A150 plastic ͑Exradin, Lisle IL͒, Virtual Water™ ͑MED-CAL INC., WI͒ and polystyrene when used with beta particles.…”

Section: Detectorsmentioning

confidence: 99%

“…8 Unlike the pinpoint chamber, the diamond detector does not require temperature and pressure corrections and has very little energy dependence. 8,9 Phantom materials This study investigated the properties of A150 plastic ͑Exradin, Lisle IL͒, Virtual Water™ ͑MED-CAL INC., WI͒ and polystyrene when used with beta particles. The Virtual Water is an epoxy-based water substitute equivalent to Solid Water™ ͑Gammex-RMI, Middleton WI͒.…”

Section: Detectorsmentioning

confidence: 99%

The water‐equivalence of phantom materials beta particles

2001

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Intravascular brachytherapy requires that the dose be specified within millimeters of the source. High dose gradients near brachytherapy sources require that the source-detector distance be accurately known for dosimetry purposes. Solid phantoms can be designed to accommodate these stringent requirements. This study reports dosimeter readings from 90 Sr-90 Y sources measured in water, A150, polystyrene and in an epoxy-based water-equivalent plastic. Measurements showed that while A150 and the epoxy-based plastic agreed well with water when the surface of the source contacted the detector housing, the relative response in the phantoms decreased with increasing depth in phantom, falling to ϳ0.55 those of water at a depth of 5 mm. Readings in polystyrene were within 4% of those in water between 1 and 2 mm depth. However, while polystyrene followed water more closely than the other two materials, at greater depths the relative response in polystyrene to water varied from 0.65 to 1.34. When the density of the materials is accounted for, the relative response in A150 is nearly constant with increasing areal density. Furthermore, the response in A150 shows the closest agreement with that in water of any of the solid materials for higher areal densities. For values below 0.3 g/cm 2 , polystyrene shows the closest agreement with water.

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Evaluation of a PTW diamond detector for electron beam measurements

Cited by 57 publications

References 6 publications

Characterization of a synthetic single crystal diamond Schottky diode for radiotherapy electron beam dosimetry

Characterization of a synthetic single crystal diamond Schottky diode for radiotherapy electron beam dosimetry

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

The water‐equivalence of phantom materials beta particles

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