Diamond Detectors in Relative Dosimetry of Photon, Electron and Proton Radiation Fields

Khrunov, V. S.; Martynov, S. S.; Vatnitsky, Stanislav; Ermakov, Igor V.; Chervjakov, A.; Karlin, D.L.; Fominych, V.I.; Tarbeyev, Yu.V.

doi:10.1093/oxfordjournals.rpd.a080780

Cited by 44 publications

(15 citation statements)

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“…The characteristics of diode and diamond detectors have been extensively studied and reported. [43][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58] The characteristics of the detectors employed in this study are summarized in Table I. For the microchambers, the effective point of measurement was determined by comparison with the Exradin T14P parallel-plate chamber, whose effective point of measurement was assumed to lie on the inner surface of the upper plate.…”

Section: Iia Experimental Measurementsmentioning

confidence: 99%

Total scatter factors of small beams: A multidetector and Monte Carlo study

2008

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The scope of this study was to estimate total scatter factors ͑s c,p ͒ of the three smallest collimators of the Cyberknife radiosurgery system ͑5-10 mm in diameter͒, combining experimental measurements and Monte Carlo simulation. Two microchambers, a diode, and a diamond detector were used to collect experimental data. The treatment head and the detectors were simulated by means of a Monte Carlo code in order to calculate correction factors for the detectors and to estimate total scatter factors by means of a consistency check between measurement and simulation. Results for the three collimators were: s c,p ͑5 mm͒ = 0.677± 0.004, s c,p ͑7.5 mm͒ = 0.820± 0.008, s c,p ͑10 mm͒ = 0.871± 0.008, all relative to the 60 mm collimator at 80 cm source-to-detector distance. The method also allows the full width at half maximum of the electron beam to be estimated; estimations made with different collimators and different detectors were in excellent agreement and gave a value of 2.1 mm. Correction factors to be applied to the detectors for the measurement of s c,p were consistent with a prevalence of volume effect for the microchambers and the diamond and a prevalence of scattering from high-Z material for the diode detector. The proposed method is more sensitive to small variations of the electron beam diameter with respect to the conventional method used to commission Monte Carlo codes, i.e., by comparison with measured percentage depth doses ͑PDD͒ and beam profiles. This is especially important for small fields ͑less than 10 mm diameter͒, for which measurements of PDD and profiles are strongly affected by the type of detector used. Moreover, this method should allow s c,p of Cyberknife systems different from the unit under investigation to be estimated without the need for further Monte Carlo calculation, provided that one of the microchambers or the diode detector of the type used in this study are employed. The results for the diamond are applicable only to the specific detector that was investigated due to excessive variability in manufacturing.

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Section: Iia Experimental Measurementsmentioning

confidence: 99%

Total scatter factors of small beams: A multidetector and Monte Carlo study

2008

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“…75 When ionizing radiation is absorbed, it induces a temporary change in the electrical conductivity of the material. [76][77][78][79][80] The response of a diamond detector is directly proportional to the absorbed dose rate. Diamond detectors do not exhibit any directional dependence and they are tissue-equivalent.…”

Section: Iiia Experimentsmentioning

confidence: 99%

Small fields: Nonequilibrium radiation dosimetry

2007

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Advances in radiation treatment with beamlet-based intensity modulation, image-guided radiation therapy, and stereotactic radiosurgery (including specialized equipments like CyberKnife, Gamma Knife, tomotherapy, and high-resolution multileaf collimating systems) have resulted in the use of reduced treatment fields to a subcentimeter scale. Compared to the traditional radiotherapy with fields > or =4 x 4 cm2, this can result in significant uncertainty in the accuracy of clinical dosimetry. The dosimetry of small fields is challenging due to nonequilibrium conditions created as a consequence of the secondary electron track lengths and the source size projected through the collimating system that are comparable to the treatment field size. It is further complicated by the prolonged electron tracks in the presence of low-density inhomogeneities. Also, radiation detectors introduced into such fields usually perturb the level of disequilibrium. Hence, the dosimetric accuracy previously achieved for standard radiotherapy applications is at risk for both absolute and relative dose determination. This article summarizes the present knowledge and gives an insight into the future procedures to handle the nonequilibrium radiation dosimetry problems. It is anticipated that new miniature detectors with controlled perturbations and corrections will be available to meet the demand for accurate measurements. It is also expected that the Monte Carlo techniques will increasingly be used in assessing the accuracy, verification, and calculation of dose, and will aid perturbation calculations of detectors used in small and highly conformal radiation beams. rican Association of Physicists in Medicine.

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“…When ionizing radiation is absorbed, it induces a temporary change in the electrical conductivity of the material. [46][47][48][49][50] The response of a diamond detector is directly proportional to the absorbed dose rate. Diamond detectors do not exhibit any directional dependence and they are tissue equivalent.…”

Section: Iie2 Detector Typesmentioning

confidence: 99%

Accelerator beam data commissioning equipment and procedures: Report of the TG‐106 of the Therapy Physics Committee of the AAPM

Das

Cheng

Watts³

et al. 2008

Medical Physics

409

424

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For commissioning a linear accelerator for clinical use, medical physicists are faced with many challenges including the need for precision, a variety of testing methods, data validation, the lack of standards, and time constraints. Since commissioning beam data are treated as a reference and ultimately used by treatment planning systems, it is vitally important that the collected data are of the highest quality to avoid dosimetric and patient treatment errors that may subsequently lead to a poor radiation outcome. Beam data commissioning should be performed with appropriate knowledge and proper tools and should be independent of the person collecting the data. To achieve this goal, Task Group 106 (TG-106) of the Therapy Physics Committee of the American Association of Physicists in Medicine was formed to review the practical aspects as well as the physics of linear accelerator commissioning. The report provides guidelines and recommendations on the proper selection of phantoms and detectors, setting up of a phantom for data acquisition (both scanning and no-scanning data), procedures for acquiring specific photon and electron beam parameters and methods to reduce measurement errors (<1%), beam data processing and detector size convolution for accurate profiles. The TG-106 also provides a brief.discussion on the emerging trend in Monte Carlo simulation techniques in photon and electron beam commissioning. The procedures described in this report should assist a qualified medical physicist in either measuring a complete set of beam data, or in verifying a subset of data before initial use or for periodic quality assurance measurements. By combining practical experience with theoretical discussion, this document sets a new standard for beam data commissioning.

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Diamond Detectors in Relative Dosimetry of Photon, Electron and Proton Radiation Fields

Abstract: Characteristics of the diamond detector for use in the radiation therapy for the relative dosimetry of photon, electron, proton beams are given in the paper. The advantages of the detector as compared with ionising chambers and Si-diodes are presented.

Cited by 44 publications

References 0 publications

Total scatter factors of small beams: A multidetector and Monte Carlo study

Total scatter factors of small beams: A multidetector and Monte Carlo study

Small fields: Nonequilibrium radiation dosimetry

Accelerator beam data commissioning equipment and procedures: Report of the TG‐106 of the Therapy Physics Committee of the AAPM

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