Evaluation of temperature effects in p-type silicon detectors

Grusell, Erik; Rikner, Göran

doi:10.1088/0031-9155/31/5/005

Cited by 62 publications

(48 citation statements)

References 8 publications

(10 reference statements)

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“…The ion chamber was placed at maximum depth in the plastic water phantom and the diodes at surface. Diode sensitivity increases with temperature 10,15 and the use of correction factors to account for this effect is recommended. The temperature correction factor is defined as:…”

Section: Diode Calibrationmentioning

confidence: 99%

Implementation of in vivo Dosimetry with Isorad™ Semiconductor Diodes in Radiotherapy Treatments of the Pelvis

Rodríguez¹,

Abrego²,

Pineda³

2008

Medical Dosimetry

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Section: Diode Calibrationmentioning

confidence: 99%

Implementation of in vivo Dosimetry with Isorad™ Semiconductor Diodes in Radiotherapy Treatments of the Pelvis

Rodríguez¹,

Abrego²,

Pineda³

2008

Medical Dosimetry

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“…The sensitivity of a diode detector is defined as the charges generated per absorbed dose, and can be expressed as the following, for simplified steady state processes: 13,14,[16][17][18] …”

Section: Introductionmentioning

confidence: 99%

“…The most prevalent of these processes is charge recombination in a silicon diode through recombination-generation, R-G, centers, which capture excess minority carriers and facilitate recombination with a majority carrier. [14][15][16][17][18] The R-G center is not open for further capture of minority carriers until the minority-majority carrier recombination is complete. 19 Generally, the recombination of charge at a R-G center, the reopening of the R-G center, takes place between 0.25 and tens of microseconds.…”

Section: Introductionmentioning

confidence: 99%

Dependence of diode sensitivity on the pulse rate of delivered radiation

Jursinic

2013

Med. Phys.

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A decrease in diode sensitivity occurs with a decrease in the average dose rate, which corresponds to an increase in the pulse period of radiation. The sensitivity decrease is modeled by an empirical exponential function that decreases with an effective lifetime, t(eff), of 1.0-14 s. t(eff) varies widely for different diodes, dpp, and x-ray energy. It is hypothesized that the capture of excess minority carriers by charge traps, cause the observed decrease in diode sensitivity. Also, it is hypothesized that the slow reopening of these traps occurs in the hundreds of milliseconds to seconds range at ambient temperature and this underlies the slow decrease in the diode sensitivity. Calibration of a diode is best done at the average dose rate with which it will be used. This is easily accomplished for radiation deliveries in which the average dose rate is a constant. However, for a VMAT delivery the average dose rate is a variable. For measurements made under these conditions diodes can be calibrated with a median or average dose rate which splits the difference in diode sensitivity that is known to occur with changes in average dose rate.

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“…1 The physical characteristics of commercial diodes for use in IVD have been examined by several authors [2][3][4][5][6][7][8][9][10][11] and it is well established, that with careful use, high precision can be achieved. 1 The physical characteristics of commercial diodes for use in IVD have been examined by several authors [2][3][4][5][6][7][8][9][10][11] and it is well established, that with careful use, high precision can be achieved.…”

Section: Introductionmentioning

confidence: 99%

Systematic in vivo dosimetry for quality assurance using diodes 2: Assessing radiotherapy techniques and developing an appropriate action protocol

et al. 2004

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Purpose: Having previously reviewed the implementation of systematic in vivo dosimetry at the Norfolk and Norwich Hospital this paper examines the results of entrance dose measurements for specific sites/techniques and determines whether different action/alert protocols are required for these different categories. Methods and materials: Entrance dose measurements using p-type diodes were analysed for the following treatment categories: Breast, head and neck in beam direction shell, abdomino-pelvic and intrathoracic. A 4% tolerance was applied. Results: Mean deviations from expected dose and proportion of measurements exceeding tolerance were: Breast: ϩ1.15% Ϯ 3.04% (1SD), 238/1073 Ն 4%; Head and neck: ϩ0.35% Ϯ 2.20% (1SD), 21/326 Ն 4%; Abdomino-pelvic: ϩ0.52% Ϯ 2.75% (1SD), 93/712 Ն 4%; Intrathoracic: Ϫ0.01% Ϯ 2.75% (1SD), 22/119 Ն 4%. Significant improvements in results for breast patients were noted following the introduction of a commercial breast board. The results for abdomino-pelvic patients confirmed a substantial variation in diode response under short FSD, wedged fields at 16 MV (that had not been corrected for). The statistical uncertainty in dose measurement for each treatment category was calculated in order to assist determination of appropriate tolerance levels. Conclusions: A blanket tolerance of 4% was generally too low given the extent of measurement uncertainty. The relatively high number of readings outside tolerance where identification of errors was difficult/impossible resulted in inconsistent application of the action protocol. Some widening of tolerances is likely to improve quality of procedure and treatment. Appropriate action levels are recommended for each treatment category. This value could be reduced if a variation in diode response under wedged fields at 16 MV was corrected for. § These values are larger mainly as a consequence of a relatively higher proportion of FSD inaccuracies for this category. Improvements in this respect would reduce these figures to the level seen for isocentric abdomino-pelvic techniques.

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Evaluation of temperature effects in p-type silicon detectors

Cited by 62 publications

References 8 publications

Implementation of in vivo Dosimetry with Isorad™ Semiconductor Diodes in Radiotherapy Treatments of the Pelvis

Implementation of in vivo Dosimetry with Isorad™ Semiconductor Diodes in Radiotherapy Treatments of the Pelvis

Dependence of diode sensitivity on the pulse rate of delivered radiation

Systematic in vivo dosimetry for quality assurance using diodes 2: Assessing radiotherapy techniques and developing an appropriate action protocol

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