Validation of a prototype DiodeAir for small field dosimetry.

Physics in Medicine and Biology
T S A UnderwoodJohn D Fenwick

Abstract

Standard commercial diode detectors over-respond within small radiation fields, an effect largely attributable to the relatively high mass-density of silicon. However, Monte Carlo studies can be used to optimise dosimeter designs and have demonstrated that 'mass-density compensation'-for example, introducing a low-density air-gap upstream of a diode's high-density silicon volume-can substantially improve instrument response. In this work we used egs_chamber Monte Carlo simulations to predict the ideal air-gap thickness for a PTW 60017 unshielded diode detector. We then developed a prototype instrument incorporating that air-gap and, for a 6 MV linac, tested it experimentally against EBT3 film. We also tested a further three prototypes with different air-gap thicknesses. Our results demonstrate that for a 10 × 10 cm(2) reference field the DiodeAir, a PTW 60017 diode with a built-in air-gap of 1 mm, has on-axis correction factors near unity. Laterally the DiodeAir performs very well off-axis and reports FWHM and penumbra values consistent with those measured using EBT3. For PDD measurement, the performance of the DiodeAir matches that of the original PTW 60017. The experimental focus of this work was 6 MV but we also simulated th...Continue Reading

References

Jun 15, 2007·Physica Medica : PM : an International Journal Devoted to the Applications of Physics to Medicine and Biology : Official Journal of the Italian Association of Biomedical Physics (AIFB)·F Sánchez-DobladoD M Gonzalez-Castaño
Dec 17, 2008·Medical Physics·R AlfonsoS Vatnitsky
Sep 14, 2010·Medical Physics·Saad AldelaijanJan Seuntjens
Jun 23, 2012·Physics in Medicine and Biology·Alison J D ScottJohn D Fenwick
Jun 14, 2013·Physics in Medicine and Biology·P H CharlesJ V Trapp

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Citations

May 24, 2018·Journal of Applied Clinical Medical Physics·Khalsa Al ShukailiAnatoly Rosenfeld
May 15, 2018·Physics in Medicine and Biology·John D FenwickAlan E Nahum
May 10, 2017·Physics in Medicine and Biology·A Kulmala, M Tenhunen
Dec 2, 2015·Physics in Medicine and Biology·Luis Brualla-GonzálezJuan Pardo-Montero
Jul 1, 2020·Physics in Medicine and Biology·Anatoly B RozenfeldVladimir Feygelman
Sep 14, 2019·Physics in Medicine and Biology·Sara NeiraJuan Pardo-Montero
May 12, 2020·Physics in Medicine and Biology·Georgios GeorgiouJohn D Fenwick
Aug 2, 2017·Australasian Physical & Engineering Sciences in Medicine·Benjamin PerrettScott Crowe
Aug 25, 2020·Applied Radiation and Isotopes : Including Data, Instrumentation and Methods for Use in Agriculture, Industry and Medicine·Wrya ParwaieMahdieh Afkhami Ardekani

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