title: Energy and angular anisotropy optimisation of a p-type diode for in vivo dosimetry in photon-beam radiotherapy.
abstract: We present simulation work using the Monte Carlo code MCNPX that shows that there is a possibility of improving the silicon p-type diode as a radiation dosemeter, by altering the construction of the diode. Altering the diode die thickness can reduce the inherent angular anisotropy of the diode, with little effect on its energy response. Conversely, the contact material and geometry have a large impact on the energy response with little effect on the inherent angular anisotropy. By correct choice of contact material, the typical over-response -100 keV relative to the response at 60Co energy can be reduced from approximately 20 to 4. It is expected that further enhancements may be made with different geometries and materials.
authors.affiliation: Physics Department, Clatterbridge Centre for Oncology NHS Trust, Bebington, Wirral, UK.
authors.forename: Simon
authors.initials: S
authors.lastname: Greene
authors.forename: Robert A
authors.initials: RA
authors.lastname: Price
mesh_terms: D016880:Anisotropy; D003037:Cobalt Radioisotopes / Q000032:analysis*; D017076:Computer-Aided Design; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005240:Feasibility Studies; D018499:Linear Energy Transfer; D015233:Models, Statistical; D009010:Monte Carlo Method; D017785:Photons / Q000627:therapeutic use*; D011874:Radiometry / Q000295:instrumentation* / Q000379:methods; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000295:instrumentation* / Q000379:methods; D015203:Reproducibility of Results; D012542:Scattering, Radiation; D012666:Semiconductors; D012680:Sensitivity and Specificity
chemical_list: D003037:Cobalt Radioisotopes