Investigation of the Performance of Various CVD Diamond Crystal Qualities for the Measurement of Radiation Doses from a Low Energy Mammography X-Ray Beam, Compared with MC Code (PENELOPE) Calculations

Abstract

Abstract The tissue equivalence of diamond allows for accurate radiation dose determination without large corrections for different attenuation values in biological tissue, but its low Z value limits this advantage however to the lower energy photons such as for example in Mammography X-ray beams. This paper assays the performance of nine Chemical Vapour Deposition (CVD) diamonds for use as radiation sensing material. The specimens fabricated in wafer form are classified as detector grade, optical grade and single crystals. It is well known that the presence of defects in diamonds, including CVD specimens, not only dictates but also affects the responds of diamond to radiation in different ways. In this investigation, tools such as electron spin resonance (ESR), thermoluminescence (TL) Raman spectroscopy and ultra violet (UV) spectroscopy were used to probe each of the samples. The linearity, sensitivity and other characteristics of the detector to photon interaction was analyzed, and from the I-V characteristics. The diamonds categorized into four each, of the so called Detector and Optical grades, and a single crystal CVD were exposed to low X-ray peak voltage range (22 to 27 KVp) with a trans-crystal polarizing fields of 0.4 kV.cm-1, 0.66 kV.cm-1 and 0.8 kV.cm-1. The presentation discusses the presence of defects identifiable by the techniques used and correlates the radiation performance of the three types of crystals to their presence. The choice of a wafer as either a spectrometer or as X-ray dosimeter within the selected energy range was made. The analyses was validated with Monte-Carlo code (PENELOPE)