Photon Interaction Coefficients for the Colorectal Cancer Tissue.

Abstract

The application of radiotherapy to the treatment of cancer requires the knowledge of photon interaction coefficients such as mass attenuation (μm) and mass energy-absorption coefficients (μen/ρ). Although these coefficients have been determined for different tissues, it is lacking for the colorectal cancer (CRC) tissue in the literature. This study determines the μm and μen/ρ for the CRC tissue within the radiotherapy energy range. The CRC tissue from autopsy patients was freeze-dried, grounded into a fine powder, and made into pellets of 1 cm thickness. The elements detected in the CRC tissue using Rutherford backscattering spectrometry were used in XCOM to determine the theoretical values of μm and μen/ρ. The CRC tissue was again exposed to X-rays of energies of 6 and 15MV, respectively, to determine its experimental values of μm and μen/ρ. Elements detected included carbon, oxygen and nitrogen making up 96.67%, high atomic number and trace elements making up the remaining 3.33% fraction of the CRC tissue. The theoretical and experimental μm and μen/ρ values showed a good agreement of about 2% difference between them. These values can be used to simulate the CRC tissue with respect to μm and μen/ρ.