tailieunhanh - Báo cáo vật lý: "ATTENUATION STUDIES ON DRY AND HYDRATED CROSS-LINKED HYDROPHILIC COPOLYMER MATERIALS AT 8.02 TO 28.43 keV USING X-RAY FLUORESCENT SOURCES"

Tuyển tập các báo cáo nghiên cứu khoa học trên tạp chí khoa học vật lý quốc tế đề tài: ATTENUATION STUDIES ON DRY AND HYDRATED CROSS-LINKED HYDROPHILIC COPOLYMER MATERIALS AT TO keV USING X-RAY FLUORESCENT SOURCES | Journal of Physical Science Vol. 18 1 23-32 2007 23 ATTENUATION STUDIES ON DRY AND HYDRATED CROSS-LINKED HYDROPHILIC COPOLYMER MATERIALS AT TO keV USING X-RAY FLUORESCENT SOURCES Sabar Bauk1 Nicholas M. Spyrou2 and Michael J. Farquharson3 1Physical Sciences Programme School of Distance Education Universiti Sains Malaysia 11800 USM Pulau Pinang Malaysia 2Department of Physics University of Surrey Guildford GU2 7XH Surrey England department of Radiography City University London EC1M 6PA England Corresponding author sabar@ Abstract Hydrophilic copolymers which consist of a combination of hydrophobic monomers methyl methacrylate MMA and hydrophilic monomers vinyl pyrolidone VP have all the required major elements such as hydrogen carbon nitrogen and oxygen found in tissues. They have the potential to be used as breast phantom materials since they can be made to have similar elemental composition as that of body soft tissues. Photon attenuation measurements were performed on dry and hydrated hydrophilic copolymers using X-ray fluorescent XRF photons. They were obtained by bombarding copper molybdenum silver and tin targets to X-rays from an industrial X-ray tube effectively producing and keV photons. The measured mass attenuation coefficients of the samples were compared with the calculated breast mass attenuation coefficients. Keywords attenuation hydrophilic copolymer X-ray fluorescence 1. INTRODUCTION Breast cancer is a major health problem as it is the most common cancer in women. It comprises 28 of all female Mammographic techniques used for screening programmes need to be of the highest quality hence the need of a good phantom to mimic breast response to radiation. The phantom must be sensitive to small changes in the mammographic system and provides the means for evaluating the absorbed dose to the breast. The radiation and physical properties of cross-linked hydrophilic copolymers produced