Journal de la science cellulaire et de la thérapie
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Optimization of Dose to Patient in Diagnostic Radiology Using Monte Carlo Method

Massoud E and Diab HM

Entrance Surface Dose (ESD) is one of the basic dosimetric quantities for measuring the patient dose and hence, an excellent tool for optimization purposes and for comparison with the international reference values. ESD value measurement for patient is also, an essential component of the quality assurance program for individual X-ray radiology departments. Factors affecting dose in all imaging modalities include beam energy, filtration, collimation, patient size, and image processing. Organ absorbed dose can be estimated by using a conversion factor along with a measured value of entrance exposure. When estimating the radiation dose of an individual patient, patient specific calculation methods can be used. The main objective of this study was to develop methods for assessment of ESD. In this study, image quality is quantified by modeling the whole X-ray imaging system, including the X-ray tube, and patient. This is accomplished by using Monte Carlo (MC) simulation methods that allow simultaneous estimates of measures of image quality and patient dose. In This study MCNP4C code was used to state a model for both human body and X-ray machine, to carry out such an investigation. Mathematical model of the human body with its all internal organs was used, and an image receptor of variable thickness and composition. Experimental results showed good agreement with theoretical predictions. The model may be used to generate data for a range of exposure conditions, and sample results will be presented. The usefulness and limitations of such a theoretical model will be discussed.