Monte Carlo computing applied to X-ray room design
Currently, x-ray rooms are designed by employing measured scatter and transmission data obtained nearly thirty years ago. Subsequently, there is a clear need to reevaluate this information as the use of modern equipment is becoming increasingly common. For example, x-ray tubes with medium frequency generators are replacing single phase units. Recent literature has re-evaluated transmission data. However, the scatter found in x-ray rooms has not been studied in detail. Two programs using Monte Carlo techniques have been developed for this purpose. The first program models the x-ray room including a slab phantom simulating the patient, a DAP meter, air and the room walls. The second program implements a realistic model of a patient in the imaging system. The results of the two programs have been validated by comparison with each other and by measurements. The results confirm that the patient is the primary source of scatter in a x-ray room. However, large variations in the scatter values are observed for different x-ray examinations and when the imaging parameters are changed. The results also show that there is a significant scatter contribution from other materials in the primary xray beam including the air, DAP meter and x-ray collimators. The first program has been used to calculate the scatter at a door positioned behind a protective screen at the radiographer's console. It predicts that no shielding in the door is required for the imaging system investigated. Therefore, a valuable computational tool has been developed which will aid the decision process in the design of clinical x-ray rooms.