Some of the women undergoing radiation therapy may be pregnant and the scatter radiation to the fetus and gonads is a matter of great concern. Quantitative measurement of the scatter dose in polystyrene solid phantoms with a Farmer type chamber and effects of shielding blocks under the collimators were studied. The scatter dose outside of the primary beam was found to be decreasing exponentially with increasing distance from the radiation beam edge. When the distance increased from 10 cm to 60 cm, the scatter dose drops from 1-2% to 0.15% for the Co-60 beam and from 1-2% to 0.02% for the 10 MV X-rays. The collimation system was a major source of scatter radiation because the scatter dose could be substantially reduced by placing shielding blocks under the collimators and the scatter dosed varied with field sizes. The lead apron used in diagnostic radiographic procedures reduced the scatter dose by 5-6% only. The scatter dose distribution in the body outside of the radiation field was also analyzed.
|Number of pages||7|
|Journal||Taiwan yi xue hui za zhi. Journal of the Formosan Medical Association|
|State||Published - May 1989|