Dose distribution in 42 MV roentgen irradiation of cervical carcinoma

The dose distribution obtained with two different techniques for external irradiation of cervical carcinoma is described. The dose to the central area is somewhat higher with the multiple beam technique compared with the newly introduced shielding block technique. The difference between the calculated CRE values for the two techniques is small. When the shielding block is not placed over the area corresponding to the position of the applicators from the previous intracavitary treatment the considerable difference in absorbed dose between the two techniques does not correspond to the difference in the calculated CRE values. A comparison of the relative distributions laterally, in total dose and CRE, shows that for central volumes the relative CRE is much higher than the relative dose, when the normalization is made at the pelvic wall.