Klin Onkol 1999; 12(2): 61-65.
Abstract: Background: Comparing conformal and conventional irradiation techniques in the treatment of prostate cancer. Design and Subjects: retrospective clinical study comparinmg the treatment plans of 10 patients with localized prostate cancer. Methods and results: The conformal technique (3 fields) and the conventional technique (4 fields) have been assessed; both of them were isocentric and complanar. The controus of the clinical target volume (prostate and the base of seminal vesicles) and organs at risk (rectum, urinary bladder, femoral heads) were outlined on CT scans. A margin of 10 mm was added to define the planning target volume (PTV). The fields of the conformal technique were shaped using multileaf collimator (MLC), while left opened for the conventional technique. The dose homogeneity in the PTV and the mean doses (Dm) and the fractions of the volume receiving the reference dose (V50, V80, V95) in the organs at risk were compared using dose-volume histograms. The conformal techníque was worse than the conventional technique when considering dose distribution homogeneity in the PTV. Regarding all the measured parameters, the rectum and urinary bladder were significantly spared by the conformal technique as compared to the conventional technique (p < 0.005). This benefit has been observed particularly in the high-dose region (V95). In the femoral heads, Dm was higher for the conformal technique than for conventional one (p < 0.005). The lateral parts of femoral heads were maximally exposed. Conclusions: The conformal technique, with respect to the conventional technique, provides better sparing of the organs at risk (rectum and bladder) excluding femoral heads, thus allowing for dose escalation to 75-81 Gy, which would probably result in improved local control of the disease.
