A comparison of three-field and four-field techniques in different clinical target volumes in prostate cancer irradiation using dose volume histograms: a prospective three-dimensional analysis

Abstract

The purpose of the current study was to quantitatively assess differences between irradiation techniques on normal tissue exposure in different clinical target volumes (CTVs) in irradiation of prostate cancer. 14 patients with prostate cancer undergoing external beam radiotherapy were investigated. The prostate and prostate + proximal/entire seminal vesicles were delineated as CTVs. A three-field and two different four-field plans were generated and compared concerning rectum, bladder and femoral head dose-volume histograms (DVHs). The exposure of the rectum exposed to 40-60 Gy was significantly lower for all CTVs with the three-field technique compared with both four-field techniques. The exposure of the rectum to 70 Gy was significantly lower for all CTVs with the weighted four-field technique compared with the unweighted four-field and three-field techniques. The weighted four-field technique was worst in bladder dose sparing for the three CTVs. Comparing the three-field and the unweighted four-field technique for irradiation of the prostate and prostate + entire seminal vesicles, no technique provided a clear advantage or disadvantage in bladder dose sparing. For irradiation of the prostate + proximal seminal vesicles the unweighted four-field technique provided the best bladder dose sparing. Concerning the exposure of the femoral heads, the three-field technique was significantly worse for the three CTVs compared with both four-field techniques. No difference was found between the unweighted and the weighted four-field techniques. In conclusion, none of the studied techniques consistently proved superior in different CTVs in prostate cancer irradiation with respect to sparing all organs at risk. The absolute differences between the three techniques were small and the clinical relevance of these findings is uncertain.

A Prospective Three–Dimensional Analysis about the Impact of Differences in the Clinical Target Volume in Prostate Cancer Irradiation on Normal–Tissue Exposure

“…The value of reducing the CTV in three-dimensional conformal radiation therapy has to be assessed with caution regarding improved irradiation techniques. However, a study investigating different three-dimensional techniques (two different four-field techniques and a three-field technique) found that the differences in CTVs were comparable to the differences shown with the four-field technique described in our study [21].…”

Conformal radiotherapy of prostate cancer: What is the proper technique for sparing organs-at-risk?

“…Moreover, there was a benefit for the femoral heads with the six-field technique and the three-field arrangement consisting of an anterior and a pair of posterior oblique fields. Khoo et al (25) and Hille et al (26) showed a better sparing of the rectum with the three-field technique with two lateral fields. Hille et al (26) also reported that the forenamed technique was comparable to box technique, in terms of bladder.…”

“…Khoo et al (25) and Hille et al (26) showed a better sparing of the rectum with the three-field technique with two lateral fields. Hille et al (26) also reported that the forenamed technique was comparable to box technique, in terms of bladder. These results are congruent with the results of our study.…”