A 3D conformal radiation therapy class solution for dose escalated prostate irradiation

A Comparison of Field-in-Field and Intensity Modulated Radiation Therapy in Delivering Hypofractionated Radiation Therapy for Prostate Cancer

Purpose

This study compares the dosimetric performance of the field-in-field (FIF) technique with intensity modulated radiation therapy (IMRT) for delivering hypofractionated radiation therapy to prostate patients with cancer. The FIF technique uses 6 beams, whereas IMRT uses 9 beams.

Methods and Materials

This study was conducted on 15 patients with prostate cancer treated with step-and-shoot IMRT. The prescribed dose was 60 Gy in 20 fractions. The FIF plans contained 6 photon beams, and IMRT plans were designed using a 9-field step-and-shoot technique. Dose-volume histograms and dose distributions were evaluated to compare FIF and IMRT.

Results

The results of the planning target volume indices analysis showed a significant difference in the maximum dose, dose to 2% of volume, and homogeneity index in favor of FIF and in the mean dose, dose to 98% of volume, and D95 in favor of IMRT. The results of the organs-at-risk analysis showed significant differences in the volume of the rectum and bladder receiving 60 Gy in favor of FIF and the volume of the rectum and femoral heads receiving 30 Gy, as well as the mean dose to the rectum, in favor of IMRT. IMRT had a higher median number of monitor units (MUs) and segments (886 MU, 64 segments) compared to FIF (434 MUs, 6 segments).

Conclusions

The FIF technique and IMRT had comparable results in delivering hypofractionated radiation therapy for prostate cancer. The findings of this study may aid in decision-making for patients undergoing treatment.

The comparison of 5-field conformal radiotherapy techniques for the treatment of prostate cancer: The best for femoral head sparing

External radiotherapy is a standard treatment procedure for localized prostate cancer. Given the relatively high long term survival treatment complications have been brought in center of attention. In this planning study, between 2012 and 2014, CT simulation data of 90 consecutive high-risk prostate cancer patients were collected. In the first phase, all were planned for whole pelvis irradiation up to 46Gy in 23 daily fractions. In the second phase, only the prostate gland was the target of radiation. Next, the subjects were divided randomly into three groups and each received a unique 5field conformal radiation plan including Plan A (Gantry angle: 0, 60, 120, 240, and 300), Plan B (Gantry angles: 0, 90, 120, 240, and 270) and Plan C (Gantry angles: 0, 60, 90, 270, and 300). The total dose was 70Gy. For each patient, the rectum, bladder, and both femoral heads were contoured as the at risk organs (OAR). From dose volume histograms, the proportional dose of PTV V100, the bladder and rectum V80 and V90 and femoral head V50 and V100 were calculated in all subjects and compared across plans. A statistically significant difference in the femoral head V50 and V100 was found between our studied 5field plans so that in Plan A (beam angles: 0, 60, 120, 240 and 300) less dose was received by both heads of femur. This study suggests that 5 field treatment planning including an anterior, two anterior oblique and two posterior oblique portals to be more proper for 3D conformal radiotherapy in order to spare femoral head with acceptable PTV coverage, and bladder and rectal doses.