Abstract

Purpose：The aim of this study was to compare the dose distribution of intensity modulated radiation therapy (IMRT) with 3 dimensional conformal radiation therapy (3DCRT) in prostate cancer. Materials and Methods：The IMRT plan and the 3DCRT plan used the 9 fields technique, respectively. In IMRT, tumor dose was a total dose of 50 Gy at 2.0 Gy per day, 5 days a week for 5 weeks. All cases were following the dose volume histogram (DVH) constraints. The maximum and minimum tumor dose constraints were 5,075 cGy and 4,925 cGy, respectively. The rectum dose constraints were <35% over 40 Gy. The bladder dose constraints were <35% over 30 Gy. The femur head dose constraints were <15% over 16 Gy. Tumor dose in the 3DCRT were 50 Gy.
Results
：In IMRT, the maximum dose of PTV was 101.9% and minimum dose was 89.5% for given dose. In 3DCRT, the maximum dose of PTV was 103.5% and minimum dose was 86.5% for given dose. The rectum dose was 29.2% over 40 Gy in IMRT compared with 67.9% in 3DCRT. The bladder dose was 30.1% over 30 Gy in IMRT compared with 30.6% in 3DCRT. The right femur head dose was 5.3% over 16 Gy in IMRT compared with 8.3% in 3DCRT. The left femur head dose was 6.8% over 16 Gy in IMRT compared with 9.1% in 3 DCRT.
Conclusion
：The dose of critical organs (rectum, bladder, and femur head) in IMRT showed to reduce than dose of 3DCRT. The rectum dose over 40 Gy in IMRT was reduced 38.7% than 3DCRT. The bladder dose over 30 Gy in IMRT was similar to 3DCRT. The femur head dose over 16 Gy in IMRT was reduced about 2.3∼3% than 3DCRT.

• Keywords: IMRT, 3DCRT, prostate, dose distribution, DVH