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Int J Radiat Oncol Biol Phys. 2000 Oct 1;48(3):649-56.

Reduction of small and large bowel irradiation using an optimized intensity-modulated pelvic radiotherapy technique in patients with prostate cancer.

Author information

  • 1Academic Department of Radiotherapy, Institute of Cancer Research and The Royal Marsden NHS Trust, Sutton, Surrey, UK. chrisnutting@cs.com

Abstract

PURPOSE:

To investigate the role of intensity-modulated radiation therapy (IMRT) to irradiate the prostate gland and pelvic lymph nodes while sparing critical pelvic organs, and to optimize the number of beams required.

METHODS AND MATERIALS:

Target, small bowel, colon, rectum, and bladder were outlined on CT planning scans of 10 men with prostate cancer. Optimized conventional (RT) and 3-dimensional conformal radiotherapy (3D-CRT) plans were created and compared to inverse-planned IMRT dose distributions using dose-volume histograms. Optimization of beam number was undertaken for the IMRT plans.

RESULTS:

With RT the mean percentage volume of small bowel and colon receiving >45 Gy was 21.4 +/- 5.4%. For 3D-CRT it was 18.3 +/- 7.7% (p = 0.0043) and for 9-field IMRT it was 5.3 +/- 1.8% (p < 0.001 compared to 3D-CRT). For 7, 5, and 3 IMRT fields, it was 6.4 +/- 2.9%, 7.2 +/- 2.8%, and 8.4 +/- 3.8% (all p < 0.001 compared to 3D-CRT). The rectal volume irradiated >45 Gy was reduced from 50.5 +/- 16.3% (3D-CRT) to 5.8 +/- 2.1% by 9-field IMRT (p < 0. 001) and bladder from 52.2 +/- 12.8% to 7 +/- 2.8% (p < 0.001). Similar benefits were maintained for 7, 5, and 3 IMRT fields.

CONCLUSIONS:

The reduction in critical pelvic organ irradiation seen with IMRT may reduce side effects in patients, and allow modest dose escalation within acceptable complication rates. These reductions were maintained with 3-5 IMRT field plans which potentially allow less complex delivery techniques and shorter delivery times.

PMID:
11020560
[PubMed - indexed for MEDLINE]
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