Published Report
Dislocation of small bowel volume within box pelvic treatment fields, using new "up down table" device
-Carlo Capirci M.D.a, Cesare Polico M.D. and Giovanni Mandoliti M.D., Department of Radiation Oncology, Rovigo's State Hospital, Rovigo, Italy
Purpose
To present the impact of a novel minimization device, the up down table (UDT), on the volume of small bowel included within a 4-field pelvic irradiation plan.
Methods
A polystyrene bowel displacement standard mold was created and added to a customized vacuum cushion (Vac Lok) formed around the abdomen and legs of each patient in the prone position. Two hundred seventy-seven consecutive patients with pelvic malignancies treated with the UDT device were compared with 1 historic series (68 cases) treated at our division. Small bowel contrast dyes at the time of simulation were used in all patients.
Results
The average volume of small bowel within the planning target volume (high-dose volume, calculated with Gallagher method) was 100 cm3 (median 49 ± 114) in the series treated with standard box technique and 23 cm3 (median 0 ± 64) in the series treated with the UDT (p < 0.001). The average volume of small bowel included in any isodose (any-dose volume) was 505 cm3 (median 447 ± 338) and 158 cm3 (median 69 ± 207), respectively (p < 0.001). The incidence of G1, G2, and G3 acute enteric toxicity (Radiation Therapy Oncology Group criteria) in the UDT series was 16%, 15%, and 1.5%; in the standard box technique, it was 28%, 25%, and 3%, respectively (p < 0.05). The incidence of acute enteric toxicity directly correlated with the irradiated small bowel volume. In the UDT series, the 5-year actuarial incidence of G3 chronic enteric toxicity was 1.8%. The setup procedures, analyzed in 18 cases, revealed no systematic errors and a standard deviation equal to ±5 mm for random errors.
Conclusions
The UDT technique is comfortable, inexpensive, highly reproducible, and permits an almost full bowel displacement from standard radiotherapy fields.
Author Keywords: Pelvic irradiation; Prevention of bowel injury; Small bowel tolerance
