Dislocation of small bowel volume within box pelvic treatment fields, using new "up down table" device

Area of Science:

• Radiation Oncology
• Medical Physics
• Gastroenterology

Background:

• Pelvic radiotherapy often involves small bowel within the planning target volume, leading to potential toxicity.
• Minimizing irradiated small bowel volume is crucial for reducing acute and chronic gastrointestinal side effects.

Purpose of the Study:

• To evaluate the impact of a novel "up down table" (UDT) device on reducing small bowel volume in pelvic irradiation plans.
• To assess the correlation between irradiated small bowel volume and enteric toxicity.

Main Methods:

• A polystyrene bowel displacement mold and vacuum cushion (Vac Lok) were used with the UDT in 277 patients.
• Compared UDT patients with a historic series (68 patients) using standard box technique.
• Small bowel contrast dyes were used during simulation for all patients.

Main Results:

• The UDT significantly reduced average small bowel volume within the planning target volume (23 cm³ vs. 100 cm³) and any isodose volume (158 cm³ vs. 505 cm³).
• Incidence of acute enteric toxicity (G1-G3) was lower with UDT (16%, 15%, 1.5%) compared to standard technique (28%, 25%, 3%).
• Acute enteric toxicity correlated with irradiated small bowel volume; 5-year G3 chronic toxicity was 1.8% with UDT.

Conclusions:

• The up down table (UDT) technique effectively displaces small bowel from pelvic radiotherapy fields.
• UDT is comfortable, inexpensive, and highly reproducible, leading to reduced enteric toxicity.
• UDT offers a significant improvement in managing small bowel dose in pelvic irradiation.