The Impact of Patient Positioning and Use of Belly Board on Small Bowel and Urinary Bladder Volume Irradiated in Patients Receiving Radiotherapy for Rectal Cancer: A Prospective Phase II Study
This is a prospective non-randomized open study to evaluate the impact of patient's
positioning and use of belly board in rectal radiotherapy.
In contrast to previous studies, the clinical target volume and organ at risk will be
contouring for three-dimensional planning. With the aid of modern imaging, correlation can
be obtained between dose and volume (DVH) since both parameters have an impact on organ
tolerance to ionizing radiation.
Thirty patients with rectal cancer scheduled to receive "rectal radiotherapy", pre or
postoperative will be included (15 patients from each group).
In addition to radiotherapy, the patients will receive concomitant chemotherapy.
Chemotherapy: The chemotherapy will consist of one of the following:
1. Capecitabine (Xeloda) 825mg/m2 ×2/day, given every day of radiotherapy.
2. 5FU continuous infusion 180 mg/m2, D1-5/week X 5
The clinical target volume (CTV) for preoperative radiotherapy will include the entire
rectum and regional lymph nodes. The following lymph nodes will be contoured: peri rectal,
pre sacral, obturator, internal iliac and distal common iliac. The contouring of the rectum
will start 1 cm above the anal verge until the sigmoid (average 15 cm).
The planning target volume will be included in the CTV + 5mm The following organs at risk
will be contoured: small intestine, urinary bladder and femoral joints.
The prescription dose will be: 180cGy/day, 5 times a week for a total 5,040cGy (38b fraction
over 6 weeks.
Each patient will undergo two simulations, one in the supine position on a flat table and
another in the prone position on belly board. No contrast media will be used. The urinary
bladder will be full in an attempt to push the small bowel away from the treatment volume.
Three dimensional conformal radiotherapy planning will be done twice (one in each position).
Three and four fields plan will be evaluate in each position. Therefore a comparison will
be between four plains and the optimal plan will be chose for treatment..
The following parameters will be calculated:
1. Total volume of the small bowel
2. Total volume of urinary bladder
3. Intersection of PTV Volume and of small bowel volume
4. Intersection of PTV volume and of urinary bladder volume
5. Volume of small bowel included in the treatment volume
6. Volume of urinary bladder in the treatment volume
Endpoint Classification: Efficacy Study, Intervention Model: Single Group Assignment, Masking: Open Label, Primary Purpose: Treatment
Dose and irradiated volume of small bowel and urinary bladder
Eliahu Gez, MD
Israel: Ministry of Health