J Korean Soc Ther Radiol Oncol.  2001 Sep;19(3):287-292.

The Role of Air-Vacuum Cushion Device in Patients with Rectal Cancer in Radiation Therapy

• Kim KH
• Cho MJ
• Kang NH
• Kim DW
• Kim JS
• Jang JY
• Kim JS

Abstract

PURPOSE: We analyzed setup errors induced by using air-vacuum cushion as immobilization device in patients with rectal cancer.
MATERIALS AND METHODS
We had treated the twenty patients with rectal cancer by 6 MV, 10 MVx-ray from Aug. 1998 to Aug. 1999 at Chungnam National University Hospital. All patients were treated at prone position. They were separated to two groups, control group, 10 patients using styrofoam, and test group, 10 patients using styrofoam and air-vacuum cushion. We measured errors of posterior field forx, y axis and lateral field for z, y axis with simulation film and EPID image using a matching technique.
RESULTS
In control group, the mean displacement values of pelvic bone landmark forx axis and y axis were 0.02 mm. 0.78 mm, respectively and the standard deviations of systematic error were 2.13 mm, 2.40 mm, respectively and the standard deviation of random error were 1.46 mm. 1.51 mm, respectively. In test group, the mean displacement values ofx axis and y axis were -0.33 mm. 0.81 mm, respectively and the standard deviations of systematic error were 1.71 mm, 3.08 mm, respectively and the standard deviations of random errors were 1.40 mm. 1.88 mm, respectively. The mean displacement values of z axis and y axis were 2.98 mm. 0.74 mm, respectively and the standard deviations of systematic error were 4.75 mm, 2.65 mm, respectively and standard deviations of random error were 2.69 mm. 1.86 mm, respectively. The statistical difference of field size by using air vacuum cushion between two groups in posterior direction and lateral direction was not shown.
CONCLUSION
We think that use of air-vacuum cushion may not be an advantage for improving setup accuracy in rectal cancer patients.

Keyword

Immobilization; Radiation therapy; Rectal neoplasms

MeSH Terms

Axis, Cervical Vertebra
Chungcheongnam-do
Control Groups
Humans
Immobilization
Pelvic Bones
Prone Position
Rectal Neoplasms*
Vacuum