A Study on Design and Application of Tissue Compensator for 6MV X-rays.
- Author:
Kyu Young CHAI
1
;
Eun Kyung CHOI
;
Woong Ki CHUNG
;
Wee Saing KANG
;
Sung Whan HA
;
Charn Il PARK
Author Information
1. Department of Therapeutic Radiology, College of Medicine Seoul National University, Seoul, Korea.
- Publication Type:Original Article
- Keywords:
6 MV X-ray;
Compensator;
Isoheight technique;
Laser beam system
- MeSH:
Axis, Cervical Vertebra;
Compensation and Redress;
Film Dosimetry;
Radiotherapy;
Reading
- From:Journal of the Korean Society for Therapeutic Radiology
1989;7(1):123-132
- CountryRepublic of Korea
- Language:Korean
-
Abstract:
A radiation beam incident on an irregular or sloping surface produces the non-uniformity of absorbed dose. The use of a tissue compensator can partially correct this dose inhomogeneity. The tissue compensator is designed based on the patient's three dimensional contour. After required compensator thickness was determined according to tissue deficit at 25 cmx 25 cm field size, 10 cm depth for 6MV x-rays, tissue deficit was mapped by isoheight technique using laser beam system. Compensator was constructed along the designed model using 0.5 mm lead sheet or 5 mm acryl plate. Dosimetric verification were performed by film dosimetry using humanoid phantom. Dosimetric measurements were normalized to central axis full phantom readings for both compensated and non-compensated field. Without compensation, the percent differences in absorbed dose ranged as high as 12.1% along transverse axis, 16.8% along vertical axis. With the tissue compensators in place, the difference was reduced to 0~4.3% Therefore, it can be concluded that the compensator system constructed by isoheihnt technique can produce good dose distribution with acceptable inhomogeneity, and such compensator system can be electively applied to clinical radiotherapy.
