Dose Distribution of Rectum and Bladder in Intracavitary Irradiation

Chu,  S S; Oh,  W Y; Suh,  C O; Kim,  G E

J Korean Soc Ther Radiol > Volume 2(2); 1984 > Article

Original Article

Journal of the Korean Society for Therapeutic Radiology 1984;2(2): 261-270.

Dose Distribution of Rectum and Bladder in Intracavitary Irradiation

S S Chu, W Y Oh, C O Suh, G E Kim

Department of Radiation Oncology, College of Medicine, Yonsei University, Yonsei Cancer Center, Korea.

ABSTRACT

The intrauterine irradiation is essential to achieve adequate tumor dose to central tumor mass of uterine malignancy in radiotherapy. The complications of pelvic organ are known to be directly related to radiation dose and physical parameters. The simulation radiogram and medical records of 206 patients, who were treated with intrauterine irradiation from Feb. 1983 to Oct. 1983, were critically analyzed. The physical parameters to include distances between lateral walls of vaginal fornices, longitudinal and lateral cervix to the central axis of ovoid were measured for low dose rate irradiation system and high dose rate remote control after loading system. The radiation doses and dose distributions within cervical area including interesting points and bladder, rectum, according to sources arrangement and location of applicator, were estimated with personal computer. Followings were summary of study results; 1. In distances between lateral walls of vaginal fornices, the low dose rate system showed as 4~7cm width and high dose rate system showed as 5~6cm. 2. In Horizontal angulation of tandem to body axis, the low dose rate system revealed mid position 64.6%, left deviation 19.2% and right deviation 16.2%. 3. In longitudinal angulation of tandem to body axis, the mid position was 11.8% and anterior angulation 88.2% in low dose rate system but in high dose rate system, anterior angulation was 98.5%. 4. Down ward displacement of ovoid below external os was only 3% in low dose rate system and 66.6% in high dose rate system. 5. In radiation source arrangement, the most activities of tandem and ovoid were 35 by 30 in low dose rate system but 50 by 40 in high dose rate system. 6. In low and high dose rate system, the total doses and TDF were 80, 70Gy and 131, 123 including 40 Gy external irradiation. 7. The doses and TDF in interesting points Co, B, were 98, 47Gy and 230, 73 in high dose rate system but in low dose rate system 125, 52Gy and 262, 75 respectively. 8. Doses and TDF in bladder and rectum were 70, 68Gy and 124, 120 in low dose rate system but in high dose rate system 58, 64Gy and 98, 110 respectively and then grades of injuries on bladder and rectum were 25, 30% and 18, 23% respectively.