| Author: | Wong, Hiu-ming |
| Title: | To establish optimum dose referencing points for bladder and rectum in intracavitary brachytherapy of cervical cancer |
| Degree: | M.Sc. |
| Year: | 2004 |
| Subject: | Hong Kong Polytechnic University -- Dissertations Radioisotope brachytherapy Bladder -- Cancer -- Treatment Rectum -- Cancer -- Treatment |
| Department: | Department of Optometry and Radiography |
| Pages: | x, 113 leaves : ill. (some col.) ; 30 cm |
| Language: | English |
| Abstract: | Purpose: This study aimed to evaluate the current dose referencing system for bladder and rectum in intracavitary brachytherapy of cervical cancer in terms of prediction of the late complications and representation of the maximum doses of the two organs. In addition, a new dose referencing system will be developed which can give a better indication of the maximum organ doses than the current one. Methods and Materials: Thirty-seven patients were retrospectively studied on the relationship between the current ICRU reference doses and the severity of late complications of the bladder and rectum. Using CT, the locations of the maximum bladder and rectal doses of seven patients were determined. Based on the locations of maximum dose points, a new dose referencing system was established. The clinical relevance of the new dose referencing system was evaluated by studying the relationship of the new reference doses with the severity of organ complications. Results: There was no correlation between the ICRU reference doses and development and severity of late complications for both bladder and rectum. With the help of CT, the maximum doses to the bladder and rectum were found to be, on average, 1.9 and 1.7 times higher than the ICRU reference doses respectively. Making use of the locations of the maximum dose points, a new referencing system was established in which the new bladder reference point was located at 1.28 cm right, 1.28 cm superior and 1.60 cm posterior to the ICRU bladder reference point and the new rectal reference point was located at 1.67 cm superior to the ICRU rectal refrence point. The new bladder reference dose was found to have positive association with the severity of bladder complications (r=0.38).Low risk of bladder complications could be achieved if the new bladder reference dose was kept below 95Gy.The new rectal reference dose did not show correlation with severity of rectal complications. Conclusion: Oncologists should be cautious when applying ICRU reference doses in predicting complications because these doses are poor surrogates of complications and maximum doses. With the new dose referencing system established in this study, it is recommended to use the new bladder reference point to supplement the current one. |
| Rights: | All rights reserved |
| Access: | restricted access |
Files in This Item:
| File | Description | Size | Format | |
|---|---|---|---|---|
| b17557513.pdf | For All Users (off-campus access for PolyU Staff & Students only) | 6.04 MB | Adobe PDF | View/Open |
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