Mathematical estimation and in vivo dose measurement for cone-beam computed tomography on prostate cancer patients

Jeng, Shiu-Chen; Tsai, Chiao-Ling; Chan, Wen-Tung; Tung, Chuan-Jong; Wu, Jian-Kuen; Cheng, Jason Chia-Hsien

doi:10.1016/j.radonc.2009.03.010

« Previous Next »Radiotherapy & Oncology
Volume 92, Issue 1 , Pages 57-61, July 2009

Mathematical estimation and in vivo dose measurement for cone-beam computed tomography on prostate cancer patients

Shiu-Chen Jeng
- Department of Oncology, National Taiwan University, Taipei, Taiwan
- These authors contributed equally to this work.
Chiao-Ling Tsai
- Department of Oncology, National Taiwan University, Taipei, Taiwan
- These authors contributed equally to this work.
Wen-Tung Chan
- Institute of Biomedical Engineering and Environmental Science, National Tsing Hua University, Hsinchu, Taiwan
Chuan-Jong Tung
- Institute of Biomedical Engineering and Environmental Science, National Tsing Hua University, Hsinchu, Taiwan
- Institute of Medical Physics and Imaging Science, Chang Gung University, Taoyuan, Taiwan
Jian-Kuen Wu
- Department of Oncology, National Taiwan University, Taipei, Taiwan
Jason Chia-Hsien Cheng
- Department of Oncology, National Taiwan University, Taipei, Taiwan
- Graduate Institute of Clinical Medicine, National Taiwan University College of Medicine, Taipei, Taiwan
- Corresponding author. Address: Division of Radiation Oncology, Department of Oncology, National Taiwan University Hospital, No. 7, Chung-Shan South Rd., Taipei 100, Taiwan.

Received 30 October 2008; received in revised form 8 March 2009; accepted 8 March 2009. published online 01 May 2009.

Abstract

Background and purpose

Cone-beam computed tomography (CBCT) increases the doses on normal tissues. Our study sought to develop a mathematical model that would provide an estimate of and verify in vivo rectal dose from CBCT in prostate cancer patients.

Materials and methods

Thermoluminescent dosimeters (TLDs) and Rando phantoms were used to measure doses to the pelvic region. We used an endorectal balloon to measure rectal doses for 10 prostate cancer patients who underwent radiotherapy and for whom we were able to acquire CBCT images. A solid water phantom and TLDs were used to correlate the rectal doses with body thickness/widths. A mathematical method was established to simulate the dose to which the patient is exposed during CBCT for the determined body parameters. The estimated doses were compared with the measured doses to determine the effectiveness of the model.

Results

The average measured rectal dose from CBCT was 2.8±0.3cGy. The mathematical method was able to predict the rectal dose, with the limits of agreement of −0.03±0.18cGy. The average difference between predictions and measurements was −1.1±3.6%.