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Abstract

BACKGROUND AND PURPOSE:

The present study aims to investigate the feasibility of two-dimensional (2D) in vivo rectal dosimetry using an endorectal balloon for the radiotherapy of prostate cancer.

MATERIALS AND METHODS:

The endorectal balloon was equipped with an unfoldable radiochromic film. The film was unrolled as the balloon was inflated, and rolled as it was deflated. Its mechanical and imaging properties were tested, and the dosimetric effectiveness was evaluated in clinical photon and proton beams.

RESULTS:

The size of the endorectal balloon including the film was linearly proportional to the volume of water filled in the balloon, and its position could be identified by X-ray radiography. The loss of dose information due to film cutting was within ±1mm from the cutting line. Applying linear interpolation on cut film, the gamma passing rate was more than 95% for 2%/2mm criteria. The measured dose profiles agreed with the plan within 3% and 4% for the photon and proton beams, respectively. A dose-volume histogram of the anterior rectal wall could be obtained from the measured dose distribution in the balloon, which also agreed well with the plan.

CONCLUSIONS:

2D in vivo rectal dosimetry is feasible using the endorectal balloon with a radiochromic film in the radiotherapy of prostate cancer. 

Author information

Jeang EH1, Min S1, Cho KH1, Hwang UJ2, Choi SH3, Kwak J4, Jeong JH1, Kim H1, Lee SB1, Shin D1, Park J1, Kim JY1, Kim DY1, Lim YK5.​

1Proton Therapy Center, National Cancer Center, Goyang, Republic of Korea.

2Department of Radiation Oncology, National Medical Center, Seoul, Republic of Korea.

3Department of Radiation Oncology, Korea Cancer Center Hospital, Seoul, Republic of Korea.

4Department of Radiation Oncology, Asan Medical Center, Seoul, Republic of Korea.

5Proton Therapy Center, National Cancer Center, Goyang, Republic of Korea. Electronic address: yklim@ncc.re.kr.