Comparison of bladder and rectal doses between conventional 2D and 3D brachytherapy treatment planning in cervical cancer

Authors: Chottaweesak P1, Shotelersuk K*,1, Amornvichet N1, Khorprasert C1, Oonsiri P2


Purpose:

Two-dimensional (2D) treatment planning has long been the standard in brachytherapy for cervical cancer
patients. However, 3-dimensional (3D) treatment planning using more advanced imaging techniques is increasingly used
to improve treatment efficacy. This is a retrospective study comparing radiation doses at the bladder and rectum between
2D and 3D treatment planning of brachytherapy in cervical cancer patients.




Materials and methods:

Between September 2009 and April 2011, nine cervical cancer patients treated with
brachytherapy underwent conventional 2D treatment planning using two orthogonal films and 3D treatment planning
using computed tomography (CT) simulation data. Radiation dose to point A, bladder and rectum were first calculated in
conventional 2D treatment planning using standard ICRU 38 recommendation, then 3D treatment planning was applied
in CT data set. Bladder D2cc and rectum D2cc were calculated in 3D treatment planning. Bladder and rectal point doses in
2D were compared to bladder D2cc and rectal D2cc in 3D treatment planning.




Results:

There were 16 brachytherapy applications. The mean bladder dose in 2D was 4.81 Gy while that in 3D was
7.49 Gy (p value < 0.001) The mean rectal dose in 2D and 3D were 5.26 Gy and 6.12 Gy, respectively (p value = 0.001).




Conclusion:

Bladder and rectal doses calculated in 2D brachytherapy treatment planning were statistically
significantly lower than bladder and rectum D2cc in 3D planning.