A comparative study of two reconstructive methods and different recommendations in intracavitary brachytherapy

Area of Science:

• Radiation Oncology
• Gynecologic Oncology

Background:

• Intracavitary brachytherapy (ICB) is a standard treatment for cervical cancer.
• Conventional planning involves various reconstruction methods for ICB.
• Discrepancies exist between ICRU-38 and American Brachytherapy Society (ABS) recommendations for bladder dose point selection.

Purpose of the Study:

• To compare critical organ doses using different reconstructive methods in conventional ICB planning.
• To evaluate differences in bladder dose based on ICRU-38 and ABS recommendations.

Main Methods:

• Two reconstruction methods were compared: variable angle (M1) and orthogonal (M2).
• Radiographs from a conventional simulator were used for reconstruction.
• Bladder and rectum doses were calculated per ICRU-38 guidelines.
• ABS recommendations for maximum bladder dose reference points were also applied.

Main Results:

• The variable angle method (M1) showed higher bladder dose in 64% of plans and higher rectum dose in 50% of plans compared to the orthogonal method (M2).
• Maximum bladder dose points often differed from the ICRU-38 designated point in both methods.
• Significant dose variations exceeding 5% were noted in a considerable number of plans.

Conclusions:

• A notable difference in critical organ doses was observed between the variable angle and orthogonal reconstruction methods.
• The variable angle method appears advantageous for catheter identification in ICB.
• Adhering to ABS recommendations is beneficial for accurately determining maximum bladder dose.