Cervical brachytherapy utilizing ring applicator: comparison of standard and conformal loading

Area of Science:

• Radiation oncology
• Medical physics
• Gynecologic oncology

Background:

• Cervical cancer treatment often involves high-dose-rate brachytherapy (HDR).
• Traditional dosimetry relies on fixed point-A, which may not optimize target coverage or spare organs at risk (OAR).
• Advanced imaging and 3D reconstruction enable more precise, individualized treatment planning.

Purpose of the Study:

• To compare the dosimetric outcomes of individualized conformal planning versus standard fixed point-A dosimetry for HDR brachytherapy in cervical cancer.
• To evaluate the coverage of the planning target volume (PTV) and the dose delivered to organs at risk (OAR) using both planning techniques.

Main Methods:

• Fifteen patients with cervical cancer received radical external-beam radiotherapy and concurrent cisplatin chemotherapy.
• High-dose-rate brachytherapy was administered using intrauterine tube and ring applicators.
• Clinical target volumes (CTV) and OAR (rectum, bladder, small bowel) were delineated on CT scans. Conformal plans targeting the PTV were compared to standard point-A plans using the Conformal Index (COIN).

Main Results:

• Conformal plans achieved significantly better coverage of the planning target volume (PTV) compared to standard plans, as indicated by mean COIN values of 0.39 versus 0.33 (p = 0.001).
• Mean D95 values for the PTV were 4.79 Gy for conformal plans and 4.50 Gy for standard plans.
• The conformal approach demonstrated superior PTV coverage and dose distribution compared to the fixed point-A method.

Conclusions:

• Individualized conformal planning in HDR brachytherapy for cervical cancer offers superior PTV coverage.
• This technique effectively minimizes radiation dose to normal tissues (OAR) compared to fixed point-A dosimetry.
• Conformal loading, measured by COIN, represents an advancement in optimizing brachytherapy for cervical cancer treatment.