Brachytherapy dose changes: comparing in-room and out-room image-guided brachytherapy. A randomized study.

Area of Science:

• Radiation oncology
• Medical physics
• Oncological imaging

Background:

• Image-based brachytherapy techniques, including in-room brachytherapy (IRBT), offer advantages by limiting patient movement.
• However, IRBT may not be suitable for centers with high patient workloads.
• Out-room brachytherapy (ORBT) requires patient transfer, raising concerns about potential changes in organ at risk (OAR) positioning and dose delivery.

Purpose of the Study:

• To compare the changes in dose and volume of organs at risk (OARs) between in-room brachytherapy (IRBT) and out-room brachytherapy (ORBT).
• To evaluate the feasibility of ORBT in high-workload clinical settings.

Main Methods:

• A randomized prospective study was conducted comparing IRBT and ORBT.
• Patients underwent two CT scans: CT1 for treatment planning and CT2 immediately before brachytherapy delivery.
• Changes in D2cc doses and OAR volumes were analyzed by comparing CT1 and CT2 data.

Main Results:

• No significant differences were found in the mean D2cc dose changes to the bladder, rectum, and sigmoid between IRBT and ORBT.
• A total of 294 brachytherapy fractions were analyzed.
• Significant correlations were observed between D2cc dose changes and volume changes in OARs (p < 0.001).

Conclusions:

• In-room brachytherapy (IRBT) does not lead to significant differences in dose changes compared to out-room brachytherapy (ORBT) between planning and pre-treatment imaging.
• ORBT is a feasible and comparable alternative for routine practice, particularly in high-workload centers.
• The study confirmed correlations between volume changes and dose changes in OARs, highlighting the importance of monitoring these parameters.