Assessment of additional radiation exposure during low-dose-rate brachytherapy for prostate cancer performed using computed tomography guidance.

Objective: To substantiate the feasibility of using computed tomography (CT) for monitoring the implantation of radioactive micro sources in terms of radiation exposure during low-dose-rate brachytherapy (LDRB) for prostate cancer (PCa).

Materials and Methods: Between October 2007 and April 2024, 2928 LDRB procedures for PCa were performed under CT guidance at the Federal State Budgetary Institution "North-Western district scientific and clinical center named after L. G. Sokolov Federal Medical and Biological Agency", St. Petersburg. An analysis was conducted on the radiation doses received by 168 patients treated in 2023. CT scanning of the small pelvis was performed during the stages of needle insertion and position control, as well as after source implantation and additionally, if necessary (average 5.2 scans). A comparison was made between the average radiation doses during LDRB and those of diagnostic and therapeutic procedures involving the organs of the small pelvis using ionizing radiation sources.

Results: The average radiation dose during CT-guided LDRB for PCa was 10.40 mSv (range: 4.5 to 18.6 mSv) per procedure. The dose varied depending on the number of CT series and the patient's body mass. Compared to diagnostic CT scans of the small pelvic organs, the dose during LDRB was higher than that of unenhanced CT scans (n=109) by an average of 2.1 mSv, and 13.6 mSv lower than doses from contrast-enhanced CT scans (n=126). Compared to the radiation doses from interventional therapeutic procedures, the dose from LDRB was 2.1 mSv higher than that of iliac artery stenting (n=44) and 1.96 mSv lower than that of prostatic artery embolization (n=26).

Conclusion: The radiation exposure during CT-guided LDRB for PCa exceeds the doses received during standard diagnostic procedures without contrast enhancement due to the need for multiple scans during a single procedure. However, the radiation doses from LDRB were lower than those from contrast-enhanced diagnostic CT scans and prostatic artery embolization. In 80% of cases, the radiation dose from CT during LDRB did not exceed 14 mSv.