Photo Credit: Paul Biris

The following is a summary of “Improving prostate brachytherapy outcomes through MRI-Assisted dominant lesion dose painting,” published in the March 2025 issue of BMC Urology by Rahmani et al. 

Researchers conducted a retrospective study to assess the feasibility of using magnetic resonance (MR) images to implement a dose painting (DP) approach in prostate high-dose-rate brachytherapy.  

They included 45 patients with prostate tumors of varying grades. DILs were manually segmented with a 0.5 cm margin on T2W MR images. The bladder, rectum, and urethra were considered organs at risk (OARs). The treatment used LLA300-KB plastic needles and the HDRplus system, with an external dose of 45 Gy and a boost dose based on malignancy. Dosimetric evaluations and radiobiological analysis followed the RTOG protocol using equivalent doses in 2 Gy fractions (EQD2). 

The results showed no significant differences in rectal dose values between DP methods and conventional planning for tumor grades 2 to 5 (P > 0.05). However, 2 grade 5 patients had rectal V75cc values exceeding the limit with DP and a 43 Gy boost, though the average V75 remained below 1 cc. No significant differences were found in bladder dose values for grades 2 to 4 (P > 0.05), but the mean bladder V75cc in grade 5 patients with a 43 Gy boost exceeded the limit at 1.09. Urethral V125cc values showed no difference for grades 2 and 3 (P > 0.05) but were significantly different for grades 4 and 5. The average V125% and V150% of the whole prostate remained within 50–65% and 20–35%, respectively, across all tumor grades. However, V125 and V150 DILs exceeded standard limits and differed significantly from conventional planning (P < 0.05). EQD2 values for the whole prostate and DIL showed a significant difference in the DP method for all tumor grades (P < 0.05). 

Investigators provided individualized doses with the DP approach but faced limitations due to the proximity of DILs to OARs. 

Source: bmcurol.biomedcentral.com/articles/10.1186/s12894-025-01731-9