Premium
Dose reduction in LDR brachytherapy by implanted prostate gold fiducial markers
Author(s) -
Landry Guillaume,
Reniers Brigitte,
Lutgens Ludy,
Murrer Lars,
Afsharpour Hossein,
de HaasKock Danielle,
Visser Peter,
van Gils Francis,
Verhaegen Frank
Publication year - 2012
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.3685582
Subject(s) - brachytherapy , fiducial marker , nuclear medicine , imaging phantom , dosimetry , medicine , prostate cancer , radiation therapy , prostate , voxel , monte carlo method , radiation treatment planning , external beam radiotherapy , radiology , cancer , mathematics , statistics
Purpose: The dosimetric impact of gold fiducial markers (FM) implanted prior to external beam radiotherapy of prostate cancer on low dose rate (LDR) brachytherapy seed implants performed in the context of combined therapy was investigated. Methods: A virtual water phantom was designed containing a single FM. Single and multi source scenarios were investigated by performing Monte Carlo dose calculations, along with the influence of varying orientation and distance of the FM with respect to the sources. Three prostate cancer patients treated with LDR brachytherapy for a recurrence following external beam radiotherapy with implanted FM were studied as surrogate cases to combined therapy. FM and brachytherapy seeds were identified on post implant CT scans and Monte Carlo dose calculations were performed with and without FM. The dosimetric impact of the FM was evaluated by quantifying the amplitude of dose shadows and the volume of cold spots. D 90 was reported based on the post implant CT prostate contour. Results: Large shadows are observed in the single source‐FM scenarios. As expected from geometric considerations, the shadows are dependent on source‐FM distance and orientation. Large dose reductions are observed at the distal side of FM, while at the proximal side a dose enhancement is observed. In multisource scenarios, the importance of shadows appears mitigated, although FM at the periphery of the seed distribution caused underdosage (