Gold marker displacement due to needle insertion during HDR-brachytherapy for treatment of prostate cancer: A prospective cone beam computed tomography and kilovoltage on-board imaging (kV-OBI) study

Abstract

PurposeTo evaluate gold marker displacement due to needle insertion during HDR-brachytherapy for therapy of prostate cancer.Patients and methods18 patients entered into this prospective evaluation. Three gold markers were implanted into the prostate during the first HDR-brachytherapy procedure after the irradiation was administered. Three days after marker implantation all patients had a CT-scan for planning purpose of the percutaneous irradiation. Marker localization was defined on the digitally-reconstructed-radiographs (DRR) for daily (VMAT technique) or weekly (IMRT) set-up error correction. Percutaneous therapy started one week after first HDR-brachytherapy. After the second HDR-brachytherapy, two weeks after first HDR-brachtherapy, a cone-beam CT-scan was done to evaluate marker displacement due to needle insertion. In case of marker displacement, the actual positions of the gold markers were adjusted on the DRR.ResultsThe value of the gold marker displacement due to the second HDR-brachytherapy was analyzed in all patients and for each gold marker by comparison of the marker positions in the prostate after soft tissue registration of the prostate of the CT-scans prior the first and second HDR-brachytherapy. The maximum deviation was 5 mm, 7 mm and 12 mm for the anterior-posterior, lateral and superior-inferior direction. At least one marker in each patient showed a significant displacement and therefore new marker positions were adjusted on the DRRs for the ongoing percutaneous therapy.ConclusionsNeedle insertion in the prostate due to HDR-brachytherapy can lead to gold marker displacements. Therefore, it is necessary to verify the actual position of markers after the second HDR-brachytherapy. In case of significant deviations, a new DRR with the adjusted marker positions should be generated for precise positioning during the ongoing percutaneous irradiation.

Catheter displacement prior to the delivery of high-dose-rate brachytherapy in the treatment of prostate cancer patients

“…Herrmann et al . [ 14 ] also reported displacement of markers after HDR brachytherapy, especially in the superior-inferior direction (mean: 3 mm). They discussed possible reasons for displacement such as localized bleeding into the prostate gland, or dislocation of prostate tissue inside the gland due to needle insertion.…”

Evaluation of a mobile C‐arm cone‐beam CT in interstitial high‐dose‐rate prostate brachytherapy treatment planning

“…Cone‐beam CT (CBCT) scanners are becoming more available in surgical theatres and are commonly used in image guidance in radiotherapy, angiography, mammography and orthopaedics . Previous studies have investigated CBCT in the context of brachytherapy. Al‐Halabi et al .…”

“…This issue could be solved by readjusting the catheters. Herrmann et al . studied the displacement of fiducial gold markers due to needle insertion in HDR brachytherapy for prostate cancer.…”