Investigating the dosimetric and tumor control consequences of prostate seed loss and migration

Journal Article · Fri Jun 15 04:00:00 EDT 2012 · Medical Physics

DOI:https://doi.org/10.1118/1.4712227· OSTI ID:22098877

Knaup, Courtney; Mavroidis, Panayiotis; Esquivel, Carlos; Stathakis, Sotirios; Swanson, Gregory; Baltas, Dimos; Papanikolaou, Nikos ^[1]

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1. Department of Radiation Oncology, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229 (United States)

Purpose: Low dose-rate brachytherapy is commonly used to treat prostate cancer. However, once implanted, the seeds are vulnerable to loss and movement. The goal of this work is to investigate the dosimetric and radiobiological effects of the types of seed loss and migration commonly seen in prostate brachytherapy. Methods: Five patients were used in this study. For each patient three treatment plans were created using Iodine-125, Palladium-103, and Cesium-131 seeds. The three seeds that were closest to the urethra were identified and modeled as the seeds lost through the urethra. The three seeds closest to the exterior of prostatic capsule were identified and modeled as those lost from the prostate periphery. The seed locations and organ contours were exported from Prowess and used by in-house software to perform the dosimetric and radiobiological evaluation. Seed loss was simulated by simultaneously removing 1, 2, or 3 seeds near the urethra 0, 2, or 4 days after the implant or removing seeds near the exterior of the prostate 14, 21, or 28 days after the implant. Results: Loss of one, two or three seeds through the urethra results in a D{sub 90} reduction of 2%, 5%, and 7% loss, respectively. Due to delayed loss of peripheral seeds, the dosimetric effects are less severe than for loss through the urethra. However, while the dose reduction is modest for multiple lost seeds, the reduction in tumor control probability was minimal. Conclusions: The goal of this work was to investigate the dosimetric and radiobiological effects of the types of seed loss and migration commonly seen in prostate brachytherapy. The results presented show that loss of multiple seeds can cause a substantial reduction of D{sub 90} coverage. However, for the patients in this study the dose reduction was not seen to reduce tumor control probability.

• OSTI ID: 22098877
• Journal Information: Medical Physics, Journal Name: Medical Physics Journal Issue: 6 Vol. 39; ISSN 0094-2405; ISSN MPHYA6
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
BIOLOGICAL RADIATION EFFECTS
BRACHYTHERAPY
CESIUM 131
COMPUTER CODES
DOSE RATES
DOSIMETRY
EVALUATION
IODINE 125
NEOPLASMS
PALLADIUM 103
PATIENTS
PLANNING
PROSTATE
RADIATION DOSES
RADIATION SOURCE IMPLANTS
RADIOBIOLOGY
SIMULATION
URINARY TRACT