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Title: Effects of seed migration on post-implant dosimetry of prostate brachytherapy

Abstract

Brachytherapy using permanent seed implants has been an effective treatment for prostate cancer. However, seeds will migrate after implant, thus making the evaluation of post-implant dosimetry difficult. In this study, we developed a computer program to simulate seed migration and analyzed dosimetric changes due to seed migration at various migration amounts. The study was based on 14 patients treated with Pd-103 at the James Cancer Hospital. Modeling of seed migration, including direction, distance as well as day of migration, was based on clinical observations. Changes of commonly used dosimetric parameters as a function of migration amount (2, 4, 6 mm respectively), prostate size (from 20 to 90 cc), and prostate region (central vs peripheral) were studied. Change of biological outcome (tumor control probability) due to migration was also estimated. Migration reduced prostate D90 to 99{+-}2% of original value in 2 mm migration, and the reduction increased to 94{+-}6% in 6 mm migration. The reduction of prostate dose led to a 14% (40%) drop in the tumor control probability for 2 mm (6 mm) migration, assuming radiosensitive tumors. However, migration has less effect on a prostate implanted with a larger number of seeds. Prostate V100 was less sensitive to migration thanmore » D90 since its mean value was still 99% of original value even in 6 mm migration. Migration also showed a different effect in the peripheral region vs the central region of the prostate, where the peripheral mean dose tended to drop more significantly. Therefore, extra activity implanted in the peripheral region during pre-plan can be considered. The detrimental effects of migration were more severe in terms of increasing the dose to normal structures, as rectum V50 may be 70% higher and urethra V100 may be 50% higher in the case of 6 mm migration. Quantitative knowledge of these effects is helpful in treatment planning and post-implant evaluation.« less

Authors:
; ; ;  [1];  [2];  [3];  [2]
  1. Department of Radiation Medicine, Arthur G. James Cancer Hospital and Richard J. Solove Research Institute, Ohio State University, Columbus, Ohio 43210 (United States) and Department of Radiation Oncology, Stritch School of Medicine, Loyola University Medical Center, Maywood, Illinois (United States)
  2. (United States)
  3. (United States) and Kaiser Permanente Radiation Oncology, Santa Clara, California (United States)
Publication Date:
OSTI Identifier:
20951040
Resource Type:
Journal Article
Resource Relation:
Journal Name: Medical Physics; Journal Volume: 34; Journal Issue: 2; Other Information: DOI: 10.1118/1.2409748; (c) 2007 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
62 RADIOLOGY AND NUCLEAR MEDICINE; BRACHYTHERAPY; CARCINOMAS; COMPUTER CODES; DOSIMETRY; HOSPITALS; PALLADIUM 103; PATIENTS; PROSTATE; RADIATION DOSES; RADIATION SOURCE IMPLANTS; RECTUM; URINARY TRACT; VANADIUM 50

Citation Formats

Gao, M., Wang, J. Z., Nag, S., Gupta, N., Department of Radiation Medicine, Arthur G. James Cancer Hospital and Richard J. Solove Research Institute, Ohio State University, Columbus, Ohio 43210, Department of Radiation Medicine, Arthur G. James Cancer Hospital and Richard J. Solove Research Institute, Ohio State University, Columbus, Ohio 43210, and Department of Radiation Medicine, Arthur G. James Cancer Hospital and Richard J. Solove Research Institute, Ohio State University, Columbus, Ohio 43210. Effects of seed migration on post-implant dosimetry of prostate brachytherapy. United States: N. p., 2007. Web. doi:10.1118/1.2409748.
Gao, M., Wang, J. Z., Nag, S., Gupta, N., Department of Radiation Medicine, Arthur G. James Cancer Hospital and Richard J. Solove Research Institute, Ohio State University, Columbus, Ohio 43210, Department of Radiation Medicine, Arthur G. James Cancer Hospital and Richard J. Solove Research Institute, Ohio State University, Columbus, Ohio 43210, & Department of Radiation Medicine, Arthur G. James Cancer Hospital and Richard J. Solove Research Institute, Ohio State University, Columbus, Ohio 43210. Effects of seed migration on post-implant dosimetry of prostate brachytherapy. United States. doi:10.1118/1.2409748.
Gao, M., Wang, J. Z., Nag, S., Gupta, N., Department of Radiation Medicine, Arthur G. James Cancer Hospital and Richard J. Solove Research Institute, Ohio State University, Columbus, Ohio 43210, Department of Radiation Medicine, Arthur G. James Cancer Hospital and Richard J. Solove Research Institute, Ohio State University, Columbus, Ohio 43210, and Department of Radiation Medicine, Arthur G. James Cancer Hospital and Richard J. Solove Research Institute, Ohio State University, Columbus, Ohio 43210. Thu . "Effects of seed migration on post-implant dosimetry of prostate brachytherapy". United States. doi:10.1118/1.2409748.
@article{osti_20951040,
title = {Effects of seed migration on post-implant dosimetry of prostate brachytherapy},
author = {Gao, M. and Wang, J. Z. and Nag, S. and Gupta, N. and Department of Radiation Medicine, Arthur G. James Cancer Hospital and Richard J. Solove Research Institute, Ohio State University, Columbus, Ohio 43210 and Department of Radiation Medicine, Arthur G. James Cancer Hospital and Richard J. Solove Research Institute, Ohio State University, Columbus, Ohio 43210 and Department of Radiation Medicine, Arthur G. James Cancer Hospital and Richard J. Solove Research Institute, Ohio State University, Columbus, Ohio 43210},
abstractNote = {Brachytherapy using permanent seed implants has been an effective treatment for prostate cancer. However, seeds will migrate after implant, thus making the evaluation of post-implant dosimetry difficult. In this study, we developed a computer program to simulate seed migration and analyzed dosimetric changes due to seed migration at various migration amounts. The study was based on 14 patients treated with Pd-103 at the James Cancer Hospital. Modeling of seed migration, including direction, distance as well as day of migration, was based on clinical observations. Changes of commonly used dosimetric parameters as a function of migration amount (2, 4, 6 mm respectively), prostate size (from 20 to 90 cc), and prostate region (central vs peripheral) were studied. Change of biological outcome (tumor control probability) due to migration was also estimated. Migration reduced prostate D90 to 99{+-}2% of original value in 2 mm migration, and the reduction increased to 94{+-}6% in 6 mm migration. The reduction of prostate dose led to a 14% (40%) drop in the tumor control probability for 2 mm (6 mm) migration, assuming radiosensitive tumors. However, migration has less effect on a prostate implanted with a larger number of seeds. Prostate V100 was less sensitive to migration than D90 since its mean value was still 99% of original value even in 6 mm migration. Migration also showed a different effect in the peripheral region vs the central region of the prostate, where the peripheral mean dose tended to drop more significantly. Therefore, extra activity implanted in the peripheral region during pre-plan can be considered. The detrimental effects of migration were more severe in terms of increasing the dose to normal structures, as rectum V50 may be 70% higher and urethra V100 may be 50% higher in the case of 6 mm migration. Quantitative knowledge of these effects is helpful in treatment planning and post-implant evaluation.},
doi = {10.1118/1.2409748},
journal = {Medical Physics},
number = 2,
volume = 34,
place = {United States},
year = {Thu Feb 15 00:00:00 EST 2007},
month = {Thu Feb 15 00:00:00 EST 2007}
}