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Sci—Fri AM(2): Brachy—03: A Guide to Systematically Load Radioactive I‐125 Sources in Prostate Implant
Author(s) -
Tran MN,
Malkoske K,
Ong A,
Chowdhury A,
Bews J
Publication year - 2009
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 - 10.1118/1.3244195
Subject(s) - brachytherapy , dosimetry , prostate brachytherapy , prostate , implant , prostate cancer , radiation treatment planning , medicine , nuclear medicine , medical physics , radiation therapy , computer science , biomedical engineering , radiology , surgery , cancer
Objectives: To develop a generalized treatment planning strategy for prostate brachytherapy, and evaluate the interdependence of the radioactive125 I seed strength (activity), volume, implant dosimetry, and number of seeds per implant. Methods: Prostate brachytherapy is utilized in the management of clinically localized prostate cancer. It involves the trans‐perineal insertion of seed‐containing needles into the prostate. Prior to the implant, the patient undergoes a volume study where semi‐axial images of the prostate are obtained. A physicist uses these images to come up with a plan outlining the appropriate locations of the seeds to achieve the desired implant dosimetry. The dose is related to the activity and the separation of seeds. To maintain a similar dose distribution, an increase in seed activity must be balanced by an increase in the seed spacing. To eliminate the time‐consuming trial & error approach, we have come up with a set of rules to position seeds to achieve an acceptable plan. The technique has been tested on several prostates of different volumes, and the quality of the plans was evaluated. Results and Conclusions: For the cases examined so far, the technique has been efficient in determining the ideal seed locations. By appropriately increasing the activity and repositioning seeds, the total number of seeds can be reduced without appreciably altering plan quality. This will reduce material costs and the number of needles inserted, thereby increasing efficiency and lowering the associated trauma. Issues such as sensitivity of placement error need to be examined fully before the decision to increase the activity is made.