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Experimental measurements of dosimetric parameters on the transverse axis of a new 125 I source
Author(s) -
Li Zuofeng,
Fan J. J.,
Palta Jatinder R.
Publication year - 2000
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 - 10.1118/1.599005
Subject(s) - dosimetry , kerma , imaging phantom , thermoluminescent dosimeter , nuclear medicine , nist , calibration , brachytherapy , detector , thermoluminescent dosimetry , ionization chamber , materials science , optics , physics , medicine , dosimeter , radiation therapy , computer science , radiology , ionization , ion , quantum mechanics , natural language processing
Permanent prostate implant using125 I or103 Pd sources is a common treatment choice in the management of early prostate cancer. As sources of new designs are developed and marketed for application in permanent prostate implants, it is of paramount importance that their dosimetric characteristics are carefully determined, in order to maintain a high accuracy of patient treatment. This report presents the results of experimental measurements of the dosimetric parameters performed for a newly available125 I seed source, the model MED3631‐A/M source (IoGold™), manufactured by North American Scientific, Inc. The measurements were performed in a large scanning water phantom, using a diode detector. The positioning of the source and the diode detector was achieved by a computer‐controlled positioning mechanism in the scanning water phantom. The dose rate constant in water for the new125 I source was measured in comparison with an existing125 I source of similar design and verified using thermoluminescent dosimetry (TLD) measurement. The radial dose function values for the source were measured using the diode detector. The measurement technique and the results are compared with the dose distribution parameters for the125 I sources discussed in the AAPM TG43 report and elsewhere [Med. Phys. 26 , 570–573 (1999)]. For the dose rate constant in water of the new source, it is recommended that a value of 0.950 cGy/U‐hr be used based on the NIST 1985 air‐kerma strength calibration standard, or 1.060 cGy/U‐hr based on the 1999 NIST air‐kerma strength standard. The measured radial dose function values for the MED3631‐A/M source agree closely with those of the model 6702 source. It is therefore recommended that the radial dose function values for the model 6702125 I source, as recommended by the AAPM TG43 report, be adopted for the new source as well.