Experimental determination of the dosimetric characteristics for the I‐Plant™ model 3600 I125 brachytherapy source

The dosimetric characteristics for a new brachytherapy seed source (I‐Plant™ model 3600) were measured using LiF thermoluminescent dosimeters and appropriate phantom materials in conformance with the methodology and guidance provided by the AAPM Task Group 43. The I‐Plant™ model 3600 is the successor to the I‐Plant™ model 3500. The major difference between these sources is that the model 3600 contains a leaded‐glass core to provide radio‐opacity (while the model 3500 contains a silver core), which does not produce spectral contamination upon neutron activation. The dose rate constant Λ for the model 3600 was determined to be 1.00Gyh−1U−1 (with a 6% overall relative standard deviation), compared to 1.01cGyh−1U−1 reported for the model 3500 in previous studies. The remaining dosimetric characteristics also are similar for both sources.