American Brachytherapy Society recommendations for clinical implementation of NIST-1999 standards for 103palladium brachytherapy

Abstract Purpose: Recent important developments in palladium-103 ( 103 Pd) dosimetry mandate a reevaluation of 103 Pd brachytherapy prescribing practices. Methods and Materials: The clinical research committee of the American Brachytherapy Society (ABS) convened a consensus session of brachytherapists and physicists to develop recommendations regarding future dose prescribing guidelines for National Institute of Standards and Technology (NIST-1999) calibrated 103 Pd sources. Results: The ABS recommends that clinicians attempt to reproduce the implant doses delivered and reported in the literature through the past decade. Conclusions: The following should be immediately implemented for 103 Pd dosimetry: 1) All practicing physicians, physicists, dosimetrists, and suppliers implement NIST-1999 air-kerma strength standard for 103 Pd brachytherapy. 2) All treatment planning systems and dose calculation algorithms must be updated to reflect new dose rate constants. The AAPM-recommended validated value for Theraseed model 200 is 0.665 cGy h −1 U −1 . The dose rate constant for the Mentor MED3633 seed is currently reported as 0.68 cGy h −1 U −1 . This latter value and the values for seeds from other manufacturers are awaiting independent confirmation. 3) Physicians who previously prescribed 115 Gy for 103 Pd monotherapy prostate implants should now prescribe 125 Gy. When using 103 Pd as a boost following 45 Gy of external beam irradiation, 100 Gy should be prescribed instead of the previous 90 Gy. It is critical that all three changes be implemented concurrently , because they are interdependent.