Dosimetry for Cf-252 neutron emitting brachytherapy sources: Protocol, measurements, and calculations

The mixed-field dosimetry for Cf-252 Applicator Tube (AT) type medical sour ces available from Oak Ridge National Laboratory (ORNL) has been characteri zed using ionization chambers, a GM counter, and Monte Carlo methods. Unlik e the AAPM Task Group No. 43 (TG-43), specification of dose to muscle inste ad of water is recommended for clinical dosimetry of Cf-252 medical sources . A dosimetry protocol similar to ICRU 45 was formulated with parameters de termined specifically for Cf-252 brachytherapy. Comparisons of experimental and calculative dosimetry results with Colvett er al. [Phys, Med. Biol. 17 , 356-364 (1972)] and Krishnaswamy [Phys. Med. Biol, 17, 56-63 (1972)] were performed, and correction factors were determined to compare the different dosimetry formalisms. Using a Maxwellian model for the Cf-252 neutron ener gy spectrum, kerma relative to muscle was determined for a variety of mater ials, and compared with relative kermas for external neutron beams of three different energies. Neutron isodose distributions and data necessary for c linical implementation of Cf-252 AT sources are also presented. (C) 1999 Am erican Association of Physicists in Medicine. [S0094-2405(99)01508-4].