MABDOSE. II: Validation of a general purpose dose estimation code

The MABDOSE software represents a general tool to assess internal radiation dose. A suite of tests are described that validate the dosimetry system's implementation; Methods: The validation suite is divided among tests that v erify target digitalization, tumor digitalization and organ replacement, cu mulated activity calculation, random number generation, radiation transport , and dose calculation. Results: A comparison between Reference Man organ v olumes and MABDOSE organ volumes at (5 mm)(3) resolution demonstrates volum e correspondence within 10% save for ten organs having dimensions smaller t han the target lattice resolution. An accounting of normal organ volume rep laced by an arbitrary tumor volume indicates mass is conserved. A compariso n between cumulated activities generated by MABDOSE and solutions obtained analytically demonstrates exact correspondence for curve-fitting algorithms . For mathematical modeling algorithms, cumulated activity;solutions conver ge to their correct values provided sufficient data of high precision are i nput, accompanied by reasonable initial estimates of rate constants. A comp arison of MABDOSE results with the MIRD 3 report demonstrates good agreemen t (<8% difference) in absorbed fractions for spheres at energies from 20 ke V to 2.75 MeV. A comparison of MABDOSE results with the Cristy-Eckerman rep ort demonstrates marginal agreement (specific absorbed fractions within a f actor of 2 for all Reference Man organs) at simulation energies of 20, 50, and 100 keV. Lack of exact correspondence is attributed to volume digitaliz ation errors, and to differences in cross-section libraries, interpolation schemes between cross-section data points, and random number generators. Fi nally, the doses reported by MABDOSE correspond to the correct algebraic co mbination of paired cumulated activities and "S" values. Conclusions: The M ABDOSE program has been validated as a general purpose computation tool for use in internal radionuclide dosimetry. (C) 1999 American Association of P hysicists in Medicine. [S0094-2405(99)01207-9].