An excellent reference would be George Sgouros papers. I am assuming by best you mean most reliable (accurate and precise). Your question has multiple aspects, including what is the best software tool to perform dosimetry, or what is the best way to provide inputs from the patients (e.g. radiotracer uptake) to these software tools. For the latter, several methods are available, such as imaging, blood samples, etc., and finding out which method is the best is an area of active research. Perhaps you might be interested in the following publication: https://www.ncbi.nlm.nih.gov/pubmed/26982626
Agree with Jha, OLINDA is the newest software for the estimation of patient internal organ absorbed dose and the GATE Monte Carlo package together with patient specific images (quantitative images) is validated method for this purpose. http://www.wjnm.org on Friday, May 13, 2016, IP: 2.182.119.43