Track structure simulation for positron emitters of medical interest. Part I: The case of the allowed decay isotopes

With the increasing use of positron emission tomography in nuclear medicine, the knowledge and the expertise of β+ emitters have improved. However, numerous questions remain still unresolved and it appears today of prime importance to access to a detailed and accurate description of the complete track structure of the most used radio-isotopes in order to determine the damages potentially induced during medical exams in the investigated organs.In this work, we present a detailed inter comparison of the main isotopes used in nuclear medicine namely 18F, 11C, 13N, 15O, 68Ga, 82Rb, 62Cu, 52Fe and 44Sc. To do that, we use a home-made Monte Carlo code developed for positron tracking in water [C. Champion, C. Le Loirec, Phys. Med. Biol. 51 (2006) 1707] and recently adapted for simulating the complete decay of β+ radioisotopes in the biological matter, this latter being commonly modelled by liquid water.We also access, for each isotope, to quantitative data such as spatial and energetic (dosimetric) profiles. The results are in a major part given in an analytical way in order to be easily usable and then extrapolated to more complex situations. Furthermore, comparisons to existing experimental and theoretical data exhibit relatively good agreement.