A compilation of microdosimetry for uniformly distributed Auger emitters used in medicine.
OBJECTIVE
To provide a compilation of microdosimetric characteristics for 12 Auger emitters commonly used in medicine.


METHODS
Monte Carlo electron track structure simulations are performed for 12 Auger emitters. They are (55)Fe, (67)Ga, (99m)Tc, (111)In, (113m)In, (115m)In, (123)I, (125)I, (193m)Pt, (195m)Pt, (201)Tl, and (203)Pb. Proximity functions of 12 Auger emitters are calculated from the simulated track structures and compared with that of gamma rays from (60)Co.


RESULTS
Some of those Auger emitters are highly radiotoxic compared to hard gamma rays from (60)Co. The more electrons per decay and the lower electron energies, the more effective an Auger emitter could be.


CONCLUSIONS
The high radiotoxicity of Auger emitters is due to correlations of low-energy electrons released from decay processes. If these correlations were disregarded, Auger emitters would not differ significantly from other low linear energy transfer (LET) radiation sources. Even in the case of uniform distribution, some of those Auger emitters are highly radiotoxic compared to hard gamma rays. For Auger emitters to bond to radiosensitive sites in cell nucleus, much higher radiation effectiveness could be expected.
Chen
Jing
J
Radiation Protection Bureau, Health Canada, Ontario, Canada. Jing-chen@hc-sc.gc.ca
D004583:Electrons; D005720:Gamma Rays; D009010:Monte Carlo Method; D011851:Radioactivity; D011868:Radioisotopes / Q000009:adverse effects / Q000737:chemistry*; D012062:Relative Biological Effectiveness
D011868:Radioisotopes