[Gate-users] positron range

[Kris Thielemans]

Dear Sam
> 
> I'm not a ''king'' in positron range questions, but isn't 0.2 
> mm about the MEDIUM range and 0.43 mm about the MAX range in 
> water for the 18-F positron ?
>

sounds small to me.

For instance, Pagani European Journal of Nuclear Medicine, Vol. 24, No. 10,
October 1997 
gives 0.7 mm for F-18 in soft tissue (although they use a (wrong)
mono-exponential model).

Unfortunately, the positron literature is not very consistent. Different
models are being used, and different mistakes are being made... I've looked
at this a while ago and found reasonable correspondence between curves from
Palmer and Brownell (TMI 92) and Levin and hoffman (but I thought they have
a mistake when evaluating consequences on images). However, the tails are
somewhat different, and this has large consequences for computing a "mean
distance travelled" (due to an r^2 term in the integral). So, I don't think
this "mean range" can really be reliably computed.

Kris