1. The problem statement, all variables and given/known data Why does SPECT produce images with higher contrast compared with its alternatives such as PET? 3. The attempt at a solution I HAVE NO IDEA! I honestly researched everywhere, they only say that it has a higher contrast. I think its something to do with the hardness (penetrating power) of the gamma rays but that doesnt make sense. Can someone please help me as i am doing some research for some assignment and i need it ASAP. Thanks.