Someone please help will mark as brainliest

a1

The main difference between SPECT and PET scans is the type of radiotracers used. While SPECT scans measure gamma rays, the decay of the radiotracers used with PET scans produce small particles called positrons. A positron is a particle with roughly the same mass as an electron but oppositely charged.

Explanation:

a2

While imaging tests such as X-rays can show what the structures inside your body look like, a SPECT scan produces images that show how your organs work. For instance, a SPECT scan can show how blood flows to your heart or what areas of your brain are more active or less active.

a3

PET and SPECT have been extensively evaluated as diagnostic procedures for dementia. Substantial progress has been made in developing radioligands that bind to amyloid deposits in the brain, which should provide new opportunities for early diagnosis and treatment monitoring in Alzheimer's disease

a4

What are the disadvantages of spect as compared to pet?

However, SPECT has issues, including long scan times and low-resolution images prone to artifacts and attenuation. Some artifacts can easily be misidentified as perfusion defects. SPECT also does not provide a quantifiable estimate of the blood flow, whereas PET does, experts say.

precipitation

explanation:

when it goes from cloud to rain/back to earth in the form of rain

h let me think