Physical principle of nuclear medicine imagining:
Since the gamma camera obtain the image in less time, it is usually preferred over the rectilinear scanner 

Thyroid imagining:

-About 4MBq of 131I is given orally the body the day before scan, or we can use 99mTcO4 which is taken by the same tissues that take up iodine.
-Tc is preferred since it gives a much smaller radiation dose to the patient.
-123I it lack of beta emission is also used

Liver:
- Normal liver tissue will filter radioactive submicroscopic particles from the blood ,while the tumor in the liver will not and appear on the scan as an area of reduced radioactivity.
- For liver scan ,200 Mq of 99m Tc –labeled sulfur colloid with particles about 0.5 µm in diameter is injected into a vein and image is obtained after 10 min.

Brain Tumor:
-  When injected into the blood ,different radioactive material are taken up bitterly by brain tumors than by surrounding normal brain tissue.
- About 500MBq of 99mTc is given ,after 2 hour four gamma camera images (the front ,back ,left and right sides of head) are taken