1. Principles of Nuclear Medical Imaging ??????? ??? ?????? ????? ?????- ??? ?????? ????? ?????? ???? ????-????? ?????? ???????????? ????????

2. Technetium 99m (Tc 99m) It is the main isotope used in nuclear medicine imaging. It is used in more than 70-80% of cases. It emits gamma ray. It can easily label different kind of pharmaceuticals. It is always given intravenously.

3. Physiologic distribution of free Tc99m Salivary glands Choroids plexus Thyroid gland Gastric mucosa Kidneys and bladder

4. Biodistribution of Tc99m Pertechnetate ion Rapidly diluted in vascular space, partly bound to plasma proteins Unbound ion rapidly leaves vascular space via simple diffusion into interstitial spaces Removed from interstitial spaces by stomach, salivary glands, thyroid glands, bowel, choroid plexus, sweat glands, and kidneys Major routes of excretion are bowel and kidneys Pertechnetate ion Rapidly diluted in vascular space, partly bound to plasma proteins Unbound ion rapidly leaves vascular space via simple diffusion into interstitial spaces Removed from interstitial spaces by stomach, salivary glands, thyroid glands, bowel, choroid plexus, sweat glands, and kidneys Major routes of excretion are bowel and kidneys

5. Radiopharmaceuticals Pharmaceuticals are chemical compounds that have pharmacokinetics but do not have pharmacological effects. They are usually labeled with Tc99m. For each organ there is certain radiopharmaceuticals In general, nuclear medicine images the function (physiology), not the anatomy as in conventional radiology.

6. The Gamma Camera It is a device that uses gamma rays to make an image of radiopharmaceutical distribution and uptake in patients. Its crystal has a chemical propriety that if it is hit by a photon it will scintillate.

8. Gamma camera-cont.. Scintillation means light production. The light is converted into electrical current which then is stored in the computer as dot.

9. Scintillation Detectors The detection of radiation (gamma rays) by the camera is 2 step process. First a scintilation crystal is used to stop and absorb the gamma ray emitted by the patient. Here the gamma energy is converted into light Block of crystal material. Come in all shapes and sizes. Most expensive component in gamma cameraThe detection of radiation (gamma rays) by the camera is 2 step process. First a scintilation crystal is used to stop and absorb the gamma ray emitted by the patient. Here the gamma energy is converted into light Block of crystal material. Come in all shapes and sizes. Most expensive component in gamma camera