Radionuclide imaging (a form of functional imaging) provides a means of assessing such physiologic changes.
Radionuclide is a diagnostic modality in which radio-pharmaceuticals are used to get images.
Nuclear medicine examinations are commonly used to assign function of the brain, thyroid, heart, lungs, and gastrointestinal system as well as for diagnosis and follow-up of metastatic disease, bone tumors and infection.
Radionuclide imaging uses radioactive atoms or molecules that emits gamma (y) rays.
Radio-pharmaceuticals are administered intravenously in the body and they reach the affected bone and bind with pathological lesion by tagging with the tissue resulting in the release of gamma rays by the disintegration of radioactive substances.
This gamma rays are detected by gamma camera, forms planar images showing the locations of radionuclides in the body.
This image is recorded as scintigraphy.
SPECT and PET imaging are advanced nuclear medicine techniques that form tomographic views.
Principles
Widely used radionuclides are
99m Tc (Technetium): t1/2- 6 hours, mimics
Iodine distribution when given i.v – for brain tumors, thyroid gland, skeletal
system, respiratory system diagnostics — bound to Methylene diphosphate (MDP)
mu
131 I (Iodine): t1/2 – 804 days, for iodine
metabolism, liver, kidney function.
67 Ga (Gallium): for infection like
Osteomyelitis
74 Se (Selenium)
51 Cr: t1/2- 277 days, In hematology
198 Au: t1/2- 2.697 days
111 In: for liver, brain diagnosis
Gamma emitting Isotopes
Iodine (131 I)
Gallium (67 Ga)
Selenium (74 Se)
Target (Critical) Organs
Target organ is organ in which radio-pharmaceuticals are maximally accumulated and which is exposed by excessive radiation.
Mostly it is organ we want to examine.
Be safely regulations, there are 3 groups of target/ organs due to decreasing / radio sensitivity.
Group: whole body, genitals, bone marrow, small
intestine mucosa
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