What is a Gamma Camera?
A Gamma Camera is a device, which is used as an imaging technique to produce functional scans of the brain, lungs, thyroid, liver, skeleton, gallbladder and kidneys. This technique is known as Scintigraphy. Large crystal of sodium iodide is used to detect the gamma photons. Whenever gamma photon hits the crystal, it gives a tiny flash of visible light. Photomultipliers picked the gamma photons to convert the flash into an electrical signal. The computer then evaluates electrical signals from the photomultipliers to construct an image. It is a painless, minimally invasive way to obtain a complete image that is highly helpful in the treatment that follows.
How does it help?
The Gamma Camera will track the radioisotope in the area to be scanned and will measure how the part processes it. There are multiple types of diagnostic scans performed by the Gamma Camera.
Types of scans
A Thallium stress test is a form of scintigraphy, where the amount of Thallium – 201 detected in cardiac tissues correlates with tissue blood supply. Viable cardiac cells have normal Na +/ K+ ion exchange pumps. Thallium binds the K+ pumps and is transported into the cells. Exercise or dobutamine induces reduction of radiotracers in the ischemic (compromised blood supply) regions of heart muscle. Areas of infracted tissue will remain "cold". Pre- and post-stress thallium may indicate areas that will benefit from myocardial revascularization. Redistribution indicates the presence of ischemic coronary artery diseases.
Renal Scintigraphy is a test in which dynamic images of the kidneys/renography are taken for quantifying the renal function (GFR) under a Gamma camera following the intravenous (I.V) injection of a radiopharmaceutical known as Tc99m DTPA.
It is performed by radiotracer technetium 99m MDP, which can be transported and attached to bone via the hydroxyapatite for imaging.
The most common indication for lung scintigraphy is to diagnose pulmonary embolism, e.g. with a ventilation/ perfusion scan. Less common indications include evaluation of lung transplantation, preoperative evaluation, and evaluation of right to left shunts.
A Tc-99m [pertechnetate] thyroid scan is a form of scintigraphy which reveals the general structure of the thyroid gland (e.g. nodular or diffuse enlargement) and its function.
Parathyroid scintigraphy is a test to localize parathyroid adenomas or parathyroid hyperplasia in patients with hyperparathyroidism that is determined on the basis of elevated parathyroid hormone levels in the setting of an elevated serum calcium level.
Biliary system (Cholescintigraphy)
Scintigraphy of the biliary system is called cholescintigraphy and is done to diagnose obstruction of the bile ducts by a gallstone (cholelithiasis), a tumor, or another cause. It can also diagnose other gall bladder diseases.