Physical principle of imaging with gamma-rays

Imaging with gamma rays is creating medical diagnostic images using gamma rays, photons of penetrating electromagnetic radiation emitted from an atomic nucleus. This procedure is an advanced modern medical technique that allows whole body scans (PET), or more organ and tissue specific scans (SPECT) e.g.: lung scan, heart scan, bone scan, brain scan It is used in several branches of medicine and is an important part of practical medicine.

Medical uses

Imaging with gamma rays is used in court medicine, as well as nuclear medicine. This technique can be used for both diagnosis and prevention. Imaging with gamma rays has a wide range of functions, such as:
 * Tumor imaging  http://sydney.edu.au/health-sciences//images/newsevents/news/LungSPECT-CT.JPG
 * Infection imaging
 * Bones imaging
 * Thyroid imaging
 * Cardiac functionality
 * Brain imaging                             https://meditronics.files.wordpress.com/2010/11/mrspectunreg.gif
 * Diagnosis of Alzheimer

Different types

Both 2D and 3D images can be produced. 2D images are produced using Scintigraphy ("scint"); using internal radionuclides. 3D images can be produced using SPECT, a 3D tomographic technique that uses gamma camera data from many projections which can be reconstructed in different planes. http://www.medgadget.com/wp-content/uploads/2011/08/gjq340jjr.jpg

How it works

In nuclear medical imaging, radiopharmaceuticals are taken internally- intravenously or orally. Then, external detectors called gamma cameras capture and form images from the radiation emitted by the radiopharmaceuticals. The procedure begins by the patient taking in a gamma-emitting radioisotope (a radionuclide), normally through injection into the bloodstream. Occasionally, the radioisotope is a simple soluble dissolved ion, for example a radioisotope of gallium(III). Most often, though, a marker radioisotope is attached to a specific ligand. This creates a radioligand. The properties of the radioligand allow it to bind to certain types of tissues. This union allows the combination of ligand and radiopharmaceutical to be carried and bound to a place of interest in the body. It is then possible to see the ligand concentration by a gamma camera. Single-Photon Emission Computed Tomography (SPECT) is a nuclear medicine tomographic imaging technique using gamma rays. The procedure is very similar to the typical nuclear medicine planar imaging using a gamma camera. However, it is able to provide true 3D images. This information is typically presented as cross-sectional slices through the patient, but can be easily reformatted and manipulated as needed.

Advantages and disadvantages

The advantages of imaging using gamma rays include the fact that it is non-invasive, and there are no ethical issues.Some disadvantages are present however, such as the possibility of a patient that is worried about being exposed to the radiation. There may also potentially be harmful effects of radiation. To counteract these issues, the benefit of the examination must be identified before a patient is exposed for a nuclear medicine examination, If the benefit does validate the procedure, then the radiation exposure (the amount of radiation given to the patient) should also be kept as low as reasonably practicable.

Future of imaging with gamma rays

Forthcoming systems are being designed with the aim of "low cost" clinical applications. New prototypes are being designed and built. The future of nuclear imaging holds cheaper, safer instruments that are more accessible and easier to use.

Reference list

References

Habib Zaidi, http://www.ncbi.nlm.nih.gov/pubmed/16696367#

Sarah Lamberti, Jun 04, 2009 http://www.molecularimaging.net/topics/practice-management/quality/nuclear-medicine-2020-what-will-landscape-look?page=0%2C1

Wikipedia, https://en.wikipedia.org/wiki/Nuclear_medicine#Practical_concerns_in_nuclear_imaging