Nuclear medicine has various background of scientists in medicine, chemistry, physics, and engineering. The birth of nuclear medicine was considered in 1934 discovery of artificial radioactivity.
Along with radionuclides in 1946 by Oak Ridge National Laboratory. Nuclear medicine started out treating thyroid cancer furthering seeing the thyroid function. This open up a new view of how the body organ function in medicine. Nuclear medicine uses a scintillator gamma camera which was first develop by Hal Anger in 1958.
The gamma camera was then developed into a single photon emission computed tomography (SPECT) by David E. Kuhl and Roy Edwards. The gamma camera consists of detector which picks up ”the high-energy photons emitted by the patient, estimating the photon energy and location of interaction” (Khoshakhlagh, Islamian, Abedi, & Mahmoudian, 2015). Therefore, this allow data to be collected to reconstruct an image of the anatomy.
Detectors play a big role in nuclear medicine. (Khoshakhlagh et al., 2015). Nuclear medicine imaging has the ability to show organ function on the molecular level.
This is done by administrating radioactive substances. Radiopharmaceuticals can be through ingestion, intravenous injection, or inhalation. Nuclear medicine is dependent on radiopharmaceuticals, which is a radionuclide pair with pharmaceutical to target a specific organ. When radionuclide decay it gives off gamma ray. The detectors then pick up the positron emission, forming the image (Bontrager, Lampignano, & Kendrick, 2018).The most common radiopharmaceutical substance used is technetium-99cm (99mTc).
99mTc have a short half-life so the radioactivity the patient receive is a low. ”Half-life is the time it takes for radiation to decay by one-half of its original activity” (Bontrager et al., 2018). As the detectors picks up the amount of radioactivity it forms the image showing the severity of pathology.
In nuclear medicine professionals that are found are nuclear medicine technologist, nuclear medicine physician, radiation safety officer (RSO), and health physicist. The technologist is the one who perform the exams and able to process results to the radiologist. The nuclear medicine physician is a radiologist who read the results and is knowledgeable of nuclear medicine. The physician can also be the RSO and overlook the protocols and dosimetry records. The health physicist inspects the equipment in the department (Bontrager et al., 2018). To minizine patients concern and avoid stressful experience nuclear medicine procedure are explain before appointment. Either by appointment letter or by the nurse addressing information prior to exam.
Common procedures seen in nuclear medicine are bone scan, myocardial perfusion scan, lung scan, and thyroid uptake study. Bone scan are usually long due to the wait time after uptake of radiopharmaceutical before scan begin. For instance, 99mTc is a phosphate compound used to see how it metabolize into the bone. This takes up to two and four hours. The image display ”normal bone metabolism…in shades of grey and any areas of increased bone turnover will appear black”(Hogg & Lawson, 2015). Some area may appear darker like in the pelvic area.
It is because radiopharmaceutical is excreted into urine. Therefore, this is normal and expected. Patient may have to increase their fluid intake to flush out radiopharmaceutical and not obscure the pelvic area.
”A bone scan is used in some patients with known cancers, for example prostate cancer, to assess the extent of disease and to investigate bone pain because of suspected metastatic tumours” (Hogg & Lawson, 2015). A bone scan helps to indicate if diagnosis is on the right track and if not, it still contributes for other possible diagnosis (Hogg & Lawson, 2015). A myocardial perfusion scan is a comparison of the heart at rest and under stress. The scan shows the blood flow to the hear muscle. This procedure is to detect ischemia.
The stress part of the exam either done by physical exercise or a stressing agent/drug. ”When the heart is adequately stressed they will be given an intravenous injection of a radiopharmaceutical, which concentrates in the myocardium in proportion to the local blood flow at maximum stress” (Hogg & Lawson, 2015). The stress scan would follow after an hour before obtaining the images to allow radiopharmaceutical to pass through the rest of body. This ensure for good images of the heart. For rest scan it can either be done the same day or schedule for another day.
Patient will still be injected with radiopharmaceutical but without the physical exercise. If both scans show abnormal results it is an indication patient have had a myocardial infarction (Hogg & Lawson, 2015). A lung scan is usually done to see if pulmonary embolism is present.
Perfusion and ventilation are scan for this. As for thyroid uptake study the radiopharmaceutical is ingested and after 6 hours images are taken; follow by a 24-hour image. If the result show high active accumulation this could mean possible of hyperthyroidism (Graves disease). If it is the opposite, with lower result and thyroid is not visible this would be hypothyroidism (Bontrager et al., 2018). Gastroparesis is a condition where the stomach empty slower than usual and there is no mechanical obstruction present.
To diagnose patient with gastroparesis nuclear medicine have been ”accepted as the gold standard to evaluate patients with symptoms related to gastric emptying disorders” (Alipour, Khatib, Tabib, Jafari, Aghaghazyini, Pashazadeh, & Javadi, 2017). This scintigraphy gastric emptying procedure either use a liquid or solid meal mix with radionuclide for the patient to consume. This is a noninvasive test and this show motility function. It also allows for quantifying time of delay. With the solid meal this assess the functional activity of the stomach as how food is pass through; seeing intestinal absorption and metabolism. As concluded nuclear medicine is a diagnostic image demonstrate the physiology and function of an organ. Therefore, gastroparesis is best diagnosed by nuclear medicine (Alipour et al., 2017).
