The Role of Nuclear Medicine Technologists in Diagnostic and Therapeutic Procedures

A Nuclear Medicine Technologist is a specialised healthcare professional affiliated with a Nuclear Medicine Department or Radiopharmacy. Nuclear medicine encompasses several disciplines, including medical physics, imaging algorithms, radiochemistry and medical sciences, to help create a treatment plan for each patient.  The role of the Nuclear Medicine Technologist is to prepare and formulate a radiopharmaceutical imaging or radiotherapeutic agent and organise the administration of the individual dose to the patient.  The aim is to help form a patient treatment plan for the diagnosis of a range of disease states.  These disease states include stages of cancers, neurological disorders, heart disease, and endocrine and gastrointestinal conditions, amongst others.

Thinking of a career as a nuclear medicine technologist?

The radiopharmaceutical contains a radionuclide that spontaneously emits radiation via alpha particles, beta particles or gamma rays.  The Nuclear Medicine Technologists – in association with the medical physicists – operate SPECT imaging (single photon emission tomography) and PET imaging (positron emission tomography) gamma camera systems to detect the radiation from the radiopharmaceuticals emitting from inside the human body.  This setup enables the generation of images that are analysed to show the regions of the radiopharmaceuticals localised within the organs of the human body.  The abnormal areas will retain a level of radioactivity compared to the healthy surrounding tissues.  The nuclear medicine technologists and physicians analyse the generated images to diagnose molecular and metabolic processes. It is also useful in evaluating physiological, anatomical and pathological conditions.  The duties of the Nuclear Medicine Technologist extend to the operation of computed tomography (SPECT) and magnetic resonance imaging (MRI) scanners. Both these systems can be hybrids of SPECT and PET scanners.

Nuclear Medicine Imaging: An Overview of PET, SPECT, and CT

Nuclear medicine imaging generates non-invasive images except when a radiopharmaceutical is given intravenously. In most cases, the procedure is pain-free to help in the diagnosis and evaluation of the disease state of the patient. These SPECT and PET  imaging scans utilise radioactive materials called radiopharmaceuticals or radiotracers.  The radiotracer can be inhaled as a gas, injected into the bloodstream or swallowed.  The tracer will then accumulate in the human body during the examination.  The radioactive emissions from the radiotracer are detected by a gamma camera or another imaging device that is capable of producing images from inside the human body to generate molecular information.  The advantages of these systems are that nuclear medicine images can be combined with computed tomography (CT) or magnetic resonance imaging (MRI) to generate image fusion.  This approach enables two scans to be done in one patient sitting, and the information can be correlated with one image combined to produce an accurate diagnosis.  These hybrid scanners extend to single-photon emission computed tomography (SPECT)/computed tomography (CT) systems, including positron emission tomography (PET)/computed tomography (CT) machines.  Another technology platform being developed uses a combination of the PET/MRI hybrid scanner.

Nuclear medicine technologist also offers radiotherapeutic procedures, which include radioactive iodine (I-131) therapy using SPECT imaging.  This procedure uses a tiny amount of radioactive material to treat cancer and other medical conditions affecting the thyroid gland.  Also, non-Hodgkin’s lymphoma patients may undergo radioimmunotherapy (RIT) if they are unresponsive to chemotherapy.  The radioimmunotherapy (RIT) approach to cancer treatment combines radiation therapy with the targeting ability of immunotherapy. It is designed to imitate cellular activity in the human body’s immune system.

Radiation Therapy Physics and Brachytherapy: Applications and Innovations

Radiation therapeutic physics (radiotherapy physics or radiation oncology physics) is mostly concerned with linear accelerator (Linac) systems and kilovoltage X-ray treatment units, as well as more advanced modalities such as cyberknife, tomotherapy, brachytherapy, and proton therapy.

Therapeutic physics may include boron neutron capture therapy, sealed source radiotherapy, and terahertz radiation systems. It also involves high-intensity focused ultrasound, optical radiation lasers, ultraviolet, and others. Furthermore, it extends to photodynamic therapy, including nuclear medicine using unsealed source radiotherapy and photomedicine.

Nuclear Medicine is a discipline that uses radiation to gain information about the functioning of the human body’s organs, to diagnose diseases, and to apply appropriate therapy treatments. The information generated helps physicians make a reasonable and accurate diagnosis of the patient’s disease state.

The organs of the human body which can easily undergo imaging include the thyroid, bones, heart, liver, etc. Another use of radiation is its ability to treat diseased organs and/or tumours. Radiotracers in medicine are widely used throughout the World of healthcare organisations, extending to mobile facilities. About 10,000+ hospitals worldwide use radioisotopes in medicine for diagnosis and therapy procedures.  The most diverse radioisotope used in diagnosis is technetium-99m.  This radionuclide accounts for over 30 million procedures per annum and accounts for 80% of all nuclear medicine procedures.  In context, the USA produces some 18 million nuclear medicine procedures per year. In Europe, there are about 10 million procedures from a population of 500 million people. Marketing suggests that the use of radiopharmaceuticals in diagnosis is growing at a rate of 10% per annum.

The Evolution of Radiopharmaceuticals and Radiotracers in Nuclear Medicine

Nuclear medicine began in the 1950s when physicians investigated the endocrine system using iodine-131 to diagnose and treat thyroid disease. The medical physicist liaises with a radiologist due to the hybrid PET-CT systems, including SPECT scanners.  CT scanning and nuclear medicine contribute to over a third of the total radiation exposure.  The average total yearly radiation exposure in the USA per person is 6 mSv per year.

The Health Physicist’s (Radiation Safety or Radiation Protection Officer) responsibility is to evaluate and control health hazards associated with the safe handling of radiation sources. Therefore, the supervision and monitoring of radionuclides or ionising radiation in the clinical setting are of paramount importance to regulatory requirements.

The application of more advanced computer systems enables processes to analyse complex driven by the generation of computer algorithms for delineating anatomical structures for the next generation of PET and SPECT scanners.  For example, image segmentation is central to various biomedical imaging applications.  These include quantification of tissue volumes, diagnosis and localization of pathology.

In addition to studying the anatomical structure, treatment planning, and computer-integrated surgery, a 3-D volume extraction algorithm was suggested for segmenting the cerebrovascular structure of the brain. The initial image identifies previous knowledge of the cerebrovascular structure and multiple seed voxels.

In light of the preserved voxel connectivity, the seed voxels were grown within the cerebrovascular structure area throughout the 3-D volume extraction procedure. This algorithm improved the segmentation results compared to other methods, such as the histogram approach. Furthermore, this 3-D volume extraction algorithm is also applicable to segment tree-like organ structures. For example, the renal artery and coronary artery can be derived from these medical imaging modalities.

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