Single Photon Emission Computed Tomography and Bone Scanning - Term Paper Example

SPECT/CT AND BONE SCANNING By student’s Name: Code+ Course: Instructor’s Name: University Name: City, State: Date of submission: INTRODUCTION Radiopharmaceuticals are drugs used in Nuclear medicine; they contain radioactive materials referred to as radioisotopes, which are put in the body of the patients as a way of treatment of their diseases. These radioactive substances use the referred to as tracers .Once in the body of the patient they image the anatomy of disease causing pathogens hence assist in treatment. This is done through metabolic monitoring of these radioactive substances and tracking their photon emissions in the body after they localize to specific organs or cellular receptors where they image the extent of a disease process in the body based on the cellular function and psychology rather than relying on physical changes in the anatomy of the tissue. The photons emitted by these radio labeled substances are tracked with SPECT (Single Photon Emission Tomography) and PET (Positron Emission Tomography) which are used in molecular imaging (MI).Conventional imaging with x-ray was used as a snapshot of the anatomy and it depicted the tissue by physical characteristics .Radio-pharmacology is important since the anatomical changes are detected long before the structural changes appearance (Fred, 2012). Almost all traditional radiopharmaceuticals used in molecular medicine are used in molecular imaging since the concept of radioactive tracers commonly used in nuclear medicine is a specific radio labeled molecule, which can trace the molecular behaviour and provide information about specific biological process of the molecule (Paul, 2012). Among the most used radio-pharmaceuticals include; Chronic phosphate(P-32) Tc-99m MDP Tc-99m MDP P-C-P Tc-99m D Strontium 89 Samarium 153 18F-Fluoride PET 18F-FDG PET RADIATION DOSIMETRY Dosimetry involves the calculations and measurement of the dosage received hence radiation dosimetry involves analysis and measurement of the radioactive substance in the body tissues of the subject after exposure to the radioactive substance. It involves the measurement of internal and external levels of radioactive materials through a process referred to as thermo-luminescence hence the term thermo-luminescent dosimeter. Internal dosimeter is analyzed through the use of physiological processes whereas external dosimeter analyzed through the use of a specific radioactive measuring device known as the dosimeter. The Hormesis Effect suggests that a small dosage of radioactive materials is good for the people since a study showed that people who are exposed to little amounts of radiation are less likely to have cancer than their counterparts who are never exposed to radioactive materials. However, increased exposure to radiation leads to malignant maladies such as cancers, it also lead to birth defects and mutations as it were the case in Japan. Exposure to radioactive materials to women on the eighth to fifteenth week of pregnancy leads to serious mental retardation of the foetus hence should be avoided (Doug, 2012) Radioactive dosimetry must be performed on the patients before application of radio-pharmaceuticals so as to establish the levels of accumulated radioactive materials. This is important so as not to exceed the minimum radiation levels in the subject. It is important to note that the minimum radiation exposure that is considered harmless is only from extrapolation from use of larger exposure. BONE THERAPY It is important that bone involvement is detected early so that there is maximum therapy to patients. This early detection can be done through use of radioactive pharmaceuticals through imaging of the affected bone area. Radionuclide bone scanning method has up to date extensively used in bone therapy. It assists in knowing the type and extent of skeletal disease or complication and thereby treating or controlling the spread of the disease. Skeletal diseases are identified by complications such as pathologic fractures or compressions of the spinal cord. These can be prevented if therapy is provided before hand, in which case early detection has to be done.MRI identifies early involvement of the bone marrow whereas CT provides information about bone morphology hence the bone has to be destroyed beforehand. Uptake of other radiopharmaceuticals such as Tc-99MD F-18 shows presence of tumor cells in case there is a n osteoblastic reaction of the bone (Dominique and Ora, 2010). In a bid to detect bone involvement at early stages, more hybrid techniques have been introduced. These include SCANT/CT and PET/CT which, through the use of CT provide more accurate imaging meant to increase accuracy in bone therapy, and also to check the performance of patients undergoing therapy. SCANT and PET provides a more elaborate evaluation for tracer uptake than the conventional planar scintigraphy. Incorporation of CT (computed tomography) has improved the imaging and characterization of tracer uptake since CT provides additional atomic information. This helps to prevent tumours which though not all, tend to arise from the skeleton SPECT Single photon emission computed topography (SPECT) has made it possible to assess progression of diseases founded on metabolic and functional information of cells and organs through functional imaging. The images of SPECT are three dimensional from a specific part of the bone and it offers a great improvement in analysis and treatment of bone diseases. SPECT technology is largely used in locating the damaged brain cells whereby a layer of radioactive material such as Tc-99m MDP P-C-P is injected into the body of the patient.After a while, the material decays and emits gamma rays which extend all over the brain and divide it smaller brain units. The gamma camera picks up the light from the gamma rays and relays them in form of images. The image is analysed and the damaged brain tissues are identified hence treatment is given (Paul and Kristen, 2012). Reports shows that introduction of SPECT to BS has improved treatment accuracy for detecting the malignant bone diseases since it detects bone lesions more accurately than the conventional planar X ray SPECT/CT This is an integration of X-ray computed tomography (CT) into SPEC a combination that has improved medical imaging.. CT makes atomic characterizations of the cells and organs hence improved images sensitivity and improved specifity to scintigraphic technique. Hybrid SPECT/CT ensures reduction of time taken in molecular imaging and provides accurate images. CT has a good topographic information since it has contrast agents which are used to increase the visibility of the vessels being tested as well as a higher anatomic resolution hence better information about the disease causing organisms. SPECT/CT helps in providing information through functional imaging whereby functional processes such as blood flow and metabolic activities are relayed in form of images. The radioactive labeled substances migrate up to their specific sites where required so as to relay images from their specified locations. This new advancement in nuclear medicine has greatly assisted in bone imaging thereby assisting in curing previously incurable bone diseases. This is made possible since SPECT/CT has improved the characterization of lesions of the bones through increasing sensitivity scintigraphic sensitivity. Traditionally bone treatment was through use of conventional bone scan using planar X ray; this has greatly changed since introduction of SPECT/CT. Initially, the conventional methods such as use of Ga-67 which was used to visualize infections would be excreted after uptake hence interpretation of the scan results were hindered. SCANT/CT has solved this challenge through differentiating soft and bone tissue infection One of the major disadvantages of SPECT/CT is the high uptake of radioactive components from SPECT/CT by patients, which raises the radiation level of the patient which may lead to serious malignant diseases (Strobel, 2007). The uptake of radioactive materials used in bone therapy reduces the normal count of the blood cells especially the white blood cells hence increased susceptibility to diseases and also reduced platelet count hence reduced clotting power leading to more blood loss in case of an open skin. Other disadvantages of SPECT/CT are the high cost of installation of SPECT/CT equipment. The equipment require larger space more power and higher cooling requirement. Another challenge, which may be faced by the complete adoption of SCANT /CT, is the high training required for specialists who will be using the SCANT/CT devices.Some of the bone pathologies where SPECT/CT is preferred include Facet joint arthritis. This is an inflammation of synovial joins which leads to severe backaches. SPECT/CT is recommended in this treatment because it is best seen on SPECT/CT rather than while using planar imaging. Another bone pathology where SPECT/CT is commonly used for treatment is in Osteoporoses. A disease which is a gradual loss of calcium minerals mostly by the aging people which makes the bones fail to repair themselves leading to hollow spaces between the bones. Due to this, the bones are inflammatory and may lead to bonny growth. SPECT/CT lounges the radioactive materials in the affected areas. Reduced motions of the radioactive material indicate presence of the disorder. SPECT/CT is also useful in fractures of the metatarsals. This is because some of the fractures can be seen using the single Planar image but other fractures are particularly impossible due to the small structures involved such as in the ankles and on the feet. SPECT/CT due to its high resolution is able to differentiate between stress factors and the small structures of the bones (Ora and Stanley 2006). CONCLUSION Radiopharmaceuticals such as SPECT/CT have improved bone therapy by improving imaging of the damaged bones since they help in detecting disease causing pathologies so that there is better therapy to patients. The improvement of incorporating CT into SPECT has seen to a great improvement in molecular imaging such that there is better improved images which are able to clearly show the existing bone pathologies which was initially not possible using the conventional planar X ray. REFERENCE Doug, E.& Leanne, M. ; Australian College of Critical Care Nurses.2012. ACCCN's critical care nursing. Chatswood, N.S.W. : Mosby/Elsevier Ora, I. & Stanley, J.(2006). Hybrid SPECT/CT tumor imaging. New York : Taylor & Francis Fred A. Mettler ; Milton J. Guiberteau (2012). Essentials of Nuclear Medicine Imaging. Philadelphia, PA : Elsevier/Saunders Paul Christian, CNMT.; Kristen M Waterstram-Rich. 2012. Nuclear medicine and PET/CT : technology and techniques. St. Louis, Mo. : Elsevier/Mosby Dominique Delbeke; Ora Israel. 2010. Hybrid PET/CT and SPECT/CT imaging : a teaching file. New York: Springer. Strobel K, Burger C, Seifert B, Husarik DB, Soyka JD, and Hany TF. Characterization of focal: Performance of planar bone scintigraphy compared with SPECT and SPECT fused with CT. Am. J. Roentgenol. 2007;188:W467-W474. Hansis E. Da Silva, A. Hines, H. Garrard J, Sowards-Emmerd D,and Shao L. 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Pubmed link Radiolabelled GLP-1 analogues for in vivo targeting of insulinomas. M. Brom, L. Joosten, W.J.G. Oyen, M. Gotthardt and O.C. Boerman. Contrast Media Mol Imaging. 2012 Mar- Apr;7(2):160-6. Pubmed link Read More