Radiation dose should be taken into account when performing a medical imaging technique that utilizes X-ray or gamma ray to create images, such as radiography, CT, and nuclear medicine imaging modalities. Recently the Image Gently (pediatrics) and Image Wisely (adults) campaigns have emerged to further reinforce radiation dose reduction awareness. For years medical imagers have followed the ALARA principle (as low as reasonably achievable) with the knowledge that there is some qualitative increased cancer risk associated with any dose of radiation. The amount of radiation that is directly attributed to medical imaging continues to increase, raising attention to radiation dose control in medical imaging. When evaluating the risk and benefits of different imaging strategies, radiation dose needs to be considered. These radiopharmaceuticals then give off energy in the form of gamma rays detected by a gamma camera or a PET scanner. Nuclear medicine imaging, such as bone scan and positron emission tomography (PET), uses small amounts of radioactive materials called radiopharmaceuticals selected to accumulate in the target organ system. The relaxation times of these protons following the radio wave pulses can be measured and are tissue specific, allowing exquisite soft tissue contrast. While radiographic and CT imaging are obtained by passing photons (X-ray beam) through portions of a patient’s body, MRI uses pulses of specific radio wave frequencies within a constant magnetic field to change hydrogen atom alignment in the patient’s body. The main imaging techniques to evaluate the spine include conventional radiography, computed tomography (CT), magnetic resonance imaging (MRI), bone scan, and positron emission tomography–computed tomography (PET–CT). While conventional radiography and CT are effective in the evaluation of the osseous structures, MR is optimal for the evaluation of soft tissues, including, but not limited to, intervertebral disks, ligaments, paravertebral muscles, and the spinal cord. The osseous spine is connected by intervertebral disks and supporting ligaments. The spine is formed by 7 cervical vertebrae, 12 thoracic vertebrae, 5 lumbar vertebrae, 5 fused sacral vertebrae, and four small bones extending from the sacrum to form the coccyx. The purpose of this chapter is to discuss the different diagnostic imaging techniques and an imaging-based approach to common spine pathologies. Imaging is an essential tool in diagnosis and management of spine pathology.
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