Imaging Modalities PDF

IMAGING MODALITIES INSTRUCTOR: CHANEN M. ASIS, RRT, RSO, MSRT LEARNING OBJECTIVES AT THE END OF THE COURSE, THE STUDENTS WILL UNDERSTAND THE FOLLOWING AND WILL BE ABLE TO:  KNOW THE DIFFERENT IMAGING MODALITIES  ULTRASOUND  FLUOROSCOPY  COMPUTED AND DIGITAL RADIOG...

IMAGING MODALITIES INSTRUCTOR: CHANEN M. ASIS, RRT, RSO, MSRT LEARNING OBJECTIVES AT THE END OF THE COURSE, THE STUDENTS WILL UNDERSTAND THE FOLLOWING AND WILL BE ABLE TO:  KNOW THE DIFFERENT IMAGING MODALITIES  ULTRASOUND  FLUOROSCOPY  COMPUTED AND DIGITAL RADIOGRAPHY  COMPUTED TOMOGRAPHY  MAGNETIC RESONANCE IMAGING  NUCLEAR MEDICINE  BONE DENSITOMETRY  PET SCAN  SPECT SCAN  RADIATION THERAPY ULTRASOUND Diagnostic ultrasound, also called sonography or diagnostic medical sonography, is an imaging method that uses sound waves to produce images of structures within your body. The images can provide valuable information for diagnosing and directing treatment for a variety of diseases and conditions. ULTRASOUND Ultrasound is used for many reasons, including to:  View the uterus and ovaries during pregnancy and monitor the developing baby's health  Diagnose gallbladder disease  Evaluate blood flow  Guide a needle for biopsy or tumor treatment  Examine a breast lump  Check the thyroid gland  Find genital and prostate problems  Assess joint inflammation (synovitis)  Evaluate metabolic bone disease ADVANTAGE OF ULTRASOUND 1. Most ultrasound scanning is noninvasive (no needles or injections). 2. Occasionally, an ultrasound exam may be temporarily uncomfortable, but it should not be painful. 3. Ultrasound is widely available, easy to use, and less expensive than most other imaging methods. 4. Ultrasound imaging is extremely safe and does not use radiation. 5. Ultrasound scanning gives a clear picture of soft tissues that do not show up well on x-ray images. 6. Ultrasound is the preferred imaging modality for the diagnosis and monitoring of pregnant women and their unborn babies. 7. Ultrasound provides real-time imaging. This makes it a good tool for guiding minimally invasive procedures such as needle biopsies and fl uid aspiration. DISADVANTAGE OF ULTRASOUND 1. Ultrasound waves are disrupted by air or gas. Therefore, ultrasound is not an ideal imaging technique for the air-filled bowel or organs obscured by the bowel. Ultrasound is not as useful for imaging air-filled lungs, but it may be used to detect fl uid around or within the lungs. Similarly, ultrasound cannot penetrate bone but may be used for imaging bone fractures or infections surrounding a bone. 2. Large patients are more diffi cult to image by ultrasound because greater amounts of tissue weaken the sound waves as they pass deeper into the body and need to return to the transducer for analysis. 3. Ultrasound has diffi culty penetrating bone and, therefore, can only see the outer surface of bony structures and not what lies within (except in infants who have more cartilage in their skeletons than older children or adults). Doctors typically use other imaging modalities such as MRI to visualize the internal structure of bones or certain joints. ULTRASOUND ULTRASOUND FLUOROSCOPY Fluoroscopy is a medical imaging procedure that uses several pulses (brief bursts) of an X-ray beam to show internal organs and tissues moving in real- time on a computer screen. Standard X-rays are like photographs, whereas fl uoroscopy is like a video. Healthcare providers use fl uoroscopy for two main purposes: for diagnostic purposes and to help guide certain treatment procedures (known as interventional guidance), such as surgeries and catheter placements. FLUOROSCOPY (DIAGNOSTIC FLUOROSCOPY)  Barium swallow (esophagogram): A barium swallow is a fluoroscopy imaging test that checks for problems in your upper gastrointestinal (GI) tract, which includes your mouth, back of the throat, esophagus, stomach, and the first part of your small intestine. The test involves drinking a chalky-tasting liquid that contains barium, a safe substance that makes parts of your body show up more clearly on X- ray imaging. These tests can help diagnose esophageal disorders, ulcers, hiatal hernia, GERD (gastroesophageal reflux disease), structural problems in the GI tract, and tumors.  Barium enema: A barium enema, which is also called lower gastrointestinal tract radiography, is a fluoroscopy imaging test that checks for problems in your colon and rectum (parts of your large intestine). A healthcare provider pours a safe liquid containing barium through a tube inserted into your anus. This liquid coats the inside of the large intestine and clearly shows its outline on X-ray imaging. This test can help diagnose inflammatory bowel disease (Crohn’s disease or ulcerative colitis), diverticulosis, colon cancer, polyps, and colonic volvulus (abnormal twisting of the bowel). FLUOROSCOPY Angiography: Angiography, or angiogram, uses fl uoroscopy to identify and diagnose narrowing or blockages in the arteries in your body. Sometimes, providers may perform an angioplasty, a procedure used to open blocked coronary arteries, during a diagnostic angiography, if necessary. BARIUM SWALLOW (ESOPHAGOGRAM) BARIUM ENEMA ANGIOGRAPHY FLUOROSCOPY FOR PROCEDURE GUIDANCE Cardiac catheterization: In this procedure, fl uoroscopy shows blood fl owing through your arteries. It can help visually guide healthcare providers in performing angioplasties. Placement of stents: Fluoroscopy can help ensure the proper placement of stents, which are devices that help open narrow or blocked blood vessels. Orthopedic surgery: Your surgeon may use fl uoroscopy to help guide orthopedic procedures, such as joint replacement and fracture (broken bone) repair. CARDIAC CATHETERIZATION PLACEMENTS OF STENT ORTHOPEDIC SURGERY ADVANTAGE OF FLUOROSCOPY Allows healthcare providers to see movement and function (like in a movie) that cannot be seen in other fixed imaging studies (like a photograph). Guides sometimes life-saving surgical treatments. DISADVANTAGE OF FLUOROSCOPY Radiation doses are usually higher than in common imaging like X-rays. This means these procedures are slightly more likely to increase the possibility you may get cancer later in life. Some fl uoroscopy procedures are longer and use more radiation than others. These could cause skin reddening and hair loss. Contrast dye, if used, can produce an allergic reaction in some people. COMPUTED RADIOGRAPHY CR for short — is the use of a Phosphor Imaging Plate to create a digital image. CR uses a cassette-based system like analog film and is more commonly considered to be a bridge between classical radiography and the increasingly popular fully digital methods. Pros  Low initial investment  Compatible with a wide range of traditional systems  Effective for smaller or low-volume clinics  Multiple sizes allow for greater flexibility Cons  Long time to view image  Risk of overexposure  High Maintenance ADVANTAGE OF COMPUTED RADIOGRAPHY The same plate can be used again and again It does not require a dark room and developing chemicals The produced image is digital and can be stored and manipulated electronically These images have greater dynamic range, wider exposure latitude, and reduced patient exposure. DISADVANTAGE OF COMPUTED RADIOGRAPHY The risk of damaged equipment is one of the main drawbacks, as CR cassettes are susceptible to damage from mishandling or abuse. CR systems also have more intensive maintenance needs than other digital radiography methods. COMPUTED RADIOGRAPHY DIGITAL RADIOGRAPHY (DR) It is the latest advancement in the radiography field, using a digital X-ray detector to automatically acquire images and transfer them to a computer for viewing. This system is additionally capable of fixed or mobile use. While it is the more expensive option, the Digital Radiography system comes to the table with much higher effi ciency and quality that more than justifies the price for many users. Given its high volume capabilities, it is often the choice for larger or busier clinics. ADVANTAGE OF DIGITAL RADIOGRAPHY Image Quality- DR is also much more forgiving than film due to the image processing algorithms. Practices can expect images with a balanced presentation of bone structures and overlapping soft tissue along with a realistic representation of the anatomy. Cost Savings- Film, chemicals, and processing costs are expensive, not to mention your staff ’s time that is required for developing film. Switching to digital radiography eliminates these outdated expenses. Plus, darkroom space and real estate used to archive radiographs can be converted for other uses. What’s more, digital radiography images are sent to a computer and viewable seconds after being taken, meaning technicians will spend less time on menial tasks like filing and retrieving films leaving more time for productive tasks. Ease-of-Use-Digital technology is also much faster than conventional radiography, and computer software allows adjustment of brightness, contrast, zoom, and pan to optimize both bone and soft tissue in one exposure. As long as the patient is positioned correctly, most everything else can be adjusted with a few clicks of a mouse or even gestures with your fingers on the viewing screen. ADVANTAGE OF DIGITAL RADIOGRAPHY Fewer Retakes- Film radiography takes time to process. Each image can then only be assessed after it comes out of the processor and put on a light- ¬box, but digital radiography can be viewed immediately. This instant access allows technicians to see if the patient is positioned correctly or if the exposure is balanced. With advanced features like creating shot lists and 3D position assistants placed at the technicians’ fingertips, users from novice to expert can get more out of radiography than ever before. Decreased Radiation Exposure- The safety benefits of digital radiography are twofold: First, fewer retakes mean fewer exposures, resulting in a decrease in radiation exposure to patients and staff. Second, current state-of-the-art digital sensors are more responsive than film so less radiation (up to 70%) is required to produce a digital image. Both staff members and patients benefit from lessened exposure to radiation with digital systems giving staff peace of mind. DISADVANTAGES OF DIGITAL RADIOGRAPHY  Digital radiography systems are very expensive. It requires computers, servers, storage devices, etc.  It requires more storage space which depends on image sizes.  Digital images are prone to intentional manipulation for any misuse.  Most of the storage phosphor systems offer low optimal resolution compared to radiographic film.  It requires radiologists to learn and adopt machinery, technology, and positioning techniques. DIGITAL RADIOGRAPHY DIGITAL RADIOGRAPHY COMPUTED TOMOGRAPHY SCAN A CT (computed tomography) scan is a type of imaging test. Like an X-ray, it shows structures inside your body. But instead of creating a fl at, 2D image, a CT scan takes dozens to hundreds of images of your body. To get these images, a CT machine takes X-ray pictures as it revolves around you. Healthcare providers use CT scans to see things that regular X-rays can’t show. For example, body structures overlap on regular X-rays and many things aren’t visible. A CT shows the details of each of your organs for a clearer and more precise view. The term “computed tomography,” or CT, refers to a computerized X-ray imaging procedure in which a narrow beam of X-rays is aimed at a patient and quickly rotated around the body, producing signals that are processed by the machine’s computer to generate cross-sectional images, or “slices.” These slices are called tomographic images and can give a clinician more detailed information than conventional X-rays. Once some successive slices are collected by the machine’s computer, they can be digitally “stacked” together to form a three-dimensional (3D) image of the patient that allows for easier identification of basic structures as well as possible tumors or abnormalities. ADVANTAGES COMPUTED TOMOGRAPHY SCAN determining when surgeries are necessary reducing the need for exploratory surgeries improving cancer diagnosis and treatment reducing the length of hospitalizations guiding treatment of common conditions such as injury, cardiac disease, and stroke improving patient placement into appropriate areas of care, such as intensive care units CT scanning provides medical information that is different from other imaging examinations, such as ultrasound, MRI, SPECT, PET, or nuclear medicine. Each imaging technique has advantages and limitations. The principal advantages of CT are its abilities to:  Rapidly acquire images.  Provide clear and specific information.  Image a small portion or all of the body during the same examination. DISADVANTAGES COMPUTED TOMOGRAPHY SCAN Concerns about CT scans include the risks from exposure to ionizing radiation and possible reactions to the intravenous contrast agent, or dye, which may be used to improve visualization. The exposure to ionizing radiation may cause a small increase in a person’s lifetime risk of developing cancer. Exposure to ionizing radiation is of particular concern in pediatric patients because the cancer risk per unit dose of ionizing radiation is higher for younger patients than adults, and younger patients have a longer lifetime for the effects of radiation exposure to manifest as cancer. COMPUTED TOMOGRAPHY SCAN COMPUTED TOMOGRAPHY SCAN MAGNETIC RESONANCE IMAGING Magnetic resonance imaging, or MRI, is a noninvasive medical imaging test that produces detailed images of almost every internal structure in the human body, including the organs, bones, muscles, and blood vessels. MRI scanners create images of the body using a large magnet and radio waves. No ionizing radiation is produced during an MRI exam, unlike X-rays. These images give your physician important information in diagnosing your medical condition and planning a course of treatment. ADVANTAGES OF MAGNETIC RESONANCE IMAGING An MRI scanner can be used to take images of any part of the body (e.g., head, joints, abdomen, legs, etc.), in any imaging direction. MRI provides better soft tissue contrast than CT and can differentiate better between fat, water, muscle, and other soft tissue than CT (CT is usually better at imaging bones). These images provide information to physicians and can be useful in diagnosing a wide variety of diseases and conditions. DISADVANTAGE OF MAGNETIC RESONANCE IMAGING The strong, static magnetic field will attract magnetic objects (from small items such as keys and cell phones to large, heavy items such as oxygen tanks and fl oor buffers) and may cause damage to the scanner or injury to the patient or medical professionals if those objects become projectiles. Careful screening of people and objects entering the MR environment is critical to ensure nothing enters the magnet area that may become a projectile. The magnetic fields that change with time create loud knocking noises which may harm hearing if adequate ear protection is not used. They may also cause peripheral muscle or nerve stimulation that may feel like a twitching sensation. The radiofrequency energy used during the MRI scan could lead to heating of the body. The potential for heating is greater during long MRI examinations. MAGNETIC RESONANCE IMAGING MAGNETIC RESONANCE IMAGING NUCLEAR MEDICINE Nuclear medicine is a specialized area of radiology that uses very small amounts of radioactive materials, or radiopharmaceuticals, to examine organ function and structure. Nuclear medicine imaging is a combination of many different disciplines. These include chemistry, physics, mathematics, computer technology, and medicine. This branch of radiology is often used to help diagnose and treat abnormalities very early in the progression of a disease, such as thyroid cancer. Because X-rays pass through soft tissue, such as intestines, muscles, and blood vessels, these tissues are diffi cult to visualize on a standard X-ray, unless a contrast agent is used. This allows the tissue to be seen more clearly. Nuclear imaging enables visualization of organ and tissue structure as well as function. The extent to which a radiopharmaceutical is absorbed, or "taken up," by a particular organ or tissue may indicate the level of function of the organ or tissue being studied. Thus, diagnostic X-rays are used primarily to study anatomy. Nuclear imaging is used to study organ and tissue function. NUCLEAR MEDICINE Nuclear medicine tests use a small amount of radioactive material combined with a carrier molecule. This compound is called a radiotracer. These tests help diagnose and assess medical conditions. They are non-invasive and usually painless. When a radiotracer is injected into the body, it builds up in certain areas of the body. Radiotracers go to the area of the body that needs to be examined, such as a cancerous tumor or infl amed area. They can also bind to certain proteins in the body. The most common radiotracer is F-18 fl uorodeoxyglucose (FDG). It is just one of many radiotracers in use or development. FDG is a compound similar to glucose, or sugar. Highly active cancer cells need more energy than normal cells. As a result, they absorb more glucose. An imaging device that detects energy given off by FDG creates pictures that show the location of the radiotracer in the body. Radiotracers are usually given via injection, but they may also be swallowed or inhaled. ADVANTAGES OF NUCLEAR MEDICINE Provides information on how organs, tissues, and cells are working. (Other common imaging procedures only show the structures.) Can be used also in targeted treatments to kill or damage harmful or cancerous cells, reduce the size of tumors, or reduce pain. DISADVANTAGES OF NUCLEAR MEDICINE Radiation doses are usually higher than in common imaging like x-rays. This means these procedures are slightly more likely to increase the possibility you may get cancer later in life. Some nuclear medicine procedures are longer and use more radiation than others. These could cause skin reddening and hair loss. You may give off small amounts of radiation right after your procedure and need to take steps to protect others from exposure. NUCLEAR MEDICINE NUCLEAR MEDICINE BONE DENSITOMETRY Bone densitometry, also called dual-energy x-ray absorptiometry, DEXA or DXA, uses a very small dose of ionizing radiation to produce pictures of the inside of the body (usually the lower (or lumbar) spine and hips) to measure bone loss. It is commonly used to diagnose osteoporosis, to assess an individual's risk for developing osteoporotic fractures. DXA is simple, quick and noninvasive. It's also the most commonly used and the most standard method for diagnosing osteoporosis. ADVANTAGE BONE DENSITOMETRY A DXA test cannot predict who will experience a fracture but can provide a relative risk and it is used to determine whether treatment is required. Despite its effectiveness as a method of measuring bone density, DXA is of limited use in people with a spinal deformity or those who have had previous spinal surgery. The presence of vertebral compression fractures or osteoarthritis may interfere with the accuracy of the test; in such instances, CT scans may be more useful. DISADVANTAGE BONE DENSITOMETRY Central DXA devices are more sensitive and better standardized than DXA devices but they are also somewhat more expensive. A test done on a peripheral location, such as the heel or wrist, may help predict the risk of fracture in the spine or hip. These tests are not as helpful in following response to treatment, however, and if they indicate that drug therapy is needed, a baseline central DXA scan should be obtained. Follow-up DXA exams should be performed at the same institution and ideally with the same machine. Bone density measurements obtained with different DXA equipment cannot be directly compared. BONE DENSITOMETRY PET SCAN A PET (positron emission tomography) scan is an imaging test that uses radioactive material to diagnose a variety of diseases. Doctors use it to find tumors and diagnose heart disease, brain disorders, and other conditions. A PET scan provides a picture of the body working, not just a picture of its structure, like some other scans. If you have a PET scan, you’ll be given an injection of a small amount of short- acting radioactive liquid, known as a tracer. The one most commonly used is FDG (fl uorodeoxyglucose). FDG is a simple sugar — it’s glucose that has been radiolabelled, and it gives off energy in the body, which can be seen by the scanner. The rate that which sugar is taken up by the body’s tissues indicates how active the tissue is. For example, cancer cells grow quickly, which needs a lot of energy, and hence a lot of sugar. This increased uptake of sugar makes them show up as bright hot spots on the scan. Healthy tissue also uses more sugar than unhealthy tissue, so an area where there is little tracer may indicate unhealthy tissue or reduced blood fl ow. ADVANTAGES OF PET SCAN An advantage of a PET scan is that it can show how well certain parts of your body are working, rather than showing what it looks like. They’re particularly helpful for investigating confirmed cases of cancer, to determine how far the cancer has spread and how well it’s responding to treatment. Sometimes PET scans are used to help plan operations, such as a coronary artery bypass graft or brain surgery for epilepsy. They can also help diagnose some conditions that affect the normal workings of the brain, such as dementia. DISADVANTAGES OF PET SCAN The amount of radiation exposure from PET is similar to that from CT. When PET and CT are done during a single examination, the radiation dose is significantly increased. Because radionuclides used in PET give off radiation for only a short time, PET can be done only if the radionuclide is produced at a nearby location and can be obtained quickly. PET is relatively expensive and not widely available. PET SCAN SPECT SCAN Single-photon emission computed tomography (SPECT) is a nuclear imaging modality used frequently in diagnostic medicine. It allows the clinician to assess the perfusion and functionality of specific tissues. This activity reviews the basics of single-photon emission computed tomography imaging, including the underlying mechanism of imaging, indications, and contraindications, the technique utilized and personnel required, complications, and the clinical significance of this imaging modality in medicine. SPECT SCAN Indications for SPECT imaging are developed by imaging societies, and some important ones are listed below. These indications include:  Evaluating patients with suspected dementia  Localizing epileptic foci preoperatively  Diagnosing encephalitis  Monitoring and assessing vascular spasm following subarachnoid hemorrhage  Mapping of brain perfusion during surgical interventions  Detecting and evaluating cerebrovascular disease  Predicting the prognosis of patients with cerebrovascular accidents  Corroborating the clinical impression of brain death ADVANTAGE OF SPECT SCAN Important advantages of SPECT are that it has been extensively validated and has a good sensitivity, compared to other methods of assessment of myocardial viability. The cost of SPECT is lower than PET (positron emission tomography) imaging and is more widely available than PET in most regions. SPECT can be used in the presence of cardiac implantable electronic devices (CIED) while cardiac magnetic resonance (CMR) imaging has important limitations in this setting. DISADVANTAGE OF SPECT SCAN SPECT has a much higher cost compared to echocardiography and less availability compared to echo. The spatial resolution of SPECT is limited. There is a potential diffi culty in interpreting SPECT results in patients with three-vessel disease and balanced myocardial ischemia as the SPECT interpretation depends on comparing the counts between normal abnormal regions. Compared to CMR and echocardiography, SPECT has some radiation risk, though not very high. SPECT SCAN SPECT SCAN RADIATION THERAPY At high doses, radiation therapy kills cancer cells or slows their growth by damaging their DNA. Cancer cells whose DNA is damaged beyond repair stop dividing or die. When the damaged cells die, they are broken down and removed by the body. Radiation therapy does not kill cancer cells right away. It takes days or weeks of treatment before DNA is damaged enough for cancer cells to die. Then, cancer cells keep dying for weeks or months after radiation therapy ends. ADVANTAGE OF RADIATION THERAPY death of a large proportion of cancer cells within the entire tumor (there are minimal, if any, cancer cells are left behind in small tumors; thus, radiation alone may be used to cure certain small tumors) death of microscopic disease at the periphery of the tumor that would not be visible to the naked eye (e.g. at the time of surgery) ability to shrink tumors (which may help to relieve mass effect; or it may be done before surgery, to convert certain patients from unresectable to resectable status) relative safety for the patient (radiation can be delivered from outside of the body and focused on the tumor, is painless, and generally does not require anesthesia) synergy with systemic therapy(i.e. the ability to kill more cells together than either therapy could do alone) organ preservation (e.g. not removing a breast, larynx, or part of the gastrointestinal tract, which would have significant negative impact on a patient’s quality of life possible stimulation of an immune response against the tumor DISADVANTAGE OF RADIATION THERAPY damage to surrounding tissues (e.g. lung, heart), depending on how close the area of interest is located to the tumor inability to kill tumor cells that cannot be seen on imaging scans and are therefore not always included on the 3D models (e.g. in nearby lymph nodes; metastatic disease) of radiation planning inability to kill all cancer cells in tumors (this is true in particularly large tumors) inability to relieve mass effect (i.e. the pushing of tumor on surrounding normal structures) in certain parts of the body (e.g. brain), thereby requiring surgery poor killing of cancer cells in areas that do not have a good supply of oxygen (e.g. in an area after surgery; in a limb with poor blood supply) increased incidence in wound complication and poor healing (e.g. if surgery is used after radiation; or in parts without good circulation) inconvenience of radiation therapy (e.g. in some cases it must be delivered daily, 5 days per week, for 1-2 months) contraindications to radiation therapy (e.g. prior radiation; certain medical disorders RADIATION THERAPY There are two main types of radiation therapy, EXTERNAL BEAM and INTERNAL. The type of radiation therapy that you may have depends on many factors, including:  the type of cancer  the size of the tumor  the tumor’s location in the body  how close the tumor is to normal tissues that are sensitive to radiation  your general health and medical history  whether you will have other types of cancer treatment  other factors, such as your age and other medical conditions EXTERNAL BEAM RADIATION THERAPY External beam radiation therapy comes from a machine that aims radiation at your cancer. The machine is large and may be noisy. It does not touch you, but can move around you, sending radiation to a part of your body from many directions. External beam radiation therapy is a local treatment, which means it treats a specific part of your body. For example, if you have cancer in your lung, you will have radiation only to your chest, not to your whole body. INTERNAL RADIATION THERAPY Internal radiation therapy is a treatment in which a source of radiation is put inside your body. The radiation source can be solid or liquid. Internal radiation therapy with a solid source is called brachytherapy. In this type of treatment, seeds, ribbons, or capsules that contain a radiation source are placed in your body, in or near the tumor. Like external beam radiation therapy, brachytherapy is a local treatment and treats only a specific part of your body. RADIATION THERAPY 1. It is commonly used to diagnose osteoporosis and to assess an individual's risk for developing osteoporotic fractures. 2. It is a local treatment, which means it treats a specific part of your body. 3. is a medical imaging procedure that uses several pulses (brief bursts) of an X-ray beam to show internal organs and tissues moving in real time on a computer screen. 4. It is a specialized area of radiology that uses very small amounts of radioactive materials, or radiopharmaceuticals, to examine organ function and structure. 5. In this procedure, fluoroscopy shows blood flowing through your arteries. It can help visually guide healthcare providers in performing angioplasties. 6. What is the most commonly used radiotracer in nuclear medicine? 7. It is an imaging method that uses sound waves to produce images of structures within your body. The images can provide valuable information for diagnosing and directing treatment for a variety of diseases and conditions. 8. It refers to a computerized X-ray imaging procedure in which a narrow beam of X-rays is aimed at a patient and quickly rotated around the body, producing signals that are processed by the machine’s computer to generate cross-sectional images, or “slices.” 9. It is an imaging test that uses radioactive material to diagnose a variety of diseases. Doctors use it to find tumors and diagnose heart disease, brain disorders, and other conditions. 10. In this type of treatment, seeds, ribbons, or capsules that contain a radiation source are placed in your body, in or near the tumor.