X-Ray Equipment and General Procedure Radiography equipment consists of

Transcription

1 Learning Modalities - 17 Learning the Modalities We Staff Before we can get in and drive, it helps to know what we re driving. When we know what we re working with, we can more confidently work at our highest potential. In this section, we briefly examine the different radiology modalities we staff. At the end of the section, you can view common jargon you will encounter on calls. X-Ray X-ray (a.k.a. general diagnostic imaging or radiography) allows radiologists and other doctors to see straight through human tissue to examine broken bones, cavities, and swallowed objects with extraordinary ease. We can also modify the general X-ray procedures to examine softer tissue such as lungs, blood vessels, and intestines. X-rays are basically the same thing as visible light rays, but X-ray waves travel at a shorter wavelength (and at a higher energy level) than visible light. With such high energy, X-rays can pass through matter that is not dense enough to absorb all of the energy as it passes though. If X-rays pass through denser matter, their energy is absorbed. So, X-ray pass through less dense matter like blood and soft tissues and are absorbed by more dense matter like bones. The X-rays that do pass through the body collect on film as light. When you look at an X- ray film, you are actually looking at a negative image (dark areas are where X-rays have passed through). X-Ray Equipment and General Procedure Radiography equipment consists of Apparatus (large flat table, box) holding the x-ray film cassette Apparatus holding the x-ray tube which x-ray technologists can move to direct the x-ray to an area of the body they are scanning Radiography involves exposing a part of the body to a small dose of radiation to produce an image of the internal organs. The images may be placed on film or may be stored electronically on PACS (Picture Archiving and Communication System). Usually, the medical facility keeps films for approximately seven years (unless the patient is a child, then until age 21). The facility can also archive x-ray records using PACS. Chest X-Rays Chest x-ray is the most commonly performed diagnostic x-ray examination. Approximately half of all x-rays obtained in medical institutions are chest x-rays. A chest x-ray is usually done for the

2 Learning Modalities - 18 evaluation of lungs, heart and chest wall. Pneumonia, heart failure, emphysema, lung cancer and other medical conditions can be diagnosed or suspected on a chest x-ray. Fluoroscopy Fluoroscopy modifies general x-ray procedures by monitoring movement of substances through the body. Using a device called a fluoroscope, radiography technologists perform a fluoroscopic exam by projecting radiographic images in a movie-like sequence onto a monitor. Radiologists use fluoroscopy to examine the organs or organ systems while they are functioning. They retrieve these images by introducing a contrast medium (such as liquid barium), which has a different opacity from soft tissue. For example, barium will make parts of the gastrointestinal tract visible so a radiologist can diagnose a patient for ulcers. Upper and Lower GI Series Radiologists perform an upper GI series (or barium swallow) to observe digestive function or to detect abnormalities such as ulcers, tumors or inflammation of the esophagus, stomach and small intestine. In an upper GI series, the patient will drink barium on an empty stomach. Physicians may order a lower GI series (or barium enema) to look for ulcers, benign tumors (polyps, for example), cancer, or signs of certain other intestinal illnesses. As with the upper GI exam, patients need to fast for this type of procedure. In this dynamic fluoroscopic procedure, a barium contrast agent is administered through the colon. Mammography Mammography is a specific type of x-ray imaging that uses a low-dose system to examine the breasts. Diagnostic images of the breasts can be recorded to film at a view box or digitally. Mammography helps medical professionals detect breast cancers early because scans can show changes in the breast up to two years before a patient or physician can feel them. Mammography Equipment and General Procedure A mammography unit is a rectangular box that houses the x-ray tube. The unit is dedicated equipment because medical professionals use it exclusively to examine an x-ray of the breast, and its special accessories expose only the breast to x-rays. A device attached to the unit holds and compresses the breast, positioning it to obtain images of the breast at different angles.

3 Learning Modalities - 19 When mammographers perform exams, they scan the breast using the following definitions of direction: Caudal (C) from the tail Cranial (C) from the head Lateral (L) from the side Medial (M) from the middle Oblique (O) at an acute angle For instance, if a mammographer needs to take a right CC-MLO view, they would scan the right breast at an acute angle from head to foot (bottom to top) and from the middle of the breast out to its side. Stereotactic Breast Biopsy Mammography is an excellent way to detect breast abnormalities; but in many cases, imaging studies alone cannot show whether a growth is benign or cancerous. To make determine this, physicians must obtain a tissue sample for microscopic examination. Instead of an open surgical biopsy, which removes an entire breast lump, a medical professional can extract the tissue sample by passing a hollow needle through the skin into the suspicious lesion using breast x-rays. This procedure is much less invasive than the surgical approach. A special computerized mammography machine uses intersecting coordinates to pinpoint the area of tissue change. This method is called stereotactic biopsy or x- ray-guided biopsy. Information The more slices the CT equipment can produce, the more advanced the technology. Computed Tomography (CT) Computed tomography (CT), sometimes called CAT scan, uses specialized x-ray equipment to obtain many images from different angles, and then joins these images together to show a cross-section of body tissues and organs. Unlike conventional x-rays, which produce pictures of the shadows cast by body structures of different density, CT scanning uses x-rays in a much different way. When the rays pass through the body, special sensors measure the amount of radiation absorbed by different tissues (and lesions such as tumors). As a patient lies on the bed, the scanner parts revolve around him or her, emitting and recording x-ray beams from as many as a thousand points on the circle. A special computer program then uses the differences in x-ray absorption to form cross-sectional images, or slices, of the head and brain. These slices are called tomograms, hence the name computed tomography. The more slices the CT equipment can produce, the more advanced the technology and the higher the quality of images medical professionals can obtain.

4 Learning Modalities - 20 CT Equipment and General Procedures The CT scanner is a large unit with a hole in the center, giving it the appearance of a doughnut. The patient lies on a table that can move up or down and can slide into and out of the doughnut hole. The computer they use to examine a patient is not in the examining room but in an adjoining room. Using CT equipment, physicians can examine parts of the body such as these: Brain TMJ (Temporo-Mandibular Joint) jawbone IAC (Inner Auditory Canal) inner ear Orbits eye sockets Larynx Chest Spine Pancreas Abdomen Liver Pelvis Using the data obtained from the CT scans, professionals can also perform three-dimensional (3-D) reconstructions of the target areas. Magnetic Resonance Imaging (MRI) Rather than x-rays, magnetic resonance imaging (MRI) uses radio waves and a strong magnetic field to provide remarkably clear and detailed pictures of internal organs and tissues. This technique has helped radiologists diagnose tumors of the brain as well as disorders of the eyes (orbits) and the inner ear (IAC). It requires specialized equipment and expertise and allows radiologists to evaluate some body structures that x-rays cannot differentiate. For example, MRI can detect tiny areas of tissue abnormality in patients. MRI Equipment and General Procedure Conventional MRI equipment consists of a closed cylindrical magnet called a bore. The number of coils in the magnet determines the machine s strength (measured in tesla). The more coils in the bore, the higher the tesla and the more powerful the electromagnet. Typically, the magnet s strength in the healthcare setting does not exceed 2 tesla; but research uses much more powerful systems as high as 60 tesla. Because these magnets are so extremely powerful, patients must remove all metal objects from their bodies. No metal of any kind can be near the field of an MRI machine, lest it risk being drawn in my its field.

5 Learning Modalities - 21 Information Because the magnet will pull on its metal parts, patients with pacemakers cannot receive MRI scans Once in the bore of the MRI machine, the patient must lie totally still for several seconds at a time and consequently may feel claustrophobic. However, new patient-friendly designs are rapidly coming into routine use. The "short-bore" systems are wider and shorter and do not fully enclose the patient. Some newer units are open on all sides; however, the image quality may vary. MRI procedures scan all of the same types of areas as CT scans, but consider the differences with this generalization: CT scans the hard parts, MRI scans the soft parts. Nuclear Medicine Nuclear medicine is a subspecialty within the field of radiology. It comprises diagnostic examinations that result in images of body anatomy and function. The images are developed based on the detection of energy emitted from a radioactive substance (chemical isotope) given to the patient, either intravenously or orally. Generally, radiation to the patient is similar to that resulting from standard x-ray examinations. Nuclear medicine imaging is useful to help physicians detect Tumors Aneurysms Irregular or inadequate blood flows Blood cell disorders Organ function deficiencies Nuclear Medicine Equipment and General Procedures During most nuclear medicine examinations, a patient lies on a scanning table. Consequently, the only piece of noticeable equipment is the specialized gamma camera used during the procedure. It is enclosed in metallic housing designed to facilitate imaging of specific parts of the body. It can look like a large round metallic apparatus suspended from a tall, moveable post or a sleek one-piece metal arm that hangs over the examination table. Medical professionals usually administer the isotope intravenously but sometimes orally. This compound, called a radiopharmaceutical or tracer, eventually collects in the organ and gives off energy as gamma rays. The camera detects the rays and works with a computer to produce images and measurements of organs and tissues.

6 Learning Modalities - 22 Generally nuclear medicine technologists perform procedures in the following techniques: Positron Emission Tomography (PET): using fast-decay tracers, PET produces double gamma rays and provides images of blood flow, glucose metabolism in the brain, and other biochemical functions Single Photon Emission Computed Tomography (SPECT): using long-decay tracers, SPECT produce single gamma rays and provides information about blood flow and other processes; less sensitive, detailed, and expensive than PET scans Cardiovascular Nuclear Medicine: using tracers to flow through the heart and blood vessels, these techniques help detect blocked arteries or arterioles in the heart and other tissues; uses procedures similar to cardiac ultrasound (see Ultrasound below) Bone Scan: using tracers (such as radioactive phosphorus) that collect in bone tissue, these procedures help detect tumors based on their high metabolic activity (more phosphorus collects there) Ultrasound Ultrasound (US) imaging, or Sonography, obtains images of internal organs by sending high-frequency sound (i.e. ultrasound) waves into the body. Ultrasound imaging is follows the same principles involved in the sonar used by bats. The waves echoes display a real-time visual image that can identify the size, shape, and internal consistency (fluid, solid) of a target area. Sonographers can scan in the following specialty areas: Abdominal (AB) Obstetric (OB) Vascular Cardiac (Echo) Ultrasound Equipment and Procedure Ultrasound scanners consist of the following components: Computer Video Monitor Transducer (hand-held device that transmits and receives ultrasound waves)

7 Learning Modalities - 23 For the procedure, the Sonographer 1. Spreads lubricating gel on the area he or she is scanning (gel creates an airtight seal between transducer and skin) 2. Presses the transducer firmly against the skin and obtains images immediately 3. Observes the monitor during the exam and records the images (using videotape or a series of still photographs) Pros of Ultrasound Noninvasive Usually painless Easy to use Uses sound waves instead of ionizing radiation Provides real-time imaging Presents a risk-free procedure for patients (standard procedures) Cons of Ultrasound Since air or gas can reflect ultrasound waves, ultrasound is not ideal for scanning the bowel. (Barium exams (Fluoro) and CT are better equipped.) Ultrasound hardly penetrates bone and only shows the outer surface of bony structures (not what lies within and beyond). (MRI is better equipped.) Abdominal Ultrasound Abdominal ultrasound (AB) is used extensively for evaluating the kidneys (find kidney stones), liver, gallbladder, pancreas, spleen, and blood vessels of the abdomen. Because US images are captured in real time, they can show movement of internal tissues and organs and enable physicians to see blood flow. Using information about blood flow (i.e. speed and volume) physicians can often determine whether a patient is a good candidate for other procedures such as angioplasty (see Cath Lab/Special Procedures). Obstetric Ultrasound Obstetric ultrasound (OB) is generally used to: Establish the presence of a living embryo or fetus Estimate fetal age Diagnose congenital abnormalities (e.g. ectopic pregnancy) Evaluate the position of the fetus Evaluate the position of the placenta Determine a multiple pregnancy

8 Learning Modalities - 24 The obstetric ultrasound exam takes about 20 minutes. OB Sonographers can obtain images by scanning the lower abdomen. However, to obtain more detailed images of the uterus and ovaries, the radiologist will order the scan using a transvaginal probe (see right). The probe (narrow end) is placed about two to three inches into the vagina; the Sonographer uses the other end (handle) of the probe to control the scan. High-Risk OB General OB cannot reveal all fetal abnormalities. When radiologists or doctors suspect a possible abnormality, they may request the patient to undergo nonradiologic, invasive procedures, known as high-risk OB. Patient undergoes testing such as amniocentesis (the evaluation of fluid taken from the sac surrounding the embryo or fetus) or chorionic villus sampling (CVS) (evaluation of placental tissue) to determine the health of the embryo or fetus, or may be referred by her primary care physician to a perinatologist (an obstetrician specializing in highrisk pregnancies). Vascular Ultrasound Ultrasound imaging of the body's veins and arteries can help the radiologist to see and evaluate blockages to blood flow, such as clots in veins and plaque in arteries. With information about the arterial blood flow, the radiologist can often determine whether a patient is a good candidate for a procedure such as angioplasty. Vascular ultrasound images can also provide information to plan or review the success of procedures that graft or bypass blood vessels such as renal artery bypass. Ultrasound of the veins may reveal blood clots that require treatment such as anticoagulant therapy (blood thinner) or filters to prevent clots from traveling to the lungs (embolism). Ultrasound of the vascular system also provides a fast, noninvasive means of identifying blockages of blood flow in the neck arteries to the brain that might produce a stroke or mini-stroke. Specific Types of Vascular Procedures The definitions below briefly explain some terms and procedures related to vascular ultrasound: Aortic-Iliac Duplexing: Measuring blood flow through Aortic-Iliac Arterial Pressure: Measuring the systolic blood pressure in the arm and at four levels in the leg; and interpreting this information as an ankle-brachial pressure ratio and as pressure decrements in the extremity (segmental pressure)

9 Learning Modalities - 25 Carotid Duplexing: Determining extent of blood flow through the carotid arteries in the neck; used to diagnose strokes. Color Flow: Colorized ultrasound image (different colors based on frequency) of blood flow. Allows clinicians not only to hear (Doppler alone), but also to clearly see blood flow within vessels, providing an opportunity to make an accurate diagnosis faster. Especially useful in vessels that are too small to visualize with conventional imaging Doppler: Doppler Effect is a change in the frequency of a wave because the source or receiver of the wave is moving, or in the case of a reflected wave (echo), the reflector is moving. Doppler allows the professional to analyze the waveforms in order to determine if the veins or arteries are narrowing in certain area DVT: (Deep Venous Thrombosis) Blood clot, or thrombus, in a major vein that may partially or completely block the flow of blood Popliteal: Ultrasound exam of the popliteal area of the knee; helps identify a Baker's cyst or popliteal artery aneurysm Stenosis: Narrowing of the arteries or veins Cardiac Ultrasound Cardiac ultrasound (Echo) uses ultrasound to examine the heart. General echoes are obtained by pressing the transducer on the chest (transthoracic echo). In addition to providing single-dimension images, the echocardiogram also offers far more sophisticated and advanced imaging. This is known as two-dimensional (2-D) Echo and is capable of displaying a cross-sectional "slice" of the beating heart, including the chambers, valves and the major blood vessels that exit from the left and right ventricle. Specific Types of Echo Procedures The definitions below briefly explain some terms and procedures related to cardiac ultrasound: Color Flow: Colorized ultrasound image (different colors based on frequency) of blood flow. Allows clinicians not only to hear (Doppler alone), but also to clearly see blood flow within vessels and the heart, providing an opportunity to make an accurate diagnosis faster. Dobutamine: Dobutamine affects the heart in a similar manner to exercise. Patient receives an IV of Dobutamine (and possibly other agents such as Atropine) while the echo is performed.

10 Learning Modalities - 26 Doppler: Doppler Effect is a change in the frequency of a wave because the source or receiver of the wave is moving, or in the case of a reflected wave (echo), the reflector is moving. Doppler allows the professional to analyze the waveforms in order to determine if the veins or arteries are narrowing in certain area M-Mode: Single-dimensional echo images that allow measuring heart chambers Stress Echo: Echo images obtained while the patient exercises on a treadmill. Echo performed before exercise and after exercise also TEE: (Trans Esophageal Echo) Echo images obtained by inserting a transducer through the throat of the patient, providing for more detailed images Radiation Oncology Radiation oncology or cancer therapy uses x-rays to treat cancer. The radiation doses are extremely controlled and precise. Modern technology has combined the use of three-dimensional imaging technology, computerized treatment planning and high-energy x-ray machines to make this possible. It is not just the technology that cures patients, but the professionals who use it. At V Platinum we staff the following professionals in radiation oncology: Radiation Therapists Dosimetrists Radiation Therapy Radiation therapy is the careful use of high-energy radiation to treat cancer and works because radiation destroys the cancer cells ability to reproduce. The body then naturally gets rid of these cells. Radiation therapists work administer the daily radiation treatment under the doctor s prescription and supervision. The most popular treatment method today is called Intensity Modulated Radiation Therapy (IMRT), which uses CT images for a 3-D reconstruction of the dose site and linear accelerators (LINAC) to deliver the dosage. They also maintain daily records and regularly check the treatment machines to make sure they are working properly. As you encounter terms associated with radiation therapy, check the glossary of terms to get a better idea of the processes involved. Dosimetry In dosimetry, a professional dosimetrist carefully calculates the dose of radiation to make sure the tumor gets enough radiation. Dosimetrists develop a number of treatment plans that can best destroy the tumor

11 Learning Modalities - 27 while sparing the normal tissues. Dosimetrists calculate dosages for cancer treatments plans, which radiation therapists implement. Many of these treatment plans are very complex. Dosimetrists work with the doctor and the medical physicist to choose the treatment plan that is just right for each patient. Many dosimetrists start as radiation therapists, and later become dosimetrists after continuing their education in a one-to-two-year dosimetry programs, or they undergo intense training to gain the skills they need. The Medical Dosimetrist Certification Board (MDCB) certifies dosimetrists. Interventional Radiology (Cath Lab/Specials) Interventional radiology is a rapidly growing area of medicine, in which interventional radiologists (IRs) use imaging procedures such as x-rays, MR, CT, and ultrasonography to diagnose disease. IRs are physicians who specialize in performing minimally invasive, targeted treatments that use imaging procedures as guidance. Interventional radiology procedures are an advance in medicine that replace open surgical procedures. They are generally easier for the patient because they involve no large incisions, less risk, less pain and shorter recovery times. Interventional radiology procedures can fall under two major categories: Cardiac Cath Lab Special Procedures Both of these categories are similar but typically involve different types of procedures. As you learn more about interventional radiology, you will also learn to differentiate which procedures generally fall under which category. Regardless of category, interventional procedures will typically use imaging to guide small instruments such as catheters (tubes that measure just a few millimeters in diameter) through the blood vessels or other pathways to treat disease percutaneously (through the skin). Cardiac Cath Lab Professionals who work in the cardiac cath lab will usually be performing or assisting physicians with interventional procedures performed on the heart. Cardiac Cath Lab Technologists, also called Cardiovascular Technologists (CVT) or Registered Cardiac Invasive Specialists (RCIS), assist the cardiologists that perform cath lab procedures. RCIS is a certification administered by the Cardiovascular Credentialing International (CCI), which we consider a level above

12 Learning Modalities - 28 CVT status. Whether RCIS or CVT, a cath lab tech can assist in procedures by Scrubbing: working with the doctors during the procedures Monitoring: monitoring and charting the procedures Circulating: working in the room, circulating where needed during procedures Cardiac Cath Lab techs will commonly assist physicians with the following types of procedures (see glossary for definitions): Ablation Angioplasty Brachytherapy Heart Catheterization IVUS (Inravascular Ultrasound) Rotoblation Stent Implantation Special Procedures Where Cath Lab Techs typically are registered CVT or RCIS, Special Procedures Techs are usually certified radiographers by the American Registry of Radiologic Technologists (ARRT). Cath Lab Techs are usually assisting with the actual cardiac invasive procedures and do not rely heavily on operating the radiography equipment. Special procedures however does require a technologist to operate radiographic equipment, so the certification is usually required. This is not to say that CVT do not know how to operate radiographic equipment nor does it mean that Special Procedures Techs do not know how to perform cath lab procedures. In fact, you will find that procedures in these two modalities often intertwine. Still, special procedures positions involve interventional radiology associated with systems other than the heart, such as peripheral veins and arteries. When you hear about special procedures, you can expect to hear about procedures such as Angioplasty Clots Peripherals Stenting You will find that two modalities, cath lab and specials, have many similarities. Use the glossary to help find definitions of procedures that you encounter in these modalities.