CH 1 Preliminary Steps in Radiography PDF

CH 1: Preliminary Steps in Radiography Friday, January 17, 2025 8:28 AM The Radiographer Administers ionizing radiation to perform radiographic procedures Produces radiographic images at the request of a physician Interacts with patients to make diagnostic images using technical sk...

CH 1: Preliminary Steps in Radiography Friday, January 17, 2025 8:28 AM The Radiographer Administers ionizing radiation to perform radiographic procedures Produces radiographic images at the request of a physician Interacts with patients to make diagnostic images using technical skills combined with knowledge of physics, anatomy, physiology, and pathology Must evaluate images for technical quality, accuracy, and appropriateness relative to diagnosis or reason for procedure Fundamental responsibility of the radiographer is to ensure that each radiation exposure is "as low as reasonably achievable," or ALARA Patient care responsibilities include communication, assessment, monitoring, support Has a shared responsibility to support and advance the mission of the health care provider for whom they work Must adhere to the moral and ethical code of the profession, as well as work in the practice standards that describe the scope of practice Radiography Practice Standards Written and maintained by the American Society of Radiologic Technologists (ASRT) The ASRT define the practice of radiography, describe necessary education and certification, and include the Radiographer Scope of Practice Includes Clinical Performance Standards, Quality Performance Standards, and Professional Performance Standards Ethics in Radiologic Technology Ethics - applies to a health professional's moral responsibility and the science of the appropriate conduct towards others The American Registry of Radiologic Technologists (ARRT) created and maintains the Standards of Ethics that apply to all radiologic technologist who are certified by the organization Purpose is to describe professional values that translate into practice that are in the best interests of patients Standards of Ethics include Code of Ethics and Rules of Ethics The ARRT Code of Ethics serves as a professional behavior to which radiologic technologists may aspire The ARRT Standards of Ethics also contain 22 Rules of Ethics that are "mandatory standards of minimally acceptable professional conduct for all Certificate Holders and Candidates. The Rules of Ethics are enforceable" *Standards are printed PDF* Advanced Clinical Practice: Radiologist Assistant (RA) / Radiology Practitioner Assistant (RPA) In response to increased demands on a radiologist's time, a level of advanced clinical practice has developed for the radiographer Advanced clinical role allows the radiographer to act as a radiologist extender, similar to the physician assistant for a primary care physician These radiographers take a leading role in patient care activities, perform selected radiologic procedures under the radiologist's supervision, may be responsible for making initial image observations that are forwarded to supervising radiologist for incorporation into final report Title of RA or RPA may be used only after passing an advanced level certification exam RADT 1030 Page 1 Care of the Radiographic Room Room should be cleaned as any other room used for medical purposes Mechanical parts of x-ray machine, such as table, supporting structure, and collimator, should be wiped daily with a clean, damp cloth Metal parts of the machine should be periodically cleaned with disinfectant Overhead system, x-ray tube, other parts that conduct electricity should be cleaned with alcohol or a clean, dry cloth NEVER USE WATER TO CLEAN ELECTRICAL PARTS Tabletop should be cleaned after each patient procedure with department approved disinfectant cleaner Accessories, such as gonad shields and nonporous positioning devices, need daily cleaning and after any contact with a patient Adhesive tape residue left on image receptors (IR) should be removed, and all surfaces disinfected Protect IRs from bleeding patients (use protective covers) and disposable protective covers should be manipulated so that they do not come in contact with ulcers or other discharging lesions Do not used stained or damaged IRs The radiographic room should be prepared for procedure before the patient arrives and should look clean and organized A fresh pillowcase should be put on pillow, and accessories need during procedure should be placed nearby Control of Pathogen Contamination The US Centers for Disease Control and Prevention (CDC) provides directives for infection control The foundation of infection control practices is included in the Standard Precautions for All Patient Care. "They're based on a risk assessment and make use of common-sense practices and personal protective equipment (PPE) use that protect health care providers from infection and prevent the spread of infection from patient to patient Standard precautions include the following aspects of professional practice: a. Perform hand hygiene b. Use PPE whenever there is expectation of possible exposure to infectious materials c. Follow cough etiquette principles d. Ensure appropriate patient placement e. Properly handle, clean, disinfect patient care equipment and instruments/devices; clean and disinfect environment appropriate ly f. Handle textiles and laundry carefully g. Follow safe injection practices; wear surgical mask when performing lumbar punctures h. Ensure health care worker safety, include proper handling of needles and other sharps i. Transmission-based precautions are used in addition to standard precautions for patient with known or suspected infections Standard Precautions are designed to reduce risk of transmission of unrecognized sources of pathogens in health care institutions Radiographers are engaged in caring for sick patients and should be thoroughly familiar with standard precautions Handwashing is the easiest and most convenient method of preventing the spread of microorganisms Radiographers should wash their hands before and after working with each patient Hands must always be washed, without exception, in the following specific situations: a. After examining patients with known communicable diseases b. After coming in contact with blood or body fluids c. Before beginning invasive procedures d. Before touching patients who are at risk for infection Radiographers should practice cleanliness when handling all patients, whether or not the patients have an infectious disease RADT 1030 Page 2  If radiographer is to examine patient's head, face, or teeth, the patient should ideally see the radiographer perform handwashing If patient face is to come in contact with the IR front or table, they should see radiographer clean device with disinfectant or cover with drape Under all circumstances, the radiographer must wear disposable gloves A sufficient supply of gowns and disposable gloves should be kept in radiographic room to be use to care for infectious patients Before bringing a patient from an isolation unit to the radiology department, the transporter should drape the stretcher or wheelchair with a clean sheet to prevent contamination of anything the patient might touch When patient must be transferred to the radiographic table, the table should be draped with a sheet When free IR is used, it may be placed under the sheet Gloved radiographer should position patient with sheet when possible After exam is finished, contaminated lined should be folded inward (clean side out) and disposed according to institution policy Minor Surgical Procedures in Radiology Department Procedures that require a rigid aseptic technique, such as cystography, intravenous urography, spinal puncture, arthrography, and angiography, are performed in the radiology department The radiographer can make necessary preparations and provide assistance in many procedures For procedures that don’t require nurse, the radiographer should know which instruments and supplies are necessary and how to prepare and sterilize them Control of Contamination Outside the Radiology Department Radiographer is frequently required to provide imaging services to patients in hospital departments outside of radiology Most often involve mobile radiography and C-arm fluoroscopy procedures in areas such as the emergency department (ED), intensive care units, medical-surgical units, and pain management clinics Strict adherence to standard precautions will help ensure safety of radiographer, patients, and other healthcare workers Radiographer must practice transmission-based precautions and isolation precautions when the situation warrants Providing imaging services in the operating room (OR) requires additional cleanliness considerations beyond those required in other hospital areas Radiographer must safely enter and perform imaging procedures without contaminating the sterile surgical field The radiographer must perform handwashing and wear scrub clothing, shoe covers, a scrub cap, and mask and should survey the particular setup in the OR before bringing in the x-ray equipment Radiographer should never approach the operative side of surgical table unless directed to do so After checking the room setup, the radiographer should thoroughly wipe x-ray equipment with damp cloth before taking it to OR The IR is placed in a sterile covering for some procedures Radiographer should gently drop IR into the sterile covering, being careful not to touch the sterile case Interacting With Patients Patients who are coherent and capable of understanding should be given explanation of procedure to be performed Patient should understand exactly what is expected and be made comfortable If procedure will cause discomfort or be unpleasant, radiographer should calmly and truthfully explain the procedure Patients should be told that it will cause some discomfort or be unpleasant, but because the procedure is a necessary part of the RADT 1030 Page 3  Patients should be told that it will cause some discomfort or be unpleasant, but because the procedure is a necessary part of the exam, full cooperation is necessary Patients with special needs, such as autism or Alzheimer's disease, may require specialized strategies to gain cooperation during radiography procedures Patients usually respond incorrectly when given multiple instructions at once, therefore give one instruction at a time Radiographer should never rush patient When moving or adjusting patient into position, radiographer should manipulate the patient gently, but firmly To reduce possibility of injury, the radiographer should inform patients to keep fingers on top of table at all times When patient is in an oblique (partially rolled to side) position, radiographer should use support devices and adjust to patient to relieve any strain Immobilization devices should be used whenever necessary, but not the point of discomfort When making final adjustments to patient position, radiographer should stand with eyes in line with the position of x-ray tube, visualize internal structures, and adjust part accordingly Ill or Injured Patients Great care must be exercised in handling trauma patients, particularly patients with skull, spinal, and long bone injuries Positioning technique should be adapted to each patient and should necessitate as little movement as possible When a patient who is too sick to move alone must be moved, the following considerations should be kept in mind: 1. Patient should be moved as little as possible 2. Radiographer should never try to lift a helpless patient alone 3. When lifting a heavy patient, one should flex the knees, straighten back, and bend from the hips 4. When patient's shoulders are lifted, the head should be supported. While holding the head with one hand, slide opposite arm under the shoulders 5. When moving patient's hips, the patient's knees are flexed first. In this position, patients may be able to raise themselves. If not, lifting body when patient's knees are bent is easier 6. When a helpless patient must be transferred to the radiographic table from a stretcher or bed, he or she should be moved on a sheet or moving device by at least 4 or preferably 6 people. Many hospitals now have a specially equipped radiographic room adjoining the ED These units often have radiographic equipment and stretchers with radiolucent tops that allow severely injured patients to be examined on the stretcher and in the position in which they arrive Trauma patients must be giving priority over nonemergency patients Age-Specific Competencies Age-specific competence - the knowledge, skills, ability, and behaviors that are essential for providing optimal care to defined groups of patients Examples: neonatal (1-30 days) , pediatrics, adolescent, and geriatric patients The Joint Commission requires that age-specific competencies be written for all health care personnel who provide direct patient care The Joint Commission requires radiology departments to document that radiographers maintain competency in providing radiologic exams to defined groups of patients Age specific competence is based on the knowledge that different groups of patients have special physical and psychosocial needs A radiographer who is obtaining radiograph images on a neonatal or pediatric patient must be skilled at interpreting nonverbal communication Working with geriatric patient requires radiographer to have knowledge and skills necessary to assess and maintain integrity of fragile skin When The Joint Commission surveys organizations, it looks for evidence of competence assessment primarily in personnel records RADT 1030 Page 4  When The Joint Commission surveys organizations, it looks for evidence of competence assessment primarily in personnel records The Joint Review Committee of Education is Radiologic Technology (JRCERT), the organization that accredits radiography programs, makes site visits of radiography programs and looks for evidence that students not only learn basic theories supporting age-related competence but also are competent Radiographers must learn the specifics of how to adapt and modify procedures for extreme groups such as neonate and geriatric patients, and for those in between, such as adolescents Clinical History Radiographer is responsible for performing radiographic exams according to the standard department procedure, except when contraindicated by patient condition Radiologist - physician who is board certified to read or interpret diagnostic images Radiologist depends on radiographer to perform technical aspects of patient care The additional responsibility makes it necessary for radiographer to know the following: 1. Normal anatomy and normal anatomic variations so the patient can be accurately positioned 2. Radiographic characteristics of numerous common abnormalities Although radiographer is not responsible for explaining the cause, diagnosis, or treatment of the disease, the radiographer's professional responsibility is to produce an image that clearly shows the abnormality The radiographer is responsible for obtaining the necessary clinical history and observing an apparent abnormality that might affect the radiographic result Examples include: 1. Jaundice or swelling 2. Body surface masses possibly casting a density that could be mistaken for internal changes 3. Tattoos that could contain ferrous pigment 4. Surface scars that may be visible radiographically 5. Some decorative or ornamental clothing The request for an imaging procedure received by radiographer should clearly identify the exact region to be radiographed and the reason for the procedure It is the radiographer's responsibility to determine whether the procedure ordered is consistent with the reason for the exam Radiographers must understand the rationale behind the exam; otherwise, radiographs of diagnostic value cannot be produced This may result in delayed or missed diagnosis Having the info in advance prevents delay, inconvenience, and more importantly, unnecessary radiation exposure for the patient The radiographer will likely be using the computer system to enter information about the patient The radiographer needs to observe rule of confidentiality, as required by the Health Insurance and Portability and Accountability Act of 1996 (HIPAA) , restrict access to that part of patient's protected health info that is relevant to the current procedure Diagnosis and the Radiographer The radiographer should tactfully advise patient that the referring physician will receive report as soon as radiographs have been interpreted by radiologist Interpretation of images, beyond the assessment of quality, is outside the scope of practice for a radiographer It may be appropriate for a radiographer to notify the radiologist before the patient is released if something is seen on a radiograph that may indicate a potentially serious or life-threatening condition Bowel Preparation Radiologic exams involving abdominal organs often require the entire colon be cleansed before the exam so the diagnostic quality radiographs can be obtained Patient's colon may be cleansed by one or any combination of the following: RADT 1030 Page 5 Patient's colon may be cleansed by one or any combination of the following: ○ Limited diet ○ Laxatives ○ Enemas The technique used to cleanse the patient's colon generally is selected by the medical facility or physician Patient should be questioned about any bowel preparation that may have been completed before an abdominal procedure is begun Patient Clothing, Jewelry, and Surgical Dressings Patient should be dressed in a gown that allows exposure of limited body regions under exam Patient is never exposed unnecessarily; a sheet should be used when appropriate If a region of the body needs to be exposed to complete the exam, only the area under exam should be uncovered while rest of patient's body is completely covered for warmth and privacy If washable gowns are used, they should not be starched; starch is radiopaque, which means it cannot be penetrated easily by x- rays Any radiopaque object should be removed from the region to be radiographed Zippers, necklaces, snaps, thick elastic, and buttons should be removed when radiographs of the chest and abdomen are produced When radiographing the skull, the radiographer must make sure that dentures, removeable bridgework, earrings, necklaces, and all hairpins are removed When the abdomen, pelvis, or hips of an infant are radiographed, the diaper should be removed Some diaper rash ointments are radiopaque, the area may need to be cleansed before the procedure Surgical dressing, such as metallic salves and adhesive tape, should be examined for radiopaque substances If permission to remove the dressings has not been obtained or the radiographer does not know how to remove the dressing and the radiology department physician is not present, the nurse should be asked to accompany the patient to radiology department to remove the dressings When dressing are removed, the radiographer should always ensure that a cover of sterile gauze adequately protects open wounds Motion and Its Control Patient motion plays large role in radiography Because motion is the result of muscle action, radiographer needs to have some knowledge about functions of various muscles Radiographer should use this knowledge to eliminate or control motion for the exposure time necessary to complete satisfactory exam Three types of muscular tissues that affect motion are: ○ Smooth (involuntary) ○ Cardiac (involuntary) ○ Striated (voluntary) Involuntary Muscles Visceral (organ) muscles are composed of smooth muscular tissue and are controlled partially by the autonomic nervous system and the muscles' inherent characteristics of rhythmic contractility These muscles perform the movement of the internal organs Involuntary motion is caused by the following: ○ Heart pulsation ○ Chill ○ Peristalsis ○ Tremor Spasm RADT 1030 Page 6  ○ Spasm ○ Pain The primary method of reducing involuntary motion on radiographic images is to control the length of exposure time - the less exposure time, the better Voluntary Muscles Voluntary, or skeletal, muscles are composed of striated muscular tissue and are controlled by the central nervous system These muscles perform the movements of the body initiated by the individual In radiography, the patient's body must be positioned in such a way that the skeletal muscles are relaxed Voluntary motion resulting from lack of control is caused by the following: ○ Nervousness ○ Discomfort ○ Excitability ○ Mental Illness ○ Fear ○ Age ○ Breathing Radiographer can control voluntary patient motion on images by doing the following: ○ Giving clear instructions ○ Providing patient comfort ○ Adjusting support devices ○ Applying immobilization Decreasing the length of exposure time is the best way to control voluntary motion for patients who are unable to cooperate, such as young children, the elderly, and those with mental illness The radiographer should always be watching the patient during the exposure to ensure the patient has complied with breathing instructions when an exposure is made Radiolucent positioning sponges and sandbags are commonly used immobilization devices Leg holder is used to stabilize the opposite leg for lateral radiographs of the legs, knee, femur, and hip Thin, radiolucent mattress, called a table pad, may be placed on the radiographic table to reduce movement related to patient discomfort caused by lying on the hard surface Preexposure Instructions Radiographer should instruct the patient in the appropriate breathing method and should have the patient practice until necessary actions are clearly understood Most, but not all, radiographic projections require a breath in some phases of respiration Most common are breath holds at the end of inspiration and at the end of expiration A breathing technique is defined as instructing the patient to breathe during a long exposure time combined with a low mA technique setting During trunk exam, the patient's phase of breathing is important Inspiration (inhalation or breathing in) depresses the diaphragm and abdominal viscera, lengthens and expands lung fields, elevates sternum and pushes it anteriorly, and elevates the ribs and reduces their angle near their spine Expiration (exhalation or breathing out) elevates the diaphragm and abdominal viscera, shortens lung fields, depress sternum, lowers ribs and increase their angle near the spine When exposures are to be made during shallow breathing, patient should practice slow, even breathing, so that only the structure above the one being examined move RADT 1030 Page 7  The eyes of radiographer should always be on the patient when exposure is made to ensure that an exposure is not made if the patient moves or breathes Image Receptor The image receptor is the device that receives the energy of the x-ray beam and forms the image of the body part The IR is one of the following four devices: 1. Solid-state digital detector ○ Often referred to as digital radiography (DR) ○ Uses a flat-panel IR to cover x-ray into digital signal ○ Digital signal converter may be a thin-film transistor (TFT) or a changed coupled device (CCD) ○ Image capture system may be indirect, using a light-emitting scintillator coupled to the digital converter ○ Image capture system may be direct, consisting of a photoconductor integrated with the digital converter ○ These solid-state detectors may be built into the x-ray table or upright wall unit ○ Portable solid-state detectors may be wired, or tethered, directly to the digital imaging system computer 2. Photostimulable storage phosphor image plate (PSP IP) ○ Device used for computed radiography (CR) ○ The IP stores much of the x-ray energy it receives for later processing ○ After exposure, the cassette is inserted into a CR reader device, which scans the IP with a laser to release the store x -ray energy pattern as light ○ The emitted light, consisting of the radiographic image, is converted to digital format and viewed on a computer monitor, exported to a CD or is printed on film 3. Fluoroscopic IR: ○ Designed for real-time imaging, to guide procedures, or capture full-motion video ○ IR may be a conventional image intensifier tube, coupled to a video camera, or a solid-state flat-panel digital detector ○ Resulting images are viewed on monitor and may be saved as static images, video recordings, or video files 4. Cassette with film ○ Device that contains special intensifying screens that emit light when struck by x-rays and imprint the x-ray image on film ○ Use of a darkroom, where the film is developed in a processer, is required ○ Film-screen cassettes are the oldest type of IR and are rarely used in modern medical imaging IR Dimension Radiographic IR systems are manufactured in English and metric sizes CR IPs are commonly manufactured in 5 sizes Most departments only use the 10 x 12 inch (24 x 30-cm) and the 14 x 17 (35 x 43-cm) plates for all routine imaging Active surface for IRs used in for DR are manufactured approximately 10 x 12, 14 x 17, and 17x17 IR Dimensions in This Atlas IR dimensions recommended in this atlas are for adult These sizes are subject to modification as needed to fit the size of the body part Radiographic Positioning and Procedure An essential projection, also called routine projection, is identified in the Summary of Projections in each chapter with a symbol Initial or Routine Procedure Radiographs obtained for the initial or routine procedure for each body part are based on the anatomy or function of the part and the type of abnormality indicated by clinical history These radiographs are usually the minimum required to detect any demonstrable abnormality in the region and are set by department protocol Common steps for a Radiographic Procedure Radiographers follow a set of common steps for each radiographic procedure This improves efficiency, ensure patient safety, reduces mistakes, and minimizes patient radiation exposure RADT 1030 Page 8 Accessory Equipment Performance of radiographic procedures may require the use of equipment to ensure a body part remains in the appropriate position during exposure Most common positioning aids are radiolucent sponges of various shapes and sizes based on the anatomy of interest Other devices may be needed to enhance image quality These devices are placed between the patient and the IR These include grids, lead shields, and filters Grids and lead shields reduce scattered radiation to the IR Grids reduce scattered and off-focus radiation reaching the IR and may be attached to the IR or may be built into the IR holder or Bucky tray Compensating filters are designed to compensate for significantly varied tissue thickness and density with a body part The filter results in a more uniform image brightness Equally important, the filter reduces the entrance skin exposure and, thus, the absorbed dose to some of the organs in the body Wedge is the most common filter The wedge is the simplest and most common of the compensating filter shapes Compensating filters are composed of a substance of sufficiently high atomic number to attenuate the x-ray beam The most common filter materials are aluminum and high density plastics Aluminum is an efficient attenuator and a common filter material Some manufacturers offer compensating filters made from clear leaded plastic, known as Clear Pb, that allows the field light to shine through to the patient but still attenuates the x-ray beam Compensating filters are most often placed in the x-ray beam between the x-ray tube and patient Broadly, filters fall into two categories based on their location during use: collimator-mounted filters and contact filters Collimator-mounted filters are mounted on the collimator, using rails installed on both sides of the window on the collimator housing or magnets Contact compensating filters may be placed directly on the patient or between the anatomy and the IR Technical Factors Variations in electricity delivered to the x-ray tube permits the radiographer to control several prime technical factors: RADT 1030 Page 9 Variations in electricity delivered to the x-ray tube permits the radiographer to control several prime technical factors: ○ Milliamperage (mA) ○ Kilovolt peak (kVp) ○ Exposure time (seconds) Radiographer selects specific factors required to produce quality radiograph using the generator's control panel after consulting technical chart Manual and automatic exposure control (AEC) systems are used to set the factors Foundation Exposure Techniques and Chart An exposure technique chart should be placed in each radiographic room and on mobile units, including machines that use AE Foundation technique chart is one made for all normal-size adults A well designed chart includes suggest adjustments for pediatric, emaciated, and obese patients Chart should be organized to display all radiographic projections performed in the room A measuring caliper should be used to ascertain part thickness for accurate technique selection The following primary factors must be taken into account when the correct foundations are being established for each unit: mAs kVp AECs SID Relative patient or part thickness Grid CR/DR exposure indicators or other digital exposure value estimates IR or collimated exposure field dimensions Electrical supply characteristics (phase, frequency) It is the responsibility of all radiographers to ensure that the programmed techniques are appropriate and optimum for their particular patient Adaptation of Expose Technique to Patients Radiographer's responsibility is to select the combination of exposure factors that produce the desired quality of radiographs for each region of the body and to minimize radiation exposure to the patient These foundation factors should be adjusted for every patient's size to maintain uniform radiation exposure to the IR In addition, congenital and developmental factors, age, and pathologic changes must be considered Certain conditions require radiographer to compensate when establishing an exposure technique Conditions that require a decrease in technical factors include: ○ Old age ○ Pneumothorax ○ Emphysema ○ Emaciation ○ Degenerative arthritis ○ Atrophy Some conditions that require increase in technical factors include: ○ Pneumonia ○ Pleural effusion ○ Hydrocephalus ○ Enlarged heart ○ Edema ○ Ascites Gonad Shielding RADT 1030 Page 10  The routine use of gonadal shielding to reduce the risk of damages to fetuses and reproductive cells 2021, recommended no gonad shielding to be done during abdomen and pelvic exams Shield gonads any other time Placement or Orientation of Anatomy on the Image Receptor The part to be examined is usually centered on the center point of the IR or at the position where the angulation of the central ray (CR) projects it to the center The three general positions of the IR: ○ Lengthwise ○ Crosswise ○ Diagonal The lengthwise IR position is used most frequently An IR large enough to include at least one joint should be used on all long bone studies This method is the only means of determining the precise position of the part and localizing the lesion Many institutions require that both joints be shown when a long bone is initially radiographed Regardless of the IR size, it is the radiographer's responsibility to collimate the exposure field to the body part dimensions regardless of its location on the detector A standard rule is radiography is that the body part must be placed as close to the IR as possible However, in some situations, this rule is modified The radiographer can increase the SID to compensate for the increase in OID, thereby reducing the magnification Placement and Direction of the Central Ray The central or principle beam of rays, simply referred to as the central ray, is always centered on the anatomy of interest and usually to the IR, when practical The CR (central ray) is angled through the part of interest under the following conditions: When overlying or underlying structures must not be superimposed When a curved structure, such as the sacrum or coccyx, must not be superimposed on itself When projection through angled joints, such as the knee joint and the lumbosacral junction is necessary When projection through angled structures must be obtained without foreshortening or elongation, such as with a lateral image of the neck of the femur The general goal is to place the CR perpendicular to the structure of interest Accurate positioning of the part and accurate centering of the CR are of equal importance in obtaining a true structural projection with minimal distortion Source-to-Image Receptor Distance The distance from the anode focal spot inside the x-ray tube to the IR Is an important technical consideration in the production of radiographs of optimal quality Directly affect the magnification of the anatomy of the image, the spatial resolution, and the dose to the patient The greater the SID, the less the anatomy is magnified and the greater the spatial resolution An SID of 40 inches (102) has been used traditionally for most conventional exams It has been determined that an increase in the SID when practical will result in reduced magnification and increased spatial resolution, with a reduction in patient dose of approximately 10% SID must be established for each radiographic projection, and it must be indicated on the technique chart RADT 1030 Page 11 In certain exams, such as exam of odontoid in the open mouth position, a short SID of 30 inches may be used In chest radiography, a 72 inch (183 cm) SID is the minimum distance, and in may department, a distance of up to 120 inches is used These long distances are necessary to ensure that the lungs fit onto the 14 inch (35cm) width of the IR (via reduced magnification of the body part) and, most importantly, to ensure that the heart is minimally magnified to allow the diagnosis of cardiac enlargement Source-to-image receptor distance in this atlas When a specific SID is necessary for optimal image quality, it is identified on the page of the specific projection If not mentioned, it can be assumed that a minimum of 40 inches (102 cm) is recommended Source-to-Skin Distance The distance between the focal spot of the radiography tube and the skin of the patient This distance affects the dose to the patient and is addressed by the NCRP Current NCRP recommendations state that the SSD shall not be less than 12 inches and should be less than 15 inches Collimation of Radiation Field The radiation field, also known as exposure field, must be restricted to irradiate only the anatomy of interest This restriction of the radiation field, called collimation, serves two purposes 1. Minimizes the amount of radiation to patient by restricting exposure to essential anatomy only 2. Reduces amount of scatter radiation that can reach the IR, which reduces potential for a reduction in contrast quality Many experts regard collimation as the most important aspect of producing an optimal image This is true regardless of the type of IR use For cassette-based or free detector IR systems, positive beam limitation (PBL), also called automatic collimation, is possible In all cases, PBL is designed to limit only the exposure field to the dimensions of the IR This does not take the place of proper collimation to the dimensions of the body part It is a violation of the ARRT Code of Ethics and ASRT Practice Standards to collimate larger than the required radiation field size When a larger than required area is exposed, the patient receives unnecessary radiation to areas not needed on image In addition, the increased scatter radiation decreases contrast resolution and spatial resolution in the image, reducing the ability to ensure an accurate diagnosis The collimator should be manually adjusted to result in a field size that will include all anatomy pertinent to the radiographic procedure ordered. The software included in the computers of DR systems allows for shuttering Shuttering is used DR to provide a black background around the original collimation edges This black background eliminates the distracting clear areas and the associated brightness that comes through to the eyes Radiographers may be tempted to open the collimator larger than necessary and use the shutter software to "crop-in" or mask unwanted peripheral image information and create proper collimation This technique irradiates patients unnecessarily, increases scatter radiation, and increases radiation dose In addition, the imaging team is exposed to legal liability because captured image info has been masked If it is later determined that the pathology in the obscured area of the image was missed, causing a missed or delayed diagnosis, the radiographer may be held liable RADT 1030 Page 12 Anatomic Markers Each radiographer must include an appropriate marker that clearly identifies the patient's right ( R ) or left (L) side Medicolegal requirements mandate that these markers be present Radiographers and physicians must see the markers to determine the correct side of the patient or the correct limb Markers typically are made of lead and are placed directly on the IR or tabletop Basic marker conventions include the following: ○ R or L markers must be placed on all radiographs ○ The marker should never obscure anatomy ○ The marker should always be placed in the exposure field on the edge of the collimation border ○ The marker should always be placed outside of any lead shielding ○ R and L must be used with CR and DR digital imaging The development of digital imaging and the use of CR and DR have enabled an environment in which the R and L markers can be annotated or placed on the image electronically after exposure at computer work station This is not recommended because of the great potential for error, which has legal implications related to side identification n The Radiograph The image recorded by exposing any of the IR to x-rays is called a radiograph Each step in performing a radiographic procedure must be completed accurately to ensure the maximal amount of info is recorded on the image The info that is obtained by performing the radiographic procedure generally shows the presence or absence of abnormality or trauma This info assists in the diagnosis and treatment of patient The radiographer must evaluate each radiograph to determine the acceptability of image features, proper radiation safety practices, and whether the objectives for performing the procedure have been met Additional image evaluation criteria to be considered include the presence of patient identification, proper radiographic marker placement, proper collimation, evidence of require patient shielding, and absence of artifacts This requires an understanding of anatomy, image geometry, image display characteristics, and image appearance of pathology Display of Radiographs Radiographs are generally oriented on the display device according the preference of the interpreting physician Because methods of displaying radiographic images have developed largely through custom, no fixed rules have been established Traditional standards of practice are followed regarding orientation of radiographs on the display monitor RADT 1030 Page 13 Traditional standards of practice are followed regarding orientation of radiographs on the display monitor Anatomic Position Radiographs are usually oriented on the display monitor so that the person looking at the image sees the body part as though viewed facing the patient This is called anatomic position When in anatomic position, the patient stands erect with arms extended by the sides with the palms of the hands facing forward, heels together, and toes pointing anteriorly When the radiograph is displayed in this manner, the patient's left side is on the viewer's right side and vice versa Medical professionals always describe the body, a body part, or a body movement as though it were in anatomic position Posteroanterior and anteroposterior radiographs The anterior aspect of the patient's chest is placed closest to the IR for a posteroanterior (PA) projection The posterior aspect of the patient's chest is placed closest to the IR for an anteroposterior (AP) projection Regardless of whether the anterior or posterior body surface was closest to the IR during the exposure, the radiograph is usually oriented in the anatomic position Exceptions to these guidelines include the hands, fingers, wrist, feet, and toes Hand, finger, and wrist radiographs are routinely displayed with the digits pointed to the ceiling Foot and toe radiographs are displayed with the toes pointed to the ceiling Hand, finger, wrist, toe, and foot radiographs are viewed from the perspective of the x-ray tube or exactly as the anatomy was projected on the IR This perspective means that the individual looking at the radiograph is in the same position as the x-ray tube Lateral Radiographs Lateral radiographs are obtained with the patient's right or left side placed against the IR Lateral images are displayed in the same orientation as though the viewer were looking at the patient from the perspective of the x-ray tube at the side where the x-ray first enter the patient Oblique Radiographs Oblique radiographs are obtained when the patient's body is rotated so that the projection obtained is not frontal, posterior, or lateral These radiographs are viewed with the patient's anatomy placed in the anatomic position Other radiographs The most common of displaying the radiograph that is used in the radiology department and in most clinical practice areas is generally in the anatomic position or from the perspective of the x-ray tube; however, there are expectations Some physicians prefer to view all radiographs from the perspective of the x-ray tube rather than in the anatomic position Identifications of Radiographs All radiographs must include the patient and procedure information required by institutional policy This info customarily includes: ○ Date ○ Patient's name or identification number ○ Right or left marker ○ Institution identity Correct identification is vital and should always be confirmed Radiographs should develop the habit of rechecking the identification side marker just before placing it on the IR RADT 1030 Page 14 Radiographs should develop the habit of rechecking the identification side marker just before placing it on the IR Side markers should be physically placed on the IR The workstation should not be used to add, or annotate, right and left markers to the image Other patient identification info includes the patient's age or date of birth, the time of day, and the name of the radiographer or attending physician For certain exams, the radiograph should include such info as cumulative time after the introduction of contrast medium ( ex : 5 minutes post injection ), the position of the patient ( ex : upright, decubitus) , or with other markings specified by institution Working Effectively with Obese Patients Obesity is defined as an increase in body weight caused by excessive accumulation of fat A BMI of 30-39.9 is classified as obese A BMI greater than 40 is classified as morbidly obese or approximately 100 lb. overweight The BMI is not of primary importance when radiographic exams are performed: the patient's body diameter and weight are the 2 important considerations One of both these factors can determine whether a radiographic exam can be performed Obese patients have an effect on the functionality of the imaging equipment, and many obese patients cannot be placed onto radiographic or computed tomography (CT) tables Patient transportation to the imaging department, as well as transfer to and from imaging equipment, are more challenging The increased body size and weight of obese patients have a negative impact on image quality and create technical challenges for the imaging professional Equipment Manufactures of imaging equipment have defined weight limits Radiographic table weight limits cannot be exceeded without voiding the warranty Fluoroscopy towers have a maximum diameter and many obese patients cannot fit under the tower of those with under-table units Over-table IR units have much greater distance between the tube and the table, making them popular for use with obese patients CT and MRI scanners have gantry and bore diameters that cannot accommodate some obese patients Radiology departments without appropriate equipment cannot perform exams on patients who weigh more than 350 to 450 lb. Radiographers must be aware of the weight and aperture limits of the radiographic equipment in their department The radiology department should have a protocol for working with obese patients, and all equipment should be marked with the limits To accommodate obese patients, most radiography equipment manufacturers are redesigning their equipment and increasing table weights and aperture dimensions Radiograph and fluoroscopic table weight limits have doubled to 700 lb. CT and MRI table weights and aperture opening have also increased Transportation Obese patients require larger wheelchairs and larger transport beds or stretchers The availability of these special chairs and beds may be limited and may affect the scheduling of these patients Morbidly obese patients who can stand are often imaged in an upright position An important consideration during transportation and transfer of obese patients is the potential risks of injury to the radiographer and other health care workers during movement and positioning of patients Appropriate measures must be made in the patient's room in advance by trained radiology personnel RADT 1030 Page 15 Appropriate measures must be made in the patient's room in advance by trained radiology personnel An obese patient should not be transported to the radiology department and find on arrival that he or she cannot be accommodated An appropriate number of staff members must be available to ensure that moving assistance is appropriate Obese patients are not manually lifted; they are moved by sliding Creative use of high-capacity power lifts allows transfer of obese patients in situations where sliding is not practical Regardless of the transfer method used, it is imperative that proper body mechanics be used by all personnel moving these patients Communication Communications with obese patients are no different than with nonobese patients However, communication with obese patients may require personnel to be more aware of the issues of obesity The radiographer must be able to assess the difficulties created by the limitations of equipment in handling an obese patient and must be able to communicate with the patient without offending him or her The dignity of the patient must be kept in mind; reference to the patient's weight should not be made The radiographer should be sensitive and display compassion This can be accomplished by clearly explaining the procedure to gain the patient's confidence and trust There should never be discussion about the patient in the radiographic room and no discussion within hearing distance of the patient about poor image quality or the difficulty involved in obtaining images Imaging Challenges When the patient is on the imaging table, it is imperative that he or she is centered accurately on the table This is necessary because it may be impossible to palpate traditional landmarks One of the most important considerations in positioning an obese patient is the need to recognize that the bony skeleton and most organs have not changed in position and the organs are not larger Most positioning landmarks used on obese patients will serve as reference points in the midsagittal plane of the patient Radiographic projections of the skull, cervical spine, and upper limb are obtainable on all obese patients in addition to projections of the lower limb from the knee distally Shoulder and femur projections may be difficult to position but are usually obtainable All projections of the thorax including lungs, abdomen, thoracic and lumbar spines, pelvis, and hips are very challenging to position and may be impossible to obtain in morbidly obese patients The patient's lack of mobility makes lateral hip projections virtually impossible Imaging of organs such as the stomach, small bowel, and colon may be very difficult, if not impossible on morbidly obese patients CT may be the only imaging alternative if the equipment can support the weight and girth of the patients Landmarks Finding traditional positioning landmarks may be possible in some obese patients and impossible in morbidly obese patients It is appropriate to enlist patient assistance in identifying landmarks if possible; gives patient a sense of being involved in their exam In some obese patients, the abdominal fat is very soft, movable, and layered in "folds" For these patients, the radiographer can gently move or push the folds of skin out of the way to palpate the ASIS or iliac crest The patient should be informed of what the radiographer is doing every step of the way The jugular notch may be the only palpable landmark on morbidly obese patients The jugular notch is an essential landmark when obese patients are imaged; most projections of the thorax, abdomen, and pelvis can be RADT 1030 Page 16 The jugular notch is an essential landmark when obese patients are imaged; most projections of the thorax, abdomen, and pelvis can be obtained only using this landmark to perform this localization procedure Two items should be available in the radiographic room: tongue depressors and a tape measure When the jugular notch is found, a tongue depressor should be placed on the notch. With the tape measure kept horizontal, the radiographer measures straight down the midsagittal plane, from the jugular notch point to the pubic symphysis The pubic symphysis is found at the following distances from the jugular notch: Patient height: Less than 5ft : 21 inches 5-6 ft: 22 inches Greater than 6ft: 24 inches The second tongue depressor is placed at the level of the pubic symphysis The two depressors present a visual indication of the superior and inferior boundaries of the trunk of the body The symphysis will not be palpitated because of the pendiculum (the fat skirt that hangs down over the symphysis) The indicators presented will determine its location When the radiographer knows where these two anatomic points are, nearly all projections of the trunk can be obtained with moderate accuracy Oblique and lateral projections Caution should be used when turning patients on their side for oblique and lateral projections Turning should always be done with the assistance of the patient and with an appropriate number of additional personnel Positioning aids or equipment should be used to prevent injury to the patient and personnel Measurements should be taken of the body part width to determine whether the exposure technique can be made before turning patient Oblique and lateral projects may be impossible to obtain on a morbidly obese patient Cross-table projections may be impossible because of the patient's size and the very large amount of scatter radiation produced Image Receptor sizes and collimation If care is taken to find landmarks, in particular the jugular notch and the pubic symphysis, relatively accurate positioning can be accomplished Collimation is one of the most important considerations when obese patients are imaged Setting the collimator to the smallest dimensions possibly reduces scatter radiation The reduced scatter increases contrast, which enables improved visibility of the structures The collimator should never be set larger than the size of the IR A very large collimator setting produces more scatter, which degrades overall image quality A significantly improved diagnostic image is obtained on obese patients when IRs and collimation settings of appropriate size are used For colon and other abdominal images, it may be necessary to take multiple images on quadrants of the body Field light size When the collimator size is set automatically for IRs in the Bucky or manually on the collimator for DR equipment, the field light is visible on a nonobese patient body relatively close to the actual dimensions of the IR This light gives the radiographer an accurate visual indication of where the radiation field falls On obese patients, in whom the vertical dimension of the thorax and abdomen is very large, the field light visible on top of the patient appears much smaller than the IR size because the abdomen is closer to collimator bulb and less light divergence occurs RADT 1030 Page 17 appears much smaller than the IR size because the abdomen is closer to collimator bulb and less light divergence occurs The natural tendency may be open the collimator when this small field is seen The collimator should NOT be opened larger than the size of the IR or the stated collimator dimensions for DR Exposure factors Modified x-ray exposure techniques need to be used for obese patients The main factors have to be increased, including the mA, kVp, and exposure time The major limitations in obtaining images of obese patients is inadequate penetration of the body part This situation results in increased quantum mottle (noise) and decreased contrast resolution The increased exposure time required for these patients can also contribute to motion artifacts in the image The most important adjustment that should be made is an increase in kVp Increasing kVp increases the penetration of the x-ray beam Body motion is not a major problem in imaging obese patients because the weight of the patient prevents most body parts from moving, and mA settings of approximately 320 can be used With the repeated use of high-exposure factors, the x-ray tube can become very hot Radiographers should ensure that adequate cooling of the anode and tube as a whole occurs; this can be accomplished simply by taking more time between exposures The Focal Spot The focal spot in the x-ray tube is controlled by the mA that is selected The mA for obese patient radiographs may be higher than 250 to 320 mA, which may automatically engage the large focus Use of the small focal spot, which enables greater spatial resolution, may be restricted to the distal limbs because of the higher exposure Radiographers must have a full understanding of the focal spot limits for the machines they use Bucky and grid The use of a Bucky grid or mobile grid can minimize scatter radiation significantly Grid is automatically use when standard projections are obtained in the x-ray table and for some cross-table lateral images of the limb Although a grid is never used for elbow, ankle, and leg projections on nonobese patients, it can significantly improve image quality on obese patients, in particular on morbidly obese patients Radiology departments should have a high-ratio mobile grid available for use with obese patients Automatic exposure control and anatomically programmed radiography systems AEC and anatomically programmed radiography (APR) systems are widely used in radiology departments to control technical factors automatically Machine-set exposure factors are frequently inappropriate for obese patients, so kVp, mA, exposure time, AEC detectors, and focal spot should be manually adjusted With AEC, the radiographer should ensure that a high kVp and a moderate mA are used Mobile radiography Mobile radiography machines may be used for imaging obese patients; however their use is very limited RADT 1030 Page 18 Because the x-ray tube on these machines have limited ratings, exposures high enough to penetrate these patients can be difficult to obtain The greater dynamic range of digital IRs is allowing all but the largest patients to be imaged Depending on the size of the patient, mobile projections may be restricted to the chest and limbs only Radiation Dose Radiographers must use cation in all aspects of working with obese patients, including keeping repeat exposure to a minimum Precautions must be taken to minimize patient dose Radiographers should especially be cautious when holding a limb or IR during an x-ray exposure on an obese patient The increased exposure techniques prompt increased scatter, which reaches the person holding the patient RADT 1030 Page 19