Mobile X-Ray Systems & Chest Mobile(1) PDF

Radiography and Contrast Imaging RMI 226 Mobile Radiography Bontrager ch.28 fchs.ac.ae fchs.ac.ae Principles of Mobile Radiography Mobile radiography uses transportable x-ray equipment to bring imaging services to the patient. Commonly performed in p...

Radiography and Contrast Imaging RMI 226 Mobile Radiography Bontrager ch.28 fchs.ac.ae fchs.ac.ae Principles of Mobile Radiography Mobile radiography uses transportable x-ray equipment to bring imaging services to the patient. Commonly performed in patient rooms, emergency departments, intensive care units, surgery and recovery rooms, and nursery and neonatal units Mobile X-ray was first used in the military – Units were carried to field sites fchs.ac.ae fchs.ac.ae Mobile X-Ray Machines Not as sophisticated as stationary units – Vary in power sources (generators) and exposure controls Typical unit has controls for setting kVp and mAs – mAs range = 0.04 to 320 – kVp = 40 to 130 Power varies between 15 and 26 kilowatts fchs.ac.ae Mobile X-Ray Machines Some machines have preset anatomic programs (APRs) similar to stationary units. Automatic exposure control (AEC) is also available for mobile units. Mobile units with direct digital capability – Flat panel detector connected by a cord or communicates through wireless technology fchs.ac.ae  Technical Considerations Three important technical factors must be clearly understood to perform optimum mobile examinations 1. Grid 2. Anode heel effect 3. Source–to–image-receptor distance (SID) Exposure technique charts are also essential to optimum examinations fchs.ac.ae Grid Optimum performance requires the grid to be – Level – Centered to CR – Used at a recommended focal distance Use of grid on an unstable surface may cause absorption of primary beam = grid cutoff fchs.ac.ae Anode Heel Effect More pronounced – Short SID – Larger field sizes – Small anode angles Short SID and large field sizes are common in mobile Proper placement of anode-cathode axis with anatomy is essential fchs.ac.ae fchs.ac.ae SID Should be maintained at 40 inches (102 cm) Standardized distance ensures consistent images Longer SID requires increased mAs, which results in longer exposure time – Increases risk of imaging motion fchs.ac.ae  Technique Charts Should be available for every machine. Should display standard technical factors for all projections performed with the machine. fchs.ac.ae  Radiation Safety Mobile radiography produces some of the highest occupational radiation exposure for radiographers Protection for self, patient, and other personnel critical Wear a lead apron Stand as far away from the patient, tube, and beam as possible fchs.ac.ae  Radiation Safety Minimal safe distance is 6 feet (2 m). Least exposure is at the right angle to the patient and primary beam. Distance is the single most effective radiation protection measure. fchs.ac.ae  Radiation Safety Inform all persons in the area that exposure is going to be made – Advise persons to move back at least 6 feet (2 m) from patient and/or tube – Provide lead aprons for those who cannot leave room fchs.ac.ae Radiation Safety Shield patient’s gonads – When x-raying children – When x-raying persons of reproductive age – On patient request – When gonads lie in or near useful beam – When shield will not interfere with anatomy of interest Minimum source-to-skin distance is 12 inches (30 cm) fchs.ac.ae Isolation Considerations Two types of patients in isolation 1. Those who have contagious infectious microorganisms 2. Those who must be protected from exposure to infectious microorganisms (reverse isolation) Wear all required protective apparel for specific situations Wash hands before gloving Protect IR with a protective cover fchs.ac.ae fchs.ac.ae  Isolation Considerations 1. After the procedure, discard protective apparel according to protocol. 2. Wash hands. 3. Wear clean gloves to clean equipment and use the appropriate aseptic technique 4. Wash hands after removing gloves. fchs.ac.ae Performing Mobile Examinations Plan for trip out of the department Gather all necessary devices – IR – Grid – Tape – Caliper – Markers – Sponges fchs.ac.ae  Performing Mobile Examinations Check battery charge on battery-operated units – Inadequate charge affects output and image quality. Before entering room with machine, check patient identity and examination to be performed. Communicate with nursing staff for proper patient care – Obtain nursing assistance, if necessary fchs.ac.ae Performing Mobile Examinations Introduce yourself to patient when entering room Explain procedure Observe medical equipment – IVs – Chest tubes – Catheter bags Ask family and visitors to step out of room until examination is finished fchs.ac.ae Performing Mobile Examinations Move chairs, IV poles, wastebaskets, and other objects out of path of machine. 1. If patient is to be examined in supine position, move base of machine to middle of bed. 2. If patient is to be examined seated upright, position base of mobile unit at end of bed. 3. For lateral and decubitus positions, place base of mobile unit parallel or perpendicular to bed. fchs.ac.ae  Performing Mobile Examinations Make sure collimation is not open larger than IR size Check CR and IR alignment to prevent distortion Use consistent system for keeping exposed and unexposed IRs separate(for Old CR not new Dr system) Keep a log of procedures, time of examination, and technical factors for image identification (ID) fchs.ac.ae Patient Considerations Assessment of patient’s condition Patient mobility Fractures Interfering devices Positioning and asepsis fchs.ac.ae fchs.ac.ae fchs.ac.ae  Assessment of Patient Condition Allows necessary adaptation of procedure to ensure quality patient care and image. Assess 1. Alertness 2. Respiration 3. Ability to cooperate 4. Limitations to procedure fchs.ac.ae  Patient Mobility Never move a patient or part without assessment of ability to move or ability to tolerate movement. Check with the nursing staff or physician to obtain assistance and permission to move a part that has had surgery or is fractured. Inappropriate movement can further injure patient! fchs.ac.ae  Fractures There are a wide variety of fractures and therefore a wide range of patient ability to assist with procedure. Key is to be cautious and gentle and to obtain plenty of assistance for patient safety and comfort fchs.ac.ae  Interfering Devices Orthopedic beds, fracture frames, tubes, wiring, etc., produce artifacts Experienced radiographers know which objects can be moved and which require procedure modification to obtain the image Some procedures may have to be performed with the object in the image Get assistance if unsure whether an object can be moved fchs.ac.ae Positioning and Asepsis Warn patient of potential discomfort of IR – Cold – Hard IR can damage skin of older patient – Use cloth or paper cover to reduce risk of injury Protect IR from contamination by use of appropriate impermeable cover. IR cover makes positioning easier because cover does not stick to skin. fchs.ac.ae Mobile Chest x-ray fchs.ac.ae Learning Outcomes After this lecture you will be able to; 1. List the required features of an AP Mobile Chest X-Ray 2. Discuss the positioning requirements of AP Mobile Chest X- Rays 3. Understand the different radiographic techniques used in mobile radiography of the chest 4. Discuss the radiation protection needs in mobile chest radiography 5. Understand and describe infection control requirements for mobile chest radiography fchs.ac.ae Lecture Outline 1. Indications 2. Radiation Protection 3. Adjusting Your Technique 4. Taking a mobile x-ray 5. Positioning 6. Exposure Technique 7. Infection Control 8. Image processing 9. Follow-up fchs.ac.ae  1. Indications: When is a mobile CXR performed? – Critically ill patients are impractical to move: trauma or surgery (Resus Bay in ED, ICU, Recovery) – Patients with heart failure/cardiac arrest/pulmonary edema/low sats. Often in CCU. – Patients on wall suction fchs.ac.ae 2. Radiation Protection Are taking Mobile Chest X-rays safe? Average annual radiation dose per person in the USA is 6.2mSv Average person in Australia receives 2.2mSv per year of Ionizing Radiation Dose Examples: Seven Hour Aeroplane Flight 0.05 mSv Chest X-Ray 0.04 mSv ARPANSA 2011 fchs.ac.ae Radiation Protection - ALARA Minimising the risks – Ask anyone who doesn’t need to be there to leave “e.g. relatives” – Ensure all staff are at least 2 metres away – Alert staff before taking the exposure Radiation Protection is Your Responsibility fchs.ac.ae Positioning away from the beam The radiographer should stay as far away as possible from the X-ray beam during exposure to minimize radiation exposure. 1. If it is not possible to leave the room, the radiographer should stand behind a lead shield or a protective barrier. 2. If no such shield exists, the radiographer should stand at least 2 meters away from the X-ray source and at an angle of 90 degrees or greater to the direction of the primary beam. This position minimizes exposure to scatter radiation, which is the main source of radiation risk for radiographers during mobile X-rays. fchs.ac.ae Scattered Radiation Mobile Radiography Primary Beam Scattered Radiation Learning Points: Stand at least 2 metres away Best place to stand will be looked at in the mobile scatter practical fchs.ac.ae 3. Adjusting Your Technique Ideal CXR is PA Erect at 180cm with a grid Portable CXRs don’t deal with the ‘ideal’ patient This needs to be taken into account fchs.ac.ae PA versus AP 180 cm Heart close to film Heart further from film Pt fully erect Pt not fully erect Even beam Limited SID Grid No Grid Scapulae removed Scapulae cover lungs fchs.ac.ae AP vs PA Projection Comparison of pneumonia on patients taken one day apart using different techniques B A Which image is AP and which is PA? Consider: heart size, rib and clavicle positioning, scapulae, use of grid. fchs.ac.ae Aiming for ERECT where possible Advantages of ERECT Position: Allows air to rise Allows fluid to fall Allows for a good inspiratory effort Gives a truer indication of heart size Gives truer indication of mediastinal width Was this Radiograph taken erect? How can you tell? fchs.ac.ae  AP Erect Chest Requirements Correct rotation: The medial portion of the clavicles should be equidistant from the vertebral column Ribs should be symmetrical in appearance Trachea should be seen mid line Exposure should demonstrate the lung fields clearly Faint shadow of the ribs and thoracic vertebrae should show through the heart shadow 3 posterior ribs should be seen above the clavicles (Bontrager and Lampignano 2014 p94) fchs.ac.ae 4. Taking a Mobile Radiograph Do you have a valid request? – Don’t take the x-ray without one! Is this the right patient? (Perform positive patient ID) – Just going by the bed number is not sufficient! Introduce yourself to nursing staff/PSAs – Do you need their assistance? fchs.ac.ae Taking a Mobile Radiograph Check the patient’s condition with nursing staff – e.g. Is the patient allowed to sit up? Aim for reproducibility: – Check the previous image before you go to the ward – Are there any techniques you could use to improve on the previous image? fchs.ac.ae 5. Positioning Prepare the patient Artefacts – Necklace – Buttons – Patient’s chin – Arms – Oxygen tubing What error has occurred here? Leave the bedside the way you How do you think it happened? found it fchs.ac.ae  Erect - Patient Positioning True AP Projection – Minimise rotation Ask the patient to relax their shoulders Use pillows to minimise rotation Patient Position – ‘up the bed’ The patient is positioned too far down the bed fchs.ac.ae Result if the patient is not ‘up the bed’ when sitting the back of the bed up fchs.ac.ae AP Erect - Positioning the IR Portrait Vs Landscape Can the patient lean forward? – use a slide board to save your back Use Pillowcase for Infection Control fchs.ac.ae  AP Erect - Positioning the IR Align centre of cassette with vertebral prominence (C7) Make sure you can see ~3-5cm of cassette above patient’s shoulders Example of Cassette Position for an ‘average’ pt Cassette Centre fchs.ac.ae AP Erect - Positioning the Tube Need to angle the tube to patient’s sternum – otherwise lordotic chest results General Rule of Thumb: – The more erect the patient is, the less angle that is needed fchs.ac.ae AP Erect - Positioning the Tube PA Erect - straight tube AP Erect - the more recumbent the patient is, the more tube angle that is required Start off with the tube horizontal, then increase the angle caudally until it’s parallel with the patient’s sternum – it’s easier to judge your angle from the plane parallel to the floor fchs.ac.ae AP Erect - Positioning the Tube AP Erect with patient bolt upright - ~5-10deg caudal angle Line Parallel to the Floor Angle of the Tube fchs.ac.ae AP Erect - Positioning the Tube This is the angle that is measured fchs.ac.ae AP Erect - Positioning the Tube As the patient becomes more recumbent, this angle needs to increase fchs.ac.ae Central Ray Placement When taking an AP chest x-ray, the more the tube angle is increased, the higher the C.R. needs to be positioned. fchs.ac.ae Central Ray Placement Floor Level If adjustment to the C.R. for the semi-erect patient is not made, too much abdomen will be unnecessarily exposed. Kyphotic patient: may need straight tube or 5-10° cephalic angle fchs.ac.ae  AP Erect - Collimation Collimation improves image quality Reduces patient’s (and your) dose For majority of patients you can cone in side-to-side to the region of the patient’s gleno-humeral joint There is no gain in irradiating outside the cassette Aim for four borders! fchs.ac.ae AP Supine - Patient Positioning Ask nursing staff for assistance if by yourself Use a slide board – wipe it down afterwards Locate centre of sternum and insert slide board at this level Beware of patient’s arms rolling up fchs.ac.ae AP Supine - Positioning the Tube & Exposure May need ~5° caudal angle Lower the bed as far as possible If SID < 180cm decrease exposure fchs.ac.ae AP Supine – Common Positioning Error Shoulders rolled up → False understanding of where apices are fchs.ac.ae Supine CXR examples fchs.ac.ae 6. Exposure Technique – AP Erect Computed Radiography 90 kV (no grid) (Will see range of 80-100) 180cm SID – use measuring tape on mobile machine – measure your own arm span ~2.5-3.2mAs for average patient – adjust for change in SID Workout what you would give yourself fchs.ac.ae Exposure Technique – AP Erect Digital Radiography ? Higher kV ? Use of grid – What are the considerations? 180cm SID ~1.8mAs for average patient (or less!) – adjust for change in SID Be prepared to adjust your technique from CR to DR as required fchs.ac.ae Exposure Technique - Examples NGT – increase exposure Muscle versus fat Emphysema – decrease exposure fchs.ac.ae Taking the Exposure The white line indicates the stage of the patient’s respiration Equivalent to inspiration Explain to patient breathing instructions before taking the Equivalent to expiration x-ray If intubated look at the ventilator Call out to surrounding staff fchs.ac.ae 7. Infection Control Standard precautions: all body fluids are potentially infectious Use gloves/gown/safety glasses – These need to be changed between each patient Cover cassette and/or clean after use Be careful not to touch the patient, then touch the tube and then touch the next patient without first cleaning the tube fchs.ac.ae  Infection Control Clean surfaces with suitable cleaner. For example: alcohol wipes, Detsol500. Dispose of gowns, gloves in the appropriate bin/laundry basket in that ward/unit. Hand hygiene Wash/Debug your hands before & after EVERY patient! fchs.ac.ae 8. Image Processing If using CR, process the image as soon as you return to the department Annotation: – Mobile – Time of X-ray – Degree of Elevation (erect, semi-erect or supine) – AP or PA (occasionally PA mobiles are taken) – Exposure Factors/SID (including this will vary across centres) Do not place annotations over anatomy fchs.ac.ae Image Processing Example of incorrect placement of post-processed annotations. Why is this unacceptable? fchs.ac.ae 9. Follow-up What do you do if you see something on a mobile chest x-ray that is medically urgent? Is it okay to leave it to the Radiologist or referring doctor to pick up? No, it is not okay, because the x-ray may not be reviewed straight-away. As a Radiograher who has viewed the image, you need to alert someone (Radiologist or referring doctor) what you think is on the image, or at least that the image needs to be reviewed urgently. fchs.ac.ae Summary Portable CXRs are not like routine CXRs Be aware of Radiation Protection Issues Patient’s position in the bed is very important Work as a team with the nursing and PSA staff Tube angle needs to match angle of patient’s sternum Exposure factors need to be adjusted Make sure any urgent changes seen on the x-ray are followed-up fchs.ac.ae References Australian Radiation Protection and Nuclear Safety Agency (2010), Ionising Radiation and Health, viewed 8th March, 2011. http://www.arpansa.gov.au/radiationprotection/FactSheets/i s_rad.cfm http://www.arpansa.gov.au/RadiationProtection/basics/unde rstand.cfm National Council on Radiation Protection and Measurements (2009), Sources of Radiation Exposure: NCRP Report No. 160. Available at: http://www.ncrppublications.org/ fchs.ac.ae