Field Radiography 2021 PDF

MY SURREY AT T E N D A N C E  FIELD RADIOGRAPHY ALISON PRUTTON BVSC SFHEA MRCVS SENIOR LECTURER IN EQUINE CLINICAL PRACTICE LEARNING OBJECTIVES Be able to: Apply the principles of safe use of radiation in a field setting. Understand the compromise between safe use of ionisi...

MY SURREY AT T E N D A N C E  FIELD RADIOGRAPHY ALISON PRUTTON BVSC SFHEA MRCVS SENIOR LECTURER IN EQUINE CLINICAL PRACTICE LEARNING OBJECTIVES Be able to: Apply the principles of safe use of radiation in a field setting. Understand the compromise between safe use of ionising radiation and creating a safe working environment in relation to equine handling. Describe how to optimise image quality when obtaining radiographs of the horse. FIELD RADIOGRAPHY I O N I S I N G R A D I AT I O N S R E G U L AT I O N S 2 0 1 7 Approved code of practice and guidance Dose limits set Estimate doses to members of the public Outline duties of employees and employers to meet the requirements of these regulations FIELD RADIOGRAPHY  H E A LT H A N D S A F E T Y E X E C U T I V E 2021 update All generators must be placed on a stand Not acceptable to hold the generator Increases exposure Risk of serious or fatal electric shock FIELD RADIOGRAPHY R A D I AT I O N S A F E T Y: 3 M A J O R P R I N C I P L E S Must be a clear clinical indication for performing any procedure involving the use of ionising radiation. Avoid x-ray safaris Justify radiographic use by detailed clinical examination and diagnostic analgesia where applicable Exposure of personnel to radiation should be kept as low as reasonably achievable (ALARA principle) Dose limits for the individual personnel should not be exceeded. FIELD RADIOGRAPHY C H A L L E N G E S A S S O C I AT E D W I T H F I E L D R A D I O G R A P H Y Using expensive equipment around large animals No (permanent) control zone – need to follow IRR within context and apply local rules Variable facilities Working with owners and untrained staff Time pressures FIELD RADIOGRAPHY PERSONNEL How many people are required to take a radiograph of a horse’s limb? In most cases you need three people to take an equine radiograph in the field: Someone to hold the horse Someone to hold the plate Someone to take the image (the vet) FIELD RADIOGRAPHY  CONTROLLED AREA Ideally try to avoid taking radiographs in a stable Too confined to work safely around the horse Can’t visualise behind stable wall Flat, level, dry ground Enough space to work around the horse safely Power Supply (if not battery powered) Dark enough to allow visualisation of the centring and collimation lights Quieter part of the yard (minimal traffic) FIELD RADIOGRAPHY T E M P O R A RY R A D I AT I O N C O N T R O L Z O N E Biggest risk for scatter = 2m around the horse Minimise the number of people in the controlled zone Everyone should stand as far from the beam as possible Double the distance reduces the exposure risk 4-fold “For mobile X-ray sets, the controlled radiation area extends in the direction of the X-ray beam until the beam is sufficiently attenuated by distance (approximately 8 m) or shielding (e.g. solid floor or wall) and out to 3 m from the X-ray tube head and patient in all other directions” FIELD RADIOGRAPHY R A D I AT I O N P R OT E C T I O N Personnel within the ‘controlled area’ must wear appropriate protective clothing Lead lined gown Lead lined gloves Lead lined thyroid protector Staff must also wear a radiation dosimeter beneath protective clothing Generator stand Utilise cassette holders or plate holding blocks when possible All personnel assisting with radiographic procedures should be over 18years of age and not pregnant. Any clients assisting should be made aware of the risks of radiation Obtain signed consent FIELD RADIOGRAPHY W H AT I S W R O N G W I T H T H E S E P I C T U R E S ? A B FIELD RADIOGRAPHY PERSONAL PROTECTIVE EQUIPMENT Always avoid placing any body part behind the plate Always be aware of scatter Will be directly in the primary beam Everyone will be exposed to Gowns/gloves do not prevent this scatter exposure Wear gloves and gowns FIELD RADIOGRAPHY PERSONAL MONITORING Specific dose limits for different classes of person: 20mSv a year for 18yr+ employee 6mSv for 16-18yr old 1mSv for members of the public and others NB: this is occupational exposure only, not any other personal exposure. FIELD RADIOGRAPHY PERSONAL MONITORING Two types of dosimeter you will see: Electronic Personal radiation dosimeter Film badge dosimeter FIELD RADIOGRAPHY A B C PAT I E N T P R E PA R AT I O N Horses must be adequately restrained Person controlling the head Stocks? Sedation Light to moderate sedation with an alpha-2 agonist Xylazine- 0.5-1.0mg/kg IV Short acting Detomidine 0.004-0.02mg/kg IV Long acting Romifidine 0.04-0.08mg/kg IV +/- Butorphanol Safety & better quality images But: heavy sedation may result in more movement (More of a problem with proximal anatomy and or/ when longer exposure times needed) FIELD RADIOGRAPHY PAT I E N T P R E PA R AT I O N Ensure horse is standing on a flat even surface Clean the area thoroughly Remove all mud Artefact on radiographs from organic matter and water Hoof preparation Remove the shoe if indicated Clean and pare the foot Pack the sole and the frog with Playdoh to remove air interface FIELD RADIOGRAPHY  PA C K I N G T H E F E E T Image from AAEP: Value of Quality Foot radiographs FIELD RADIGRAPHY  EXPOSURE FACTORS Use exposure charts to minimize retake rate Tailored to your particular system Know the FFD for the generator/exposure chart If radiographing a greater tissue thickness than is typical for the setting listed, increased mAs is required If radiographing a decreased tissue depth, the mAs will need to be reduced accordingly. FIELD RADIOGRAPHY  POSITIONING Consider: The position of the horse The position of the area/joint of interest The position of the X-ray generator The position of the X-ray plate Ensure the limb or joint is vertical in the dorsal and sagittal places for both weightbearing and flexed views Horse on a firm level standing with limbs squarely beneath them Foot blocks for foot series Make sure the power cable will reach both sides of the horse (if relevant) Field Radiography PROCESSING Pick the right body part in the DR system Algorithms enable the best quality image for that body part Can’t be changed afterwards MARKERS Should always be placed dorsal or lateral to the region being imaged Particularly important for symmetrical areas such as foot, fetlock FIELD RADIOGRAPHY SPOT THE DIFFERENCE  WHEN TO REFER When higher exposures are required eg for neck, backs, chests etc Portable generators usually only go to 100-110Kv. Higher exposure → increased scatter. Very hard to maintain alignment between generator and plate without using bucky system Grid may be needed for some FIELD RADIOGRAPHY A N ATO M I C A L P O S I T I O N I N G T E R M I N O LO GY FIELD RADIOGRAPHY FOOT Standard series: Lateromedial Dorsopalmar/Dorsoplantar Dorsoproximal-palmarodistal oblique (to assess the pedal bone – ‘Upright pedal’) Dorsoproximal-palmarodistal oblique (collimated to assess the navicular bone) Palmaroproximal-palmarodistal oblique (‘Skyline navicular’) Additional views (depending on pathology): Dorsoproximal-palmarodistal oblique ‘medial and lateral oblique’ views (‘Pedal wing’ views) FIELD RADIOGRAPHY FOOT FIELD RADIOGRAPHY FOOT FIELD RADIOGRAPHY FETLOCK Standard series: Lateromedial Dorsopalmar/Dorsoplantar Dorsolateral-palmaromedial oblique Dorsomedial-palmarolateral oblique Additional views (depending on pathology): Flexed lateromedial FIELD Radiography FETLOCK FIELD RADIOGRAPHY M E TA C A R P U S / M E TATA R S U S Standard series: Lateromedial Dorsopalmar/Dorsoplantar Dorsolateral-palmaromedial oblique Dorsomedial-palmarolateral oblique FIELD RADIOGRAPHY  CARPUS Standard series: Lateromedial Dorsopalmar/Dorsoplantar Dorsolateral-palmaromedial oblique Dorsomedial-palmarolateral oblique Additional views (depending on pathology): Flexed lateromedial Dorsoproximal palmarodistal oblique (to skyline the distal radius, the proximal row of carpal bones or the distal row of carpal bones). FIELD RADIOGRAPHY HOCK Standard series: Lateromedial Dorsopalmar/Dorsoplantar Dorsolateral-palmaromedial oblique Dorsomedial-palmarolateral oblique Field Radiography  STIFLE Standard series: Lateromedial Caudocranial 60 degrees caudolateral- craniomedial oblique Additional views (depending on pathology): Flexed lateromedial Cranioproximal-craniodistal oblique (skyline patella) Field Radiography OTHERS Heads & dental radiographs – possible in field (but better in clinic!) Necks – Quality from field inadequate. Better in clinic Backs – Quality from field inadequate. Clinic Chests – Must be in clinic Abdomen – Must be in clinic Field Radiography TA K E H O M E M E S S A G E S Protect your own and others’ safety, know the local rules. *Good working practices, minimise time and maximise distance, use shielding* Appropriate restraint Good patient preparation Good positioning Appropriate exposures More to come in Collimate Year 4! Know the projections for each area Understand the limitations of what can be achieved in the field FIELD RADIOGRAPHY