What are the potential risks of X-Rays?
Carcinogenic - have the potential to cause cancer
Teratogenic - have the potential to cause abnormalities of physiological development
What type of damage can radiation cause?
DIRECT damage - ionisations of macromolecules (e.g. DNA)
INDIRECT damage - ionisation of the water in your cells leading to free radical production (main route of damage from X-Rays)
*rapidly dividing cells are at highest risk
What safety precautions should be followed when taking radiographic images?
- Wear appropriate PPE - lead gowns, gloves, neck protectors (only block scatter - still not safe to be in the path of an x-ray beam)
- Use a lead lined table and shielded room
- Legally required to have a warning light on when the x-ray machine is switched on
- Good practice: give a verbal warning and ensure no one in the controlled zone before taking a radiograph
- Involve minimum numbers of people
- no one under 18 or pregnant
- Exit the area before initiating exposure - min. 2 metres from patient
- Use dosimeter badges to monitor exposure
- worn by every person in the building
- in room where machine situated
- outside the room
- Limit scatter
- collimate wall
- use a grid when appropriate - device made of parallel strips of lead interspaced with either aluminium or other organic material which is placed between the patient and the x-ray plate and acts the reduce the scatter of radiation
How to take a good radiograph?
- Restrain the patient adequately
- likely involve sedation/general anaesthesia for all but the very sickest of patients
- use of sandbags/ties dependent on the animals level of consciousness (only applies to small animals) - Position the patient carefully
- area of interest at centre of beam
- main axis of patient/limb should be parallel to the plate
- any extraneous bits of anatomy out of the way
- ensure you have labelled the view (L/R) - Label your radiograph (date/patient name/number/owner name)
- Collimate the beam so that only the area of interest is exposed (minimises unnecessary exposure to x-rays)
- Set the correct exposure parameters adequate for the size of the patient
- Follow safety procedures, before pressing the button!
What is a lateral view?
The outside of the animal/area of interest is ON the plate
-> Head/thorax/abdomen/pelvis/tail:
Left lateral - animal lying on its left side
Right lateral - animal lying on its right side
-> Limbs: mediolateral/lateromedial
Small animals - beam is travelling from medial (inside) to lateral (outside)
Large animals: beam is travelling from lateral (outside) to medial (inside)
What is a dorso-ventral/ventro-dorsal view?
Taken when the animal is lying with its:
- ventral surface on the plate (for dorsoventral)
- back on the plate (for ventrodorsal)
How does the name of the view relate to the positioning?
The name described the direction the beam is travelling in
How to achieve the views?
-> lateral thorax
- Place the patent in lateral recumbency with the plate under the thorax, centred caudal border of the scapula (x)
- Extend forelimbs cranially and secure with sandbags/ties
- Extend hindlimbs caudally and secure with sandbags/ties
- Place foam pad between forelimbs and hindlimbs is they are parallel to one another
- Check sternum to spine height, they should be level. If not, place a foam wedge under the sternum or spine to correct any rotation
- Ensure the whole thorax and diaphragm will be within the view
- Collimate to the skins edge dorsal and ventrally, to include the thoracic inlet cranially and the last rib caudally
- Place the left/right marker
How to achieve the views?
-> Dorsoventral thorax
- Place patient in sternal recumbency with type plate centred under the thorax, the beam will be centred mid sternum on midline
- Place the chin of the patient on a small foam wedge to keep the head straight and comfortable
- Place sandbag over neck
- Partially extend forelimbs cranially
- Visual check for axial rotation
- Palpate scapulae to ensure they are of equal height
- Palpate spine to ensure the spine is straight
- Collimate as before
- Place left/right marker
How to achieve the view?
-> Lateral abdomen
- Place patient in lateral recumbency with cassette centred under abdomen
- Extend forelimbs cranially and secure with sandbags/ties
- Extend hindlimbs caudally and secure with sandbags/ties
- Place foam pads between forelimbs and hindlimbs so they are parallel to one another
- Check sternum to spine height; they should be level. If not place foam wedge under sternum or spine to correct rotation. (Do not place wedge under ventral abdomen)
- Collimate to include the xiphisternum cranially, the skin edges dorsally and ventrally and the perineum caudally
- Beam centered two fingers width caudal to the last rib and midway between the umbilicus and lumbar spine
How to achieve the view?
-> Mediolateral elbow
- Place patient on lateral recumbency with limb to be radiographed closest to the plate
- Centre the plate under the elbow - medial epicondyle of the humerus
- Leave limb to be radiographed in a neutral position
- Upper limb should be drawn caudal/dorsal and secured with a rope/sandbag
- Palpate medial and lateral condyles - should overlie each other
- Place a foam wedge if needed under the carpus to correct rotation
- Collimate to include the distal third of the humerus and the proximal third of radius and ulna, and the skin edges
How to achieve the view?
-> Craniocaudal elbow
- Place patient in sternal recumbency, raise opposite forelimb and place on large foam pad
- Turn head away from limb to be radiographed and place on foam pad with opposite forelimb. Secure with sandbag over neck
- Extend limb to be radiographed cranially alongside the neck
- Palpate medial and lateral condyles to ensure they are parallel with the plate
- Centre the plate under the elbow to be radiographed. Centre point = midway between the condyles.
Palpate olecranon - should be central on the plate - Collimate to include the distal third of the humerus and the proximal third of the radius and ulna, and the skin edges
- Beam centred midway between the humeral epicondyles, centre of elbow joint
How to achieve the view?
-> Mediolateral stifle
- Place patient in lateral recumbency with limb to be radiographed closest to the plate
- Leave limb to be radiographed in a neutral position
- Upper limb should be flexed, drawn cranially and slightly dorsally and secured with sandbags/ties
- Place foam wedges under hock of limb to be radiographed to correct any rotation
- Centre plate under stifle, centre point = cranial and distal to medial femoral condyle (just distal to femoral condyles and caudal to patellar ligament)
- Collimate to include the distal third femur proximally, the proximal third of tibia and fibula distally and the skin edges
How to achieve the view?
-> Caudocranial stifle
- Place patient in sternal recumbency
- Extend limb to be radiographed caudally
- Raise opposite hindlimb and place on large foam pad
- Place foam wedge under caudal abdomen to support and stabilise
- Centre the plate under the stifle. Centre point = midway between and distal to the media and lateral femoral condyles
- Palpate medial and lateral femoral condyles - should be parallel to each other and at equal distances from the plate
- Collimate to include the distal third femur proximally, the proximal third of the tibia and fibula distally and the skin edges
- Make sure tail is out of the way
How does this positioning differ for large animals?
Less likely yo use lateral views of thorax/abdomen in horses in general practice as portable machines do not have the ability to obtain good X-rays.
For investigation of abdomen in larger species - ultrasound/rectal exam might be used
Restraints: Larger animals likely to be standing, sandbags/ropes not required to position limbs
