Principles of radiography Flashcards by Leah Stevenart

How far away from the primary beam should you be at exposure?

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When should you use a grid?

When the tissue depth of area we are radiographing is over 10cm

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Why are grids beneficial?

They reduce amount of scatter radiation & improve contrast of image

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What are the 2 types of grids?

Stationary
- placed on top of cassette on tabletop

Moving
- cassette is placed in bucky tray underneath in-built grid

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Which positioning aid is radiopaque (would appear in an x-ray image?)

A. foam wedge
B. tape
C. Trough
D. sandbag

D. Sandbag

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What should you do first?

A. Collimate beam to x-ray cassette

B. put grid in bucky tray

C. centre beam over area of interest

A. collimate beam to x-ray cassette

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Why is it important to collimate as specifically as possible?

Reduce scatter

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The area of interest should be … to the cassette

Parallel

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True or false:
A L/R marker should be included on every radiograph

True

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Altering the kV affects what?

Contrast

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Why is correct X-ray exposure important?

Ensures better visualisation of anatomy by balancing contrast & density for optimal diagnostic image

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What does mA (milliampere-second) control in radiography?

Controls no. of electrons crossing tube

Affects no. of X-rays produced

Does NOT affect contrast, but does affect radiographic density (degree of film blackening)

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What does kV (kilovoltage) control in radiography?

Controls number & speed of electrons crossing tube

Affects X-ray penetration & image contrast

Higher kV = greater penetration & better contrast

If kV is too high, X-rays pass straight through patient, reducing contrast

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How do over-exposure and under-exposure affect an X-ray image?

Over-exposure = Image appears too black (too many X-rays penetrate)

Under-exposure = Image appears too white (not enough X-rays penetrate)

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Why is correct positioning important in radiography?

Ensures consistent diagnostic-quality images

Reduces repeat exposures, minimising radiation exposure

Saves time and resources in clinical practice

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What does “Pink Camels Collect Extra Large Apples” stand for in radiography?

Pink – Positioning
Camels – Centring
Collect – Collimation
Extra – Exposure
Large – Labelling
Apples – Artefacts

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How do you position a patient for an ML elbow radiograph?

Place in lateral recumbency (affected side down)

Retract contralateral limb dorsally to prevent superimposition

Ensure elbow is parallel to cassette

Centring: Over medial humeral epicondyle

Collimation: Include distal 1/3 humerus & proximal 1/3 radius/ulna

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How do you position a patient for a CrCd elbow radiograph?

Place in sternal recumbency

Extend affected limb cranially

Elevate head with foam block to avoid interference

Ensure humerus, radius & ulna are in a straight line

Centring: Over humeral epicondyles

Collimation: Include distal 1/3 humerus & proximal 1/3 radius/ulna

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How do you position a patient for a VD hip radiograph?

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Dorsal recumbency, support with trough/sandbags

Extend & rotate hindlimbs medially, securing with tape

Ensure pelvis is straight (equal obturator foramina size)

Centring: Cranial edge of pubis

Collimation: Ilial wings → Mid-femur

How do you position a patient for a DV thoracic radiograph?

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Sternal recumbency, elbows symmetrically positioned

Extend neck slightly, place on foam block

Centring: Slightly caudal to scapula (midline)

Collimation: Thoracic inlet → Diaphragm

Expose at peak inspiration

How do you position a patient for a right lateral thoracic radiograph?

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Right lateral recumbency, extend forelimbs cranially

Place foam wedge under sternum for proper alignment

Centring: Caudal edge of scapula, halfway down thorax

Collimation: Thoracic inlet → Diaphragm

How do you position a patient for a VD abdominal radiograph?

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Dorsal recumbency, support with trough

Ensure spine is straight, hindlimbs flexed

Centring: Midline, caudal edge of last rib

Collimation: Diaphragm (rib 7) → Femoral trochanters

Expose during expiratory pause

How do you position a patient for an ML stifle radiograph?

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Lateral recumbency, affected stifle down

Retract contralateral limb dorsally

Centring: Medial femoral epicondyle

Collimation: Distal 1/3 femur → Proximal 1/3 tibia/fibula

What are the 2 standard views taken for a canine stifle radiograph?

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Medio-lateral & caudo-cranial views

How is the dog positioned for a medio-lateral stifle projection, and what technical considerations apply?

Dog is in lateral recumbency with limb to be imaged against table, flexed at 90 degrees Upper limb is moved out of way with rope tie or sandbag Foam pad should be placed under hock to keep tibia parallel to table & sandbag is used to stabilise hock Collimation should include 50% of femur & tibia/fibula, centered on stifle joint or slightly distal (tibial tuberosity) L/R label should be used

How can you tell if a lateral view is well-positioned?

Femoral condyles should be superimposed without rotation

Label the stifle

How is the dog positioned for a caudo-cranial stifle view, and what are the key technical factors?

Dog is in ventral recumbency with affected limb extended caudally Sandbag on pelvis helps maintain hip extension, while opposite hind limb is lifted laterally with sandbag to keep affected limb non-rotated Limb should be rotated so patella is in midline Collimation should be centered on middle of stifle joint, including 50% of femur & tibia/fibula, plus surrounding soft tissues L/R label should be used.

How can you tell if a caudo-cranial view is well-positioned?

Femoral condyles should be of equal size & patella should be in midline, ensuring good visualisation of joint space

Label the stifle

Why is the cranio-caudal view less commonly used, and what adjustments are needed?

It can cause magnification distortion & is difficult to achieve without rotation Femur needs to be rotated medially for proper positioning

What are the main categories of skeletal disease?

Skeletal diseases can be congenital, developmental, traumatic, infectious, neoplastic, metabolic, or degenerative

What is going on in these joints?

Normal joint vs Joint effusion (a sign of some diseases) accumulation of excess fluid in joint

What is going on in these joints?

Cranial movement of tibia with cranial cruciate ligament rupture (progressive worsening from A to D) (i.e. traumatic)

What is going on in this joint?

Chronic stifle arthrosis (i.e. degenerative [could be secondary to traumatic]) Lots of new bone (osteophytes) Joint effusion Underlying cause often not evident

What is going on in this joint?

Osteochondrosis (i.e. developmental) Radiolucent defect with surrounding sclerosis Could be seen years later as chronic arthrosis

What are the 2 standard views taken for canine shoulder radiograph?

Medio-lateral and caudo-cranial

How is the dog positioned for a medio-lateral shoulder radiograph, and what technical considerations apply?

Dog is in lateral recumbency with limb to be imaged against table Limb is pulled into extension using rope tie to separate shoulder from neck soft tissues Upper limb is moved caudally with rope tie Neck is flexed dorsally & secured with sandbag to move cervical spine away from shoulder joint Foam pad is placed under chest to ensure parallel alignment & assist shoulder extension Collimated to include distal 50% of scapula, proximal 50% of humerus & soft tissues cranial & caudal to shoulder Centre of collimation should be shoulder joint (just distal to acromion) Use L/R label

How can you tell if a lateral shoulder radiograph is well-positioned?

Joint space should be well visualised with no overlying tissue (e.g. opposite limb, neck tissue, trachea, cervical spine) Some radiographers deliberately overlay trachea to increase contrast

Label the shoulder

How is the dog positioned for a caudo-cranial shoulder radiograph, and what are the key technical factors?

Dog is in dorsal recumbency with affected limb pulled cranially into extension & slightly away from midline Sandbag may be used to push head & neck slightly away from limb Scapula & humerus should be aligned along long axis Centre at middle of shoulder joint (just distal to acromion) Collimate to include distal 50% of scapula, proximal 50% of humerus & lateral & medial soft tissues Use L/R label

How can you tell if a caudo-cranial shoulder radiograph is well-positioned?

Scapula & humerus should be in line with each other & proper centering on joint allows good visualisation of joint space

Label the shoulder

What is going on here?

Medial shoulder luxation commonly traumatic & involves displacement of humeral head medially

What is going on here?

Osteochondrosis (i.e. developmental) - Loss of rounded contour of caudal surface of humeral head - Radiolucent defect - May have surrounding sclerosis - May have calcified free body in joint

What is going on here?

Chronic shoulder arthrosis - Lots of new bone (osteophytes) - Underlying cause often not evident

Principles of radiography Flashcards

(46 cards)