PNA 1 Flashcards
what’s polydactyly?
more than 5 fingers
How are x-ray images formed?
- radiation source passes through body and casts shadow on film
- shadows of tissues and body parts overlap
- the shadows expand with distance
What does attentuation of xrays depend on?
on the density and thickness of tissues
There are five different densities depending on the anatomical structure. What are those?
Air: black
Fat: dark grey
Soft tissue: grey
Bone: light grey
Metal: white
What does film density refer to?
The blackness of the film
What is it determined by?
by the number of xray photons
which xray factor primarily controls the density?
mAs (milliampere seconds). if mAs are increased, the density is also increased
What does film contrast refer to?
the difference between film densities
What is it determined by?
the energy produced by xray photons
Which xray factor primarily controls the contrast?
KVp (kilovoltage potential). If KVp is increased, the contrast is decreased
What are the most common radiographic positions?
Anterioposterior (AP)
Posteroanterior (PA)
Left & Right lateral (LL,RL)
Left & Right Anterior Oblique (LAO, RAO)
Left & Right Posterior Oblique (LPO, RPO)
What is a fundamental low of radiographic positioning?
a minimum of two views at 90° must be obtained
What is standard series?
list of routine views which are considered as standard set of projections for certain region
What are optional projections?
non-routine views that may be employed in special circumstances for certain region
what is a lateral decubitus position?
patient lying on side and the beam passes through horizontally
when should gonadal shields be used?
- when gonads lie within primary xray field
- if clinical objective will not be compromised by it
- if patient has reasonable reproductive potential
How do you adjust to obese patients?
the fat may cause overexposure. therefore, KVp should reduced to improve the contrast
How do you adjust to muscular patients?
increase in KVp of 10 from original setting
How do you adjust to pediatric patients?
proper immobilization
What is the optimal position to take xrays?
standing
How can you avoid overexposure in (older) patients with decreased bone density?
by reducing the mAs by 25%
What should you not do with a traumatized (as in injured) patient?
to properly position them. it may exacerbate the injury
How do you prepare the patient for an examination?
removal of objects, maybe provide a gown, emptying of bladder or bowel if abdomen, sacrum or coccyx is going to be examined
Why is the breath usually being held?
to prevent movement of body parts
When may breathing be useful?
to blur out overlying structures like ribs
When and why is either deep inspiration or expiration used?
inspiration: for chest and thorax to depress the diaphragm
expiration: for abdomen to elevate the diaphragm
Typical artifacts of skull
hairpins, wigs, false teeth, eyeglasses, necklaces, earrings, bizzare hair styles
Artifacts of Csp
hairpins, wigs, false teeth, eyeglasses, necklaces, earrings, bizarre hair styles, clothing
Artifacts of Tsp
necklaces, brassieres, clothing
Artifacts of Lsp
orthopedic supports, brassieres, underwear, pants with objects in pockets
Artifacts of pelvis, hips and shoulders
orthopedic supports, brassieres, underwear, pants with objects in pockets
