PCE Introduction Flashcards
What is the function of a “grid” when used in plain imaging
A) to reduce the amount of scatter produced
B) To increase sharpness of the image
C) To improve image brightness
D) To improve image contrast
E) To attenuate backscatter
F) To reduce patient dose
B) To increase sharpness of the image
D) To improve image contrast
Increasing SID, decreases magnification
True or false
True
Which of the following correctly describes radiographic contrast?
A) The density difference between adjacent areas on the image
B) The intensity values of individual pixels in an image
C) How light or dark the image appears
D) The size of the smallest object that must exist before the imaging system records the object.
A) The density difference between adjacent areas on the image
What is Spatial resolution?
The size of the smallest object that must exist before the imaging system records the object.
To x-ray the urinary bladder with the patient supine a 15° caudal angle may be used. How would this angle change if you were asked to image the patient in the prone position?
15 cranially
You are asked to x-ray this patient’s left ankle.
She also has a known fracture of the
left neck of femur.
Where would you position the image receptor to undertake the LATERAL projection? (The patient is lying supine on an x-ray trolley)
Give ONE answer only *
A vertical on the lateral aspect of the - ankle
B - vertical on the medial aspect of the ankle
C - directly under the patient’s ankle (possibly under the sheet)
D - under the trolley
B - vertical on the medial aspect of the ankle
D - under the trolley
A 75 year old lady is referred from her GP for a CXR with the clinical history: persistent cough, ?cause. She is able to walk and stand with ease but has a kyphosis making her unable to lift her chin.
When the patient is positioned for a PA erect CXR there is an OID (object IR distance) of 15cm caused by her kyphosis.
How can magnification of the heart and other mediastinal structures be kept to a minimum?
Click as many as you think are correct. *
Increase kVp and mAs
Apply a 10 degree caudal angle
Take the image AP with an increased SID
Take the image AP with a decreased SID
Take the image PA with an increased SID
Take the image PA with a decreased SID
Apply a 10 degree cranial angle
Change the distance
Ask the patient to lift her head
Decrease the kVp and mAs
Take the image AP with an increased SID
You are asked to undertake an OM facial bones projection. The patient is unable to lift their head so that the OMBL is at 45° to the floor. Their OMBL is raised to 30°.
How far and in which direction should you angle the tube to compensate for the reduced angle of the patient’s head? **
15 degrees caudally
The DRL for a PA chest x-ray is 0.1Gy.cm2; you undertake a PA chest and the DAP is shown as 0.4Gy.cm2. Which of the following could explain the difference between these figures?
The image is over exposed
Collimation was open too wide
The patient is obese
The incorrect chamber was selected
The exposure factors were too low
The SID was 100cm
The patient is obese
The image is over exposed
Collimation was open too wide
The incorrect chamber was selected
You are asked to x-ray abdomen on a 8 months pregnant lady for NJ tube position. Describe and explain what adaptations you would make to keep dose low
Use a high kVp, low mAs technique
- this reduces absorbed dose to both mother and foetues (we dont use this for all because it reduces contrast in normal cases)
Use the AEC, selecting all 3 chambers
-To ensure correct exposure first time
Take the image on full expiration
-This raises the diaphragm and fully extends the abdominal contents, reducing the depth and therefore exposure.
Collimating to the upper half of the abdomen only
- The jejunum sits in the epigastric region of the abdomen and since the position of a NJ tube is the clinical question we dont need to include the abdomen to the symp pubis.
Undertaking an erect AXR with the patient standing
-This will encourage the foetus to sit lower in the abdomen, moving the foetus away from the central ray beam. Gravity
Use a high SID
- To decrease magnification ensuring area of interest fits on the image receptor …
Use an air gap rather than a grid to minimize scatter
-use of an air gap does required an increased exposure compared to that with no grid. However SID will need to be increased
Search pattern note
A – Assess adequacy and alignment
B – Assess bones (cortex, texture and trabeculae)
C – Examine cartilages (joint spaces)
S – Examine the soft tissues (fat pads, joint effusion, swelling, gas etc.)
Search pattern note
A – Assess adequacy and alignment
B – Assess bones (cortex, texture and trabeculae)
C – Examine cartilages (joint spaces)
S – Examine the soft tissues (fat pads, joint effusion, swelling, gas etc.)
Fracture forces types
Tension = opposing directions along long axis - sporting injury - transverse Fx
Compression = towards each other along long axis - FOOSH - Oblique Fx or a T/Y shape Fx
Shear = opposite directions perpendicular to long axis- sporting injury, RTCs
Rotation = twisting around long axis - inversion/twisting - spiral fx
Angulation (bending) = greenstick in children and complete break in adults (transverse fx), sporting injury RTCs
Angulation & compression = combined transverse and oblique fx
Fracture types
Transverse - tension force or direct blow (nightstick)
Oblique -
Spiral (toddlers fx) - rotational force
Comminuted -
Segmental - 2 fractures segment in middle
Avulsed - ligament
Impacted - compression force
Torus (paeds)
Greenstick (paeds)
Vertical fx - compression force with comminuted parts usually (fall from height)
Salter Harris types
Type 1 - Straight across
type 2 - above
type 3 - lower or below
type 4 - two or through
type 5 - crushed
How to describe fracture location
Distal or proximal?
Rule of thirds
Involvement of anatomical points? e.g medial malleolus
At metaphysis or epiphysis?
Intra-articular?
