MRS1.1.5.0

Question 1

What is the bone anatomy of the chest
both anteriorly and posteriorly

Answer 1

Anterior: Clavicles; Sternum & Sternocostal articulations
Posterior: 12 thoracic vertebrae;12 paired ribs & Scapulae

Question 2

Recall the visceral anatomy of chest

Answer 2

Airway
Lungs
Mediastinum:
* Heart
* Great vessels
Diaphragm

Question 3

Why is cardiothoracic ratio important?

Answer 3

The cardiothoracic ratio (CTR) is the ratio of maximal horizontal cardiac diameter to maximal horizontal thoracic diameter

Question 4

What are the important devices used in imaging

Answer 4

Table bucky, and erect bucky

Question 5

Why are scatter removal grids important to radiographic imaging

Answer 5

The antiscatter grid plays an important role for enhancing image quality in projection radiography by transmitting a majority of primary radiation and selectively rejecting scattered radiation.

Question 6

State the general rules for antiscatter grids

Answer 6

Exposure must be increased if using grid (usually at least doubling mAs)
* Do not angle against grid lines
* Do not place detector back to front in holder
* Do not place grid on back to front
* Use at a certain FFD

Question 7

Why is FFD important?

Answer 7

Focal-film distance (FFD) is the the distance between the center of the anode of the x-ray tube (the focal spot) and the film (top of cassette). Also known as, Source-image distance (SID) which this measurement effects magnification, distortion, and x-ray beam intensity.

Question 8

How does AUTOMATIC EXPOSURE CONTROL
(AEC) work?

Answer 8

Ionisation chamber is a hollow cell containing air
connected to a timer circuit
* Radiation hits the chamber, and the air inside
becomes ionised, creating an electrical charge
* The electrical charge travels along the wire to the
timer circuit and terminates the radiation exposure
when a sufficient charge has been received
* “Sufficient charge” is a predetermined value that
helps keep the dose as low as possible to see
anatomical detail of the lung

• The radiographer chooses the AEC chambers that
  they would like to use- this is determined by the
  anatomy in question

Question 9

What does (AEC) mean?

Answer 9

AUTOMATIC EXPOSURE CONTROL

Question 10

For PA,

Answer 10

109kV & 2 dots on the first row

Question 11

For lateral,

Answer 11

125kV & middle dot

Question 12

State the procedure for patient prep

Answer 12

• ID & Consent
• Explanation
• Pregnancy
• Remove clothing &
  jewellery
• Patient gown

Question 13

State the criteria for a good radiographic image

Answer 13

• Sharp outlines of heart and diaphragm
• Faint shadows of the ribs and superior thoracic
  vertebrae visible through the heart shadow
• Lung markings visible from the hilum to the
  periphery of the lung
• Inspiration
• Proper shoulder rotation demonstrated by scapulae
  projected outside the lung fields

Question 14

State artefacts on the patient

Answer 14

On the patient
* Clothing
* Jewelry/money/phone etc.
* Dirt/food/hair/blood etc.

Question 15

State artefacts inside the patient

Answer 15

• Medical devices
• Penetrating trauma
• Inhaled/swallowed FB

Question 16

State examples of systemic error

Answer 16

• Grid lines
• Dead pixels
• AEC chambers
• Scatter

Question 17

State the exposure error

Answer 17

• Saturation/burn (over exposure)
• Noise/quantum mottle (under exposure)

Question 18

State the points for criteria

Answer 18

• Anatomy
• Collimation & Centring
• Positioning
• Exposure

Question 19

What do we have to ensure for collimation?

Answer 19

• Superior collimation including apex of lung and surrounding soft tissue/ribs.
• Inferior collimation distal to the costophrenic angles.
• Lateral collimation close to skin edge.
• Centered midsagittal plane.

Question 20

For positioning in the criteria of an image,

Answer 20

• Apical lung visible above clavicles.
• Scapulae projected clear of the lung fields.
• No rotation
  o Trachea is midline
  o Medial ends of the clavicles are equidistant
  from the spinous processes
• Good inspiratory effort (8-10 posterior ribs above the diaphragm).

Question 21

What is kyphosis?

Answer 21

An increased front-to-back curve of the spine is called kyphosis. Kyphosis is an excessive forward rounding of the upper back. In older people, kyphosis is often due to weakness in the spinal bones that causes them to compress or crack.

Question 22

What are the criteria for lateral x-ray

Answer 22

M: Correct post processed anatomical
marker clear of anatomy.
A: Both lungs from apices to bases
included. Soft tissues included
surrounding lung fields as appropriate.
C: Inferior collimation distal to the
diaphragm. Forward bending of the patient
(or tilting of the light beam diaphragm)
would allow collimation to parallel the
anterior and posterior thoracic margins

Question 23

For lateral image of chest, the positioning should be

Answer 23

• Chin is not superimposing lungs
• Ribs posterior to the vertebral column
  are superimposed.
• Sternum is seen in profile
• Arms raised to demonstrate both lungs
  free from soft tissue superimposition.
• Superimposition of the posterior
  costophrenic recess
• Clear outline of diaphragm

Question 24

For lateral image, the exposure should be

Answer 24

Contrast and density sufficient to visualise bone and soft tissue whilst able to appreciate lung markings
The ribs and thoracic cage are seen only faintly over the heart

Question 25

State the conditions for a supine chest x-ray

Answer 25

Pt lying flat
Midsagittal plane in centre of image receptor (IR)
IR under back/trolley recess/bucky
Centre beam to IR under bed/in bucky
Caudal angle 5-10° (perpendicular to
sternum)
Note: reduced FFD

Question 26

State the conditions for an erect AP x-ray

Answer 26

Pt sits upright – bring bed as close to 90 degrees
IR behind back approx. 3cm above shoulders.
Midsagittal aligned to middle of IR
Caudal angle 5-10° (CR perpendicular to sternum)
Portrait/landscape detector depending on patient presentation