MRSC1150 DR Methods 1

What anatomy is labelled with the blue asterisk?

costophrenic angles

What anatomy is labelled with the red asterisk?

cardiophrenic angles

What anatomy is labelled with the orange circles?

Hilum

How do focused grids reduce scatter radiation from a radiograph?

Focused grids have strips which are slightly angles to account for divergent beam. Must be used at a specific distance.

What must you do to the exposure if using a grid?

Increase the exposure (at least doubling mAs)

How does Automatic Exposure Control (AEC) work to control exposure?

An ionisation chamber (which is a hollow cell containing air) is connected to a timer circuit. When the radiation hits the chamber, the air becomes ionised, creating an electric charge. Once sufficient charge has been received, the radiation exposure is terminated.

What is the standard series of radiographs for a chest?

PA and lateral

For a PA CXR, where should the central ray be?

Mid-saggital plane at level of T7 (inferior angle of scapulae)

Distance for a CXR

180cm

Collimation for a PA CXR

Include lung apices to costophrenic angles, laterally to skin border

kVp for a PA CXR

Adult 90-110 kVp

mAs for a PA CXR

Both lateral cells of AEC estimate: 1.2 mAs

Instructions for a CXR

Breathe in and hold your breath (suspended inspiration)

How can you ensure no rotation in a PA CXR (3 points)?

• Sternal ends of the clavicles equidistant from the verterbral column

• Trachea visible in the midline

• Equal distance from the vertebral column to the lateral border of the ribs on each side

How can you ensure proper shoulder rotation for a CXR?

Patient should roll shoulders forward, scapulae should be projected outside of lung fields on radiograph

How can you ensure proper inspiration for a CXR?

10 posterior ribs visible above the diaphragm

What should you ensure about placement of side markers?

Correct placement (correct side) and not over anatomy

How can you ensure that anatomy of interest is assessed adequately for a PA CXR (4 points)?

1. Apical lung visible above clavicles

2. Scapulae projected clear of the lung

3. No rotation (trachea midline and medial ends of clavicles equidistant from the spinous processes)

4. Good inspiratory effort (8-10 posterior ribs above the diaphragm)

Lateral CXR central ray

Mid-coronal place at level of T7 (inferior angle of scapulae)

Distance of lateral CXR

180cm

kVp for lateral CXR

110-120 kVp

mAs for lateral CXR

Central cell of AEC Estimate: 4 mAs

Where should the hilum be located in a lateral CXR

In the approximate centre of the radiograph

How to ensure correct position and no rotation in lateral CXR (3 points)?

1. Superimposition of the ribs posterior to the vertebral column

2. Lateral sternum with no rotation

3. Open thoracic intervertebral spaces

Where should IR be placed in AP erect CXR?

Behind back approx 3cm above shoulders

What is the appropriate angle for an AP erect CXR?

Caudal angle 5-10 degrees (CR perpendicular to sternum)

Where should IR be placed in AP supine CXR?

Behind back approx 3cm above shoulders

What is the appropriate angle for an AP supine CXR?

Caudal angle 5-10 degrees (CR perpendicular to sternum)

Why would an expiration CXR be performed?

To increase the conspicuity of small pneumothoraces. It increases the attenuation of normal lung, thereby increasing the contrast between lung and pneumothorax.

What should be shown in a lordotic CXR?

1. Apices in their entirety

2. Superior lung region adjacent to the apices

3. Clavicles lying horizontally with their sternal ends overlapping only the first or second rubs

4. Ribs distorted, with their anterior and posterior portions superimposed

Pathology?

COPD - emphysema (abnormal permanent enlargement of the airspaces and alveolar wall destruction)

Pathology?

Pneumonia (alveolar air replaced with fluid, obscures lung markings)

Pathology?

Cancer - metastases

Pathology?

Lung cancer - hilarious mass

Pathology?

Pleural effusion (fluid in pleural space)

Pathology?

Pneumothorax

Pathology?

Pneumothorax

Pathology?

Pneumothorax

Pathology (in right image)?

Cardiomegaly

Pathology?

Hiatus hernia (stomach herniates through oesophageal hiatus)

What anatomy is labelled 1 on this diagram?

Xiphoid

What anatomy is labelled 2 on this diagram?

Inferior costal margin

What anatomy is labelled 3 on this diagram?

Iliac crest

What anatomy is labelled 4 on this diagram?

ASIS

What anatomy is labelled 5 on this diagram?

Greater trochanter

What anatomy is labelled 6 on this diagram?

Symphysis pubis

What anatomy is labelled 7 on this diagram?

Ischial tuberosity

What anatomy is outlined in this image?

Diaphragm

What anatomy is outlined in this image?

Stomach

What anatomy is outlined in this image?

Spleen

What anatomy is outlined in this image?

Liver

What anatomy is outlined in this image?

Kidneys

What anatomy is outlined in this image?

Psoas muscle

Standard projections for AXR?

AP supine and PA erect

If a patient presented ?SBO and could not stand, which projection would you take?

Left lateral decubitus (check for air and fluid levels)

Supine AP AXR positioning

Patient on back, on xray table. No rotation, with shoulders and hips equidistant from table

Supine AP AXR central ray

Mid-saggital plane at level of iliac crests

Supine AP AXR distance

100-110cm

Supine AP AXR collimation

Include diaphragm to symphysis pubis, laterally to skin border or receptor size (whatever is smaller)

AXR kVp

Adult 75-80 kVp

Supine AP AXR mAs

Lateral cells of AEC estimate: 30-35 mAs

Grid for Supine AP AXR?

Yes

Breathing for AXR

Suspended inspiration

Criteria for all abdomen radiographic projections (6 points)

1. As much diaphragm as possible

2. Mid pubic symphysis included

3. Psoas muscle seen

4. Nil rotation (pelvic symmetry)

5. Wide window width

6. Markers to indicate side and position

When would a PA prone AXR be done?

Only if a patient is unable to lay on their back. Rarely done.

Erect AP AXR central ray

Mid-saggital plane, half-way between the lower costal margins and the iliac crests

Erect AP AXR mAs

Centre-cell AEC or 30mAs (estimate)

Why would a left lateral decubitus AXR be completed?

To show fluid levels in abdomen, especially if patient cannot stand

Pathology?

Small bowel obstruction (SBO)

Pathology?

Free air under diaphragm

Pathology?

Calcifications

Projections for hand, fingers and thumb

At least two projections of any region

Hand x-ray positioning

Patient seated at end of xray table with legs at right angle to table, hand on image receptor

PA hand central ray

3rd MCP joint

Hand/finger/thumb xray distance

100-110 cm

Collimation for hand x-ray

Four sides of collimation seen to include skin edges of hand

kVp PA hand

50kVp

mAs PA hand

2mAs

Standard hand xray series

PA, PA oblique, lateral

What is an alternate hand projection and when would it be done?

Ball-catchers view (both hands in a ball catching position PA). When suspected rheumatoid arthritis and hands cannot fully open