Radiologic Technology: Radiography of Lower Limb Part 2

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Questions and Answers

What is the purpose of using lead masking in digital IR?

To produce uniform density of phalanges and tarsals (correct)

To obtain better image resolution

To reduce patient dose

To increase exposure latitude

What is the recommended angle of the CR in an AP projection of the foot?

10o posteriorly (correct)

15o laterally

15o medially

10o anteriorly

What is the minimum SID recommended for an AP projection of the foot?

90 cm

110 cm

100 cm (correct)

120 cm

Why is it necessary to flex the opposite knee in an AP projection of the foot?

To support the affected knee Signup and view all the answers

What is the purpose of collimation in an AP projection of the foot?

To restrict the x-ray beam to the area of interest Signup and view all the answers

How should the part be positioned in an AP projection of the foot?

Extend the foot and maintain the plantar surface flat on the IR Signup and view all the answers

What is the recommended kVp range for an AP projection of the foot?

70-75 kV Signup and view all the answers

Why is shielding of the pelvic area recommended in an AP projection of the foot?

To reduce radiation exposure to the pelvic area Signup and view all the answers

What is the required angle for a high arch to be perpendicular to the Metatarsals (MT's)?

15o Signup and view all the answers

What is the direction of the CR in relation to the IR for foreign bodies?

Perpendicular to the IR Signup and view all the answers

What is the primary purpose of the AP oblique projection?

To demonstrate the extent of fractures and fragments Signup and view all the answers

What is the recommended kV range for the AP projection?

70-75 kV Signup and view all the answers

What is the purpose of using lead masking with digital IR?

To increase the detail of the image Signup and view all the answers

What is the recommended position of the patient's knee during the AP oblique projection?

Flexed Signup and view all the answers

What is the direction of the general plane of the dorsum of the foot in relation to the IR?

Parallel to the IR Signup and view all the answers

What is the minimum Source-to-Image Distance (SID) required for the AP oblique projection?

100 cm Signup and view all the answers

What is the typical part position for a mediolateral projection?

Plantar surface ┴ to IR Signup and view all the answers

What is the purpose of shielding the pelvic area?

To reduce radiation exposure to the patient Signup and view all the answers

What is the minimum SID recommended for this procedure?

100 cm Signup and view all the answers

What is the direction of the central ray (CR) in a lateral foot projection?

┴ to the IR, directed to the medial cuneiform Signup and view all the answers

What is the recommended kV for this procedure?

60 ± 5 kV Signup and view all the answers

What is the purpose of collimation in this procedure?

To reduce the radiation dose Signup and view all the answers

Why is the lateromedial projection often used?

Because it may be easier to achieve a true lateral Signup and view all the answers

What is the purpose of flexing the knee of the affected limb about 45 degrees?

To prevent over rotation of the affected leg Signup and view all the answers

Study Notes

AP Projection: Foot (Dorsoplantar)

Demonstrates location and extent of fractures, fragments, and joint space abnormalities
Shows soft tissue effusion and foreign bodies
Technical factors:
- Detail screen and tabletop
- Digital IR with lead masking
- 60 ± 5 kV or 70-75 kV with reduced mAs for uniform density of phalanges and tarsals
- Technique and dose: 70 kV, 2 mAs, 10 cm part thickness, 8 mrad patient dose
Patient position:
- Supine with pillow under head
- Knee flexed with plantar surface of affected foot flat on IR
- Foot extended and centered to CR and IR
CR angle: 10° posteriorly (toward heel) directed to base of 3rd MT
Collimation: four sides of digit of interest

AP Oblique Projection – Medial Rotation: Foot

Demonstrates location and extent of fractures, fragments, and joint space abnormalities
Shows soft tissue effusion and foreign bodies
Technical factors:
- Detail screen and tabletop
- Digital IR with lead masking
- 60 ± 5 kV or 70-75 kV with reduced mAs for uniform density of phalanges and tarsals
- Technique and dose: 70 kV, 2 mAs, 7 cm part thickness, 11 mrad patient dose
Patient position:
- Supine or sitting with knee flexed and plantar surface of affected foot flat on IR
- Body turned slightly away from side in question
- Foot rotated medially 30°-40° to plane of IR
CR angle: perpendicular to IR, directed to base of 3rd MT
Collimation: four sides of digit of interest

Lateral – Mediolateral or Lateromedial Projections: Foot

Demonstrates location and extent of fractures, fragments, and joint space abnormalities
Shows soft tissue effusion and foreign bodies
Technical factors:
- Detail screen and tabletop
- Digital IR with lead masking
- 60 ± 5 kV
- Technique and dose: not specified
Patient position:
- Lateral recumbent with pillow for head
- Knee flexed at 45° and opposite leg behind injured limb
- Foot dorsiflexed to assist in positioning
- Plantar surface perpendicular to IR
CR angle: perpendicular to IR, directed to medial cuneiform (at level of base of 3rd MT)
Collimation: four sides of foot to include 2-3 cm proximal to ankle joint

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Description

This quiz focuses on the AP projection of the foot in radiography, covering the pathology demonstrated, including fractures, foreign bodies, and joint space abnormalities.