principles 4

Question 1

Who invented the first exposure system?

Answer 1

Ed. C Jerman, 1925

Question 2

Mobile radiography is defined as

Answer 2

Bedside radiographic exams. Using a standard (fixed) system to image pt in their room. 3 keys to portables
1. Good communication
2. Careful manipulation of equipment
3. Appropriate positioning

Question 3

Digital Mobile X-Ray Imaging System

Answer 3

Flat panel detector (FPD), instantaneous digital image display, motor direct, and wireless LAN to PACS

Question 4

Positioning keys

Answer 4

Maintain accurate SID
Avoid size distortion
–> Minimize rotation of patent and part
–> Part PARALLEL to IR (if possible) pt, CR parallel to floor
Avoid shape distortion
–> CR perpendicular to coronal plane
Demonstration of air-fluid level
–> Fully erect patient, CR parallel to floor
Check for potential artifacts (Personal items, sheets, blankets, IV lines, etc.

Question 5

Mobile Units

Answer 5

Battery powered
Constant Potential Generators ( CPG’s)
High frequency power for consistent tube output
Powered-drive feature for ease of use
Usually single mAs control (not separate mA and time)
Rechargeable battery that must be plugged into AC source between exposures

Question 6

Radiation protection

Answer 6

AT least 2 lead aprons (one for u, one for pt). Clear room of everyone besides pt
Position yourself at least 6 feet away and at a right angle from the patient during exposure

Question 7

Types of exposure systems

Answer 7

1. “Technique charts”
2. Fixed kilovoltage systems
3. Variable kilovoltage systems
4. AEC systems
5. Anatomically programmed radiography

Question 8

Technique adjustment: Best practice is

Answer 8

User calipers to measure part thickness

Question 9

Technique chart

Answer 9

Hold a large number of variables constant, while a single factor varies. Produces consistent results: fewer repeats; reduced dose

Question 10

Variable kilovoltage systems

Answer 10

First exposure “system” (Ed. C Jerman 1925)
Small incrememntkla. hnzgdx in kVp to compensate for variation in body part thickness.
2 kV per cm
Baseline (2KVP x part cm) + 30 kVp=kVp
Advantages- High contrast images
Disadvanatges- Insufficient changes in kV in the higher range/

Question 11

Fixed kilovoltage

Answer 11

Arthur Fuchs (1940s)
kVp remains constant while the mAs is altered with increasing part thickness
mAs settings are adjusted by at least 30 %
Double or half mAs for every 4-5 cm in change in part size
Advantage- Greater exposure latitude due to higher kVp’s selected
Decreased pt dose
Disadvantage- Changes do not compensate for inadequate penetration
Typically results in a higher than necessary kVp being used –> which reduces contrast

Question 12

Balance technique

Answer 12

Based on part size/thickness
Select mAs that results in proper iR exposure according to the EI and displayed noise (quantum mottle).
Select the kVp that assures adequate penetration while exhibiting the subject contrast appropriate for the exam & clinical indication