5.1 Mobile Radiography Notes

mAs range for mobile radiography machine

0.04-320 mAs

kVp range for mobile radiography machine

40 to 130 kVp

Total power for mobile machines are

15-25 kW

3 important factors must be clearly understood to

• The Grid

• Anode Heel Effect

• Source - to - image receptor distance (SID)

• exposure technique charts are also essential to optimum examinations

Grid

• optimum performance requires grid to be

• level- use of grid on unstable surface may cause absorption of primary beam= “off-level” grid cut off

• centered to CR- midline of grid more than 1 to 1 ½ inches off transversely from the CR causes “off-level” grid cutoff

• used at recommended focal distance , or radius - exposures outside of the recommended focal range may produce cut-off on the lateral margins

The anode heel effect is more pronounced in

• short SID

• larger field sizes

• small anode angles

Short SID and large field sizes are

common in mobile

Longer SID requires increased mAs, which results in

longer exposure time

Mobile radiography produces some the

highest occupational radiation exposure for radiographers

Distance is the

most effective means of radiation protection

Minimum source to skin distance (SSD) is

12 inches (30 cm)

2 types of patients in isolation

• those who have contagious infectious microorganisms

• those who must be protected from exposure to infectious microorganisms