mahoney4

Question 1

geomtry effects on spatial resolution

Answer 1

• Focal spot size
  
  • large size leads to decreased detail
• OID (object to image distance) or distance between foot and film
  
  • the GREATER the distance, the less detail or sharpness
• SID (source to image distance) or the distance from the tubehead to the film
  
  • the GREATER the dsitance, the SHARPER THE IMAGE
    
    • requires increased mA’s to maintain the same radiographic density

Question 2

material (films/screens) effects on spatial resolution

Answer 2

• slower speed produces sharper image (but requires more radiation)

Question 3

motion effects of spatial resolution**

Answer 3

• motion causes blurring
• to LIMIT MOTION of a part (pediatric or parkinsons patient)
  
  • DECREASE EXPSOURE TIME BY 1/2 and INCREASE kVp by 15% to produce the same radiographic density

Question 4

cast radiography + soft tissue masses

Answer 4

• Plaster = increase mAs 2x normal or + 10 kVp
• Fiberglass = increase mAs 1.5x normal
• Soft tissue masses, foreign bodies
  
  • decrease kVp 15% and double mAs