Author Question: The AP axial Townes method will need which tube angle if IOML is perpendicular to the image ... (Read 26 times)

bcretired · **on:** Jul 17, 2018

The AP axial Townes method will need which tube angle if IOML is perpendicular to the image receptor?

30 degrees caudal
25 degrees cephalic
30 degrees cephalic
37 degrees caudal

Question 2

Sheets of metal that are positioned outside the glass window, but above the shutters, are considered:

inherent filtration
total filtration
added filtration
effective focal spot

srodz · **Reply #1 on:** Jul 17, 2018

Answer to Question 1

37 degrees caudal

Rationale: If IOML is aligned perpendicular to the IR, a 37 degree caudal tube angle is needed to accurately project the dorsum sellae within the foramen magnum. There is a seven degree difference between the OML and IOML.

Answer to Question 2

added filtration

Rationale: Added filtration means thin sheets of aluminum are added to the existing inherent filtration. The effect of added filtration is to remove low energies from the beam that contribute to patient skin dose.