Surface dose for tangentially incident photon beams in the presence of air gap and air cavity.
Dose to a surface parallel to an incident photon beam has been investigated in the presence of air gaps and air cavities. Measurements have been made in an acrylic phantom with a parallel plate chamber. Photon beams of Co 60, 4-MV, 6-MV, and 15-MV X-rays have been investigated. The results of our measurements show that in the case of air gaps, the dose reduction to a tangential surface is considerable. On the other hand, the dose reduction is 2% or less in the case of air cavity for volumes encountered in clinical situations.
Prasad
S C
SC
SUNY Health Science Center, Department of Radiology 13210, USA.
Chung
C T
CT
D000388:Air; D008961:Models, Structural; D017785:Photons; D011829:Radiation Dosage