543.True regarding X-ray tubes of CT
scanner
a.anode-cathode axis parallel to the
axis of rotation of the scanner to minimize heel effect
b.typically have two focal spots ,the
smallest being about 0.6mm
c.heat capacities of 4MJ or more
d.incorporation of heat exchanger to
cool oil
e.typically scanners are operated at
120 kv
ANS OF PREVIOUS BLOG
506.True regarding digital radiography
.
a. Detective quantum efficiency (DOE)
reflects the efficiency of phosphor detection and noise added to the detector
signal
b.DQE may be 100% in DR system
c.DQE of CR system and film-screen
system is close to 30%
d.Disadvantage of DR in comparison to
CR are cost and versatility
e.a DR system have the same flexibility in positioning as a
CR plate
506.acd-- Detective quantum efficiency (DOE) reflects the
efficiency of phosphor detection and noise added to the detector signal. DQE
for DR system may be as high as
65%.DQE are lower than 100% because of
less than 100% absorption of X-rays in the device and internal sources of
noise.(Chapter 5, page no.87,second edition (2008),Farr’s Physics for Medical
Imaging).
No comments:
Post a Comment