Set the exposure time to 1.0 sec.
Remove the lead cap from the collimator of the X-ray head.
(a) Use the MDH X-ray monitor or equivalent to measure the dose.
(b) Position the X-ray head to the ion chamber as shown in figure 3-15
(90 same central plane). For reproducibility, a special holding device with a radiation
barrier can be used.
Make the following adjustments to the MDH X-ray monitor.
(a) Set the THRESHOLD to 0.2.
Set to the proper BAROMETRIC PRESSURE.
Set to EXPOSURE RATE.
(d) Set to MEASURE.
Make an exposure.
(a) The measured dose should be 700 millirads (mr) plus or minus
(b) For reproduceability, note the distance (D) where the measured
dose value is obtained.
(5) If the dose levels are lower than specified above, you need to replace
the X-ray head.
d. If no X-rays are emitted from tube head, but all visual and audible indicators
are functioning, the X-ray head is defective.
To verify that the X-ray head is defective, use a fluorescent screen.
(a) Place the fluorescent screen on a table or counter top as shown in
(b) Place a coat over the X-ray head in order to dim the surrounding
Set exposure time 1.0 sec.
Make an exposure. Refer to figure 3-17.