7) Complete steps #8-#12 of Test Method II
found in Section I-7-A.
HVL Test Method II: Noninvasive, Maximum
kVp
Test Point
1) Use identical geometry described in steps
1 and 2 in Test Method I, Section II-7-A.
2) Place an Aluminum or Copper attenuator
(1" or 1 mm thickness respectively) in
the beam to protect the image intensi-
fier from unattenuated x-rays.
3) Adjust the collimator during fluoroscopy
to minimize the x-ray field size at the
ionization chamber.
4) Remove attenuators of step 2 and place
Lead attenuator directly in front of image
intensifier to drive the system to
maximum
kVp
during fluoroscopy.
5) Record the
kVp
indicated and exposure
during fluoroscopy.
6) Complete steps 5 through 7 of Test Method
I, Section I-7-A.
The two test methods described above are noninvasive.
The following method requires the AERC circuitry to be
overridden so the
kV
and
mA
can be controlled manually.
Test Method III: Invasive
Most fluoroscopic systems with only AERC contain an
override that enables manual control of the fluoroscopic
technique factors.
In the override manual mode, Test
Method I of Section I-7-A may be used.
override is usually a
However, the
service and maintenance feature
which is not readily accessible to the operator.
II-7-B. Entrance Exposure Rate
After verifying that the total filtration of the
unit is in compliance with Federal Standards. the patient
entrance exposure rate must be measured.
The entrance
exposure rate of fluoroscopic equipment with automatic
exposure rate control (AERC) shall not exceed 10 R/min
(2.6 mC/(kgmin)) (at the point where the center of the
useful beam enters
(Reference #l).
If an optional
the patient during fluoroscopy
high exposure
rate
control is present, the entrance exposure rate shall not
rate control is activated (Reference #l). Continuous
exceed 5 R/min (1.3 mC/(kgmin)), unless the high exposure
manual pressure by the operator shall be required to
activate the high exposure rate control (Reference #l).
During the activation of this mode, a continuous audible
signal to the fluoroscopist shall be available.
Federal
Standards do not specify a maximum entrance exposure rate
31
Manymanuals.com
Manymanuals.de
Manymanuals.fr
Manymanuals.it
Manymanuals.pl
Manymanuals.cz
Manymanuals.es
Manymanuals-pt.com
Kommentare zu diesen Handbüchern