Specifications

Table 5-2 ALUMINUM EQUIVALENT OF PRIMARY BEAM TOTAL FILTRATION
Operating Voltage (kVp) Total Filtration (mm Al Equivalent)
Below 50................................... 0.5
50-70........................................ 1.5
Above 70................................... 2.5
C. PROCEDURE
Visually inspect the system and determine the aluminum equivalence of the total
filtration in the primary beam. This includes the inherent filtration of the X-Ray
tube, X-Ray tube housing, beam-limiting device, and any additional filtration that
may have been added in the useful beam (in fluoroscopic systems the tabletop is
included as part of the added filtration).
D. VERIFICATION OF COMPLIANCE
The aluminum equivalence of the total filtration must be equal to or greater than
the amount specified in Table 5-1.
NEMA Standard 5-15-1979
.02 METHOD II - STANDARD ABSORBER METHOD
A. GENERAL
This test is to be used when the surveyor cannot remove or see the total filtration
equivalence.
The HVL determinations obtained from the following procedures are to be
compared with those illustrated in Table 5-1. The HVL in millimeters of
aluminum of the system being tested must be greater than or equal to the values
shown in Table 5-1.
B. EQUIPMENT
1. Radiation detector
2. Standard absorber with equivalent filtration of 2.5 millimeters of
aluminum.
C. PROCEDURE
1. With the detection device positioned horizontally, an exposure is made at
a preselected technique factor of 80 kVp and appropriate mA and time.
The reading of the radiation output is recorded.
2. Position a total of 2.5 millimeters of aluminum at the port of the beam-
limiting device and repeat the exposure using the same technique
factors. Record the radiation output.
For X-Ray units operating at low kVp (less than 50) and for
mammography units, it will be necessary to use an aluminum absorber of
0.6 millimeters at 49 kVp.
November 2005 ( 5 - 5 ) Linear MC150-C Collimator