MTR221/A - MTR221/A DHHS
MANUALE ISTRUZIONI / INSTRUCTION MANUAL
Modello/Model R221/A - R221/A DHHS
C
OMPLIANCE
V
ERIFICATION
23
R22
1/A
- R221
/A DHHS -
C
omplia
nce V
erification
Ralco
srl
The Aluminium equivalence of each component in the primary beam (X-ray tube and housing,
beam limiting device and any additional filtration in the system) is specified on the component,
in the technical data attached to the component or can be measured. Determine the total
aluminium equivalence in the primary beam and make sure that it is equal or greater than those
specified in the above
Table Total Filtration of Primary Beam in Aluminium Equivalence.
Quick-Check of Minimum Filtration Requirement at a Particular kVp
If the total inherent filtration cannot be seen, then the HVL must be obtained with the following
procedures:
The HVL in millimetres of aluminium in the system under test must be compared with those
specified in
Table Minimum Filtration Requirement - Beam Quality (HVL)
and must be
greater than or equal to the values shown in the table.
a) Direct the central X-ray beam perpendicular and in the center of a RAD-Check instrument.
Determine the exact distance from the X-ray tube focal spot to the window of the collimator
(273 mm - 10.75"). Place the input area of the RAD-CHECK at an equal distance from the
collimator window. Collimate the beam to an area slightly larger than the detector.
b) Make an exposure at a pre-selected technique factor of 90 kVp and appropriate mA and time
values with no added filtration in the beam; record the reading.
Using the type 1100 Aluminium Alloy, tape a total of 2.5 mm of Aluminium to the window of
the collimator. Make an exposure using the same technique factors; record the reading.
c) Verify that the radiation read with the 2.5 mm Al in the beam is greater or equal to 50% of
the radiation read with no filtration in the beam.
Standard Absorber Method
The HVL determination obtained from the following procedures are to be compared with those
illustrated in the
Table - Minimum Filtration Requirement - Beam Quality (HVL).
The HVL
in millimetres of aluminium obtained during the test must be greater or equal than the values
listed in the above mentioned table.
a) Direct the central X-ray beam perpendicular and in the center of a RAD-Check instrument.
Determine the exact distance from the X-ray tube focal spot to the window of the collimator
(273 mm - 10.75"). Place the input area of the RAD-CHECK at an equal distance from the
collimator window. Collimate the beam to an area slightly larger than the detector.
b) Select a tube potential of 100 kVp and appropriate mA and seconds, with no added filtration
in the beam make an exposure and record the reading. Using a set of several sheets of 1100
Aluminium Alloy, each having a thickness of 0.5 or 1.0 mm, tape the filtration to the window
of the collimator. Make an exposure for each increments of filtration and record the reading.
Total Filtration Of Primary Beam In Aluminium Equivalence
Operating Voltage (kVp)
Total Filtration (mm Al
Equivalent)
Below 50
0.5
From 51 to 70
1.5
Over 70
2.2
Содержание MTR 221/A
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