B
iodex Medical Systems Quality Assurance Testing of AtomLab
®
Dose Calibrators
July 8, 2004 P/N 107012 Rev. B; © 2004, Sun Nuclear Corp. page 1 of 4
Quality Assurance Testing of AtomLab
®
Dose Calibrators
(Manufacturer’s* Instructions)
Introduction
The following procedures are the manufac-
t
urer’s instructions for qualifying
AtomLab
®
100, 100+, 200, and 300 dose
calibrators in accordance with NRC regula-
tion 10 CFR 35.60 of 1 January 2003. Use of
these instructions outside the USA may
require modification in order to satisfy
local regulations.
Qua lif ic ati on i s th e d ete rminat ion of err ors
associated with the following tests at the
indicated frequency. Acceptable errors for
each test are indicated in parentheses.
• Constancy: Starting at installation and
at least once each day before measuring
patient dosages (±5 percent).
• Dial Value Setting: at receipt of isotope
activity in container other than a plastic
syringe (±10% from decay corrected cal-
ibration activity).
• Linearity: at installation and at least
q
uarterly thereafter (±5 percent).
• Geometry: at installation (±5 percent).
•
Accuracy: at installation and at least
annually thereafter (±5 percent).
After repair of the dose calibrator, repeat
the above tests as a new installation.
NOTE: A plastic well liner and source dipper
must be used in all measurements.
NOTE: If possible, leave the dose calibrator
powered-on 24 hours a day, 7 days a week. If
not, allow 1 hour warm-up after power-on
before performing these procedures.
NOTE: Assay means to place the source con-
t
ainer into the dose calibrator so that the
dipper is resting in the well liner.
Constancy
Constancy means reproducibility in mea-
suring the same source, over a period of
time, with decay correction.
Assa y a rela tivel y long -live d sour ce (su ch as
Cs-137) each day before using the
calibrator.
Cs-137, 100 µcuries, is strongly recom-
mended because the 30-year half life will
assure use of the same source throughout
the life of the calibrator, and it is readily
available.
Consider using the following procedure or
equivalent:
1 Press the Background (Bkgnd) button.
When the display zeroes, the unit has
automatically adjusted for Background.
2 Assay each reference source using the
appropriate dose calibrator setting (i.e.,
us e th e C s-1 37 se tti ng t o a ssa y Cs -1 37. )
3 Record the activity reading of the con-
stancy source in a permanent log that
has limits or tolerance bars
1
.
4 Compare the measurement with the
allowed tolerance. If the measurement
exceeds the tolerance, make correc-
tions
2
to all future measurements.
5 Repair or replace the dose calibrator if
the error exceeds ten percent (10%.)
Dial Value Settings and Source Containers (Glass Vial, Glass Syringe, etc.)
The Atomlab Dial Value (DV) settings
enable the software to convert ion cham-
ber current into a displayed activity value
for the isotope corresponding to the DV
selected. The displayed activity value is
directly proportional to the DV.
The isotope’s “source container” is either a
vial or syringe; the composition of the vial
or syringe MAY influence the accuracy of
the act iv ity me asu rem ent. T he D V su pp lie d
in the Atomlab User Guide (Instruction
Manua l), or pr e-pro gramm ed int o the fro nt
panel isotope keys, are calibrated for use
with the source material in an un-shielded plas-
tic syringe (nominal 1mm wall), while
hanging in the supplied “source dipper”
syringe support. For isotopes contained in
sealed long lived QA sources (Cs-137, etc.),
the DV supplied are calibrated for use with
type Vial E epoxy sources or equivalent.
Accurate measurement of unsealed
sources in any other configuration must be
with a new Container Dial Value “CDV”,
determined by the USER with the following
procedure. During following steps, set DV
to the Atomlab published value.
Container with no source material
1 Assay a quantity of isotope source mate-
rial in a plastic syringe, nominal wall
thickness of 1mm, record as (Plastic
Syringe Activity)
1
.
2 Transfer part or all of the source mate-
rial from the plastic syringe into the
empty Container.
3 Assay the Container with the isotope
source material, record as (Container
Activity).
4 Assay the partial or “empty” plastic
syringe for residual activity, record as
(Plastic Syringe Activity)
2
.
5 Calculate the Container Dial Value for
use with isotope assayed in that type of
container,
,
where PSA = Plastic Syringe Activity.
Container with source material
1
Assay Container with the isotope source
material, record as (Container Activity)
1
.
2 Transfer part or all of the source mate-
rial from the Container into a plastic
syringe, nominal wall thickness of 1mm.
3 Assay the plastic syringe with the iso-
tope source material, record as (Plastic
Syringe Activity).
4 Assay the partial or “empty” Container
for residual activity, record as (Container
Activity)
2
.
5 Calculate the Container Dial Value for
use with isotope assayed,
,
where PSA = Plastic Syringe Activity and
CA = Container Activity.
Typically, for glass wall source Containers,
CDV will be higher than DV when the iso-
tope has a significant portion of low
energy photons in its emission spectrum.
1. To lerance Li mits: De te rmine the t olerance l im it s
from: Low Limit = 0.95 x INITIAL; High Limit =
1.05 x INITIAL, where INITIAL = the average of
the first two weeks of constancy measurements. In
the log, decay the tolerance limits and INITIAL val-
ue using half life of the isotope (Cs-137, 30 years).
2. Correction resulting from constancy error: Cor-
rected measurement = Measurement x (INITIAL/
ACTUAL) Constancy Record.
CDV DV
PSA()
1
PSA()
2
–
Container Activity()
------------------------------------------------ -
⋅=
CDV DV
PSA()
CA()
1
CA()
2
–
------------------------------------
⋅=
*Manufactured by Sun Nuclear Corporation, Melbourne, FL; distributed by Biodex Medical Systems.
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