FujiFilm CR-IR 357 Service Manual page 39

10. Confirming the S Value
The procedure set forth below is used to read an IP, which has been exposed to 1 mR of
radiation, during a 1-minute period between 10 and 11 minutes after an X-ray exposure,
output the read image, and check that the S value for 1 mR of radiation, which is determined
from the displayed S value and average dose value, is within the control limits.
REFERENCE
The method for calculating the S value control limits is outlined below:
- S value control limits for user adjustments
Upper limit: 200 x 1.5 = 300
Lower limit: 200/1.5 = 133
- S value control limits for service technician adjustments
Upper limit: 200 x 1.3 = 260
Lower limit: 200/1.3 = 154
To eliminate the necessity for adjusting the machine within a short period of time after
service technician inspection/adjustment, the S value control range for service technician
adjustments is narrower than that for user adjustments.
1.
Position a cassette so that the cassette center coincides with the X-ray
radiation field center. Perform setup so that the X-ray radiation field outline is
approximately 3 cm outside the cassette outer frame. Temporarily remove the
cassette and then position a dosimeter at the radiation field center.
014-204-01E
11.10.2005 FM4750
2.
Set the tube voltage to 80 kVp. Confirm the exposure conditions under which the
radiation dose is 1 mR.
 NOTE 
If the radiation dose measured by the dosimeter is not 1 mR, leave the tube voltage at
80 kVp and adjust the distance, tube current, and time to obtain a radiation dose of 1
mR. Record the adjusted exposure conditions.
- Distance: ___cm
- Tube voltage: ___kVp
- Tube current: ___mA
- Time: ___sec
REFERENCE
If the exposure conditions are unknown, use the following values as the reference
values and make fine adjustments:
3.
Under the exposure conditions confirmed in step 2, measure the radiation dose
five times and average the measured values.
--- Example ---
First Second
measurement measurement measurement
0.9 1.0
4.
Enter the exposure conditions and the average radiation dose determined in step
3 in the "FCR S Value Control Table."
CR-IR 357 Service Manual
Third Fourth Fifth
measurement measurement
1.1 1.2 1.0
IN-38
Average
value
1.04
IN-38