Manual Trap Test (Without Monitor) - biodex PULMONEX II Operation Manual

Manual Trap Test (Without Monitor)

Trap exhaust is monitored by using the gamma camera without a collimator.
The following simple technique is used:
1. Remove the collimator from the camera.
2. With a five percent window, calibrate for Xe-133.
3. Fill a large plastic bag with a known volume of air (example, 25 liters).
4. Inject a known quantity of xe-133 (such as 100 µci) into the bag. The concentration will be 4
x 10-3 µCi/cm .
3
5. Place the bag in front of the crystal and count for a known period of time. The counts
per minute (cpm) obtained is a measure of the efficiency.
6. Collect the exhaust of a typical study in another bag of the same volume (25 liters) and
count as defined in step #5.
7. Ratio the count rates to the standard taken to determine exhaust concentration.
Example: If 4 x 10
-3
from the patient study was 150 cpm above the background, then:
10
µCi/cm yields 600,000 cpm above the background and collected effluent
3
Ratio = 1.5x 10
Exhaust Concentration
* MPC Xe-133 controlled areas should not exceed 1 x 10
cpm = 2.5 x 10
2
6 x 10 cpm
5
= r (2 x 10 µCi/cm
-3
= (2.5 x 10 ) (4 x 10
-4
µCi/cm ) = 1 x 10 µCi/cm
3 -6
PULMONEX II DOUBLE TRAP XENON SYSTEM
-4
)
3
-3
3
µCi/cm
-5 3