Venti-Scan Physics Test Reports

Shielding Evaluation for the Venti-Scan IV Canister

Report prepared by: Lucian Wielopolski, Ph.D.
Date: 6/15/01

Method

Venti-Scan Physics Test Reports

Shielding Evaluation for the Venti-Scan IV Canister

Report prepared by: Lucian Wielopolski, Ph.D.
Date: 6/15/01

Method

A small, 0.5 cc, plastic syringe containing a 30 mCi Tc-99m source was measured in a shielded and unshielded environment. The syringe was housed in a lead pig, on contact the reading outside the pig was 0.2 mR/hr, slightly above background conditions that were <0.2 mR/h. The unshielded syringe measured gamma on contact of 1400 mR/h and at about 1″ 60 mR/h.

The instrument used for these and subsequent measurements was an Eberline Model RO-2 Ion Chamber Survey Meter. The syringe with the source was placed inside the Venti-Scan IV canister. Gamma and gamma plus beta readings were taken in contact with the outside of the canister and about 12″ away.

Conclusion

The Venti-Scan canister provides complete patient and technologist shielding for use as a delivery system for performing lung ventilation studies in a nuclear medicine environment. As noted in this study at a distance of 12″ virtually no radiation reading was recorded, except in the obvious case 7 with the top cover open. Thus, this canister provides minimal exposure to both patient and technologist.

Measurements Points

The following nine points were used to determine the effectiveness of the shielding of the canister:

Above opening of patient delivery tube.130-691 Illustration

 

Table 1. Summary of the canister shielding readings.

Location Point  1  2 3  4  5  6  7  8  9
Contact:                  
Gamma:  0.5  <0.2 <0.2  1.0 0  0 14  0.2  0.8
Gamma + Beta:  1.0 <0.2 <0.2 5.0 0  0 30  0.2  0.8
12″ Away:                  
Gamma:  <0.2  0  0 0.2 0  0 8 <0.2  0.2
Gamma + Beta: <0.2  0 0  0.3 0  0  10  <0.2 0.2

* Somewhat elevated readings in position 4 stem from the fact that the source was held in a plastic syringe that was inserted in a place that normally is occupied by a plastic nebulizer. Consequently, the source was located somewhat higher and less spaced out than it would be when using a nebulizer resulting in a larger solid angle toward the opening of the delivery tube.