Lung Vent Imaging (Alternative gases)

Question 1

Describe Technegas

Answer 1

-It is 99m-Tc O4 vaporized in graphite crucibles, heated to 25 000 F
-Thin layer of metallic technetium encapsulating carbon particles
- 1-5 breaths required for gas to reach alveoli
-Particles behave like gas passing through lungs

Question 2

Technegas vs. Petechnegas

Answer 2

Technegas: 100% pure argon gas and carbon
Pertechnegas: 20:1 argon- oxygen mixture

Question 3

Describe the Technegas procedure

Answer 3

-Graphite crucible is primed with IPA
-Crucible is loaded into system
-370-740 MBq is injected into crucible
-Chamber is sealed and filled with argon gas
-Tc-99m is burned onto crucible
-Patient takes 2-4 breaths in a closed system, supine or semi supine

Question 4

What are the Technegas imaging parameters?

Answer 4

-LEAP collimator
Planar:
-256 x 256 matrix
-250k-500k counts for all 6 views, can be based on time of first image
SPECT:
-64 x 64 or 128 x 128 matrix
-64 steps per head,
-10 secs per view
-360 degrees

Question 5

Patient interview for ALL lung vent procedures:

Answer 5

-Signs and symptoms
-Any known diagnosis
-Underlying resp disease
-Recent surgery
-D-dimer if ordered
-Prior DVT
-Prev NM studies? V/Q results?
-Pregnancy
-Treatment for PE (prior or current)