Hematopoietic GW

Question 1

TBV formula

Answer 1

V=Q/C

Q=dose administered in CPM
C=concentration of dose after dilution in CPM

Question 2

Plasma volume determination RP and dose

Answer 2

I125 human serum albumin
10 mCi in 1.5 mL

99mTc HSA can also be used but labeling efficiency must be preformed and must be 98%

Question 3

No more than ___% of the radioactivity for TPV can be in free form because free form is removed from the intramuscular space more rapidly than the labeled albumin

Answer 3

2%

Question 4

What gauge needle for TPV

Answer 4

23 gauge

Question 5

Why must the pt be supine and at rest for 15-20 minutes before starting TPV study

Answer 5

Because plasma volume decreases when standing

Question 6

Things to remember when collecting sample for TPV

Answer 6

Pt supine
Do not rinse syringe with blood
Exact volume must be known (weight syringe)

Question 7

How to take sample collection for TPV

Answer 7

Three 10 mL blood samples are collected at 10, 20, and 30 minutes after injection

Question 8

TPV equation

Answer 8

TPV = (volume injected x net standard activity) / net patient activity at time zero

Question 9

Sources of error for TPV

Answer 9

If RP is infiltrated - high results

If pt has residual tracer from previous test - low results

Question 10

Random labeling

Answer 10

Radiolabling red blood cells for red cell volume measurement

Question 11

Random red cell labeling RP and dose

Answer 11

Cr51 sodium chromate (30 uCi)

99mTc pertechnetate
- not recommended due to high rate of elusion of tech from the RBCs

Question 12

TRCV equation

Answer 12

[Volume injected (standard counts x dilution factor) / net whole blood sample counts] x decimal hematocrit

Question 13

What to remember when labeling RBCs with chromium

Answer 13

Cr51 should not be added to the ACD solution before the patients blood is added to the vial

Dextrose in the ACD acts as a reducing agent and inhibits cell labeling

Question 14

Ratio between whole body hematocrit and venous hematocrit

Answer 14

0.89:0.92

Question 15

Which hematocrit is usually lower? Whole body or venous

Answer 15

Whole body is lower

Question 16

Red cell survival RP

Answer 16

Cr51 labeled RBCs with ascorbic acid labeling technique

1.5 uCi/kg
50 uCi minimum

Question 17

Red cell survival steps

Answer 17

Reinject RBCs, wait 24 hours, draw first blood sample

Obtain heparin used blood sample from patient every other day for the next 3 weeks

All stored at 4°C and counted on the last day

Question 18

Mean half time of Cr51 labeled RBCs

Answer 18

25-35 days

Question 19

Normal spleen to precondition ratio is between

Answer 19

0.5-1

Question 20

Normal liver to precordium ratio

Answer 20

0.5

Question 21

Initial spleen to precordium ratio greater than 2

Answer 21

Indicated increased splenic blood pool