Manipulating the conditions

Frank P. Dawry

Reduced numbers of 99mTc MAA particles should be considered for patients with pulmonary hypertension, pneumonectomy, or right-to-left shunting, and in infants and children.

Frank P. Dawry

The number of particles in any dose and volume to be administered may be calculated as follows:

Assume the average number of particles per vial = 6.0 x 106.

If:VA = volume to be administered in ml D = desired dose to be administered (mCi)C = concentration of Tc-99m to be added to the reaction vial. (mCi/ml) Fr = fraction of Tc-99m remaining after the time of calibration – taken from decay factor

chart

P = number of particles in dose to be administered VTC = volume of solution added to reaction vial

Then:

VA = __D __ and P = _Va_ x 6.0 x 106

C X Fr VTC

Frank P. Dawry

1. Determine the volume dose to be administered to the patient:

specific concentration = activity/volume

required volume = activity desired/specific concentration or ml = mCi/mCi/ml

2. Calculate the particle concentration of the reconstituted kit:

total particles in kit/ml added to kit = particles/ml

3. Calculate the particles per dose:

particles/1.0 ml = particles in patient dose/ml of patient dose

(particle concentration in particles/ml)(ml dose volume) = particles in patient dose

Frank P. Dawry

Have: 30 mCi 99mTc in 1.3

ml Calibration time =

12:00

Wanted Dose: 200, 000 – 700,000

particles 3 – 5 millicuries

Given: MAA Vial contains

6 x 106 particles (6 million)

Time = 12:00 (T=0) Add 1.3 ml 99mTc (30 mCi )

to vial Add 3.7 ml of saline=30 mCi/5.0 ml=6 mCi/ml

Inject 0.7 ml = 4 mCi = 840,000 particles!

6,000,000/5ml = x/0.7mlX = 840,000

Inject 0.5 ml = 3 mCi = 600,000 particles

6,000,000/5ml = x/0.5mlX = 600,000

Frank P. DawryFrank P. DawryPhysx.home.comcast.netPhysx.home.comcast.net Frank P. Dawry

Have: 30 mCi 99mTc in 1.3

ml Calibration time =

12:00

Wanted Dose: 200, 000 – 700,000

particles 3 – 5 millicuries

Given: MAA Vial contains

6 x 106 particles (6 million)

Time = 12:00 (T=0) Add 1.3 ml 99mTc (30 mCi )

to vial Add 5.7 ml of saline=30 mCi/7.0 ml=4.3 mCi/ml

Inject 0.9 ml = 3.9 mCi = 1,080,000 particles!!

6,000,000/7ml = x/0.9ml X = 1,080,000

more dilute = more particles injected

Frank P. DawryFrank P. DawryPhysx.home.comcast.netPhysx.home.comcast.net Frank P. Dawry

Have: 30 mCi 99mTc in 1.3

ml Calibration time =

12:00 Wanted Dose:

200, 000 – 700,000 particles

3 – 5 millicuries Given:

MAA Vial contains 6 x 106 particles (6 million)

Time = 12:00 (T=0) Add 1.3 ml 99mTc (30 mCi )

to vial Add 2.7 ml of saline=30 mCi/4.0 ml=7.5 mCi/ml

Inject 0.5 ml = 3.75 mCi = 400,000

particles☺6,000,000/7.5ml = x/0.5ml X =

400,000

more concentrated = less particles injected

Frank P. DawryFrank P. DawryPhysx.home.comcast.netPhysx.home.comcast.net Frank P. Dawry

Have: 30 mCi 99mTc in 1.3

ml Calibration time =

12:00 Wanted Dose:

200, 000 – 700,000 particles

3 – 5 millicuries Given:

MAA Vial contains 6 x 106 particles (6 million)

Time = 06:00 (T= 6 hours early)

Add 1.3 ml 99mTc (60 mCi ) to vial

Add 3.7 ml of saline=60 mCi/5.0 ml=12 mCi/ml

Inject 0.3 ml = 3.6 mCi = 360,000

particles ☺6,000,000/5ml = x/0.3ml X =

360,000

more concentrated = less particles injected

Frank P. DawryFrank P. DawryPhysx.home.comcast.netPhysx.home.comcast.net Frank P. Dawry

Have: 30 mCi 99mTc in 1.3

ml Calibration time =

12:00 Wanted Dose:

200, 000 – 700,000 particles

3 – 5 millicuries Given:

MAA Vial contains 6 x 106 particles (6 million)

Time = 18:00 (T= 6 hours later)

Add 1.3 ml 99mTc (15 mCi ) to vial

Add 3.7 ml of saline=15 mCi/5.0 ml=3 mCi/ml

Inject 1.3 ml = 3.9 mCi = 1,560,000 particles !!

6,000,000/5ml = x/1.3ml X = 1,560,000

more dilute = more particles injected

Frank P. DawryFrank P. DawryPhysx.home.comcast.netPhysx.home.comcast.net Frank P. Dawry

Consider reconstituting vial with 5.0 ml saline and discarding 2.5 ml, Consider reconstituting vial with 5.0 ml saline and discarding 2.5 ml, then add the low specific activity 99mTcthen add the low specific activity 99mTc

Calculations now based upon 3,000,000 particles in the vial of MAACalculations now based upon 3,000,000 particles in the vial of MAA

Frank P. DawryFrank P. DawryPhysx.home.comcast.netPhysx.home.comcast.net Frank P. Dawry