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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