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 If: V A = 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 V TC = volume of solution added to reaction vial Then: V A = __D __ and P = _Va_ x 6.0 x 10 6 C X Fr V TC 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 99m Tc in 1.3 ml  Calibration time = 12:00  Wanted Dose:  200, 000 – 700,000 particles  3 – 5 millicuries  Given:  MAA Vial contains 6 x 10 6 particles (6 million)  Time = 12:00 (T=0)  Add 1.3 ml 99m Tc (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/0.7ml X = 840,000  Inject 0.5 ml = 3 mCi = 600,000 particles 6,000,000/5ml = x/0.5ml X = 600,000 Frank P. Dawry Physx.home.comcast.net

 Have:  30 mCi 99m Tc in 1.3 ml  Calibration time = 12:00  Wanted Dose:  200, 000 – 700,000 particles  3 – 5 millicuries  Given:  MAA Vial contains 6 x 10 6 particles (6 million)  Time = 12:00 (T=0)  Add 1.3 ml 99m Tc (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. Dawry Physx.home.comcast.net

 Have:  30 mCi 99m Tc in 1.3 ml  Calibration time = 12:00  Wanted Dose:  200, 000 – 700,000 particles  3 – 5 millicuries  Given:  MAA Vial contains 6 x 10 6 particles (6 million)  Time = 12:00 (T=0)  Add 1.3 ml 99m Tc (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. Dawry Physx.home.comcast.net

 Have:  30 mCi 99m Tc in 1.3 ml  Calibration time = 12:00  Wanted Dose:  200, 000 – 700,000 particles  3 – 5 millicuries  Given:  MAA Vial contains 6 x 10 6 particles (6 million)  Time = 06:00 (T= 6 hours early)  Add 1.3 ml 99m Tc (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. Dawry Physx.home.comcast.net

 Have:  30 mCi 99m Tc in 1.3 ml  Calibration time = 12:00  Wanted Dose:  200, 000 – 700,000 particles  3 – 5 millicuries  Given:  MAA Vial contains 6 x 10 6 particles (6 million)  Time = 18:00 (T= 6 hours later)  Add 1.3 ml 99m Tc (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. Dawry Physx.home.comcast.net

Consider reconstituting vial with 5.0 ml saline and discarding 2.5 ml, then add the low specific activity 99mTc Calculations now based upon 3,000,000 particles in the vial of MAA Frank P. Dawry Physx.home.comcast.net