Radiopharmaceutical Preparation
The Morning Elution

Note - All the data has already been entered into the Morning Elution Sheet. The following is a description of that data that was entered. It is suggested that you compare the data entries and use a calculator to assure that you understand the calculations throughout this exercise.

Download and print the completed Morning Elution Sheet and refer to this as you read the information below

  1. 1000 mCi was eluted from the Tc99m/Mo99 generator in 10.0 mL
  2. The Moly breakthrough was 5.7 μCi

    3. molybreakthoughform.jpg - 4150 Bytes

  3. To calculate Mo99 breakthrough apply the above formula
  4. Applying our numbers to determine Moly breakthrough: 5.7 μCi/1000 mCi = 0.0057 μCi/mCi
    1. The acceptable limits of Mo99 breakthrough are
      2.
      1. 0.15 μCi/mCi and
      2. <2.5 μCi of Mo99 per dose
    2. Data filled in this portion of the elution sheet (row two) is noted below

    Morning Activity of Tc99m in mCi (A)

    Volume of Elution

    Total Mo99 Act. In uCi (B)

    Mo99 B/A Breakthrough

    1000

    10

    5.7

    0.006

  5. Start reconstituting your 900 hours - at the second line of your elution sheet you will identify the total amount of activity needed at 900 hours. (Always start your second line in the elution sheet in this manner)
    6.
    1. Since one hour has passed you need to decay mCi/mL
    2. Take 100mCi/mL (your 800 hours reading) and multiple by the one hour decay factor (df) which is 0.891
    3. Your mCi/mL reading at 900 hours becomes 89.1 mCi/mL - fill in the cell
    4. Total (mL) = 10.0 since you have yet to take any activity out of the vial
    5. Total activity = 891 mCi
    6. Remaining volume = 10.0 mL
  6. Data on your elution sheet (row four) would be filled in as follows:

    7. mCi/mL Total (mL) Total Act. (mCi) Remaining Vol. (mL)

    89.1

    10.0

    891

    10.0

  7. Determination of the amount of activity from the elution vial for kit preparation - Consider you want to prepare Tc99mMDP. The following patients have been scheduled and are listed below:
    8.
    1. 900 hours - adult 1
    2. 1000 hours - adult 2
    3. 1100 hours - adult 3
    4. 1200 hours - adult 4
    5. 1300 hours - adult 5
    6. 14 00 hours - adult 6
  8. If your adult dose is equal to 25 mCi, a rough estimate of the total amount of activity needed should be calculated in the following manner

    9. 25 mCi (per dose) x 6 (doses) x 1.5 (factor used for decay) = 225 mCi

  9. Since you need 225 mCi, let us say that you will draw up an additional 25 mCi, which means you need to extract from the elution vial 250 mCi. This value is added to the Total activity column

    10. mlfromelutionneedforkit.jpg - 9029 Bytes

  10. Determine the amount of mL needed from the elution which can be calculated from the above formula, the results are noted below

    11. 250 mCi/89.1 mCi/mL = 2.8 mL

  11. Determine the amount remaining
    1. Total volume - amount removed = remaining volume
    2. Total volume is 10 mL - 2.8 mL = 7.2 mL
  12. This portion of the elution sheet (row five) identifying below

    13. mCi/mL Total (mL) Total Act. (mCi) Remaining Vol. (mL)

    89.1

    2.8

    250

    7.2

  13. Next prepare 100 mCi of Tc99mDISIDA at 900 hours. Using the same process as defined above calculate the mCi/mL needed, Total mL, Total Activity, and Remaining Volume
  14. The following cells define this portion of the elution sheet (row six) with the correct values

    15. mCi/mL Total (mL) Total Act. (mCi) Remaining Vol. (mL)

    89.1

    1.1

    100

    6.1

  15. Finally at 1000 hours you are told to prepare 150 mCi of Tc99m sestamibi
  16. Since it's an hour later you must decay your mCi/mL. This is done as follows:

    17. 89.1 mCi/mL x 0.891 (df at 1 hour) = 79.4 mCi/mL

  17. Determine the amount of mL needed from the elution vial
  18. Doing the same thing you did above take 150 mCi/79.4 mCi/mL = 1.9 mL
  19. Now determine the amount of elution remaining in the vial

    20. 6.1 mL - 1.9mL = 4.2 mL

  20. The data below is what is filled in on your elution sheet (row seven)
    21.

    mCi/mL Total (mL) Total Act. (mCi) Remaining Vol. (mL)

    79.4

    1.9

    150

    4.2

  21. You are now ready to place this data into your Daily Radiopharmaceutical Preparation Sheet and calculate your patient doses. Let us take a look at this process by seeing what needs to be entered for Tc99mMDP
    22.

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