Name:    Test Your Knowledge: Basic Math Skills for the Technologist

True/False
Indicate whether the statement is true or false.

1.

Calculating the time that has elapsed since the time at which the activity was known is referred to as initial activity or original activity.

2.

The exponent .693 is the natural log of 2 which accounts for the halving of activity with each half life.

3.

Because a radionuclide is constantly decaying at a specific rate, the activity is constantly increasing.

4.

The Universal Decay Table allows you to determine the decay factor for any radionuclide based on the half life and elapsed time.

5.

If you know the activity and half life of a radionuclide, you can calculate the activity for any time in the future or the past.

6.

The amount of decrease per unit of time is dependent upon the half life of the radionuclide.

Multiple Choice
Identify the choice that best completes the statement or answers the question.

7.

If dipyridamole is supplied in a 50ml vial containing 250mg, and a patient weighs 205 pounds, how much volume will need to be withdrawn from the vial to prepare the dose with a concentration of 0.56mg/kg?
 a. 22.6ml c. 15.9ml b. 10.4ml d. 5.6ml

8.

If the half-value layer (HVL) for I-131 in lead is 0.3 cm, what is the minimum thickness of lead that is required to reduce the exposure rate of the I-131 source from 12 mR/h to less than 2 mR/h?
 a. 0.3 cm c. 0.6 cm b. 0.9 cm d. 1.2 cm

9.

If a MDP kit contains 230 mCi of Tc-99m in 9 ml at 7am, how much will have to be withdrawn for a 20 mCi dose at 1:00pm?
 a. 1.6 ml c. 1.9 ml b. 0.6 ml d. 0.8 ml

10.

Determine the 4 hour Decay Factor for I-123,  half life is13.2 hours.
 a. 0.8105 c. 0.8052 b. 0.8111 d. 0.8815

11.

If a bulk vial of Tc99m produces an exposure rate of 350 mR/hr at 1 cm from the surface, what is the exposure rate at 10 cm from the surface?
 a. None of these answers are correct c. 2.4 mR/hr b. 3.5 mR/hr d. 35 mR/hr

12.

If a kit has 310mCi of activity present at 8am, what will the vial assay show in 4 hours and 10 minutes if the decay factor is 0.618?
 a. 155mCi c. 501mCi b. 175mCi d. 192mCi

13.

If 740 kBq of a radiopharmaceutical are to be administered for each kilogram of body weight, approximately how much activity (in MBq) should be administered to a patient who weighs 172 pounds?
 a. 280 MBq c. 78 MBq b. 9.5 MBq d. 59 MBq

14.

Determine the 15 hour Decay Factor for Molybdennum 99, half life is 66.6 hrs.
 a. 0.853 c. 0.775 b. 0.866 d. 0.856

15.

A vial contains 200mCi of an unidentified radionuclide at 10am Thursday. At 10am Friday, the activity has decayed to 50 mCi. What is the half-life of the unidentified radionuclide?
 a. 100 hours c. 4 hours b. 12 hours d. 24 hours

16.

Convert 752 mCi to MBq:
 a. 789 c. 28724 b. 20.32 d. 27824

17.

A 20 mCi dose of Tc99m MDP results in a total body absorbed dose of .25 rads.  This value is equivalent to:
 a. .25 Gy c. .5 mSv b. .25 rem d. 2.5 mGy

18.

If a kit contains 140mCi of Tc-99m in 23ml at 8:00am, how much volume must be withdrawn to obtain a dose of 5mCi at 3:00pm? DF: .4459
 a. 1.7ml c. 1.84ml b. 1.6ml d. 2.4ml

19.

What is the easiest and most practical way for a technologist to reduce the radiation exposure from a patient?
 a. keeping a distance c. lead shielding and barriers b. limiting your time around the patient d. concrete

20.

A 10 mCi dose of Tc99m MAA is equal to what activity in MBq?
 a. 37 Bq Tc99m MAA c. 3.7 Bq Tc99m MAA b. 370 MBq Tc99m MAA d. 37 MBq Tc99m MAA

21.

From the above question, what volume must withdrawn at 11am? DF= .4695
 a. not enough information c. 2.84 cc b. 5.28 mCi/cc d. 17.84 mCi

22.

A unshielded syringe of 15 mCi of F-18 FDG is producing an exposure rate of 160 mR/hr at 1 meter.  What is the exposure rate at 3 meters?
 a. 480 mR/hr c. 53.3 mR/hr b. 17.7 mR/hr d. 2844 mR/hr

23.

If the exposure rate at 4 meters from a radioactive source is 5 mR/hr, what will the exposure rate be at 3 meters?
 a. 6.5 mR/hr c. 2.8 mR/hr b. 7.4 mR/hr d. 8.9 mR/hr

24.

How much activity of Tc99m MDP would you have at 3pm if you started with 200 mCi/cc at 7am? Half life of Tc99m is 6.01 hrs.
 a. 121 mCi c. 103 mCi b. 512 mCi d. 79 mCi

25.

1356 uCi =? mCi
 a. 135.6 mCi c. .1356 mCi b. 1.356 mCi d. 13.56 mCi

26.

A vial has 45mCi @ 8am. What is the approximate activity @ 12pm? DF:  .630
 a. 36mCi c. 18mCi b. 25mCi d. 28mCi

27.

If 175 mR/hr were measured @ 1ft, what would be the exposure rate @ 5 feet?
 a. 17mR/hr c. 4mR/hr b. 7mR/hr d. 20mR/hr

28.

A Tc99m DTPA kit contains 198 mCi in 7.6 cc’s.  What is the specific concentration of the solution?
 a. 26.1 mCi c. 26.1 mCi/cc b. 26.1 cc d. 26.1 cc/mCi

29.

A syringe of Gallium 67 Citrate contains 12.8 mCi in 4.1 cc. What is the specific concentration?
 a. 3.12 cc/mCi c. 3.12 mCi/cc b. 3.2 mCi/cc d. 3.12 mCi

30.

At some point in time a source has an activity of 1,000 mCi. At a later point in time the activity is 31.25 mCi. The half-life is unknown. How many half-lives have elapsed?
 a. three c. can’t be determined from data provided b. five d. four

31.

One Bq = ?
 a. 37 billion dps c. one dps b. one curie d. 3.7 x 10 dps

32.

Convert 1575 uCi to kBq:
 a. 58275 c. 58000 b. 1612 d. 42.56

33.

A F-18 FDG bulk vial contains 60 mCi in 4.6 cc’s.  If a 4 mCi dose is needed, how many cc’s must be administered?
 a. .39 ml c. 3.9 mCi/cc b. 13.04 mCi/cc d. .3 cc

34.

10 mCi F-18 Sodium Fluoride was calibrated for 7am.  The patient does does arrive until 8am.  What is the activity of the dose at 8am? (DF=.6852)
 a. 6.4 mCi c. 7 mCi b. 6.8 mCi d. 8.6 mCi

35.

A  4 mCi Tc99m MAA is needed at 4pm.  If the dose is being prepared at 2pm, how much activity must be used?
 a. 4.5 mCi c. 8 mCi b. 5.04 mCi d. 5.8 mCi

36.

If an assay of a vial containing I-131 shows 50mCi present on May 2, approximately what will the assay show on May 18? (Half Life I-131= 8.02 days)
 a. 6mCi c. 25mCi b. 12.5mCi d. 40mCi

37.

A vial of Thallium 201 Chloride must contain 120 mCi of activity at 8am on Tuesday.  If the vial is prepared at the radiopharmacy at 10am on Monday, how many mCi’s are needed? (Half life of Thallium 201 is 73.1 hours)
 a. 139 mCi c. 175 mCi b. 147 mCi d. 210 mCi

38.

A vial contains a mixture of 20mCi of I-124 (half-life=4 days) and 6mCi of I-131 (half-life 8 days). What will be the activity in the vial 8 days from now?
 a. 3mCi c. 5mCi b. 8mCi d. 13mCi

39.

From the above equation, what volume of radiopharmaceutical would be needed to prepare the 30 mCi dose?
 a. not enough information c. .38 ml b. 1.3 ml d. can not do the procedure

40.

A bulk vial of F-18 FDG contains 135 mCi in 12 ml at 9am . A 15 mCi dose is needed for a wholebody study to stage cancer, what volume must be withdrawn right now?
 a. 15 mCi c. 11.25 mCi/ml b. 1.3 cc d. 1.6 ml

41.

If a technogist works in a Nuclear Medicine Department for 8 hours per day, and the ambient background exposure rate is approximately 1.3 mR/hr.  What is the approximate total amount of radiation exposure this technologist will receive in one work day?
 a. 1.04 mRems c. 10.4 mRems b. 13.8 mRems d. 10.4 Rems

42.

If a MDP kit contains 230 mCi of Tc-99m in 9 ml at 7am, how much will have to be withdrawn for a 20 mCi dose at 1:00pm?
 a. 0.8 ml c. 0.6 ml b. 1.9 ml d. 1.6 ml

43.

A technologist must administer 37 MBq of Thallium 201 at 12 am on February 16.  Based on the vial label information shown here, what volume should be administered to the patient:

Calibration:  12:00 Noon: February 14
Total Activity:  222 MBq
Total Volume: 4.0cc
Concentration:  55.5 MBq/cc
Expiration:   1200: Noon: February 17
Half life:  3.04 days
 a. 1.6 cc c. 2.1 cc b. 1.05 cc d. 1.1 cc

44.

A vial contains 180mCi in 5 ml. Approximately what volume is required for 25mCi?
 a. 0.9ml c. 0.7ml b. 0.5ml d. 1.2ml

45.

A vial of TcO4 eluate contains 150mCi/ml. If 4 ml are withdrawn and added to a kit containing 16 ml of solution, what volume would need to be withdrawn to prepare a 20 mCi dose at that moment?
 a. 2.5ml c. 1.5ml b. 2.0ml d. .67 ml

46.

Calculate the Effective half life:  P= 73 hours: B= 10 days: What is the Effective half life of Thallium 201?
 a. 56 hours c. 2.33 hours b. 110 hours d. 43 hours

47.

A 15 mCi F-18 FDG syringe unshielded produces an exposure rate of 15 mR/hr to the hands.  If the technologist places a tungsten syringe shield over the syringe equivalent to 2 half value layers of attenuation absorption, what is the new exposure rate?
 a. None of these answers are correct. c. 13 mR/hr b. .6 mR/hr d. 3.75 mR/hr

48.

A Tc99m RBC kit contains 40 mCi in 5 cc of whole blood at 0800.  What would be the best volume to be withdrawn at 10:00 if a GI Bleed Scan for a patient with an acute bleed is needed STAT?  The prescribed dose is 5 mCi.   DF:  .7939
 a. 1.78 cc c. .63 cc b. .063 cc d. .79 cc

49.

From the above calculations at 3pm, you have an Add on patient who needs 30 mCi of Tc99m MDP for a triphasic bone scan to rule out osteomyelitis.  Do you have enough radiopharmaceutical at 3pm?
 a. no clue c. no b. yes d. not enough information

50.

On July 24 a solution of I-131 contains 100uCi. What was the activity on July 1? DF: .789
 a. 300uCi c. 800uCi b. 400uCi d. 200uCi

51.

A Tc99m Sodium Pertechnetate dose that is to be drawn up at 8am, the dose must be calibrated for 10 mCi at 11am.  How many mCi’s are needed at 8am? (Physical Half life of Tc99m is 6.01 hours)
 a. 10.4 c. 27.2 b. 18.4 d. 14.1

52.

The eluate from a Mo99/Tc99 Generator contains 368 mCi in 5 ml.  What is the concentration of the eluate?
 a. 78.3 mCi/ml c. 18.65 mCi/ml b. 73.6 mCi/ml d. 373 mCi/ml

53.

A dose equivalent of 20 mSv is equal to:
 a. 2 rem c. 1 rem b. 2 mrem d. 1 mrem

54.

One-hundred twenty-seven millicuries is equivalent to how many megabecquerels?
 a. 4699 MBq c. 4.6 E 2 MBq b. 4,699 Bq d. 3.4 MBq

55.

If a kit has 310mCi of activity present at 8am, what will the vial assay show in 4 hours and 10 minutes if the decay factor is 0.618?
 a. 155mCi c. 175mCi b. 501mCi d. 192mCi

56.

Calculate the Effective half life for Tc99m MDP using the following data: Physical: 6.01 hours: Biological: 11 hours:
 a. Effective= 3.9 days c. Effective= 1 day b. Effective = 1 hour d. Effective = 3.9 hours

57.

A unit dose of Gallium 67 Citrate is calibrated for 8am on July 9 measuring 5 mCi in 2.6 cc’s.  if 3 mCi’s are needed on July 10 at 8am, what volume should be retained in the syringe? (Half life of Gallium 67 is 3.26 days)
 a. 1.8 cc c. 1.53 mCi b. 1.96 cc d. 3.98 mCi/cc

58.

If the HVL of Cobalt 60 in lead is 1.25 cm, what percentage of the photons are absorbed from a shielded vial containing 2.5 cm of lead?
 a. 75% c. 88% b. 50% d. 25 %

59.

If a unit dosage of radioactivity contains 4.5 mCi in 1.2 ml, how many milliliters must be removed so that 3.5 mCi remain in the syringe?
 a. 0.93 ml c. 0.42 ml b. 0.27 ml d. 0.78 ml

60.

If the exposure rate at 10 meters from a cobalt sheet source is 15 mR/hr, what will the exposure rate be at 25 meters?
 a. 3 mR/hr c. 2.4 mR/hr b. 6 mR/hr d. 10 mR/hr