Exercises and Case studies

Exercises

1. Write the elemental formula for the following radioisotopes:

(a)        Technetium containing 48 neutrons

(b)       Radon containing 136

(c)        Francium containing 136 neutrons

(d)       Radium containing 138 neutrons

2. Write the equation for the radioactive decay of the following elements:

(a)        ²¹⁰Po (α-emitter)

(b)       ²²⁶Ra (α-emitter)

(c)        ⁹¹Tc (β-emitter – positron)

(d)       ²²⁷Ac (β-emitter – negatron)

3. A ²⁰¹Tl chloride injection has a labelled activity of 450 Ci. Express this answer in megabec-querel.

4. A radioactive material has an activity of 12.25 mCi. How many disintegrations per second are represented by this?

5. A radioactive material has been labelled with an activity of 112 MBq. Convert this activity into curie.

6. If a radioactive element has a half-life of 2 h, what percentage of material is left after

(a)        2 h

(b)       6 h

(c)        8 h

7. The disintegration constant of ²⁴Na is 0.0462 year⁻¹. Determine the half-life of this radioisotope.

Case studies

1. A sample containing ^99mTc was found to have a radioactivity of 15 mCi at 8 a.m. when the sample was tested.

(a)    Research the half-life of ^99mTc.

(b)   Calculate its activity at 5 a.m. on the same day, when it was prepared.

(c)    Calculate its activity at 3 p.m. on the same day, when it was administered to the patient.

State your answer in curies and SI units.

2. A typical intravenous dose of ^99mTc-albumin used for lung imaging contains a radioactivity of 4 mCi

(a)    Convert the dose to SI unit.

(b)   What radioactive dose is left after 12 h, when the technetium is cleared from the body?

(c)    The pharmacist prepared the sample actually 2 h before the administration. What activity did this sample have at that point of preparation?

(d)   The pharmacist prepared a 2 ml solution for injection. What is the activity concentration at the point of administration?

3. Develop a quick-reference radioactive decay chart for ¹³¹I

Research the half-life of ¹³¹I and calculate the percentage activity remaining for 20 days using 1-day intervals.

Create your own quick-reference radioactive decay chart.