Measuring Radioactivity - Video Tutorials & Practice Problems

Measuring Radioactivity Concept 1

Now, when it comes to measuring radioactivity, we're going to say that radiation can be measured in several different ways depending on which property is being measured. Now, here we're going to have some units of radiation measurement. So the first one we're going to look at is the common unit of the Curie after Madame Curie. So here it is abbreviated as Ci. We're going to say here that 1 Curie is equal to 3.7×1010 disintegrations per second. And we're going to say the SI unit is Becquerel, Bq. So for those French speakers, I know I kind of butchered the name a little bit. But here, we're going to say that 1 Bq equals 1 disintegration per second. And the property being measured here is basically the activity or decay events that occur. Next, we have Rontgen which is R, capital R. We're going to say one of these is equal to 2.1×109 charges per cubic centimeter. Here, it does not have an applicable SI unit involved. We're going to say here this deals with the exposure of ionizing intensity of gamma and x-rays. Remember these are high energy states when we look at the electromagnetic spectrum. Next, we have Rad. We're going to say here that 1 Rad is equal to 1×10-5, which is Joules per gram. 1 Rad equals 1 capital R here, and this argon is the Rontgen. Next, we have Gray which is Gy. One Gray is equal to 1 Joule over kilograms, or we can say that 1 Gray is equal to 100 rads. Here, we're looking at the energy absorbed by tissue. Alright. Next, we're going to say here we have REM. REMS equals rads times RBE. What is an RBE? Well, an RBE is your relative biological effectiveness. This factor accounts for both of our ionizing intensity as well as biological effect. And we're going to say here that X-rays, gamma rays, and beta particles, 1 RBE equals 1. And then for alpha particles, since they're larger, they are equal to 20. Now coming up here, we have a Sievert which is Sv. One of these is equal to 100 rems and then here this looks at tissue damage. So these are the most common types of units of radiation measurements that you're going to encounter when dealing with conversions between them.

Measuring Radioactivity Example 1

The initial responders of the Chernobyl nuclear disaster were exposed to 23sv of radiation. Convert this value to REM. Alright. So, all we have to do here is use the conversion factor, and realize 23 sv, the conversion factor is that for every one sv we have 100rem. So when we do that, svs cancel out and we will go off with rem at the end. This comes out to 2300rem as the new units for our radiation.

Two technicians in a nuclear laboratory were accidentally exposed to radiation. If one was exposed to 5 mGy and the other to 9 rad, which technician received more radiation?

• A. The one exposed to 5 mGy
• B. The one exposed to 9 rad
• C. The two technicians were exposed to the same amount of radiation

A solution of iodine-131, a radioisotope used in the diagnosis and treatment of thyroid disease, is found just prior to administration to have an activity of 1.08 x 10⁶ Bq/mL. If 2.57 mL were delivered intravenously to the patient, what dose of I-131 ( in µCi) did the patient receive?

• A. 7.50×10^–5 µCi
• B. 75.0 µCi
• C. 29.2 µCi
• D. 0.075 µCi
• E. 0.029 µCi