Homework

# Measuring Radiation for Safe Exposure and Medical Use

## Homework

Text Reading: Giancoli, Physics - Principles with Applications, Chapter 31: Sections 5 to 9

##### Study Points
• 31: 6 Radiation therapy is the use of radiation to kill selected cells, usually cancers. Radiation guns move constantly but target a single area, reducing exposure to the intervening tissues.
• 31: 7 Short-lived radioactive isotopes in benign dosages may also be used as radioactive tracers.
• 31: 8 PET (photon emission tomography) allows medical technicians to explore soft tissue damage that cannot be traced using X-ray technologies. Radioactive isotopes are administered intravenously in substances that collect in specific tissues, highlighting distortions.
• 31: 9 NMR and MRI technologies add to soft tissue mapping capabilities. At safe dosage levels, these techniques provide doctors with diagnostic information that could otherwise only be obtained through exploratory surgery.

All of these methods highlight the fact that human vision is limited to a very small part of the electromagnetic spectrum, and that while some substances may be opaque in that range, the same substances may be transparent to other parts of the spectrum, allowing us to see through walls...and soft tissue.

### Key Equations

• 1 Gray = 1 Joule/kg = 100 rad
• effective dose in "rad equivalents for a man" or rem units = dose * RBE of particle
• effective dose in Sv (sievert) units = dose in GY * RBE
• 1 Sv = 100 rem

### Study Activity

Use the US Nuclear Regulatory Commission calculator to determine your personal annual radiation dose from all sources. How does this compare with safe levels of radiation exposure?

### Chat Preparation Activities

• Forum question: The Moodle forum for the session will assign a specific study question for you to prepare for chat. You need to read this question and post your answer before chat starts for this session.
• Mastery Exercise: The Moodle Mastery exercise for the chapter will contain sections related to our chat topic. Try to complete these before the chat starts, so that you can ask questions.

### Chapter Quiz

• Required: Complete the Mastery exercise with a passing score of 85% or better.
• Go to the Moodle and take the quiz for this chat session to see how much you already know about astronomy!

### Lab Work

If you want lab credit for this course, you must complete at least 12 labs (honors credit); you may complete more if you are preparing for the AP exam.. One or more lab exercises are posted for each chapter as part of the homework assignment. We will be reviewing lab work at regular intervals, so do not get behind!