SmarterDA - Dental Assisting Boards Prep Courses
SmarterDA - Dental Assisting Boards Prep Courses
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Q: Using radiation measuring system conversion, 1 Gray is equal to how many rad?

Q: Using radiation measuring system conversion, 1 Gray is equal to how many rad?

4/7/2017 8:12:47 AM   |   Comments: 0   |   Views: 34

Dental Assisting Boards Prep Review, SmarterDA

Q: Using radiation measuring system conversion, 1 Gray is equal to how many rad?

  1. .100
  2. .300
  3. .1000
  4. .1,000,000

When measuring radiation, there are two types of systems used – Standard (traditional system) and System International (SI, newer system).

  • Roentgen (Standard system), Coulomb (C/kg) (SI system): measure the exposure (quantity of ionization in the air). The measurement is taken at the skin surface before radiation penetrates the tissues.
  • Rad (Standard system), Gray (Gy) (SI system): measure the absorbed dose (amount of radiation absorbed by an object). Depending on the material, the amount of radiation absorbed will vary.
  • Rem (Standard system), Sievert (Sv) (SI system): measure the dose equivalent (absorbed dose “adjusted” to the biological damage potential of the particular type of radiation). Some types of radiation produce greater effects than others.

Now, we must memorize some numbers for the dental assisting board exams on top of those definitions.

  • 1 Gray = 100 rad
  • 1 Sv = 100 rem


Answer: (A). 100


In the image above, I tried to explain how I memorize those numbers because honestly, we all get confused at some point. For example, if the dental assisting board exams asked you “5000 ram is the equivalent to how many Gray?” will you have an answer in mind quickly? This is how I do it: see 3 letters in rad and see 3 numbers in 100. Can you put them together? 100 rad. All you have to do next is to say 100 Rad = 1 Gray. Same for Rem: see 3 letters in rem and see 3 numbers in 100. Put them together, and you get 100 rem. To answer the question I just asked, 5000 rad = 50 Gray (100 rad = 1 Gray). I hope this makes sense!

When someone comes to me after failing the CDA® exam (by studying with other tools before finding SmarterDA), I ask to see the report. Radiology is one of the weakest subjects for all students who have failed the dental assisting exams. So, make sure to review radiology as much as possible before taking the Dental Assisting Examinations (RHS®, GC, NELDA®, CDA® and more). Of course, this is relevant to our Canadian students as well because dental assisting diagnosis all starts with radiographs!


You know you can always find me at and!

Author: Claire RDH, CDA, MS

Claire is the founder of StudentRDH and SmarterDA – exams prep solutions for the dental hygiene and dental assisting students. The exam review online solutions quickly became the #1 choice among students. “Studying is now “addictive!”
Prior to her career in the dental field, Claire Jeong was an education specialist at Boston Children’s Museum. Claire is licensed to practice in the United States and Canada. She can be reached at and


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