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Questions and Answers
What is the conversion rate of 1 millicurie to megabecquerel?
What is the conversion rate of 1 millicurie to megabecquerel?
- 42
- 37 (correct)
- 40
- 35
What is the purpose of a flood field or sheet phantom?
What is the purpose of a flood field or sheet phantom?
- To measure radioactivity
- To check uniformity of detector response (correct)
- To measure radiation exposure
- To calibrate the gamma camera
What type of radiation is used in a flood field or sheet phantom?
What type of radiation is used in a flood field or sheet phantom?
- Gamma radiation
- Cobalt-57 (57Co) (correct)
- Beta radiation
- Alpha radiation
What would a defective photomultiplier show as in the image?
What would a defective photomultiplier show as in the image?
What would a cracked crystal show as in the image?
What would a cracked crystal show as in the image?
Why are regular checks needed for photomultipliers?
Why are regular checks needed for photomultipliers?
What is the purpose of background radiation checks?
What is the purpose of background radiation checks?
What does a high reading obtained with the collimator in place indicate?
What does a high reading obtained with the collimator in place indicate?
What type of radiation is similar to 99mTc in gamma emission?
What type of radiation is similar to 99mTc in gamma emission?
What is the primary function of a flood field or sheet phantom?
What is the primary function of a flood field or sheet phantom?
What is the result of a non-uniform detector response?
What is the result of a non-uniform detector response?
What is the purpose of analyzing counts in each pixel?
What is the purpose of analyzing counts in each pixel?
What is indicated by a high reading obtained with the camera orientation changed?
What is indicated by a high reading obtained with the camera orientation changed?
Why is cobalt-57 used in a flood field or sheet phantom?
Why is cobalt-57 used in a flood field or sheet phantom?
What is the purpose of a gamma camera?
What is the purpose of a gamma camera?
What is the result of a defective photomultiplier?
What is the result of a defective photomultiplier?
What is the purpose of regular checks on photomultipliers?
What is the purpose of regular checks on photomultipliers?
What is the result of a cracked crystal?
What is the result of a cracked crystal?
Study Notes
Converting Units
- 1 millicurie (mCi) is equal to 37 megabecquerel (MBq)
Characteristics and Quality Assurance of Gamma Images
- A conventional gamma camera should give a uniform response to a uniform field
- A flood field or sheet phantom is used to check uniformity of detector response
- Flood field consists of a flat sealed plate, larger than the FOV, and usually filled with cobalt-57 (57Co)
- 57Co has a similar gamma emission to 99mTc but is longer-lived
- Uniform image with collimator in place indicates proper functioning
- Defective photomultiplier appears as an area of reduced counts in the image
- Cracked crystal appears as a linear defect
Uniformity of Detector Response
- Non-uniformity caused by individual photomultiplier differences can be analyzed and compensated automatically
- Regular checks are necessary to monitor photomultiplier deterioration
- Background radiation checks identify contamination of the gamma camera, collimator, or local unshielded source
- High reading obtained regardless of camera orientation indicates contamination on the crystal or camera head
- High reading obtained with collimator in place indicates collimator contamination
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Description
Test your knowledge of gamma cameras, radiation units, and quality assurance in nuclear medicine. Learn about the conversion of mCi to MBq, characteristics of gamma images, and uniformity of detector response.
