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20 Cards in this Set
- Front
- Back
- 3rd side (hint)
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Write the following number in decimal form:
10101111 |
175
Write the following decimal in binary code: 721 |
1011010001
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A 16 frame cardiac MUGA scan is acquired for 6 min/view. The count rate is 520,000 cpm. How many counts are present in each frame at the end of the study?
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at 80 bpm there are 406.25 counts/frame
at 100 bpm there are 325 counts/frame |
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What are the components of the camera head beginning with the detector face?
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collimator
aluminum enclosed crystal light pipe (optional) PMT's Positioning and other circuits The camera head is held in place by a ________ |
Gantry
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What is the normal thickness of a NaI(Tl) crystal in the camera?
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.95 to 1.25 cm but may be thinner for low energy or thicker for high energy cameras
what is the normal diameter of the crystal? |
30 - 50 cm
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What is the purpose of coupling the crystal to the PMT's with silicone grease or a light pipe?
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to reduce the index of refraction between the crystal and the glass face of the PMT
How many PMTs in a modern camera typically? |
37, 61, 75 or 91 arranged in a hexagonal array
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What are the X, Y and Z positioning circuits?
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X and Y signals position the radiation event and Z is proportional to the light produced in the crystal and is used for pulse height analysis
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How are the X and Y output signals determined?
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There is a summation from all the PMTs via a summing matrix circuit to produce the -X, +X, -Y and +Y signals
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What does the photocathode on the face of the PMT do?
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It converts light from the crystal to electrons
How are these electrons multiplied? |
by a series of dynodes within the PMT
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What is the smallest resoultion ability of a gamma camera?
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3-12 mm
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True or false:
moving an object of interest closer than the distance from the pinhole to the camera face distance causes a reduction in image size occurs |
False, moving it closer increases magnification
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In computer terminology, what is a "word" and how is it used in reference to nuclear medicine imaging?
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It is 16 bits or 2 bytes of information and is used to represent the number of counts in a single pixel and used in the positioning matrix
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What is MHz in relation to the CPU of a computer?
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millions of instructions per second clock speed rating
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Explain the difference between analog and digital?
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analog is a continuous signal while digital is a discrete quantity.
what converts analog to digital in the gamma camera? |
an ADC(analog digital converter) unit
has at least 2, one for X and one for Y |
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What is the hardware and software system that allows for image acquisition and processing at the same time and greatly speeds up acquisition?
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DMA - direct access memory, data passes directly into memory
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What is the definition of a matrix?
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the image matrix is a grid from which the image is constructed. Each matrix address or pixel is one location on the grid
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Which matrix has better resoultion, 64 x 64 or 512 x 512?
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512 x 512
which one references a larger amount of the camera face? |
64 x 64, as the matrix goes up the size goes down
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What are the 2 matrices that we need to consider when dealing with cameras and imaging?
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the acquisition and display matrix
we cannot improve the display matrix beyond the acquisition matrix |
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Planar imaging uses what kind of acquisition?
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static acquisition
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What are the two methods of obtaining dynamic acquistions?
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Frame mode and list mode
which one is used most often in NM? |
Frame mode, it is a series of images that can be replayed to simulate motion, known as cine. list mode puts all detected events in memory to be formatted in any desirable matrix size, frame rate or count density, requires a large amount of disk space
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What is a MUGA?
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multigated acquisition, a series of cyclical images triggered by a physiological event, as in the R wave of on EKG for cardiac scanning. the data is deposited into frames, typically 16 to 64 frames
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