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11 Cards in this Set
- Front
- Back
- 3rd side (hint)
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What kind of detector did a rectiliear use and what size was it typically?
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NaI(Tl) at 5 x 12.5 cm
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Why was the size image always a 1:1 ratio?
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there was a direct coupling between the scanner and image reproduced on a the accompanying dot matrix printer
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They had thicker crystals than the scintillation cameras of today so they were more ________
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sensitive
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Multi-hole focused collimators replaced the older single hole collimators, which improved speed and sensitivity. The many holes tapered to focus onto a single point called the___________. The lead partition between the holes in the collimator are called _______
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Multi-hole focused collimators replaced the older single hole collimators, which improved speed and sensitivity. The many holes tapered to focus onto a single point called the focal point. The lead partition between the holes in the collimator are called septa
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How was the best resolution obtained?
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To have the object of interest in the focal plane of the scanner. the range of this focal plane is called what?
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depth of field
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What is the definition of resolution?
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The shortest distance between two points where the two points are still visible as seperate
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Why was using a rectilinear scanner more of an art than a science?
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The technologist could change the collimator, change the scan speed, line spacing or time of acquisition
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What were the 4 advantages of a rectilinear scanner:
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1. thicker crystals provided greater sensitivity for high energy gamma emitters (I-131)
2. provide the best resolution for objects in the focal plane 3. cheap 4. no non-uniformity List the 5 disadvantages: |
1. slow
2. no dynamic, gated or SPECT 3. limited detector area 4. measures only a single point in time and space rather than a whole area as with modern cameras 5. motion artifacts |
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Until CAT scanning arrived, what was the majority of nm procedures with the rectilinear camera?
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brain scans
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With the advent of Tc99 and other pharmaceuticals at a lower energy rectilinear scanners were replaced with the scintillation cameras of today.
what did we learn from the use of the rectilinear camera? |
1. gamma ray spectrometry use in reducing scatter from patient and components
2. refinement of collimators 3. better contrast enhancement 4. use of count rate density |
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Nuclear medicine uses emission scanning for imaging while x-ray uses transmission emission to create its images. What are 2 exceptions to this for NM where transmission is used?
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1. bone density (although x-ray is now used)
2. setting up attenuation for PET scans |
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