Dose Blog

Blog 7

Elementary Aspects of Automatic Exposure Control (AEC)


Mankind has always been fascinated with the idea of autopilot, whether it is for a plane, a car, or for x-ray equipment! Automatic exposure control (AEC) or photo-timing was first introduced for plain film radiography where x-rays were automatically terminated once sufficient exposure was obtained to generate a radiograph. AEC for CT does things differently. It adapts and modulates the tube current automatically based on patient size, and body region to obtain a...

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Blog 6

Tube current in chest CT protocols


Tube current is like the bread and butter of protocol optimization. It is the most commonly modified parameter for adjusting radiation dose since it has a straightforward relation to dose. Doubling of tube current doubles the dose and vice versa. On most modern CT scanners, automatic exposure control (or AEC, to be discussed in the next blog) can automatically adapt the tube current to obtain user specified image quality. In fact most cardiothoracic CT should be performed with AEC...

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Blog 5

Patient centering in CT: To worry or not to worry


If you do not center well for a projection radiograph you might cut the lung bases or apices. But if you do not center correctly in CT, you will likely still get these and more!  So what is the big deal about the centering and CT? Well, we already discussed how off centering muddles up the automatic exposure control in CT, which can lead to erroneous calculation of optimal tube current.  Beyond that centering also helps the hardware based bow tie or beam...

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Blog 4

Planning radiographs in CT: Worth more than just scouts or localizers!


Planning radiographs in CT are images that you may commonly refer to as scouts, topograms, surview or localizers depending on your vendor preference. These are 2-D projection radiograph like images acquired prior to actual scanning. These images help you to select the scan field of view and more importantly prescribe superior-inferior scan range for CT.  On some scanners, the former selection helps in application of specific bow tie or beam...

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Blog 3

Elements of  good scan protocols: Building blocks of a good practice 

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Blog 2

Personalizing Chest CT Protocols 

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Blog 1

Chest versus Abdomen: A Regional Advantage 

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