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52 Cards in this Set
- Front
- Back
Agatston scores on mdct cardiac exam |
Minimal. 1-10 Mild. 11-100 Moderate. 101-400 Extensive. >400 |
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Type of ct best suited for evaluating of Coranary disease |
Electron beam scanners are very fast |
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Mtt mean transit time |
Time for blood to pass through a given region of brain tissue |
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Layers of the uterous |
Perimetruum Myometrium Endometrium |
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Phases of contrast administration |
Non-enhanced CT (NECT)Helpful in detecting calcifications, fat in tumors, fat-stranding as seen in inflammation like appendicitis, diverticulitis, omental infarction etc. Early arterial phase - 15-20 sec Arterial phase 20-30 sec delay Late arterial phase - 35-40 early venous portal phase", because some enhancement of the portal vein can be seen. All structures that get their bloodsupply from the arteries will show optimal enhancement.
Corticomedulary phase 30-40 sec delay in handed renal cortex (gastric and intestinal wall inhansement) liver spleen pancreas optimization Portal venous phase 60-70 sec
Hepatic or late portal phase 70-80 sec. In this phase the liver parenchyma enhances through bloodsupply by the portal vein and you should see already some enhancement of the hepatic veins. Nephrogenic phase - 100 sec This is when all of the renal parenchyma including the medulla enhances. Only in this phase you will be able to detect small renal cell carcinomas. Delayed phase - 6-10 minutes p.i. or 6-10 minutes after bolustracking. Sometimes called "wash out phase" or "equilibrium phase". There is wash out of contrast in all abdominal structures except for fibrotic tissue, because fibrotic tissue has a poor late wash out and will become relatively dense compared to normal tissue.
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Voxel dimension |
Divide dfov by matrix size multiply by length |
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On mdct cardiac exams for Coranary artery calcification areas of calcium are identified when? |
Greater than 1mm squared in area with hf values of 130 or greater. |
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Slice sensitivity profile is ____ Than the dose profile |
Narrower |
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Ssp is? |
Slice sensitivity profile Or degree of broadening or point spread that occurs along the z axis during volumetric data acquisition. |
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Pixel = |
Dfov/matrix size |
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Ct xray amount of inherent filtration = |
3.0 mm aluminum |
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Spatial resolution is affected by |
Geometric factors such as focal spot size and slice thickness,detector size,reconstruction algorithm, pixel dimention,sampling frequency. |
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Contrast resolution is affected by |
Slice thickness Algorithm And noise And detector sensitivity Collomation Window setting |
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Noise is affected by |
Dose Pixel dimention |
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Central volume principal |
Cerebral blood flow=cbv/mtt |
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A solitary pulmonary nodule May be defined as |
Ovoid focal area of increased density less than 3 cm. |
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Infarction core defind |
Cbv less than 2.5 ml/100 g |
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Angle for butterfly insertion. |
15 degrees |
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The quantity of absorbed dose based on radiosensitivity of a particular tissue type |
Effective dose |
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Harmful effects of xrays |
Stochastic- non threshold but probability increases with increased dose. |
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Enteric precautions |
Prevents infection through spread of fecal material gloves and gown. |
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R-r interval% at diastole |
55-75% |
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Gas within a degenerative disk |
Vacuum effect |
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During a spiral or helical scan how does the scanner acquire data |
Continuously as the pt moves through the table And in the form of a volumetric set. |
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Anougther name for fatty liver |
Steatosis |
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Interstitial disease of the lung |
Bronchiectasis Emphysema Asbestosis Sarcoidosis |
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Leiomyoma |
Benign mass of smooth muscle found commonly on the uterus |
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Perotoneal organs |
Stomach, liver, gallbladder, spleen, ovaries, transverse colon, and most of the small bowel. |
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Minimum intensity projection techniques used for |
Demonstrating air trapped within the trachea and bronchial tree |
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Used in pet ct as contrast |
Fludeoxyglucose f 18 (fdg) |
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Average photon energy of a ct scanner at 120 kvp |
70 kev |
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Photon flux |
Rate xrays pass through a unit area over a unit of time. |
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Linearity |
Relationship between ct number and actual linear attenuation coefficents |
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adding a math filter to remove blurring |
Convolution |
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Orthogonal |
Reformatted image that lie perpendicular to original plane of acquisition |
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Ray sum |
Measurement of transmitted radiation made by a single detector |
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Information included in a 3d recon is controlled by the |
Threshold setting |
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Normal cvb in 100 g of brain tissue |
4-5 ml |
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Quanta time computerized tomography used for |
Diagnosis of osteoporosis |
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Range of ct hu numbers on a modern ct system |
-1024 to + 3071 4096 different values on a 12 bit system |
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The Compton efect |
Xray photon ejects an outer shell electron producing scatter radiation |
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Bremstralong |
Xrays produced by acceleration or expecially deceleration of an electron while passing close by a nucleus. |
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Characteristic |
Ejection of a inner core electron being replaced by an outer shell electron drop in energy given off in xrays. |
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Pt dose Is directly effected by filtration . Detector efficiency and source to detector distance . |
But not filament size |
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First type of reconstruction used in prototype ct scanners |
Iterative technique. |
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Common areas of calcification in the brain |
Chord plexus and pineal gland |
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Dermoid tumor of the ovary Aka |
Cystic teratoma |
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Stores majority or sperm |
Vas deferens |
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Crystal material used in scintillating crystal detectors |
Cesium iodide, cadmium tungstate, bismuth germinate, gadolinium oxysulfide, and gemstone material., |
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Mathematical process by whereby data from tube rotations just above and just below a given slice position are used for image reconstruction ,which also clears up pt motion Artifacts. |
Interpolation |
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After back projection math marital filters and kernels used to remove the unwanted blurring effect |
Convolution |
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Reconstruction of ray sums onto a matrix |
Back projection. |