Absorbed dose
the amount of energy absorbed per unit mass
(grays or rads)
back projection
- 3rd step in IR loop of iterative reconstruction algorithm
- ray sum data are projected back onto a matrix.
blood urea nitrogen (BUN)
renal function (nitrogen in blood)
(7-25mg/dl)
...
CT Registry Review - ARRT questions and answers Absorbed dose - answer the amount of energy absorbed per unit mass (grays or rads) back projection - answer - 3rd step in IR loop of iterative reconstruction algorithm - ray sum data are projected back onto a matrix. blood urea nitrogen (BUN) - answer renal function (nitrogen in blood) (7-25mg/dl) bow-tie filter - answer Filter compensating for a cylindrical shape (body) -filter is thicker at the ends contiguous images - answer images with equal section thicknesses & reconstruction intervals Aliasing - answer streak artifact caused by insufficient views (data samples) obtained during data acquisition Algorithm - answer (AKA kernal) filter applied to raw data during reconstruction to remove blurring artifacts Afterglow - answer detector continues to glow after radiaiton is terminated (scintillation -type scanners) absorption efficiency - answer ability of an individual CT detector to absorb & measure the transmitted x -ray intensity incident upon it ALARA - answer As Low As Reasonably Achievable Analog -to-Digital Converter (ADC) - answer converts electrical signal to digital form (part of the DAS) array processor - answer reviews raw data & performs all major processing of image arterial phase - answer peak arterial enhancement following the bolus IV administration of iodinated contrast material. Artifact - answer noise on an image ataxia - answer lack of muscle coordination Attenuation - answer reduction in intensity of a radiation beam as it passes through a substance attenuation coefficient - answer value given to an object rating its ability to absorb an x -ray beam automatic tube current modulation (ATCM) - answer software used to adjust the mA throughout an acquisition to reduce patient dose Automatic Tube Voltage Selection (ATVS) - answer software used to adjust kVp based on the changing attenuation along the scan range to reduce patient dose beam hardening - answer the increase in average energy of x -ray beam as it penetrates tissue contrast resolution - answer ability to detect an object with a small difference in attenuation from surrounding tissue Contrast Induced Nephropathy (CIN) - answer substantial decline in renal function after a patient receives IV contrast Convolution - answer filter used to remove blurring artifact during back -
projection Creatinine - answer indication of renal function (0.5-1.5mg/dl) CT dose index (CTDI) - answer an approximate measure of the radiation dose received in a single slice cupping artifact - answer Middle of the image appears darker than periphery. data acquisition system (DAS) - answer electronic components of a CT system responsible for measuring the transmitted x -radiation absorbed by the detectors
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