ARRT CT Certification Exam Question with complete solution 2023

ARRT CT Certification Exam Question with complete solution 2023What is the Z-axis? Determines the thickness of the cross-sectional slice. What does 'X' indicate? Width What does 'Y' indicate? Height Hounsfield Units Quantify the degree that a structure attenuates an x-ray beam. -1000 (air) / 0 water) / 1000 (dense bone) The X-ray beam used in CT is? Polychromatic (beam has photons of varying energies). What are the benefits of filtering x-ray beams? 1) Improves image quality (filters low energy photons that cause artifacts). 2) Reduces dose to the patient. Volume averaging (Partial volume effect) Different tissue attenuations are averaged to produce one less accurate pixel reading (thinner slices = decreased volume averaging). How are x-rays created? When a substance is bombarded by fast moving electrons. mA (milliamperes) Controls the quantity of elections. kVp (kilovolt peak) Intensity of the x-ray beam. Dissipation Ability of the tube to rid itself of heat. DAS Data Acquisition System - measures the amount of photons that strike the detector, converts the info to a digital signal and sends the signal to the computer. CPU Central Processing Unit Pixel Two-dimensional square of data. How many CT numbers are assigned to each pixel? One. Raw Data is also known as? Scan Data. Typical aperature size? 70-90cm. Slip rings Brush-like apparatus that allows for the gantry to rotate continuously, allowing for helical scanning. Generators Located in the gantry, produce high voltages that are passed onto the x-ray tube, measured in kilowatts (kW). Reducing scatter radiation does what? 1. Improves contrast resolution. 2. Decreases patient dose. Optimal characteristics for of a detector? 1. High detector efficiency. 2. Low, or no afterglow. 3. High scatter suppression. 4. High stability. Geometric Efficiency Refers to the amount of space occupied by the detector collimator plates relative to the surface area of the detector. Capture Efficiency Refers to the ability with which the detector obtains x-ray beams that have passed through the patient.