Test Bank for Computer Tomography 100%verified Rationales.

Test Bank for Computer Tomography 100%verified Rationales. List the different views a scout image can be done. - ANSWERS AP, PA, Lateral, and Oblique What is Azimuth ? - ANSWERSThe angle of the tube and detectors in relationships the patient positioned during scout acquisition. What is the purpose of an scout image in CT ? - ANSWERSA preliminary scan taken of a body region before a definitive imaging study and serve to establish a baseline. What is another name for Conventional CT ? - ANSWERSStep-and-Shot List the steps involved in Conventional CT form Start to Finish. (Once Slice) - ANSWERSComplete revolution of x-ray tube and acquiring a SINGLE DATA AT A PRECISE ANATOMIC LOCATION.--Data is MATHEMATICALLY RECON INTO A SINGLE IMAGE. (Thickness is controlled by collocation)--Table moves (index) for next predetermined anatomic position. List the component involved in a CT system. - ANSWERS1. Powerful Computer 2. Display system 3. PT Bed 4. Gantry Components. What does the CT Gantry houses? - ANSWERS1.Generator 2.X-ray tube 3.Various type of collimators 4.Data Acquisition system (DAS) 5.Slip-Rings 6.Detectors. Example of a Conventional X-Ray Tube and Detector - ANSWERSCT system were original limited by hard-wired cables, which PREVENTED CONTINUOUS ROTATION within the gantry and needed to reverse course and travel in opposite direction at the end of each rotation. What are the Fundamental Principle of CT ? - ANSWERSImage of an object is reconstructed on the basis of the attenuation that occurs as x-radiation is transmitted through it. What are the Fundamental Principle of CT ? (Data Acquisition) - ANSWERSX-ray beam is rotated around the patient, exposing a given volume of tissue form all direction. Detector measures radiation as it transmitted through PT. What are the Fundamental Principle of CT ?(Image Reconstruction) - ANSWERSImage reconstruction is define as the magnitude of x-ray attenuation that occurs at spatially distributed points within the patient. (Spatially-of or relating to space.) What is the general process of CT imaging and the steps involved ? (Data Acquisition) - ANSWERSMeasurement of the attenuation that occurs along each path through the patient form x-ray tube to detector. What is the general process of CT imaging and the steps involved ? (Data Reconstruction) - ANSWERSComputerized processing of the transmission measurements into the CT image. What is the general process of CT imaging and the steps involved ? (Multidimensional Image Display) - ANSWERSDisplay of recon gray-scale image in 2D or 3D format; a representation of attenuation that occurred across the scanned volume of tissue. What is the general process of CT imaging and the steps involved ? (Image Archival and Communication) - ANSWERSDisplay as well as storage, both short-term and long term of images on computer workstations. SCAN MODE - ANSWERSSCAN MODE What is the most basic scan mode ? - ANSWERSScout Image (Localizer,Topogram,Scanogram,Survey Scan) What is a Scout Image in CT ? - ANSWERSDigital radiograph obtained by keeping the x-ray tube and detector array in a fixed position while the pt bed translated (moved) through the gantry. Example of a Modern X-Ray Tube and Detector - ANSWERSWith the introduction of slip-ring technology the need for cables to power the system was eliminated, instead the system of contact brushes was used to supply electricity to power the system and allowed CONTINUOUS HELICAL ACQUISITION (Continuous Rotation). Advantages of Slip-Ring Technology - ANSWERS1. Powerful X-ray Tube capable of long exposure output. 2. Continuous movement of pt bed. 3. Specialized mathematical recon techniques. Advantages of Slip-Ring Technology (Spiral & Helical) (Single Slice CT)-SSCT - ANSWERS1. Allowed for Volumetric Data Acquisition 2. Allowed for Recon of CT Section at any point along scanned volume was possible. 3.Section Width is controlled by the collimation prior to data acquisition. Advantages of Slip-Ring Technology (Spiral & Helical) (Multi Slice CT)-MSCT - ANSWERS1. Allowed for Volumetric Data Acquisition 2. Allowed for Recon of CT Section at any point along scanned volume was possible. 3. Multi-Detector Arrays enable CT section of varying widths to be recon at any point along the acquired volume. (Additive Array) (Section Width no longer is controlled my collimation.) X-RAY TUBE - ANSWERSX-RAY TUBE X-RAY TUBE - ANSWERS1.Modern X-Ray Tube are enconsled in metal instead of glass. 2.Cathode and rotating anode disc. 3.Dual Filaments ranging from 0.5 to 1.2 mm in diameter. Smaller Focal Spot - ANSWERSSmaller focal spots IMPROVE the geometric efficiency and leading to GREATER spatial resolution. Flying Focal Spot Technology - ANSWERSInvolves the electromagnetic steering of the electron beam emitted from the cathode.The beam of electron is directed toward two SEPARATE location of the rotating anode, RESULTING IN TWO SOURCE OF X-RADIATION. What is the purpose of Flying Focal Spot Technology ? - ANSWERSData Samples is essentially double owing to the electronic switching between the two focal spots. This over-sampling technology help to IMPROVES TEMPORAL and SPATIAL RESOLUTION. What Does a SSCT AND MSCT require? - ANSWERSDue to the long acquisition and relatively high exposures rate it require the need for an x-ray tube that can withstand very high heat and be able to dissipate it accordingly. what types of method are used to dissipate heat? - ANSWERS1. Oil 2. Air-Cooling 3. Increase anode diameter 4. Conduction by tube rotation Advantage of Modern CT X-Ray Tube (MSCT) - ANSWERS1. High heat rating-Ability to ABSORB tremendous heat, while dissipating it QUICKLY. 2. Small Size and Lightweight 3.Stable and Long Lasting- Capable of withstanding huge centrifugal forces with an extended useful life. Automatic Tube current Modulation (ATCM) - ANSWERSPrograms adjust the mA throughout an acquisition to reduce pt radiation dose to a minimum. (Kind of like AEC in X-RAY) mAs - ANSWERSThe mAs value directly controls the quantity of x-radiation, or photon fluence, directed toward the patient. CT (30-800 mA) Photon Flux - ANSWERSThe rate at which the photon fluence passes through a unit area over unit time. Effective mAs - ANSWERSCalculated mAs value per acquired slice. Effective mAs (Formula) - ANSWERSEffective mAs = mAs/pitch Increase Pitch=mAs Applied to each acquire slice Decrease. kVp - ANSWERSControl the quality of the x-ray beam with regard to it overall PENETRATING CAPABILITIES. CT(80-140 kVp) Higher kVp - ANSWERS1. Decrease the STREAKING ARTIFACT. 2. Produce x-ray beams with greater penetrating power. Lower kVp - ANSWERS1. Decrease the Patient radiation dose and IMPROVE CONTRAST. Dual Energy CT System - ANSWERSCapable of applying multiple x-ray energies during a single CT Acquisition. Transmission data are acquired form tissue interaction with both high and low kVp radiation. Two Method to achieving dual-angry CT Scanning - ANSWERSA. Complex Voltage Switching CT Sys