CT Boot Camp Section 1, CT Boot Camp Questions and Answers 100% Pass

CT Boot Camp Section 1, CT Boot Camp Questions and Answers 100% Pass A single "view" acquired during a CT scan is also called a: -Projection A CT scanner collects several projections as the tube and detectors spin around the patient. Each of these projections represent a unique view of the anatomy that is eventually compiled together to form the 3D volume of data The main difference between image production in CT compared to image production in radiography is: -Projections are compiled into a 3D volume of data. Projections are compiled into a 3D volume of data. Radiographic images are two dimensional, not three dimensional. An x-ray image is one single projection, while CT images are created from numerous projections. Otherwise, all steps in the image production process are very similar. Physical components located inside the CT gantry typical includes: 1. X-ray tube 2. High-voltage generator 3. Computer system 1. X-ray Tube 2. High-Voltage generator Both the x-ray tube and generator are often housed within the gantry itself. The computer system, which is responsible for reconstructing raw data into image data, is usually located somewhere outside of the gantry, like with the control panel. Increasing the mA and kVp of a CT scan will usually result in: 1. Increased patient dose 2. Increased image quality 3. Increased processing time 1. Increased patient dose 2. Increased image quality Increasing the mA and kVp of CT scan will usually improve the image quality, but this is at the expense of increased patient dose. The ideal mA and kVp should be the lowest possible dose that still results in a diagnostic scan. Changes in mA and kVp have no effect on the processing time. A common kVp setting used in CT is -120 kVp Most CT scanners are equipped with a limited number kVp options, which includes 80, 100, 120, and 140 kVp. Higher and low kVp settings are not possible. The signal produced by a detector is a(n): -Analog electrical signal When detectors capture remnant x-ray photons they produce an electrical signal that is proportional to the number of photons they received. More photons means a stronger signal. This electrical signal is sent to other components of the scanner where it is converted to a raw (unprocessed) digital signal and later a digital image (processed) signal that is suitable for viewing. An 8-slice scanner has: -8 detector rows When a scanner is referred to as an "8 slice scanner", the number refers specifically to the number of detector rows. The principal advantage of thin detector rows is: -Higher spatial resolution Thinner detector rows can image smaller parts, which is essentially the definition of high spatial resolution. The down is side is that this usually requires a higher tube output and therefore a higher patient dose. The width of the detector rows may or may not affect the scan time. Calculate the total beam width of a CT scan using 32 detector rows, 0.5 mm detectors, 100 mA and 140 kVp: -16mm The beam width is calculated as: 32 rows x (0.5 mm)/ row= 16 mm beam width. The width of the x-ray beam is controlled by: 1. kVp setting 2. Collimators 3. Pixel dimensions -Collimators The shape of the x-ray beam as it leaves the x-ray tube is controlled by the pre-patient collimators. Pixel dimensions and other technical settings have no influence on this. Only the collimators change the actually width/geometry of the beam. Reconstructed image data is produced by the: -Computer system The computer system is the last step in the data transformation process when the raw digital data is reconstructed into image data that can be viewed on the monitor and sent to PACS for reading and archival. T/F: X-ray tubes in CT are very similar to those used in diagnostic radiography. TRUE Compared to general radiography, CT x-ray tubes require: -A larger heat capacity Larger heat capacity. Compared to general radiography, most CT procedures actually require longer exposure times, more radiation, and higher mA settings. All of which are reasons for CT tubes being designed with higher heat capacity. Production of x-rays in a CT machine requires: 1. A source of electrons 2. A means of rapid acceleration of electrons 3. A means of rapid decelereation of electrons 1. A source of electrons 2. A means of rapid acceleration of electrons 3. A means of rapid decelereation of electrons ( ALL OF THE ABOVE) All three options are required for x-ray production. In an x-ray tube, the cathode supplies the electrons, kVp accelerates these electrons, and the electrons collide with the anode which releases x-rays. Which the following statements correctly describes the flow of electrons through an x-ray tube? -Cathode to anode The cathode of the x-ray tube is the same as the filament, the source of electrons, which is negatively charged. The anode is the target, which is positively charged. When a voltage (kVp) is applied, the negatively charged electrons accelerate to the positively charged anode. Electroninteractions in the anode are responsible for x-ray production. The specific process that accelerates electron in an x-ray tube is: -Application of a voltage All options listed are valuable in the x-ray production process, but only the voltage actually causes electrons to accelerate through the tube. A "voltage