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KETTERING CERTIFICATION EVALUATION
2026 SOLVED QUESTION COLLECTION
◉ (digital imaging characteristics, spatial resolution) What is sampling frequency?. Answer: the number of pixels sampled per millimeter as the laser scans each line of the imaging plate ◉ (digital imaging characteristics, spatial resolution) Sampling frequency? (4). Answer: - the more pixels sampled per millimeter, the great the sampling frequency
- the greater the sampling frequency, the longer it takes to process the plate due to the amount of info being collected
- in some systems, using a smaller IR permits more pixels per mm to be scanned yielding improved image quality
- increasing the sampling frequency results in the laser moving a smaller distance and there is an increase in spatial resolution ◉ (digital imaging characteristics, spatial resolution) What is nyquist frequency?. Answer: minimum rate which the signal can be sampled without introducing errors, which is twice the highest frequency present in the signal
◉ (digital imaging characteristics, spatial resolution) What is DEL (detector element)?. Answer: - used with direct capture radiography (cassette less)
- uses a flat panel detector
- spatial resolution is determined by the detector element size (DEL). as DEL increases, spatial resolution decreases
- DR uses detector element (DEL) size ◉ (digital imaging characteristics, image signal and noise) What is image signal?. Answer: results from X-ray deposition of energy in a detector (image data) ◉ (digital imaging characteristics, image signal and noise) contrast resolution/dynamic range?. Answer: range of values over which a digital image receptor will respond; greater dynamic range will yield great contrast resolution ◉ (digital imaging characteristics, image signal and noise) What is image noise?. Answer: results from extraneous info (interference), limits the ability to visualize objects
- noise impacts perceptibility of spatial resolution ◉ (image identification) Legal considerations? (6). Answer: - because the radiograph is considered a legal record or document of patient information, basic minimum information must be present on the radiograph
- Patient data - name and ID number
- Examination data - including postural and side markers
- Examination date
- Institutional data - hospital/clinic name
- DOB and age is optional ◉ (components of radiographic unit) What part of the tube is the only external part?. Answer: stator ◉ (components of radiographic unit) Electron sources? (4). Answer: - cathode is the negative electrode of the X-ray tube
- the cathode is made of two components, the filament wires (tungsten) and the focusing cup (molybdenum or nickel)
- most modern X-ray tubes are "dual focus" X-ray tubes, which means they contain two filaments
- the focusing cup is positioned around the filament
◉ (components of radiographic unit) Focusing cup functions? (2). Answer: - negatively charged and provides an electrostatic field designed to control the path of electrons from the cathode to the anode at the time of exposure (current flows from - to +)
- this aids in maintaining the line focus principle where the size of the focal spot directed toward the image receptor (effective focal spot) is smaller than the size of the focal spot (actual focal spot) measured on the surface of the anode ◉ (components of radiographic unit) Effective focal spot definition?. Answer: what gets projected towards patients ◉ (components of radiographic unit) Actual focal spot definition?. Answer: where electrons strike target ◉ (components of radiographic unit) Line focus principle?. Answer: incorporated angled design of anode ◉ (components of radiographic unit) Anode angle?. Answer: 7-22 degrees
- smallest number has great spatial resolution
◉ (components of radiographic unit, beam restriction devices) Aperture diaphragm?. Answer: lead plate with a hole cut in the middle that is slightly smaller than the image receptor size ◉ (components of radiographic unit, beam restriction devices) Variable aperture collimators?. Answer: permits the adjustment of the length and width of the radiation light field ◉ (components of radiographic unit, beam restriction devices) Cylinders and cones?. Answer: attaches to the bottom of the collimator housing and creates a circular shaped collimated field ◉ (components of radiographic unit, beam restriction devices) Collimation?. Answer: most common, manual and positive beam limitation (PBL)- > also called automatic collimator ◉ Parallel electric circuit?. Answer: total resistance must always be less than the least resistor and will be approximately half of it
ex: 5, 10, 15, 20, 25 = 2. ◉ Series electric circuit?. Answer: in a square ex: add all of the numbers ◉ (X-ray circuit) AC supply? (3). Answer: - located on the primary side or low voltage circuit of the X- ray unit
- supplies the X-ray unit with primary or low (220-240) voltage
- electrical energy supplied to the X-ray unit is alternating current (AC) ◉ (X-ray circuit - transformers) Transformers? (3). Answer: - principle function of the transformer is the conversion of incoming low voltage (220 volts) from the external power supply into the high voltage (kilovoltage) necessary to produce X-rays (are about 95% efficient)
- transformer regulate voltage within the basic X-ray circuitry
- transformers operate on the principle of electromagnetic induction and require alternating current to operate
ex: a transformer has 10,000 turns on its secondary side and 500 turns of its primary. what is the turns ratio for this transformer? Ts/Tp = 10,000/500 = 20: ◉ (X-ray circuit - transformers) Transformer formula for voltage and example?. Answer: - voltage is directly proportional to the turns ratio of a transformer
- as the turns ratio of transformer increases, the voltage that exits the transformer will increase at the same rate ex: A transformer has a turns ratio of 200:1. if 150 volts are supplied to the transformer, what is the output voltage? Vs/Vp = Ts/Tp 200/1 = x/150; x = (200)(150); x = 30,000 volts or 30 kV ◉ (X-ray circuit - transformers) Autotransformer? (4). Answer: - located within the primary or low voltage circuit between the incoming line voltage and the primary side of the step- up transfromer
- purpose of the autotransformer is to determine the amount of the line voltage that will be sent to the step-up transformer
- operates on the principle of electromagnetic self induction (one wire)
- a single coil of conductor material acts as both the primary and secondary sides of the autotransformer ◉ (X-ray circuit - transformers) What is the autotransformer the source of?. Answer: kVp ◉ (X-ray circuit - transformers) Step-up transformer? (4). Answer: - also known as the high-voltage or high tension transformer
- separates the X-ray circuitry into primary or low voltage and secondary or high voltage sections
- operates on the principle of electromagnetic mutual induction (two wires)
- converts the incoming low voltage from the secondary side of the autotransformer into the high voltage, or kilovoltage, required to produce x-radiation in the radiographic tube ◉ (X-ray circuit - transformers) Where or when does voltage become kilovoltage?.
electronic- complex, accurate up to 1 millisecond mAs- establishes the highest, safest mA at the shortest exposure time impulse AEC- utilizes an ionization chamber placed between the patient and the image receptor ◉ (X-ray circuit - transformers) What is a rectifier?. Answer: they are devices that convert AC into DC (pulsation direct, unidirectional) ◉ (X-ray circuit - transformers) High frequency rectifier?. Answer: the voltage ripple is 1% since the voltage waveform is nearly constant ◉ (fluoroscopy unit) What is an image intensifier function?. Answer: converts the X-ray beam into a bright visible light ◉ (fluoroscopy unit) Order or X-ray to monitor? XLELM. Answer: X-ray - light - electrons - light - monitor ◉ (fluoroscopy unit) Input phosphor? (2).
Answer: - converts the incoming X-ray photons (remnant radiation) into light photons
- typically comprised of cesium iodine ◉ (fluoroscopy unit) Photocathode?. Answer: converts light photons from the input phosphor into free electrons ◉ (fluoroscopy unit) Electrostatic lens? (2). Answer: - located along the full length of the image intensification tube
- directs or focuses the path of electrons from the photocathode to the surface of the output phosphor screen ◉ (fluoroscopy unit) Output phosphor? (2). Answer: - converts electrons sent from the photocathode into light photons
- typically made of zinc cadmium sulfide ◉ (fluoroscopy unit) Brightness gain?. Answer: - equals minification gain times flux gain BG = M x F
- minification gain equals the square of the input phosphor diameter divided by the square of the output phosphor diameter
Answer: - with all other factors remaining constant, fluoroscopic imaging of thicker body parts will result in a dimmer image
- fluoroscopic mA is directly related to the brightness of the fluoroscopic image ◉ (fluoroscopy unit) Multi-field fluoroscopic imaging? (3). Answer: - magnification of the fluoroscopic image is a function of the input phosphor size
- by reducing the size of the area of the input phosphor focused to the output phosphor screen results in an electromagnetic magnification of the fluoroscopic image
- magnifying the fluoroscopic image also results in increased patient dose since a smaller input phosphor size results in fewer photoelectrons incident on the output phosphor, better spatial resolution and better contrast resolution ◉ (components of digital imaging, CR & DR) Basic computer principles? (2). Answer: - a single unit of data is defined as a bit (binary digit). a bit is the smallest quantity of information and has two possible value - 0 or 1
- bit depth- determines the number of gray shades available per pixel (grayscale)
◉ (components of digital imaging, CR & DR) Bit depth formula and number of bit values?. Answer: formula - 2n number of bit values - 2 (0 or 1) ◉ (components of digital imaging, CR & DR) What is a digital detector?. Answer: captures the remnant beam ◉ (components of digital imaging, CR & DR) 2 types of digital detectors?. Answer: cassette-based (CR)
- photostimulable phosphor plate (PSP)
- flat panel detector/thin film transistor (FPD/TFT)
- PSP plate with a charge coupled device (CCD) cassetteless (DR)
- flat panel detector/thing film transistor (FPD/TFT)
- charged coupled device (CCD)
- complimentary medal oxide semiconductor (CMOS)
- PSP plate with a charged coupled device (CCD)
- an imaging plate reader employs the laser that reads the energy stored in the conductive layer, causing light to be emitted that is amplified by a photomultiplier
- violet light is viewed by a very sensitive photomultiplier tube, whose electronic signal is digitized and stored for display on a cathode ray tube or hard copy laser film
- a light signal digitizer assigns a number to each pixel in a matrix that represents the brightness and position of light
- CR plates are erased by exposing them to bright light ◉ (Computed Radiography; CR) Exposure number? (3). Answer: - S or sensitivity numbers have an inverse or direct relationship to the amount of exposure
- EI or exposure index has a direct relationship to the amount of exposure
- IgM or logarithm of the median exposure has a direct relationship to the amount of exposure ◉ (direct/indirect capture digital radiography) Indirect capture ( step process)?. Answer: - scintillator based systems use cesium iodine (CsI) or gadolinium oxysulfide
- *the scintillator converts X-ray photos into light photons. these light photons are emitted from the scintillator which then interact with a photoconductive material made of amorphous silicon, used to
convert the light photons into electrons. the light is imaged onto a CCD*
- the electrons migrate to thin transistors and produce an electronic signal. TFT arrays absorb X-ray photons and instantly convert them into electrical signals using amorphous silicon (TFT panel) or complimentary metal oxide semiconductor (CMOS) sensor ◉ (direct/indirect capture digital radiography) Direct capture ( step process)?. Answer: - nonscintillator based systems do not use a material that converts X-rays to light
- this system uses amorphous selenium (a-Se), which converts the x- ray beam into electrons that are collected by the TFT
- provides improved spatial resolution compared to the CsI phosphor ◉ (direct/indirect capture digital radiography) Charged coupled devices (CCD)? (3). Answer: - require a scintillator material to produce light, this is an indirect form of image capture
- light from the scintillator strikes the CCD and is converted into an electronic signal
- this signal is sent to an analog-to-digital converter where it becomes a data set to form the digital image ◉ (image processing and display) Histrogram? (2).
