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Varkey Final

2dn Year 1st semester

QuestionAnswer
1. What is the state-required filtration for radiographic x-ray tubes? • 2.5 mm Al
2. What is the state requirement for the accuracy of the collimation? How often do you need to calibrate it? • Misalignment should not exceed 2% OF SID. • The distance indicator must be accurate to 2% of SID. • Centering indicator must be accurate to 1% of SID. • Must be checked semiannually
3. Name the three methods used to evaluate focal spot size. How often calibrated? • Pinhole camara • Star pattern • Slit camara • Checked annually or when new equipment or replacement x-ray tube is installed
4. What is the most recent method used for focal spot size evaluation? • Line pair test tool.
5. ___________% change in kVp is required for a visible change in OD. • 4%
6. ___________% change in mAs is required for a visible change in OD. • 30%
7. Measured kVp should be within _______________% of the indicated kVp. • 10%
8. Accuracy of the exposure timer must be ______________% for exposure time less than 10 ms. • 20%
9. Accuracy of the exposure timer must be ____________% for exposure time greater than 10 ms. • 5%
10. ___________Provide constant OD regardless of tissue thickness, composition and exposure time. • Automatic Exposure Control (AEC)
11. A ____________________ will terminate the exposure at 6s or 600 mAs whichever occurs first. • Backup timer
12. Exposure linearity must be within __________________% of the adjacent mA stations. • 10%
13. mR/mAs value must be within ___________________% between adjacent mA stations. • 10%
15. A ____________is used to measure light intensity at various locations of the illuminator and the values should not vary more than ______% • Output Radiation • 5%
16. Incomplete erasure of a previous image on a CR Imaging plate might cause _____________ • Ghost image
17. Failure of electronic preprocessing can cause uninterpretable images due to ________________ • One dead pixel. • Rows or columns of dead pixels
18. Too rapid exposures can cause ____________________________artifacts. • Electronic memory artifacts
19. What is interpolation? • It’s a correctional algorithm. Interpolation is a mathematical process of assigning a digital value to a dead pixel based on recorded values of adjacent pixels.
20. Incorrectly oriented grid, with grid lines parallel to plate reader’s scan lines will cause: _________________ artifact. • Moiré
21. Frequency harmonics can cause_______________artifacts. • Moiré
22. Noise in the plate reader electronics can cause ____________________ patterns. • Extraneous line patterns.
23. A black line on the digital image is caused by _______________________________ • Backscatter
24. If the x-ray exposure field is not properly collimated, sized, and positioned, ___________errors may occur. • Exposure field recognition.
25. Failure of electronic preprocessing can cause uninterpretable images due to the presence of _________on the image matrix • Software artifacts: o One dead pixel. o Rows or columns of dead pixels
26. The software correction that equalizes the response of each pixel to a uniform exposure of x-rays is called ______________________________ • Flat fielding
27. Name the tools that can be used to standardize the performance of digital display devices. • SMPTE • NEMA – DICOM • DIN 2001 • VESA • AAPM TG 18
28. Study SMPTE Pattern and AAPM TG 18 • SMPTE: o Used for the measurement of the resolution of display system. o Help to point out any gross deviation in luminance adjustment. o (5% and 95% Luminance Patches)
28. Study SMPTE Pattern and AAPM TG 18 2nd part • AAPM TG 18: o Developed a set of test patterns and outlined related procedures in Task Group Report 18 o Emphasis is placed on details of associated patterns that can be used by the technologist to perform checks to ensure system performance
29. What is SMPTE stands for? • Society of Motion Pictures and Television Engineers.
30. SMPTE can be used for evaluating 1)___________________. 2)_______________ • Measurement of the resolution of display system. • Help to point out any gross deviation in luminance adjustment.
31. What is AAPM TG 18 stand for? • American Association of Physicists in Medicine.
32. What is Geometric distortion? Give two examples. • Displayed imagen appears geometrically different from the original image. • Examples: pincushion and barrel.
33. Which test pattern can be used to evaluate pincushion and barrel distortions? • TG 18 QC Test
34. Identify pincushion and barrel distortion from an image Barrel Pincushion
35. What is the acceptable level of distortions? • The acceptable level of distortion in primary class devices is 2%. • The acceptable level of distortion in secondary class devices is 5%.
36. What is the difference between specular reflection and diffuse reflection? • Specular reflection: the viewer sees a reflection at only one point. • Diffuse reflection: light from all the points on the surface reaches the viewer.
37. How can you minimize reflections from a display monitor? • Anti-reflective coating can minimize reflections.
38. What test pattern can be used to evaluate diffuse reflection? • TG 18 AD
39. What is luminance response? • Refers to the relationship between displayed luminance and input values of a standardized display system
40. What test pattern can be used for luminance non-uniformity? • TG 18 UN 10 and 80 test patterns
41. What is the acceptable value of non-uniformity? • Maximum non-uniformity of a display device should be less than 30%.
42. What test pattern can be used to evaluate display resolution? • TG 18 CX and TG 18 QC
43. What test pattern can be used to evaluate resolution uniformity? • TG 18 PX
1. In reference to body planes, name four different types of images that can be obtained in CT Scan • Axial • Coronal • Sagittal • Oblique
2. Name the plane that divide the body into superior and inferior sections. • Horizontal
3. Name the plane that divide the body into right and left sections • Sagittal (axial)
4. Name the plane that divide the body into anterior and posterior sections. • Coronal
5. Name the plane that divide the body into equal halves of anterior and posterior sections. • Midcoronal
6. Who invented clinical computed tomography? • Dr. Godfrey Hounsfield
7. Write four features of First-Generation CT scanner. • Pencil-thin x-ray beam • One detector • Translate rotate scanning motion • 4.5 minutes for one image
8. Write the name of a type of filter used in CT scan. • High Pass
9. Write four features of Second-Generation CT scanner. • Fan beam • 30 or more detectors • Rotate translate scanning motion • 15 seconds for one image
10. Write four features of Third-Generation CT scanner. • Fan beam • 960 detectors (curved detector array) • Rotate continuously around the patient for 360 degrees • Less than one second per image
11. Write four features of Fourth-Generation CT scanner. • Developed during 1980’s • Fixed ring of 4800 detectors • Rotate continuously around the patient for 360 degrees • Less than one second per image. • Not more advanced than third generation
12. Which invention in CT scan replaced the high-tension cables and made it possible for the x-ray tube and detector to rotate around the patient continuously without the need for stop and rewind? • Slip Ring
13. Write three functions of the slip ring technology. • Transfers electrical power, scanning instructions, and detected signals between stationary components and rotating gantry components.
13. Write three functions of the slip ring technology... • Eliminate the need to stop the rotation of the gantry assembly after each scan since there is no cables to wind up. • Led to the development of helical/spiral scanning (volume scanning)
14. Explain the difference between a single slice CT and a Helical CT. • Helical CT: X-ray tube rotate continuously around the patient as the patient/table increment through the gantry at selected speed and a volume of data is collected. In helical CT the data is obtained from a volume of tissue.
14. Explain the difference between a single slice CT and a Helical CT...2nd part These information need to be divided into individual cross sectional slices. The difficulty in this task is that the data needed to define a given slice was measured through projections which do not correspond to a plane.
14. Explain the difference between a single slice CT and a Helical CT...3rd part • Single Slice CT: The x-ray tube rotate around the patient 360 degree at a selected location to create an image. The patient/table moves to a new location in the gantry to create the next image. Imaging only one slice at a time.
15. What are the advantages of volume scanning (Spiral CT) • Multiplanar reconstruction • Shorter scan time • Reduced motion artifacts • Less amount of IV Contrast injection
17. List four advantages of multi-slice scanners. • Short acquisition time • Decreased amount of contrast media. • Improved spatial resolution. • Improved image quality.
18. List three major components of a CT Scanner. • Gantry • Computer • Operator console
21. Explain the structure and function of detector array in CT scan. • Solid state detectors. • Composed of photodiode coupled with scintillation crystal material. • Convert transmitted x-ray into light.
21. Explain the structure and function of detector array in CT scan... 2nd part • Light is converted into electrical energy and then into digital signal. • Affects patient dose and the efficiency of the CT unit
22. What is the function of a pre-patient collimator? • Pre-patient collimator determines the slice thickness. • Reduce patient dose and improves image quality.
23. What is the function of a post-patient collimator? • Post-patient collimator further defines the slice thickness
25. Which collimator reduces patient dose in the CT scanner? • Pre-patient collimation.
26. How many mathematical calculations per slice will be processed by the computer when using a 256 X 256 matrix size? • 65536
27. What are the components in the operator console? • Keyboard • Input device (mouse or trackball) • Monitor
28. What are the functions of the operator console? • Allows the tech to control the parameters of the examination (Protocol) • View and manipulate the image.
29. List the various image archiving devices used in CT scan • Magnetic Tape • Hard Disks • Optical disks • PACS
30. PIXEL stands for _________________ • Picture Element
31. VOXEL stands for ________________ • Volume element or volume pixel
32. The number of rows and columns in a digital CT image is known as _______________ • Image Matrix
33. A three-dimensional tissue volume in a CT image is represented by _____________(Pixel/Voxel) • Voxel
34. A Pixel in a CT image represent_________of a volume of tissue at that position in the slice. • Number
35. The depth of a VOXEL represents ___________in a CT image • The slice thickness
36. The degree of attenuation is known as ___________________ • Attenuation coefficient
37. A CT Number represent ________________ • The degree of attenuation values of each voxel
38. CT Numbers were also known as ___________________ • Hounsfield Units
39. The baseline for CT number is _______, which is assigned a CT number of ___________ • Water; 0
40. A Positive CT number indicate_____________anatomy (Radiopaque/Radiolucent) • Radiopaque
41. Iodinated Contrast media filled structures appears ____________on a CT image. • White
42. Air appears ________________on a CT image • Black
43. Fat Muscle, and organs appear ___________on a CT image • Dark gray to black (varying shades of gray)
44. Image contrast can be manipulated by ____________ (WW/ WL) • Window width (WW)
45. A wide window width indicates ______________ (low contrast/ High contrast) • Low contrast (which is long scale)
46. A narrow window width indicates _____________ (short-scale contrast/ Long scale contrast) • Short-scale contrast (high contrast)
47. Window level controls _______________ (image brightness/ image contrast) • Image brightness
48. The CT number that is at the center of the window width is represented by __________ • Window level
49. What is a Pitch means in CT scan? • The amount of anatomy covered during a particular scan.
50. Learn the formula and math application of a pitch. • Pitch=length of table travel per rotation/slice thickness.
52. What is MPR stands for in CT Scan? • Multiplanar reconstruction
53. The preliminary image during a CT procedure is called____________ (3 different names) • Scanogram • Scout • Topogram
54. What is meant by scan FOV? • Determines the area over which projection data is recollected • Determines the number of detectors collecting data for a particular scan.
54. What is meant by scan FOV? 2nd part • Should be large enough to cover all of the patient anatomy • If any part of the pt lies outside the scan FOV, out-of-field artifacts will occur
55. What is meant by reconstruction FOV? • Is the region of interest illustrated in the image and is reconstructed from the completer set of raw data. • Always equal to or smaller than the scan FOV
56. Reconstruction FOV is also known as __________________ • Display FOV
57. Reconstruction FOV is always equal to or ____________ than the scan FOV • smaller
58. To magnify an image a ___________FOV must be used (Small / Large) • Small
59. To minimize noise in a CT image a _______FOV must be used (small/ Large) • Large
60. To achieve increased spatial resolution a ________FOV must be used. • Small
FOV and Magnification: • Small FOV – more magnification • Large FOV-less magnification (shows the image smaller)
FOV and Spatial Resolution • Large FOV – reduces spatial resolution (because if you maintain the matrix size and increase the FOV means that you have bigger pixels, and the smaller the pixel the better the spatial resolution) • Small FOV – increases spatial resolution
Attenuation: • Also known as differential absorption • Each voxel in the tissue slice is assigned a number by the computer that is proportional to the degree of x-ray attenuation of that tissue volume
Attenuation coefficient • The degree of attenuation
ADC: • Analog to digital converter. • Digitizing processing assigns an integer to each amplified electrical signal
Two Types of collimators used in CT and their functions: • Pre-patient collimator: determines the slice thickness. Reduces pt dose and improves image quality • Post-patient collimator: further defines the slice thickness
Multislice CT Scanners: • Image many slices simultaneously per tube rotation • Scanners are available to image 4 slices to 256 slices per x-ray tube rotation
Multislice CT Scanners Advantages • Advantages: o Short acquisition time o Decreased amount of contrast media o Improved spatial resolution o Improved image quality
CT System Components: • Gantry • Computer • Operator Console
Gantry Components X-ray tube Detector array Collimator
X-ray tube: Similar to radiographic x-ray tube. Higher heat capacity to accommodate increased exposure time
Detector array:  Solid state detectors. Composed of photodiode coupled with scintillation crystal material. Convert x-ray into light. Light is converted into electrical energy and then into digital signal. Affects patient dose and the efficiency of the CT unit.
Collimator Pre-patient Post patient. Pre-patient collimator determines the slice thickness. Reduce patient dose and improves image quality. Post-patient collimator further defines the slice thickness.
Computer Requires two types of highly sophisticated software. 1. For the operating system. 2. For the application. Operating system manages the hardware.
Computer 2nd part Application software manages preprocessing, image reconstruction, and a wide variety of post processing operations. CT computer must have staggering speed and memory capacity. 262,144 mathematical calculations per slice for a 512 X512 matrix size.
Operator Console o Operator console is the key point of interaction between the system operator and the imaging system. 1. Keyboard 2. Input device (mouse or trackball) 3. Monitor
Operator console functions o Allows the technologists to control the parameters of the examination o View and manipulate the image.
Pitch: o The amount of anatomy covered during a particular scan is determined by the pitch. o Pitch is a ratio reflecting the relationship between table speed and slice thickness. o Pitch = length of table travel per rotation/ slice thickness
Chapter 25
1. Who invented Fluoroscopy • MR. Thomas A. Edison in 1896.
2. Unit for illumination level • Lamberts and millilamberts
3. Function of rods and cones • They are responsible for the sensation of vision. When the light arrives at the retina, it is detected by the rods and cones. • The rods are sensitive to low light levels. • The cones are sensitive to intense light levels.
4. Photopic vision • The cones are used for daylight vision, called photopic vision. • Cones have better visual acuity and contrast perception than rods.
5. Scotopic vision • Rods are used for night vision, called scotopic vision.
6. What is visual acuity? • Ability to perceive small objects better.
7. Factors that affect the brightness of fluoroscopic images • Anatomy being examined • kVp • mA
8. What is the mA used in fluoroscopy? • Less than 5 mA
9. Compare the patient dose of Fluoroscopy Vs Conventional x-ray • Fluoroscopy: o Uses small kVp, more radiation to the pt, and exposure time is in seconds. • Conventional x-ray: o Use small kVp, less radiation to the pt, and exposure time is in milliseconds.
10. Learn the components of an Image intensifier. (Very important) • Metal housing • Vacuumed glass or metal enveloped • Input phosphor • Photocathode • Electrostatic focusing lenses • Anode • Output phosphor
11. Learn the materials/chemicals used in each component (very important) • Input phosphor: o Tightly packed cesium iodine crystals. • Photocathode: o Composed of cesium and antimony compounds. • Anode o The anode is the positive electrode. • Output phosphor: o Made of Zinc Cadmium Sulfide.
12. Learn the functions of each component of the Image intensifier • Input phosphor: o Converts the x-ray energy into visible light. • Photocathode: o Emits electrons when stimulated by the light from the input phosphor (photoemission)/ Converts light into electrons
12. Learn the functions of each component of the Image intensifier . (Cont) • PMT (photomultiplier): o Multiply the electrons with the help of dynode. • Electrostatic focusing lenses: o Focuses the electron stream on the output phosphor.
12. Learn the functions of each component of the Image intensifier . (Cont) • Anode o Attracts electrons emitted by the negative photocathode (a potential difference of 25 kV across the tube) o Allows the electrons to pass through to the output phosphor.
12. Learn the functions of each component of the Image intensifier . (Cont) • Output phosphor: o Interaction with the electron stream produces light photons of much greater intensity than was produced at the input phosphor. / Converts electrons into visible light.
12. Learn the functions of each component of the Image intensifier . (Cont) • Focusing lens: converts light into CCD • CCD (Monitor Camera): to capture the real-time x-rays and display on the monitor screen.
Flux gain: Is the ration of the number of light photons at the output phosphor to the number of x-rays at the input phosphor. Flux gain=(number of output lightphotons)/(number of input x-ray photons)
• Minification Gain: Is the ratio of the square of the diameter of the input phosphor to the square of the diameter of the output phosphor. Minification gain=(D1/( D2))2 D1: diameter of the input phosphor D2: diameter of the output phosphor
• Flux Gain: Formula o Flux gain= number of output light photons/ number of input x-ray photon
• Total Brightness Gain: Formula o Brightness Gain= minification gain X flux gain
• Minification gain: Formula o D12/D22
15. What is veiling glare? • Scattered radiation in the form of x-rays, electrons, and particularly light can reduce the contrast of image intensifier tubes through a process called veiling glare.
15. What is veiling glare? (Cont) • A veiling glare signal is produced behind a lead disc positioned on the input phosphor.
16. What is vignetting? • Vignetting is the reduction in brightness at the periphery of the image. • The portion of any image resulting from the periphery of the input phosphor is unfocused and causes vignetting.
17. What is a multi-field image intensifier? • Is equipped with up to three different input phosphor sizes. • 25cm/17cm/12cm
18. Which is the magnification mode (27 or 17 or12)? o 12 (less field but more magnification)
19. Advantages of magnification mode • Better spatial resolution • Better contrast resolution
20. Which mode gives you more coverage of the anatomy? • The bigger number covers more field
21. What is focal point?
22. What happens to the focal point as you change the mode from big(25) to small(12)? • THE ELECTRON FOCAL POINT MOVES AWAY FROM THE OUTPUT PHOSPHOR • VOLTAGE ON THE ELECTROSTATIC FOCUSING LENSES INCREASES • INCREASE MAGNIFICATION
23. How can you calculate the magnification factor of a multi-field image intensifier? • The magnification factors is directly proportional to the ratio of the diameters. • MF = Initial diameter of the input phosphor New diameter of the input phosphor
24. What is the disadvantage of the magnification mode? • Higher pt dose
25. How the light from the output phosphor is converted to a visible image on the monitor? • The TV camera tube converts the light image from the output phosphor into an electrical signal
26. What is the function of television camera tube? Name the two common models. • Converts the light image from the output phosphor into an electrical signal. • 2 models: o Vidicon tube o Plumbicon tube
27. Learn the components of the television camera tube • Cathode • Electron gun • Control grids • Electrostatic grids • Steering coils • Target assembly: o Face plate (window) o Signal plate o Target plate
28. Learn how each component of the television camera tube work • Electron gun: o Consists of heated filament that supplies constant electron current by thermionic emission. • Control grids: o Converts the electrons into electron beam • Electrostatic grids:
28. Learn how each component of the television camera tube work (Cont) o Accelerate and focus the electron beam • Steering coils: o Controlling the size and position of the electron beam.
29. Learn the three layers of the target assembly and their functions • Face plate (window) o Thin part of the glass envelope • Signal plate o A thin layer of metal or graphite coated on the inside of the window. It conducts the video signal out of the tube into the external video circuit.
29. Learn the three layers of the target assembly and their functions (Cont) • Target plate o A photoconductive layer of antimony trisulfide applied to the inside of the signal plate.
30. What are the chemicals used in signal plate and target plate. • Signal plate o A thin layer of metal or graphite • Target plate o antimony trisulfide.
31. Which is the photoconductive layer of the television camera tube? • Target plate
32. What are the two systems used to connect the television camera tube to the image intensifier? • Fiber optic system • Lens system
33. Learn the advantage and disadvantages of each system • Fiber optic system: o Advantages: • Use a bundle of fiber optics (thousands of thin glass fiber) • The simplest method • Compact • Easy to move the image intensifier tower • Can withstand rough handling.
33. Learn the advantage and disadvantages of each system (Cont) o Disadvantages • Cannot accommodate auxiliary imaging devices such as cine or photo spot cameras. • Lens system o Advantages • Allows the fluoroscopist to view the image while it is being recorded.
33. Learn the advantage and disadvantages of each system (Cont) o Disadvantages • Results in a much larger assembly • To be handled with care • Lens and mirror should remain precisely adjusted • Malposition results in blurred images
34. How many lines per frames are used in CRT monitors used in regular fluoroscopy? • Standard broadcast and closed circuit television have 525 lines per frame.
35. Learn the function of a photo spot camera. What is the advantage of using it? • SIMILAR TO MOVIE CAMARA • RECEIVES IMAGES FROM THE OUTPUTPHOSPHOR • USES FILM SIZE OF 70 AND 105 MM • LARGE FILM FORMAT RESULTS BETTER IMAGE QUALITY BUT INCREASED PATIENT DOSE
35. Learn the function of a photo spot camera. What is the advantage of using it? (Cont) • PROVIDE ADEQUATE IMAGE QUALITY WITH OUT THE INTERRUPTION OF FLUOROSCOPY • PROVIDE UP TO 12 IMAGES PER SECOND • REQUIRES LESS PATIENT EXPOSURE THAN CASSETTE LOADED SYSTEM
Chapter 26
Created by: JenGlez
 

 



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