8. IITV , Digital Fluoroscopy and DSA by Ravindra Kumar.pptx

Introduction: Fluoroscopy is an important diagnostic and interventional imaging tool that enables clinicians to view dynamic real-time images of anatomy and functioning, unmatched by other imaging techniques.
The term fluoroscopy implies the use of a fluorescent screen i.e., when a patient is placed between a source of X-rays and the screen, the x-ray image becomes a visible light image that can be observed.
History: After 1896, inventor Thomas A Edison created the fluoroscope, which consisted of a ZnCdS screen.
Types of Fluoroscopic Equipment: 1. Direct Fluoroscopy:It consisted of an x-ray tube, an x-ray table and a Fluoroscopic screen.
The Fluorescence material in the screen was Copper activated Zinc Cadmium Sulfide that emitted light in the yellow-green spectrum giving rise to the term “Green-Screen”.
2.Image Intensifier TV Fluoroscopy :High performance metal ceramic tubes with high heat loading capacity is required.
Spiral groove bearing in anode rotor.
Liquid metal lubrication to maximize heat dissipation 
Enormous heat storage capacity with its 200 mm diameter anode.
A small focal spot (0.3–0.6 mm) is used for fluoroscopy, and either the small or the large focal spot (1.0–1.2 mm) can be used for image recording when high tube currents are needed.
X-ray tubes also be configured with grid-controlled pulsing to produce very short (millisecond) exposures for cine image recording or pulsed fluoroscopy.
COMPONENTS :X-ray Tube
X-ray Generator
Image Intensifying Assembly
Video-Camera
Viewing Monitors
Fluoroscopy Table
Spot Film Device.
Components of Image Intensifier : Enclosure
Input phosphor
Photocathode
Electrostatic focusing lens
Accelerating anode
Output phosphor
The image can be viewed by 2 methods:
Direct method for viewing
Indirect method for viewing.
3.
Flat Panel Digital Fluoroscopy :Flat panel detector system has replaced the I.I.T.V. system.
X-rays passing through the patient are converted into electrical signals by the F.P.D. These are then passed through the amplifier and ADC where they are converted into digital signals.
The digital image data is directly transferred to an image storage personal computer (PC) via an optic fiber link at the rate of 30 f/s .
Newer FPDs like Pixium 4700 & Pixium 4800 from Thales are used for Vascular & Cardiovascular DSA applications by permitting low – dose fluoroscopy.
DSA:The acquisition of digital fluoroscopic images combined with injection of contrast material and real-time subtraction of pre- and post-contrast images to perform examinations is referred to as digital subtraction angiography.
It was first developed in late 1970s.
In Rotational Angiography, a C-arm assembly, caused to rotate at 55 degrees per second during the imaging sequence and acquire a real-time 3D images of vessels in a single contrast injection.
Volume tomographic angiography-x-per CT.
Fluoroscopic procedure and equipment and ways to minimize study times, exposure times and radiation dose.

1. IITV , Digital Fluoroscopy And DSA 1 DEPARTMENT OF RADIODIAGNOSIS AND IMAGING PGIMER CHANDIGARH PRESENTED BY:- MR. RAVINDRA KUMAR MEDICAL TECHNOLOGIST

2. Contents Introduction History Type of Fluoroscopy Equipment. IITV. Flat Panel Digital Fluoroscopy. Digital Subtraction Angiography Subtraction Technique Radiation Protection Conclusion References 2

3. 3 Fluoroscopy is an important diagnostic and interventional imaging tool that enables clinicians to view dynamic real time images of anatomy and functioning, unmatched by other imaging techniques. The term fluoroscopy implies the use of a fluorescent screen i.e., when a patient is placed between a source of x-rays and the screen, the x-ray image becomes a visible light image that can be observed . Introduction

4. After 1896, inventor Thomas A Edison created the fluoroscope consisting of ZnCdS screen . The radiologist positioned the screen between the patient and himself or herself with the x-ray tube behind the patient. To maximize the visualization , fluoroscopist had to do dark adaptation and later red google were introduced. To overcome the deficiencies of viewing the dim fluorescent screen , the image intensifier devices were developed and introduced in 1953 . 4 History

5. 5 Types of Fluoroscopic Equipment

6. It consisted of an x-ray tube, an x-ray table and a Fluoroscopic screen. The Fluorescence material in the screen was Copper activated Zinc Cadmium Sulfide that emitted light in the yellow-green spectrum giving rise to the term “Green-Screen”. A sheet of Lead glass covered the screen, so the radiologist could stare directly into the screen without having the X-ray beam strike his/her eyes. Screen fluorescence was so faint that fluoroscopic examination were carried out in dark room by dark adapting eyes by wearing red goggles for 20-30 min. prior to the exam. 6 Direct Fluoroscopy

7. Based on the principle of fluorescence which is emission of light photons in proportion to the amount of radiation falling on it . Visible light image and can be observed directly or by television system. 7 Principle

8. Disadvantage : Only one person can see the image at a time. Image is too faint. Dark adaptation is required for 20-30 min prior to examination. More radiation dose for patient and staff. Light conversion efficiency is less. Viewing angle is very less i.e. 6 degree. Because of these reasons, in 1953 the image intensifier were developed which allows the use of cone vision (photopic vision). Two important functions of II are fluorescence (conversion of X-ray photons into visible light) and light signal amplification. 8

9. 9 IITV BASED FLUOROSCOPY

10. 10 COMPONENTS

11. High performance metal ceramic tubes with high heat loading capacity is required. Spiral groove bearing in anode rotor. Liquid metal lubrication to maximize heat dissipation  Enormous heat storage capacity with its 200 mm diameter anode. A small focal spot ( 0.3–0.6 mm ) is used for fluoroscopy, and either the small or the large focal spot ( 1.0–1.2 mm ) can be used for image recording when high tube currents are needed. X-ray tubes also be configured with grid-controlled pulsing to produce very short (millisecond) exposures for cine image recording or pulsed fluoroscopy. 11 Fluoroscopy X-ray Tube

12. Similar to generators used for radiography, with added circuitry for fluoroscopic operation, including either low continuous tube current or rapid pulsed exposure and A utomatic B rightness C ontrol (ABC). H igh powered to provide short exposure time. Coupled with continuous , rapid exposures so that dynamic real time images can be produced and recorded with high or considerable diagnostic quality . Generally used with power rating of 80 to 100 kw. 12 X-ray Generators

13. 13 In continuous fluoroscopy, the image is produced by continuously irradiating the patient . The generator provides a steady tube current while the fluoroscope is activated. Images are acquired at a rate of 30 frames per second, resulting in an acquisition time of 33 msec per image. Continuous Fluoroscopy

14. For pulsed fluoroscopy, the exposure is delivered in short pulses, 3–10 msec in length. Typically, a pulse rate of 30 pulses per second is used, with some units allowing the selection of lower pulse rates (15 , 7.5, 3.5 , 2.5 pulses per second). ADVANTAGE – Improvement in temporal resolution, so Motion blur is reduced. It can reduced the radiation dose to patient and to the radiological staff at lower frame rate. Less load on the x-ray tube so, increased life of x-ray tube. 14 Pulsed Fluoroscopy

15. ABC helps to Maintain the image intensifier exposure rate based on the subject’s thickness or during the magnification of image. The ABC monitors the light output from an area of the face of the image intensifier and it tries to maintain the signal travel within an approximate range of that output and adjust tube potential ( kVp ) and tube current (mA) between to predefined algorithm. It refers to control of x-ray exposure by: kV variability: mA constant mA variability: kVp is constant Combined control: automatic selection of kV ,mA Pulse width. 15 Automatic Brightness Control (ABC)

16. In standard conventional tables, x-ray tube lies beneath the table and Image Intensifier above. Tilt is restricted to 90-0-30 Now a days tilting can be -90°-0°-90°. Material of table is radio transparent (e.g. laminated paper / carbon fiber) MOSTLY USED NOW-A-DAYS. 16 Fluoroscopic Table

17. Enclosure Input phosphor Photocathode Electrostatic focusing lens Accelerating anode Output phosphor 17 Components of Image Intensifier

18. The II components are contained within a glass or metal envelop that provides structural support but more importantly maintains a vacuum . The glass tube of the II is about 2 to 4 mm thick and the tube is contained in Lead lines metal container to protect it from rough handling and breakage. The vacuum case itself is covered by a protective metallic housing which is made of lead to absorb scatter radiation, mu-metal to protect electrostatic lenses from external magnetic forces and an outer aluminum shell. This aluminum shell also covers and protects the input window of the II. 18 Enclosure

19. The input fluorescent screen is Cesium Iodide (CsI). Earlier it was Silver activated Zinc Cadmium Sulphide. CsI is deposited on a thin Aluminum substrate , the crystals of CsI grow in tiny needles perpendicular to the substrate exhibits minimal lateral light diffusion. When this absorbs X-ray photon it produces light and transmitted to the photocathode with little scattering. The brightness of light emitted is proportional to the intensity of the incident x-ray. The input phosphor is curved to ensure that electrons emitted at the peripheral region of the photocathode travel the same distance as those emitted from the central region. Available in 10-40cm in diameter. 19 Input phosphor

20. No inert binder is required therefore Greater packing density . It is three times more than ZnCdS. The crystals grow in tiny needles perpendicular to the substrate therefore the phosphor layer exhibits minimal lateral diffusion. The k-edge of CsI (Cs -36keV & I-33keV) match with the average energy of x-ray beam. Phosphor thickness has been reduced to 0.1 mm as compared to ZnCds that is 0.3mm. The resolution of CsI is 4 lp /mm . 20 Advantages of CsI

21. When light from the fluorescent screen strikes the photocathode it emits electrons in numbers, proportional to the brightness of the screen. It is coated onto the input phosphor . Photocathode is kept close to input phosphor otherwise the light will diffuse before it reaches to photocathode and will result in reduced resolution of the image. It is a photo emissive material usually combination of Cs and Antimony. (SbCs3) . It also serves as cathode of the image tube. It is usually kept at ground potential. 21 Photocathode

22. These are made up of a series of positive charged electrodes that are usually plated onto the inside surface of the glass envelope. These electrodes focus and accelerate the electron beam as it flows from the photocathode towards the output phosphor . The image is reduced in size due to which it is brighter. The image on the output phosphor is inverted on a point of inversion because all the electrons pass through a common focal point on their way to the output phosphor. Each point on the input phosphor is focused on a specific point on the opposite side of the output phosphor. 22 Electrostatic focusing lens

23. The anode is located in the neck of the II tube. Its function is to accelerate electrons emitted from the photocathode toward the output screen. The anode has a positive potential of 25 to 35 kV relative to the photocathode, so it accelerates electrons to tremendous velocity. 23 Accelerating Anode

24. Output phosphor is made up of ZnCdS: Ag as activator . Diameter is 2.5 cm-5 cm . The electrons are greatly accelerated they emit more light photons from the output phosphor than were originally present at the input phosphor . A thin layer of Aluminum is plated onto the fluorescent screen through which high energy photoelectron can pass . It prevents light from going to photo cathode . 24 Output phosphor

25. Most popular is trifield (25/17/12 CM) When 17 cm mode is ON, voltage to electrostatic lens is increases which shift the focal point away from output phosphor and electrons from 17cm diameter of input phosphor are incident on output phosphor. Greater the voltage more is the focal or inversion point shifted away from the output phosphor and image will appear magnified. As in 6” i.e 17 cm mode the image looks magnified in comparison to the 9” i.e 25cm mode. 25 Multi Field Image Intensifiers :-

26. The ability of II to increase the illumination level of the image is called its Brightness Gain . The Brightness Gain is the Product of the Minification Gain and the Flux gain. Brightness Gain = Minification Gain x Flux gain The Brightness Gain of most II is 5000 to 30000 and it decreases with tube age and use. Patient dose increases as a consequence of maintaining image brightness. 26 Brightness Gain

27. The M inification Gain is the ratio of the square of the Diameter of the Input Phosphor to the square of Diameter of the Output Phosphor . Minification Gain = ( )² is the diameter of Input Phosphor . is the diameter of Output Phosphor .   27 Minification Gain

28. The ratio of the number of light photons at the output phosphor to the number of X-rays at the input phosphor is the Flux gain. Flux Gain =   Flux Gain

29. The output phosphor of the image intensifier tube has a diameter about 2.5cm - 5cm and this of course is too small for an observer to appreciate detail by looking at it directly so to see the image, a magnifying optical system is necessary at the output phosphor before the image can be viewed . The image can be viewed by 2 methods: Direct method for viewing Indirect method for viewing 29 Viewing Of Intensified Fluoroscopic Image

30. The image can be viewed through a series of lenses and mirrors. Light travels a long distance, and it is reflected and focused several times. 30 Direct Method for Viewing

31. Disadvantages: Only one person can see the image at a time. Considerable loss of brightness due to multiple mirror system (loss of image) Small viewing angle ,difficult to manipulate the equipment to see the image. It restrict the movement during procedure. Operator is very close to the II system thus increased radiation dose to eyes and hands. Only one observer can view the image which is serious disadvantage for training beginner. 31

32. Viewing the image is done by a Closed Circuit Television chain in modern systems. Viewing the image in this system is a TV camera attached to the optical system of output phosphor. A video signal is given to the TV Monitor which displays the image. Coupling to the II can be: Lens Coupling Fiber optic Coupling 32 Indirect Method for viewing

33. Image Recording is also required during Fluoroscopy. Image can be recorded from the TV camera signal, but the resulting image would be degraded so it is better to expose the film directly to the output phosphor of the II tube. TV viewing, while exposing the film means that we must split the light from the output screen into two path at the time of exposure. 33 Lens Coupling

34. During Fluoroscopy all the light of output screen is directed to TV camera. When Film mode is selected , a semi-transparent, partially silvered mirror is positioned in the light beam. With this , about 90% goes to the film camera, and about 10% pass through the mirror to form satisfactory TV image. 34 Disadvantage : The camera lenses are the most critical elements in the optical chain in terms of alignment. Unit is bulky and sensitive. Cannot be used roughly. CONTI..

35. The fiber-optic bundle is only a few millimeters thick and contains thousands of glass fibers/mm². Advantages: Compact assembly Can withstand relatively rough handling. Disadvantage: It cannot accommodate the additional optics required for photo-spot or cine cameras. 35 Fiber optic Coupling

36. 36 Image Intensifier

37. A lens system or a fiber optic bundle system conveys the fluoroscopic image from output phosphor of the II to the video camera where it is converted into a series of electrical pulses called the video signal . The signal is transmitted through a cable to camera control unit where it is amplified . The amplified video signal is forwarded through another cable to Tv monitor for display. TV-Camera /CCD. Viewing Monitors 37 Components of the viewing system

38. It is a device which converts fluoroscopic image produced on the output phosphor of an II to a series of electric impulses known as video signal . Works on a principle either of Photoconductivity or Photoemission . Types Of Camera: Tube TV Camera CCD TV Camera 38 Camera

39. 39 Tube TV Camera

40. The Television camera consists of a cylindrical housing, approximately 15 mm in diameter by 25 cm in length, which contains the heart of the television camera tube. It also contains electromagnetic coils that are used to properly steer the electron beam inside the tube. A number of such television camera tubes are available for television fluoroscopy, but the vidicon and its modified version, the Plumbicon, are used most often. A typical vidicon , The glass envelope serves the same function that it does for the x-ray tube: to maintain a vacuum and provide mechanical support for the internal elements. These internal elements include the cathode, its electron gun, assorted electrostatic grids, and a target assembly that serves as an anode. 40

41. 41 A photoconductive layer of antimony trisulfide is applied to the inside of the signal plate. This layer, called the target , is swept by the electron beam. Antimony trisulfide is photoconductive because, when illuminated , it conducts electrons; when dark , it behaves as an insulator . When light from the output phosphor of the image-intensifier tube strikes the window, it is transmitted through the signal plate to the target. If the electron beam is incident on the same part of the target at the same time, some of its electrons are conducted through the target to the signal plate and from there out of the tube as the video signal. If that area of the target is dark, no video signal is produced.

42. Digital fluoroscopy TV camera tube is replaced by charge couple device because it gives better spatial resolution image. It is photosensitive silicon chips, when illuminated, an electric charge is generated which is sampled pixel by pixel to produce a digital image. CCD is mounted on the output phosphor of the image intensifier tube and is coupled by lens system or directly coupled. Vidicon stores + ve charge but it stores – ve charge. 42 CCD TV Camera

43. High spatial resolution High SNR High DQE No warm up required No lag No distortion Unlimited Life with no maintenance 43 Advantages of CCD:

44. 44 Artifacts in IITV

45. Lag is defined as persistence of Luminescence after X-ray stimulation has been terminated. With older image tubes the Lag time was 30 to 40ms whereas with CsI tube the lag time is about 1ms . 45 Image Lag

46. The peripheral image is displayed over a large area of Output screen and thus its Brightness Gain from magnification is less then that in the Center. A fall of brightness at the periphery of image is called Vignetting . Unequal focusing has another effect on image quality that is Resolution is better in the center of screen. In Summary , center of the II screen has better resolution, brighter image and less geometric distortion. 46 Vignetting:

47. Internal scatter radiation in the form of x-rays, electrons, and particularly light can reduce the contrast of image intensifiers through a process called veiling glare. A veiling glare signal is produced behind a lead disc that is positioned on the input phosphor. Advanced image intensifiers have output phosphor designs that reduce veiling glare. 47 Veiling glare

48. 48

49. 49 Pin-cushion distortion is a geometric, nonlinear magnification across the image. The magnification difference at the periphery of the image results from the projection of the x-ray beam onto a curved input surface. PIN-CUSHION DISTORTION

50. 50 Electrons within the image intensifier move in paths along designated lines of flux. External electromagnetic sources affect electron paths at the periphery of the image intensifier more than those nearer the center. This characteristic causes the image in a fluoroscopic system to distort with an S shape . S-DISTORTION

51. 51 Spot film device Automatic film changer Photofluorography Cine-fluoroscopy Image Recording Methods

52. 52 located in front of the image intensifier, accepts the screen-film cassette and “parks” it out of the way during fluoroscopy. Spot film imaging uses essentially the same Technology as conventional screen-film radiography. Cassette size can be 8x10, 10x12,and 14x14 (inches). Limitation – Magnification as cassette is away from the patient. More surface dose due to small source to skin distance. Delay due to positioning of cassette. Limitations are overcome by Photofluorography and rapid film changer . Spot Film Device

53. 53 Spot film device is replaced by Rapid film changer in vascular imaging. It is also a film-screen system used in vascular imaging. Having supply magazine for holding unexposed film , receiving magazine, mechanism for transferring film and pair of radiographic screen. Unlike with spot film devices, the requirement for rapid motion limits the automatic changer to one film size, usually 35 x 35 cm. Hold 30 films in receiving magazine Film Rate is 4 films /sec. 7.5 sec run is achieved without changing the magazine. Automatic Film Changer

54. 54 More rapid filming than that provided by film changers can be achieved by using a photo spot ( Photofluorography ) camera. Photo spot cameras can expose as many as 200 films before reloading at rates as high as 12 per second . The camera is mounted on the optical coupling system behind the image intensifier An iris or diaphragm , placed in front of the camera lens, is used to adjust the amount of light reaching the camera. 105mm wide roll film is used. Expose 200 films at rate of 12 films/sec before reloading . Photo Spot Camera/ Photo-Fluorography

55. 55 The major differences are that the film is smaller ( 35 mm wide ) and 120mm on a roll) and that the camera is capable of operating at up to 90 images per second. The higher frame rates are usually used in cardiography , particularly for peadiatric imaging. Cine Camera

56. Light enters the camera through the lens and is restricted by the Aperture, a rectangular opening in front of the camera. The size and the shape of the aperture define the configuration of the image reaching the film. While the shutter is closed the Pull Down Arm advances the film to correct position for next exposure. The Pressure Plate hold the film against the Camera Aperture so it is located in proper image plate. An electric drive motor advances the film from Supply Real to Take Up Real. The X-ray pulses and Shutter opening are synchronized either by switching in the secondary circuit of a constant potential Generator of by Use of Grid Controlled X-ray tube. 56 Working

57. 57 FLAT PANEL DIGITAL FLUOROSCOPY

58. Flat panel detector system has replaced the I.I.T.V. system. X-rays passing through the patient are converted into electrical signals by the F.P.D. These are then passed through the amplifier and ADC where they are converted into digital signals. The digital image data is directly transferred to an image storage personal computer (PC) via an optic fiber link at the rate of 30 f/s . 58 Flat Panel Digital Fluoroscopy

59. DF technology converts x-rays into electrical charges by means of a indirect readout process using scintillator and CCD/TFT arrays. 59 Flat Panel Fluoroscopy

60. Advantages of DF Distortion Free Image Constant image quality over the entire image Improved contrast Resolution High DQE Unaffected by external magnetic Field. This system permits high speed digital image acquisition, processing and display. The system is much smaller and lighter and is manipulated more easily than an image intensifier. 60 Disadvantages High initial cost. Careful handling is required due to fragile nature of most detectors.

61. Newer FPDs like Pixium 4700 & Pixium 4800 from Thales are used for Vascular & Cardiovascular DSA applications by permitting low – dose fluoroscopy. 61 Scintillator CsI:Tl Photodiode array a:Si Refresh light Integris Allura Flat Dynamic Detector

62. 62

63. 63 Digital Subtraction Angiography (DSA)

64. 64 The acquisition of digital fluoroscopic images combined with injection of contrast material and real-time subtraction of pre- and post-contrast images to perform examinations is referred to as digital subtraction angiography. It was first developed in late 1970s . DSA

65. 65 It is simply a technique by which bone structures images are subtracted or canceled out from a film of bones plus opacified vessels, leaving an unobscured image of the vessels. The Principles of subtraction are based on the following: The scout film is taken which shows the structural details of the bone and the adjacent soft tissue. Angiogram film shows exactly the same anatomic details, if the patient does not move, plus the opacified blood vessels. If all the information in the scout film could be subtracted from the Angiogram film, only the opacified vessel pattern would remain visible. Condition-no patient motion SUBTRACTION

66. Conventional subtraction technique Using a duplicating machine with subtraction light, make a positive mask from the first film of the Angiographic series without contrast. Place unexposed subtraction film, emulsion side down, over the selected mask image. Expose with subtraction light for approximately 5 seconds (depending on the type of machine). The unexposed subtraction film is run through the film processor and becomes the positive (or reversed image) mask. 7 Step 1

67. 67 First image of run without contrast media Light source

68. Choose the film with contrast-filled anatomy to be subtracted. Place the positive mask over the contrast-filled angiographic film on the duplicating machine with the light on, in order to align the boney structures and thus superimposing the two films. Turn the duplicating light off and place an unexposed subtraction film with emulsion side down over the other two films. Expose on subtraction light approximately 25 to 30 seconds (longer the time, more is the density). The unexposed subtraction film becomes the subtracted print when processed. 9 STEP-2

69. Subtraction film Positive of first film Image with contrast 69

70. 56

71. The mask subtraction is similar to the conventional film based subtraction technique. In it, the patient is positioned and before injection, initial exposure is made, that is stored in primary memory and displayed on video monitor called Mask Image . Then contrast is injected into a blood vessel, that is carried by circulation to the arteries or veins of interest. Digital images of the same area of interest are obtained after the arrival of contrast media. The mask is digitally subtracted pixel by pixel from post contrast injection images in real time and stored in primary memory and displayed on a second video monitor. Misregisteration is corrected by pixel shifting. 57 MASK SUBTRACTION

72. Useful especially in cardiology. In this, a new mask is chosen for each subtraction. The successive subtracted images are frequently displayed in a rapid sequence, that is repeated to show dynamic function. Each subtracted image is the difference between images separated by fixed interval of time. 60 TIME INTERVAL DIFFERENCING

73. It is a method that does not require the acquisition of images before and after the arrival of contrast media. Two beams (a high kV and a low kV i.e. 70-90KVp) alternatively provide a subtraction image resulting from differences in photoelectric interaction. The two images are taken in short period of time that yields the image of differing contrast. A mask image of lower contrast image is subtracted from the frame of higher contrast. Its disadvantages are : It cannot subtract soft tissues and bone simultaneously. X-ray generator capable of switching kVp and mAs rapidly is needed. 58 DUAL ENERGY SUBTRACTION

74. Combination of mask subtraction and dual energy subtraction. This technique is useful in uncooperative patients and where there is motion. Two pairs of dual energy images are obtained, one prior to the arrival of contrast and one after that. In each pair of images, one of the image is subtracted to remove soft tissue on another image. The latter images are subtracted in a second step to yield only an iodine signal in final hybrid subtracted image. 62 HYBRID SUBTRACTION

75. Post processing techniques are done after the acquisition of actual images digitally. It allow image manipulation to enhance detail of the image. Remasking Pixel Shifting Noise smoothening Land Marking Trace or Stacking of images Edge Enhancement Zooming Annotation 63 POST PROCESSING TECHNIQUES

76. If on subsequent examination, the initial mask image is inadequate because of the patient motion or improper technique or for any other reason, later images can be used as the mask image. 76 Re-masking

77. Reregistration :This process allows the mask to be shifted relative to a subsequent contrast containing image to correct for artefacts created by patient movement. Patient motion can be reduced by electronically shifting either the mask image, or the contrast-filled image until the bony landmarks line up as close as possible. 77 Pixel Shifting

78. Roadmapping is a special application of DSA. A mask image is acquired and stored. The contrast material is injected and subtraction images are acquired as in DSA. As the catheter is fluoroscopically advanced, the image is formed by subtraction from the second mask. A black guidewire or catheter in a white vessel. The final DSA image shows the complete vascular tree with good contrast. This last image is inverted and is used as the mask for additional DSA images. 78 Roadmapping

79. Reducing statistical fluctuation in each pixel by averaging pixel with its closest neighbors. Final image is blurred version of the original one, generated by applying a consistent mathematical operation to the original image to form first pixel and shifting and forming adjacent pixels. It has little effect on large structures. 79 Noise Smoothening

80. Subtraction takes out of the boney structures so that only the contrast-filled blood vessel remains. Land marking puts back some of the background information in order to locate an area of interest in the image. Surgeons in particular may need an anatomical landmark when subtraction techniques are used in angiography. Land marking can also be used during the procedure if a reference image is needed. 80 Land Marking

81. 81

82. Normal arterial blood flow is hard to capture on one image. The view trace or stacking option is used when the physician only wants to send one contrast-filled arterial phase image to the archival system. This option “stacks” several images together allowing for the capture of the entire arterial anatomy on one image instead of several. 82 Trace/Stacking of Images

83. 83

84. Edge enhancement is a post processing technique that is used to visualize the edges of the blood vessels for better detail. The higher the edge enhancement, the better the detail of the blood vessels. The image will be sharper, but the noise within the image will also be increased. Too much edge enhancement will degrade the image. 84 Edge Enhancement

85. Prior to digital imaging, geometric magnification was performed to increase the resolution of the image to obtain small vessel detail by placing the object of interest further away from the film prior to exposure. With digital imaging, geometric magnification is done by changing the magnification mode of the system. After exposure, zoom magnification can be done by using the “zoom” feature to enlarge the area of interest. 85 Zooming

86. In Rotational Angiography , a  C-arm assembly , caused to rotate at 55 degrees per second during the imaging sequence and acquire a real-time 3D images of vessels in a single contrast injection. A contrast run will be followed by mask run to allow the substraction . The provide the detail required for diagnostic and therapeutic decisions. Max rotation speed- 55 degree/sec Max rotation angle 270 degree 86 Rotational Angiography-

87. 87

88. 88 Volume tomographic angiography- xper CT Volume Tomographic Angiography is similar to  Computed Tomography   (CT) where the C-arm is rotated around the patient during the imaging sequence. Provide CT like images without transporting the patient. The image data is subject to a volume  reconstruction algorithm  which permits generation of three-dimensional images of the opacified vasculature. Angiography- xper CT

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91. 91 Radiation Protection In Fluoroscopy

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96. 96 Fluoroscopy is one of the Few Modalities that provide live imaging of the patient. In addition to real-time diagnosis, it is useful for interventional Procedures. Because Radiological Technologist are the equipment operators, an understanding of the physics of fluoroscopic imaging systems is important to perform examinations in a safe and efficient manner. Due to Development in the hardware and software in Fluoroscopy starting from screen Fluoroscopy ,than IITV based and now the Digital fluoroscopy and Digital Subtraction Angiography have raised the radiology field not towards the diagnostic side but also towards the therapeutic . For Pediatric Fluoroscopic Imaging and the ALARA principle, whether using II/TV systems or FPD systems, always important is the vigilance and understanding by the operator of the fluoroscopic procedure and equipment and ways to minimize study times, exposure times and radiation dose for the benefit of our patients. Conclusion

97. Radiologic science for technologist, staywart bushong . Essential physics of medical imaging, bushberg . Aiims –Mamc-Pgi imaging series , advances in imaging technology. Christensen physics of diagnostic radiology. The AAPM/RSNA physics tutorial for residents(general overview of fluoroscopic imaging). The AAPM/RSNA Physics Tutorial for residents fluoroscopy: (recording of fluoroscopic images and automatic exposure control). Schueler BA. The AAPM/RSNA physics tutorial for residents: General overview of fluoroscopic imaging. Radiographics . 2000;20:1115-26. Google. 97 REFERENCES

98. 98 MACHINES OF PGIMER

99. 99 SONIALVISION G4-RF SYSTEM

100. 100 OPERA SWING- RF SYSTEM

101. 101 FLUOROSCOPY C-ARM

102. 102 HYBRID DSA LAB

103. 103 ALLURA XPER FD 20

104. 104 AZURION 7 B 20/15

105. 105 IITV BASED C-ARM IN OT 4 TH FLOOR

106. 106 FPD BASED C-ARM IN ATC OT IITV BASED C-ARM IN ATC OT

107. 107 Question: What is the brightness gain for a 17-cm image-intensifier tube with a flux gain of 120 and a 2.5-cm output phosphor?

108. 108 A 23-cm image intensifier has an output phosphor size of 2.5 cm and a flux gain of 75. What is its brightness gain?

109. 109 Question: How magnified is the image of a 25/17/12 image-intensifier in the 17-cm mode compared with that produced in the 25-cm mode?

110. 110 Question: A 23/15/10 image-intensifier tube is used in the 10-cm mode. How much higher is the patient dose in this mode compared with the 23-cm mode? The increase in dose is approximately equal to the ratio of the area of the input phosphor used, or [23 2 ÷ 10 2 ≈ 5.29]—the dose obtained in the wide field-of-view mode.

111. 111 When the image intensifier is switched from 15-cm mode to 25-cm mode, what happens to patient radiation dose and contrast resolution? This increase in patient radiation dose results in better image quality. The patient radiation dose is higher because more x-rays per unit area are required to form the image. This results in lower noise and improved contrast resolution.

112. THANK YOU