Fluoroscopy Intro to EQUIPMENT RT 244 FALL 2008-10 Week 1 Wed- CONTINUED Ref: Fluoroscopy – Bushong’s Ch. 24

Basic Componets of “old” Fluoroscopy “Imaging Chain” Primary Radiation EXIT Radiation Fluoro TUBE PATIENT 105 Photospot Fiber Optics OR Image Intensifier ABC LENS SPLIT Cassette Image Recording Devices CINE CONTROL UNIT VIDICON Camera Tube TV

Conventional I I system

IMAGE INTENSIFIER

The anode of the II The anode is about 20” away from these electrons so what will help move the E’s? Electrostatic lenses have a negative charge to repel the negative electrons and push them to the anode and focus them to a narrow beam* Anode has a hole in the middle of it allowing electrons to pass through and hit the output phosphor made of zinc cadmium sulfide* The electrons are carrying the latent image and when they hit the output phosphor they are turned into light again 5

Anode and Output Screen Positively charged 25 kVp Hole in center allows electrons to pass through to output screen OUTPUT SCREEN Usually 1 inch in diameter Zinc cadnium sulfide coating Changes electrons back to LIGHT

Image Intensifier PROPERTIES Image Quality Contrast Resolution Distortion Quantum mottle

Contrast Controlled by amplitude of video signal Affected by: Scattered ionizing radiation Penumbral light scatter

reduce contrast of an image intensifier tube. Veiling glare Scatter in the form of x-rays, light & electrons can reduce contrast of an image intensifier tube.

Resolution Video viewing Limited by 525 line raster pattern of monitor Newer digital monitors 1024 - better resolution MORE ON THIS LATER IN THE LECTURE

Image distortion PINCUSHION EFFECT

Shape Distortion Geometric problems in shape of input screen Concave shape helps reduce shape distortion, but does not remove it all Vignetting or pin cushion effect Vignetting FALL-OFF OF BRIGHTNESS AT PERIPHERY (EDGES) OF THE IMAGE

VIGNETTING……. Darkness on edges (falloff of brightness)

Size Distortion Affected by same parameters as static radiography Primarily OID Can be combated by bringing image intensifier as close to patient as possible

ABC

Basic Componets of “old” Fluoroscopy “Imaging Chain” Primary Radiation EXIT Radiation Fluoro TUBE PATIENT 105 Photospot Fiber Optics OR Image Intensifier ABC LENS SPLIT Cassette Image Recording Devices CINE CONTROL UNIT VIDICON Camera Tube TV

Brightness Control Automatic brightness stabilization Automatic adjustments made to exposure factors by equipment Automatic gain control Amplifies video signal rather than adjusting exposure factors

BRIGHTNESS CONTROL ABC ABS AEC ADC MAINTAINS THE BRIGHTNESS OF THE IMAGE – BY AUTOMATICALLY ADJUSTING THE EXPSOURE FACTORS (KVP &/OR MAS) FOR THICKER PARTS SLOW RESPONSE TIME - IMAGE LAG

ABC Automatic brightness control allows Radiologist to select brightness level on screen by ↑ kVp or ↑ mAs Automatic dose control Located just beyond the Output Phosphor Will adjust according to pt thickness

Automatic Brightness Control Monitoring Image Brightness Photocell viewing (portion of) output phosphor TV signal (voltage proportional to brightness) Brightness Control: Generator feedback loop kVp variable mA variable/kV override kV+mA variable Pulse width variable (cine and pulsed fluoro)

Quantum Mottle Blotchy, grainy appearance Caused by too little exposure Most commonly remedied by increasing Ma Controlled by the ABC Affected by too little technique size of patient distance of II to patient size of collimation

Fluoroscopic Noise (Quantum Mottle) Fluoroscopic image noise can only be reduced by using more x-ray photons to produce image. Accomplished in 3 ways: Increase radiation dose (bad for patient dose) Frame-averaging: creates image using a longer effective time Can cause image lag (but modern methods good) Improve Absorption Efficiency of the input phosphor

KEEP I.I. CLOSE TO PATIENT reduces beam on time

Units of measurement INPUT PHOSPHOR – IS MEASURED IN _________________________________ OUTPUT PHOSPHOR IS MEASURED IN ______________________________

VIEWBOXES ARE MEASURED IN: lamberts (light) Units of measurement INPUT PHOSPHOR – IS MEASURED IN Milliroentgens mR OUTPUT PHOSPHOR IS MEASURED IN CANDELAS (LIGHT) VIEWBOXES ARE MEASURED IN: lamberts (light)

Fluoroscopic Imaging

Coupling I.I. to TV Monitor 2 Methods: Fiber optics directly to T.V. camera. Lens system which utilizes auxiliary imaging devices.

Directly to T.V. Only cassettes can be used.

Beam splitting mirror

Basic Componets of “old” Fluoroscopy “Imaging Chain” Primary Radiation EXIT Radiation Fluoro TUBE PATIENT 105 Photospot Fiber Optics OR Image Intensifier ABC LENS SPLIT Cassette Image Recording Devices CINE CONTROL UNIT VIDICON Camera Tube TV

Beam splitting mirror Often a beam splitting mirror is interposed between the two lenses. The purpose of this mirror is to reflect part of the light produced by the image intensifier onto a 100 mm camera or cine camera. Typically, the mirror will reflect 90% of the incident light to other RECORDING DEVICES and transmit 10% onto the television camera*. *TV MONITOR is the weakest link (low resolution)

Viewing Fluoroscopic Images

Lenses / Mirrors Used to direct image to recording devices Several mirrors in a series and angled - the last mirror is outside the II for the operator to view Image decreases as it is projected from 1 mirror to the next Only 1 person can view image

STATIC IMAGES DYNAMIC IMAGES RECORDING THE IMAGE STATIC IMAGES DYNAMIC IMAGES

Basic Componets of “old” Fluoroscopy “Imaging Chain” Primary Radiation EXIT Radiation Fluoro TUBE PATIENT 105 Photospot Fiber Optics OR Image Intensifier ABC LENS SPLIT Cassette Image Recording Devices CINE CONTROL UNIT VIDICON Camera Tube TV

Recording the Fluoroscopic Image STATIC IMAGES Cassettes 105 mm chip film = 12 frames per second Digital fluoroscopy DYNAMIC VIEWING: Cine film Videotape

Recording Fluoroscopic Images

IMAGE RECORDING OLD II - ONLY FIBER OPTICS –NO LENS SPLITTER TO OTHER RECORDING DEVICES ONLY RECORED IMAGE ON SPOT CASSETTES (9X9 ONLY) NEWER - TAKES CASSETTES or uses /105 PHOTOSPOT / VIDEO/ CINE NEWEST = USES DIGITAL !!!!!!!!! (but the tests* still have all of it!)

Basic Componets of “old” Fluoroscopy “Imaging Chain” Primary Radiation EXIT Radiation Fluoro TUBE PATIENT 105 Photospot Image Intensifier Fiber Optics ABC LENS SPLIT Cassette Image Recording Devices CINE CONTROL UNIT VIDICON Camera Tube TV

Radiographic Exposure for cassette spot films Fluoroscopy mA Low, continuous exposures .05 – 5 ma (usually ave 1 – 2 ma) Radiographic Exposure for cassette spot films mA increased to 100 – 200 mA

RECORDING IMAGES OLD (Smaller) II with fiber optic ONLY RECORDING WAS CASSETTE CASSETTE “SPOT” IMAGES TAKEN DURING FLUORO PROCEDURE VERY OLD 9X9 inch cassettes Later could take up to 14 x 14 inches

Cassettes Standard size - 9” x 9” (old) NOW CAN TAKE UP TO 14X14 Stored in lead-lined compartment until ready for exposure When exposure is made, mA is raised to radiographic level Multiple image formats

Image recording Cassette loaded spot film Where is the tube? How should you put the IR into the II slot? You can format the image, 2 on 1, 4 on 1 or 1 on 1 Cassette loaded spot film increases patient dose 49

Basic Componets of “old” Fluoroscopy “Imaging Chain” Primary Radiation EXIT Radiation Fluoro TUBE PATIENT 105 Photospot Fiber Optics OR Image Intensifier ABC LENS SPLIT Cassette Image Recording Devices CINE CONTROL UNIT VIDICON Camera Tube TV

70 & 105 PHOTOSPOT (CAMERA) Photo spot camera will take the image right off the output phosphor This requires less patient dose 70 & 105 mm roll film

CASSETTE SPOT FILMING vs PHOTOSPOT FILMING First type of recording used 9x9 cassettes then later up to 14x 14 9 on 1, 4 on 1, 2 on 1 Delay while filming (anatomy still moving) Radiographic mA - must boost up to 100 – 200 mA for filming And moving cassettes around inside tower Higher patient dose Replaced by Photospot (f/sec) filming

CASSETTE SPOT FILMING vs PHOTOSPOT FILMING Photospot (f/sec) filming – Set at control panel from 1 f/sec – 12 f/sec Used for rapid sequence: Upper Esophogram Voiding Cystourethrograms (Peds) Lower patient dose

Recording the Fluoroscopic Image Dynamic systems Cine film systems Videotape recording Static spot filming systems

TV camera and video signal & Recording the image The output phosphor of the image intensifier is optically coupled to a television camera system. Beam splitter – is a partially reflective mirror. A pair of lenses focuses the output image onto the input surface of the television camera. Often a beam splitting mirror is interposed between the two lenses. The purpose of this mirror is to reflect part of the light produced by the image intensifier onto a 105 mm PHOTOSPOT camera or cine camera.

GENERAL SCHEME OF FLUOROSCOPY VIDICON FILM PM REFERENCE kV CONTROLLER X Ray TUBE GENERAL SCHEME OF FLUOROSCOPY CINE - USED FOR CARDIAC CATH

Cine Film Systems Movie camera intercepts image 16 mm and 35 mm formats Record series of static exposures at high speed 30 – 60 frames per second Offer increased resolution At the cost of increased patient dose

Cinefluorgraphy aka CINE 35 or 16 mm roll film (movie film) 35 mm ↑ patient dose / 16 mm – higher quality images produced 30 f/sec in US – (60 frames / sec) THIS MODALITY = HIGHEST PATIENT DOSE (10X greater than fluoro) (VS SINGLE EX DOSE IS ↓)

Cine Cinefluorography is used most often in cardiology and neuroradiology. The procedure uses a movie camera to record the image from the image intensifier. These units cause the greatest patient doses of all diagnostic radiographic procedures, although they provide very high image quality. The high patient dose results from the length of the procedure and relatively high inherent dose rate. For this reason special care must be taken to ensure that patients are exposed at minimum acceptable levels. Patient exposure can be minimized in a number of ways. The most obvious means of limiting exposure is to limit the time the beam is on. CINE - 2mR per frame (60f/sec) 400 mr per “look”

More on Cine Synchronization Framing frequency F-number of the optical system Framing and patient dose

Synchronization Camera shutters and x-ray pulsed fluoro happen at the same time Only exposes pt when shutter is open to record image Patient radiation dose ↑ as #/f/sec ↑ (filming a TV show – pattern seen)

F-number of the optical system Speed of any given camera system The amount of light made available to the lens

Framing and patient dose syll = Pg 31 The use of the available film area to control the image as seen from the output phosphor. Underframing Exact Framing, (58 % lost film surface) Overframing,(part of image is lost) Total overframing

OVERFRAMING vs Exact Framing Also related to Radiation Safety………………

Framing frequency Number of frames per second Cine – division of 60 (7.5, 15,30,90,120) Organ if interest determines f/s rate Patient exposu

More on Safety later….

RECORDING DEVICES RESOLUTION P 542 (3rd ed) OPTICAL MIRROR – BEST BUT NOT PERMANENT RECORDING MEDIUM SPOT FILM CASSETTES 6LP/MM PHOTO SPOT 105 / 70 CINE 35 MM / 16 MM DIGITAL (?) (VS FILM) VIDEO – VIEWING REALTIME VIDEO TAPE - PLAYBACK

Line pair gauges

Line pair gauges GOOD RESOLUTION POOR RESOLUTION

Video disc This technique is referred to as electronic radiography. Fluoroscopic radiation continues only long enough to build up a useful image on the display monitor. The image is stored as a single television frame on the video disc recorder. There is about a 95% reduction in patient dose.

Video tape Utilizes VHS or high-resolution tapes. Patient’s exposure to radiation is not increased. Used for barium swallows.

Image Quality - Review Terms that are necessary to know: Vignetting is the loss of brightness at the periphery of the II due to the concave surface Pincushion effect is the drop off at the edges of the II due to the curved surface Quantum mottle is the grainy appearance on the image due to statistical fluctuations The center of the II will always have the best resolution. Lag is the blurry image from moving the II too fast

OVERFRAMING vs Exact Framing

Monitoring The output phosphor of the II is connected directly to a TV camera tube when the viewing is done through a television monitor. The most commonly used camera tube - vidicon Inside the glass envelope that surrounds the TV camera tube is a cathode, an electron gun, grids and a target. Past the target is a signal plate that sends the signal from the camera tube to the external video device 78

VIDEO/CAMERA TUBE PLUMICON, VIDICON, ORTHOCON VIDICON MOST COMMOM ORTHOCON – VERY $$$$ PLUMICON – BETTER RESOLUTION TRANSFERS IMAGE FROM OUTPUT PHOSPHOR TO TV MONITOR CONNECTED BY FIBER OPTICS

VIDEO/CAMERA TUBE PLUMICON, VIDICON, ORTHOCON, CCD’s TRANSFERS IMAGE FROM OUTPUT PHOSPHOR TO TV MONITOR CONNECTED BY FIBER OPTICS or Optical Lens VIDICON- MOST COMMOM PLUMICON – BETTER RESOLUTION CCD – Charged Coupling Devices ORTHOCON – VERY $$$$

VIDEO/CAMERA TUBE VIDICON MOST COMMOM – good resolution with moderate lag – ok for organs Uses ANTIMONY TRISULFATE PLUMICON (a modification of Vidicon) – BETTER RESOLUTION / (↓ dose) Better for moving part like the heart –faster response time High performance, lag may improve, but ↑quantum mottle Uses LEAD OZIDE ORTHOCON – VERY $$$$ - Larger (Not used) BEST RESOLUTION WITH NO LAG Functions as both II and pick up tube CCD – smaller & longer life, very little image lag

Type of TV camera VIDICON TV camera improvement of contrast improvement of signal to noise ratio high image lag PLUMBICON TV camera (suitable for cardiology) lower image lag (follow up of organ motions) higher quantum noise level CCD TV camera (digital fluoroscopy) digital fluoroscopy spot films are limited in resolution, since they depend on the TV camera (no better than about 2 lp/mm) for a 1000 line TV system

TV camera and video signal (II) Older fluoroscopy equipment will have a television system using a camera tube. The camera tube has a glass envelope containing a thin conductive layer coated onto the inside surface of the glass envelope. In a PLUMBICON tube, this material is made out of lead oxide, whereas antimony trisulphide is used in a VIDICON tube.

Vidicon (tube) TV Camera

camera tube have a diameter of approximately 1 inch and a length of 6 inches.

Parts of the camera tube Glass envelope Electron gun (Cathode) Control grid Electrostatic grids Target

Camera Tube steps Light is received by the camera tube. The light from the II is received at the face plate of the target assembly. Electrons are formed into an electron beam (by the control grid) at the electron gun. Electrons are burned off by thermionic emission then focused and accelerated to the target. (made of antimony trisulfide)

Target of the Camera Tube

The electrons scan the signal plate similar to reading a page. Starting in the upper left across to the right, then back to the left to right. This is called an active trace. The movement of the electron beam produces a RASTER pattern. The same pattern occurs in the TV monitor.

The signal plate sends the electrical video signal to the control unit which amplifies the signal and synchronizes the pulses between the camera tube and the TV monitor. This synchronization

Vidicon Target Assembly

Viewing Systems Video camera charge-coupled device (CCD) Video monitor Digital

Video Viewing System Closed circuit television Video cameras Video camera coupled to output screen and monitor Video cameras Vidicon or Plumbicon tube CCD

Synchronization (Sync Signals)

TV camera and video signal (V) On most fluoroscopy units, the resolution of the system is governed by the number of lines of the television system. Thus, it is possible to improve the high contrast resolution by increasing the number of television lines. Some systems have 1,000 lines and prototype systems with 2,000 lines are being developed.

TV Monitor

TV MONITOR CRT – Cathode Ray Tube Much larger than camera tube – but similar function The electrons are synchronized by the control unit – so they are of the same intensity and location as the electrons generated by the pick up (camera) tube.

TV Monitor The TV monitor contains the picture tube called cathode ray tube (CRT). It works like the camera tube. With an electron gun and control grids the electron beam is fired toward the anode. The TV screen contains small fluorescent crystals

Video Field Interlacing

Different types of scanning 11 1 INTERLACED SCANNING 13 12 3 2 15 14 5 625 lines in 40 ms i.e. : 25 frames/s 4 17 16 7 6 19 18 9 8 21 20 10 1 2 3 4 5 6 7 PROGRESSIVE SCANNING 8 9 10 11 12 13 14 15 16 17 18

Line pair gauges GOOD RESOLUTION POOR RESOLUTION 6 LP/MM AT SPOT CASSETTE 2 LP/MM AT TV

Two fields = a frame (525 lines) It take 1/30 of a second. To prevent flicker, two fields are interlaced to form on television frame. There are 60 fields and 30 frames per second. The eye cannot detect flickering above 20 frames/sec.

RASTER Pattern The electron beam moves in the same raster pattern as in the camera tube. The signal consists of many individual pulses corresponding to the individual location on the camera tube target. The varying voltage pulses are later reassembled into a visible in by the TV monitor.

TV RESOLUTION-Vertical Conventional TV: 525 TV lines to represent entire image. Example: 9” intensifier (9” FOV) 9” = 229 mm 525 TV lines/229 mm = 2.3 lines/mm Need 2 TV lines per test pattern line-pair (2.3 lines/mm) /2 lines/line-pair = 1.15 lp/mm Actual resolution less because test pattern bars don’t line up with TV lines. Effective resolution obtained by applying a Kell Factor of 0.7. Example: 1.15 x 0.7 Kell Factor = 0.8 lp/mm

Kell Factor The ability to resolve objects spaced apart in a vertical direction. More dots = more scan lines = more/better resolution Kell factor for 525 line system is 0.7

KELL FACTOR VERTICAL RESOLUTION RATIO OF VERTICAL RESOLUITON ABILITY TO RESOLVE OBJECTS SPACED APART IN A VERTICAL DIRECTION MORE DOTS(GLOBULES) = MORE SCAN LINES = MORE/BETTER RESOLUTION RATIO OF VERTICAL RESOLUITON # OF SCAN LINES KELL FACTOR FOR 525 LINE SYSTEM IS 0.7

TV RESOLUTION-Horizontal Along a TV line, resolution is limited by how fast the camera electronic signal and monitor’s electron beam intensity can change from minimum to maximum. This is bandwidth. For similar horiz and vertical resolution, need 525 changes (262 full cycles) per line. Example (at 30 frames/second): 262 cycles/line x 525 lines/frame x 30 frames/second = 4.2 million cycles/second or 4.2 Megahertz (MHz)

Bandpass/Horizantal Resolution Horizontal resolution is determined by the bandpass. Bandpass is expressed in frequency (Hz) and describes the number of times per second the electron beam can be modulated. The higher the bandpass, the better the resolution

TV SYSTEMS Images are displayed on the monitor as individual frames – which tricks the eye into thinking the image is in motion (motion integration) 15 f/sec – eye can still see previous image Weakest Link - 2 lp /mm resolution Real Time

Final Image The result of hundreds of thousands of tiny dots of varying degrees of brightness. These dots are arranged in a specific patterns along horizontal scan lines. Usually 525 scan lines. The electron gun within the picture tube scans from top to bottom in 1/60 of a second, (262 1/2 lines) called a field.

TABLE MOVEMENT horizonatal to upright ~ 30 sec

End of Week 1 Day 2

Digital Fluoro

DIGITAL FLUORO

DIGITAL Fluoro System

ADC – ANALOG TO DIGITAL CONVERTER TAKE THE ANALOG ELECTRIC SIGNAL CHANGES IT TO A DIGITAL SIGNAL TO MONITOR – BETTER RESOLUTION WITH DIGITAL UNITS

Digital Fluoroscopy Use CCD to generate electronic signal Signal is sent to ADC Allows for post processing and electronic storage and distribution

Video Camera Charged Coupled Devices (CCD) Operate at lower voltages than video tubes More durable than video tubes Semiconducting device Emits electrons in proportion to amount of light striking photoelectric cathode Fast discharge eliminates lag

CCD’s

Modern Digital Fluoro System under table tubes

Remote – over the table tube

Remote – over the table tube

Newer Digital Fluoroscopy Image intensifier output screen coupled to TFTs TFT photodiodes are connected to each pixel element Resolution limited in favor of radiation exposure concerns

Digital – CCD using cesium iodide Exit x-rays interact with CsI scintillation phosphor to produce light The light interact with the a-Si to produce a signal The TFT stores the signal until readout, one pixel at a time

CsI phosphor light detected by the AMA of silicon photodiodes

Digital Uses Progressive Scan 1024 x 1024 Higher spatial resolution As compared to 525 8 images/sec (compared to 30 in 525 system)

DSA & POSTPROCESSING

DSA

Mobile C-arm Fluoroscopy

Fluoro & Rad Protection INTRO RHB

Regulatory Requirements 1. Regarding the operation of fluoroscopy units 2. Regarding personnel protection 3. Regarding patient protection shielding for image intensifier cumulative timer dead-man switch

Fluoroscopic Positioning Previewing Radiographers are trained in positioning Unnecessary radiation exposure to patient is unethical Fluoroscopic equipment should not be used to preview patient’s position

Patient Protection Tabletop exposure rate Maximum 10 R/min Typically 1 – 3 R/min Some books ave is 4 R/min **

Patient Protection Minimum source-to-skin distance 12” for mobile equipment 15” for stationary systems Audible alarm at 5 mins. Same rules for collimation

Patient Protection Typical exposure rates Cinefluorography Cassettes 7.2 R/min Cassettes 30 mR/exposure 105 mm film 10 mR/exposure

Protection of Radiographer and Radiologist Single step away from the table decreases exposure exponentially Bucky slot cover Lead rubber drape Radiologist as shielding

Protection of Others Radiographer’s responsibility to inform others in the room to wear lead apron Do not initiate fluoroscopy until all persons have complied

PUBLIC EXPOSURE 10 % OF OCCUPATIONAL NON MEDICAL EXPOSURE .5 RAD OR 500 MRAD UNDER AGE 18 AND STUDENT .1 rem 1 mSv

COLLIMATION The PATIENT’S SKIN SURFACE SHOULD NOT BE CLOSER THAN ___________ CM BELOW THE COLLIMATOR? ____________ INCHES? 15 cm / 6.5 inches

Protection Lots to remember in the summer, for right now: Tube in never closer to the patient than 15” in stationary tubes and 12” with a C arm As II moves away from the patient the tube is being brought closer Bucky tray is connected to a lead shield called the Bucky slot cover. It must be 0.25 mm Pb There should be a protective apron of at least 0.25 mm Pb that hangs down from the II Every machine is required to have an audible timer that signals 5 minutes of fluoroscopy time Exposure switch must be a “dead man” type 151

Regulations about the operation Fluoroscopic tubes operate at currents that range from0.5 to 5 mA with 3 the most common AEC rate controls: equipment built after 1974 with AEC shall not expose in excess of 10 R/min; equipment after 1974 without AEC shall not expose in excess of 5 R/min

Other regulations Must have a dead man switch Must have audible 5 min. exposure timer Must have an interlock to prevent exposure without II in place Tube potential must be tested (monitored)weekly Brightness/contrast must be tested annually Beam alignment and resolution must be tested monthly Leakage cannot exceed 100mR/hr/meter

Fluoroscopy exposure rate For radiation protection purposes the fluroscopic table top exposure rate must not exceed 10 mR/min. The table top intensity should not exceed 2.2 R/min for each mA of current at 80 kVp

Patient Protection A 2 minute UGI results in an exposure of approximately 5 R!! After 5 minutes of fluoro time the exposure is 10-30 R Use of pulsed fluoro is best (means no matter how long you are on pedal there is only a short burst of radiation) ESE must not be more than 5 rads/min

Rad Protection Always keep the II as close to the patient as possible to decrease dose Highest patient exposure happens from the photoelectric effect (absorption) Boost control increases tube current and tube potential above normal limits Must have continuous audible warning Must have continuous manual activation

ESE FOR FLUORO TLD PLACED AT SKIN ENTRACE POINT 1 – 5 R/MINUTE AVE IS 4 R/MIN INTERGRAL DOSE – 100 ERGS OF TISSUE = 1 RAD EXPOSURE OR 1 GM RAD = 100 ERGS

SSD – TUBE TO SKIN DISTANCE FIXED UNITS 18” PREFERRED 15 “ MINIMUM MOBILE UNITS ( C-ARMS) 12’ MINIMUM

PATIENT PROTECTION LIMIT SIZE OF BEAM BEAM ON TIME DISTANCE OF SOURCE TO SKIN PBL FILTRATION (2.5 mm Al eq) @ 70 SHEILDING SCREEN/FILM COMBO

GONAD SHIELDING MUST BE . 5 MM OF LEAD MUST BE USED WHEN GONADS WILL LIE WITHING 5 CM OF THE COLLIMATED AREA (RHB) KUB. Lumbar Spine Pelvis male vs female shielding

♀ receive 3x more dose than ♂ for pelvic x-rays Gonad shielding & dose ♀ receive 3x more dose than ♂ for pelvic x-rays 1 mm lead will reduce exposure (primary) by about 50% ♀ by about 90 – 95 % ♂

KEEP I.I. CLOSE TO PATIENT

Over vs under the table fluoro tubes

Framing and patient dose syll = Pg 31 The use of the available film area to control the image as seen from the output phosphor. Underframing Exact Framing, (58 % lost film surface) Overframing,(part of image is lost) Total overframing

EXPOSURE RATES FLUORO MA IS 0.5 MA TO 5 MA PER MIN AVE DOSE IS 4 R / MIN IF MACHINE OUTPUT IS 2 R/MA/MIN = WHAT IS PT DOSE AT 1.5 MA FOR 5 MIN STUDY? 15R

EXPOSURE RATES FOR FLUORO CURRENT STANDARD 10 R/MIN (INTENSIFIED UNITS) HLC: BOOST MODE 20 R/MIN OLD (1974) NO ABC NON IMAGE INTES 5 R/MIN

DOSE REGULATIONS BEFORE 1974 - AT TABLETOP 5R/MIN (WITHOUT AEC) 5R/MIN (WITHOUT AEC) – BOOST MODE After 1974 with AEC 10 R/MIN 20R/MIN BOOST

RADIATION PROTECTION The Patient is the largest scattering object Lower at a 90 DEGREE ANGLE from the patient + PRIMARY BEAM AT 1 METER DISTANCE - 1/1000 OF INTENSITY PRIMARY XRAY or 0.1%

BUCKY SLOT COVER .25 MM LEAD

Bucky Slot Cover

ISOEXPOSURE CURVES

PERSONNEL PROTECTION SCATTER FROM THE PATIENT TABLE TOP, COLLIMATOR, TUBE HOUSING, BUCKY STRAY RADIATION – LEAKAGE OR SCATTER RADIATION

TOWER CURTAIN .25 MM LEAD EQ

Lead curtain & dose reduction

Pulsed Fluoro Some fluoroscopic equipment is designed for pulsed-mode operation. With the pulsed mode, it can be set to produce less than the conventional 25 or 30 images per second. This reduces the exposure rate. Collimation of the X ray beam to the smallest practical size and keeping the distance between the patient and image receptor as short as possible contribute to good exposure management.

PERSONNEL PROTECTION STANDING BEHIND A PROTECTIVE PRIMARY (1/16TH pb) BARRIER: PRIMARY RADIATION EXPOSURE – 99.87% REDUCED PORTABLE BARRIER = 99 % REDUCTION

PERSONNEL PROTECTION PROTECTIVE APRONS – 0.25 PB = 97% ↓ TO SCATTER THYROID SHEILDS (0.25 & 0.5) GLOVES (0.25 & 0.5)

PERSONNEL PROTECTION MONITORING FILM BADGE TLD POSL POCKET DOSIMETER RING BADGE

PERSONNEL PROTECTION MONITORING DOSE LIMITS WHOLE BODY EYES EXTREMITIES (BELOW ELBOW/KNEES)

Report at least every quarter Preserved for a minimum of 3 years

RHB NOTIFICATION (EXP IN 24 HOURS) (RP Syllabus – pg 68) IMMEDIATE reporting – WITHIN 24 HOURS TOTAL DOSE OF 25 rems Eye dose – 75 rem Extremity – 250 RADS OVEREXPOSURE – received w/in 24 hrs Must be ReportedWITHIN 30 DAYS TOTAL DOSE OF 5 rems Eye dose – 15 rem Extremity - 50 REMS

LICENSE RENEWAL WITHIN 30 DAYS OF EXPRIATION NOTIFICATION OF CHANGE OF ADDRESS

RADIAITON AREA – HIGH RADIAITON AREA – 100 mRem ( 0.1 rem / (1 msV) @ 30 cm from the source of radiaton RADIAITON AREA – RHB: 5 mRem ( 0.005 rem / (.05 msV) @ 30 cm from the source of radiation PUBLIC 2 mrem per week* (STAT)

A “controlled area” is defined as one that is occupied by people trained in radiologic safety that is occupied by people who wear radiation monitors whose occupancy factor is 1

RHB “RULES” RHB RP PG61 LICENTIATES OF THE HEALING ARTS (MD, DO, DC, DPM) MUST HAVE A RADIOLOGY SUPERVISOR & OPERATORS PERMIT & CERTIFICATE TO OPERATE OR SUPERVISE THE USE OF X-RAYS ON HUMANS SUPEVISORS MUST POST THEIR LICENSES

RHB “RULES” RHB RP PG62 ALL XRAYS MUST BE ORDERED BY A PHYSICIAN VERBAL OR WRITTEN PRESCRIPTION See Section C – “Technologist Restrictions”

DOSE CINE - 2mR per frame (60f/sec) 400 mr per “look”

Declared Pregnant Worker Must declare pregnancy – 2 badges provided 1 worn at collar (Mother’s exposure) 1 worn inside apron at waist level Under 5 rad – negligible risk Risk increases above 15 rad Recommend abortion (spontaneous) 25 rad (“Baby exposure” approx 1/1000 of ESE) www.ntc.gov/NRC/RG/08/08-013.html

FLUOROSCOPY End of wk 1 RT 244 2008