Rad Protection in Fluoro & INTRO RHB regs RT 244 - 2008 Week 1,2 Wed

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 Lead apron 0.25 mm Pb/eq Highest energy scatter 90o angle to the incident beam Same level as radiographer /radiologist’s gonads

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

ISOEXPOSURE CURVES

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 (for X-ray TUBE Collimator) The PATIENT’S SKIN SURFACE SHOULD NOT BE CLOSER THAN ___________ CM BELOW THE COLLIMATOR? ____________ INCHES? 15 cm / 6.5 inches

The Patient & Scatter

Radiation Protection (recap) 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 16

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

REDUCE DISTANCE OF IMAGE INTESIFIER PATIENT EXPOSURE REDUCE DISTANCE OF IMAGE INTESIFIER INCREASE DISTANCE FROM THE TUBE

Patient entrance skin exposure (ESE) is higher when the fluoroscopic x-ray tube is too close to the tabletop.

PATIENT EXPOSURE REDUCE SIZE OF COLLIMATED BEAM WHEN POSSIBLE

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

HIGH RADIAITON AREA – 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”

WHATS WRONG?

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

Remote – over the table tube

Under table tube vs Over table tube (remote units) Need moving shield for Remote rooms

IsoExposure Curves Where is it SAFE??

Back to the Patient & Protection

RADIATION DOSE TO PATIENTS ESE - ENTRACE SKIN EXPOSURE (MEASURED BY A TLD) SKIN DOSE GONADAL DOSE BONE MARROW DOSE (MEAN GLADULAR DOSE- MAMMO) ** SEE TABLE 1-5 PG 20 & 1-8 PG 21 (STAT)

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

1 rad (of ionizing radiation) deposits 100 ergs of energy per gram 1 RAD -100 ERGS – 1 GRAM 1 rad (of ionizing radiation) deposits 100 ergs of energy per gram

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

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

Conventional “FIXED” Fluoro

Mobile – C- arm fluoro

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.

Dose rate to patients

TUBE HOUSING 100MR / HR @ 1 METER LEAKAGE RADIATION TUBE HOUSING 100MR / HR @ 1 METER

STAT 8 & 9 Protecting Patients & Personnel COMMUNICATE COLLIMATE SHIELD

IONIZATION CHAMBER- CUTIE PIE Q = t x תּ Quantity of Radiation = time x pie (diameter of cylinder)

Mini c-arm

Some References Physics of diagnostic radiology, Curry et al, Lea & Febiger, 1990 Imaging systems in medical diagnostics, Krestel ed., Siemens, 1990 The physics of diagnostic imaging, Dowsett et al, Chapman&Hall, 1998