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RHB Rad Prot & Fluoro Syllabus

RHB Rad Prot & Fluoro Syllabus

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RHB Rad Prot & Fluoro Syllabus

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  1. RHB Rad Prot& Fluoro Syllabus RT 244 FALL 2007

  2. measurement 100 R = 1 C/kg 1Rad = 1/100 Gray 1 Rem = .01 Sievert (Rad + QF = REM) 1 REM = 10 mSv 1 Rem = 1000mRem

  3. The average person in the United States receives about 360 mrem every year whole body equivalent dose. This is mostly from natural sources of radiation, such as radon

  4. PUBLIC EXPOSURE • 10 % OF OCCUPATIONAL • NON MEDICAL EXPOSURE • .5 RAD OR 500 MRAD • UNDER AGE 18 AND STUDENT • .1 rem 1 mSv • Pg 98 RTA BOOK

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

  6. IMAGE INTENSIFIER

  7. IMAGE INTENSIFIER • FUNCTION: • CHANGE XRAY PHOTONS TO • LIGHT PHOTONS (INPUT PHOSPHOR) • TO ELECTONS (PHOTOCATHODE) • ACCERATES ELECTRONS ACROSS TUBE AT 25,000 VOLT POTIENTAL • CHANGED BACK TO LIGHT AT OUTPUT PHOSPHOR

  8. The ratio of the number of light photons striking the output screen to the ratio of the number of x-ray photons striking the input screen is called fluxgain

  9. IMAGE INTENSIFIER • INPUT PHOSPHOR – CESIUM IODIDE • PHOTOCATHODE (LIGHT TO E’S) • ELECTOSTATIC LENSES – • FOCUSES AND ACCELERATES THE E • INTENSIFIES LIGHT = BRIGHTNESS GAIN (BG) • BG = MG X FG • ENCASED IN A LEAD HOUSING • = 2MM PB (PRIMARY BARRIER)

  10. MAG USED TO ENLARGE SMALL STRUCTURE OR TO PENETRATE THROUGH LARGER PARTS FORMULA: PATIENT DOSE IS INCREASED IN THE MAG MODE – DEPENDANT ON SIZE OF INPUT PHOSPHOR MAG MODE VS PT DOSE

  11. MAG MODE FORMULA IP OLD SIZE IP NEW SIZE = MAG

  12. MORE FORMULASBG = MG X FG • BG = MINIFICATION GAIN X FLUX GAIN • MINIFICATION GAIN – same # e at input condensed to output phosphor – ratio of surface area on input screen over surface area of output screen IP SIZE 2 OP SIZE 2

  13. BG = MG X FG • FLUX GAIN – increase of light brightness due to the conversion efficiency of the output screen • 1 electron = 50 light photons is 50FG • Can decrease as II ages • Output phosphor almost always 1 inch • Zinc cadnium phosphot • Flux gain is almost always 50

  14. BG = MG X FG • Brightness gain BG • = MINIFICATION GAIN X FLUX GAIN • (old Patterson B-2 fluoro –obsolete) • Brightness gain is a measure of the conversion factor that is the ratio of the intensity of the output phosphor to the input phosphor • conversion factor = intensity of OP Ø • mR/sec

  15. VERTICAL RESOLUTION 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 KELL FACTOR

  16. 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

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

  18. 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

  19. 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

  20. 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 % ♂

  21. KEEP I.I. CLOSE TO PATIENT

  22. Over vs under the table fluoro tubes

  23. Framing and patient dosesyll = 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

  24. 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

  25. 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

  26. 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

  27. RADIATION PROTECTIONThe 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%

  28. BUCKY SLOT COVER .25 MM LEAD

  29. ISOEXPOSURE CURVES

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

  31. TOWER CURTAIN .25 MM LEAD EQ

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

  33. PERSONNEL PROTECTION • PROTECTIVE APRONS – • 0.25 PB = 97% ↓ TO SCATTER • 0.5 PB = 99.9% ↓ TO SCATTER • THYROID SHEILDS (0.25 & 0.5) • GLOVES (0.25 & 0.5)

  34. FILM BADGE TLD POSL POCKET DOSIMETER RING BADGE PERSONNEL PROTECTIONMONITORING

  35. PERSONNEL PROTECTIONMONITORING • DOSE LIMITS • WHOLE BODY • EYES • EXTREMITIES (BELOW ELBOW/KNEES)

  36. Occupational DoseANNUAL LIMITS • WHOLE BODY = 5 REMS / 5000mRem • LENS OF THE EYE = 15 REMS • EXTREMITIES = 50 REMS

  37. TLD

  38. Report at least every quarterPreserved for a minimum of 3 years

  39. RHB NOTIFICATION (EXP IN 24 HOURS) • IMMEDIATE – WITHIN 24 HOURS • TOTAL DOSE OF 25 rems • Eye dose – 75 rem • Extremity – 250 RADS • OVEREXPOSURE – WITHIN 30 DAYS • TOTAL DOSE OF 5 rems • Eye dose – 15 rem • Extremity - 50 REMS

  40. LICENSE RENEWAL • WITHIN 30 DAYS OF EXPRIATION • NOTIFICATION OF CHANGE OF ADDRESS

  41. 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)

  42. 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