RADS, REMS & ROENTGENS Jack L. Barr, M.S., R.T.R., F.A.S.R.T. Quiz True/False: Large amounts of radiation to insects will cause them to mutate! LARGE AMOUNTS OF RADIATION WILL CAUSE VEGETABLES TO BECOME LARGE KILLERS! 1
MANY CHEST X-RAYS TRANSFORMS INDIVIDUALS INTO MONSTERS!! EXCESSIVE RADIATION WILL TURN PEOPLE INTO VAMPIRES! HISTORY OF RADIOBIOLOGY MARKED BY THREE EVENTS 1) Discovery of x-ray in 1895 by William Conrad Roentgen. 2) Henri Bequerel s observance of x- rays being given off by a uraniumcontaining substance in 1896. 3) Discovery of radium by Pierre and Marie Curie in 1898. 2
THROUGH THE YEARS HIROSHIMA - 1945 3
THREE MILE ISLAND, NY 1979 CHERNOBYL1986 4
JAPAN NUCLEAR 2011 SOURCES OF RADIATION EXPOSURE IN THE U.S. POPULATION RADON 54% INTERNAL 11% MEDICAL X-RAY 11% TERRESTRIAL 8% COSMIC 8% NUCLEAR MEDICINE 4% CONSUMER PRODUCTS -3% OTHER 1% COMMON RADIATION EXPOSURE TO GENERAL POPULATION FLIGHT FROM LA NY -1.5MREM DENTAL X-RAY 9 MREM CHEST X-RAY 10 MREM MAMMOGRAM 70 MREM BACKGROUND RADIATION - 620MREM/YR. 5
CHEST X-RAY MOST COMMON PERFORMED EXAM AND MOST OFTEN REPEATED RADIATION UNITS Roentgen measurement of energy by Gamma or X-ray radiation in a cubic centimeter of air. RAD measuring unit for expressing absorption of all types of ionizing radiation. REM- measurement that correlates the dose of any radiation to the biological effect of that radiation. SI UNITS RAD REM ROENTGEN * Gray(Gy) 1Gy=100 rad * Sievert (SV) 1SV = 100rem * Coulomb/kilogram (C/kg) 6
DOSE RESPONSE LINEAR NON-THRESHOLD 7
DOSE LIMITS NCRP REPORT #91 &116 5 REM/YR (5000 mr) (50mSv) whole-body occupational.5 REM/yr (500 mr)(5msv) general public Cumulative whole-body effective dose limit is calculated by multiplying one s age in years by 1 rem (10mSv) ALARA PROTECTION OF PERSONNEL A radiographer who is subjected to chronic low doses of radiation may be affected by its damaging effects if protection measures are not applied Personnel monitoring THREE BASIC RULES TIME DISTANCE SHIELDING 8
MOBILE EXAMS most exposure standing by machine!! lead aprons minimum lead thickness equivalency of.5mm Hands in primary beam lead gloves of.25mm Radiographer position self at 90 degree angle from scattering object (patient)= around the corner, scatters twice, reduced by.01% FLOUROSCOPIC EXAMS LEAD APRON -.5mm Pb equivalent, covering sides and back LEAD GLOVES if hands in primary beam -.25mmPb equivalent Intermittent/pulsed fluoroscopy Use of high kvp Best way of reducing radiation exposure is distance PROTECTION OF PATIENT IMMOBILIZATION BEAM RESTRICTION SHIELDING OF PATIENT OPTIMAL TECHNIQUES USING ma and kvp Position right first time!!(aec)5-15% IN ADDITIONAL PATIENT EXPOSURE Pregnant patient 9
PROTECTION OF PATIENT Filters FLUOROSCOPY PROCEDURES the greatest patient radiation exposure in diagnostic radiology. Pulsed fluoro Cumulative timers (5 min) Federal code no greater than 10R/min!!!! PEDIATRIC DOSE REDUCTION IMMOBILIZATION BEAM RESTRICTION SHIELDING CORRECT TECHNIQUES AVOID REPEATS A WORD ABOUT DIGITAL IMAGING!! ATTENTION SHOULD BE PAID TO THE POTENTIAL INCREASE OF PATIENT DOSE DUE TO TENDENCY OF: 1) PRODUCING MORE IMAGES THAN NEEDED (ESPECIALLY FLUOROSCOPY) AND 2) PROVIDING HIGHER IMAGE QUALITY NOT NECESSARILY NEEDED FOR CLINICAL PURPOSES ( DOSE CREEP ) 10
DIGITAL TECHNOLOGY PROVIDES THE USER WITH A GOOD IMAGE SINCE ITS DYNAMIC RANGE AND DIGITAL IMAGE PROCESSING COMPENSATES FOR INCORRECT TECHNIQUES EVEN IF DOSE IS HIGHER THAN NECESSARY!! CR OVEREXPOSURES UP TO 500% AND UNDER UP TO 80% ARE RECOVERABLE. 11