Presentation on theme: "RADIATION PROTECTION Presented by Rose Aehle RT (R,M) MS Program Coordinator, Montgomery College."— Presentation transcript:
1RADIATION PROTECTIONPresented by Rose Aehle RT (R,M) MS Program Coordinator, Montgomery College
2REFERENCESBushong Radiologic Science for Technologists, Eighth EditionEhrlich, Patient Care in Radiography, Sixth EditionCallaway, Mosby’s Comprehensive Review of RadiographySaia, Lange Q & A Radiography Examination, 6th EditionSherer, Radiation Protection in Medical Radiography, Fifth Edition2008 ARRT REGISTRATION HANDBOOKThe College of St. Catherine, Development Testing Program for Radiography
4WHAT THE REGISTRY WANTS YOU TO KNOW (2008 ARRT handbook)
5BIOLOGIC ASPECTS OF RADIATION Dose response curves (Sherer)Line 1No level of radiation can be considered safe.Response to exposure is directly proportionalDiagnostic imagingLine 2Threshold is assumed, response expected at lower dosesCataractogenesisRadiation Therapy
6BIOLOGIC ASPECTS OF RADIATION Dose response curves (Sherer)Line 3Non linear (sigmoid or hypothetical sigmoid) dose responseDIAGRAM BNon linear, threshold dose response used in radiation therapy
7BIOLOGIC ASPECTS OF RADIATION FRACTIONATIONA fraction of a dose of ionizing radiation given over a period of timeHow to read a nonlinear threshold dose response curveDeath/ RepairPROTRACTED DOSEA low amount of ionizing radiation given continouslyDamage/eradication of abnormal cellsRepair
8Linear quadratic nonthreshold dose response curve Risks associated with low dose levels of low LET radiationsStochastic somatic and genetic effects“Leukemia, breast cancer and heritiable damage assumed to follow this curve”Sherer
9????????????????????????????College of St. Catherine
13LET – AMOUNT OF ENERGY DEPOSITED BY RADIATION PER UNIT LENGTH OF TISSUE TRAVERSED calloway RBE- QUANTITATIVE MEASUREMENT OF BIOLOGIC EFFECTQF – NUMERIC UNIT GIVEN TO RADIATION BASED ON RBE TO DETERMINE REM
14Facts about LET SPARSELY IONIZING RADIATION GAMMA AND X-RAY LOW LET OF 3 KEV per micrometer OR LESSARE PENETRATINGINTERACT RANDOMLY ALONG ITS TRACK (STOCHASTIC)AS LET INCREASES SO DOES RBEHIGH LETLOW PENETRATIONSLOW MOVINGDirect Effect
15Effective dose (E)=Wr X Wt x absorbed dose Wr -Radiation weighting factorWt –Tissue weighting factornumber assigned to different types of ionizing radiation. Dependent of the LET of particular radiationTissue radiosensitivity of irradiated material
16FACTS ABOUT RBEDOSE OF STANDARD RADIATION NECESSARY TO PRODUCE A GENETIC EFFECTDOSE OF TEST RADATION NECESSARY TO PRODUCE THE SAME EFFECTSTANDARD RADIATION IS TYPICALLY 250 kVp (Bushong has a range of 200 – 250 kVp)Test radiation can range for x-rays to other types of ionizing radiationRBE for x-rays is oneHigher LET’s have Higher RBE = Higher QF
17WT factors -which is more radiosensitive? What is more radiosensitive?Stomach or bladder?Gonads or red bone marrow?Colon or breast?Thyroid or skin?
19FACTS ABOUT QFREM IS CALCULATED BY MULTIPLYING THE QF OF A PARTICULAR TYPE OF RADIATION X RADQF FOR X-RAYS IS 1THEREFORE ONE RAD OF EXPOSURE TO X-RAY = ONE REMQF FOR ALPA IS 20HIGH LETSLOW MOVINGLOW PENETRATIONTHEREFORE ONE RAD OF EXPOSURE TO ALPHA = 20 REMS
20LD 50LD 50/60THE AMOUNT OF RADIATIONTHAT WILL CAUSE 50% OF EXPOSED INDIVIDUALS TO DIE WITHIN 60 DAYS
22WHAT DOES THE LAW OF BERGONIE AND TRIBONDEAU SAY Re RADIOSENSITIVITY? Stem cells are_____________Mature cells are ____________Cells with _________metabolic and ___________mitotic activity are radiosensitiveCells which are differentiated are _____________RadiosensitiveRadioresistentHigh/high
24SOMATIC Short Term ARS Locally Erythema 300-1000 RADS Epilation Hemopoietic (BONE MARROW SYNDROME) RAD25 RADS CAN DEPRESS BLOOD COUNTGastointestinal ( RADS)CNS (5000 RADSLocallyErythema RADSEpilationDelay/suppress menstruation 10 RADSTemporary sterility (both sexes – 200 RADSLONG TERMTHOSE EFFECTS THAT CAN BE DIRECTLY RELATED TO HIGH DOSE OF RADIATION ARE CLASSIFIED AS NONSTOCHASTICCataractReduced fertilityFibrosisOrgan atrophySterilityLONG TERM STOCHASTICCANCEREMBRYOLOGIC EFFECTS
25CARCINOGENESISThe cancer that can be ALMOST classified as radiounique is leukemiaHas a short latency periodHas a linear nonthreshold dose response curveEpidemiologic studies indicate a higher incidences in leukemia after large exposuresRadium watch dial workers –bone caUranium miners – lung caEarly medical radiation workers – leukemiaThymus gland treatment – thyroid caChildren of Marshal Island – thyroid caAtomic bomb survivors – leukemia/breast, lung and bone
26WHAT CAN HAPPEN WHEN IONIZING RADIATION HITS THE CELL? a) Nothingb) Direct effectc) Indirect effectd) All of the above
27HIGH LET is associated with which effect? No effectDirect effectIndirect effectRadiolysis of water
28The following is true regarding indirect effect I) DNA is impacted by free radicalsII) Some free radicals may chemically combine to form hydrogen peroxideIII) DNA is directly struck by radiationThe minority of the damage to body is caused by indirect effectI onlyI and II onlyI, II and III onlyAll of the above
29TARGET THEORY THE DNA IS DIRECTLY HIT ONLY SOME CELLS HAVE MASTER MOLECULES THAT DIRECT CELL ACTIVITYONE CANNOT DETERMINE IN ANY CELL DEATH IF THE DEATH WAS RESULT OF DIRECT OR INDIRECT EFFECT
31Spontaneous abortions during first 2 weeks of pregnancy-- 25 RAD or higher 2nd week to 10th week – major organogenesis –IF radiation is high enough can cause congenital abnormalitiesPrinciple response after that may be malignant disease in childhood
32PREVENTING ACCIDENTAL IRRADITATION TO PATIENT FIRST TWO MONTHS, CRITICAL10 DAY RULEELECTIVE BOOKINGQUESTIONAIREPOSTING
33IF A PREGNANT PATIENT MUST BE X-RAYED TIGHT COLLIMATIONHIGH KVPSHIELDINGREDUCED # OF IMAGESMAKE SURE TO CHECK WITH YOUR SUPERVISOR AND BE AWARE OF THE SITE’S PROTOCOL
34GSD GENETICALLY SIGNIFICANT DOSE 20 mrem estimated dose Equivalent dose to the reproductive organs received by every human would cause the same genetic injury as the actual dose received by individual population members
35The pregnant radiographer WHICH OF THE FOLLOWING IS (ARE) TRUE?5 mSv for the period of pregnancy500 mrem for the period of pregnancy0.5 mSv per month0.05 rem per monthTwo badgesTRUE
37LET’S PICK UP THE PACE NOW! KEEP THE PATIENTS SAFE!!!
38WHAT KIND OF EXPOSURE FACTORS ARE BEST FOR PATIENTS? NAME FACTORS TO KEEP PT DOSE DOWNAS SID increases, what happens to the intensity? What do we adjust and do we increase or decrease this adjustment?Which of the following impacts PT dose?Inherent filtration?Added filtration?SID?Focal spot size?Screen speed?
39WHAT GIVES HIGHEST CONTRAST BUT INCREASES PATIENT DOSE? COMPTON?CHARACTERITIC?BREMSSTRAHLUNG?PHOTOELECTRIC?
41MINIMIZING PATIENT EXPOSUER SHIELDINGGonadal shielding females reduces gonad dose by 50%Gonadal shielding males reduces gonad dose by 95%Flat, shadow shieldsCOLLIMATIONDID YOU KNOW THAT THERE ARE A HIGHER SET OF LEAD SHUTTERS PLACED NEAR THE X-RAY TUBE WINDOW TO ABSORB OFF-FOCUS RADIATION?
42FILTRATIONINCREASED FILTRATION (HVL) INCREASES THE AVERAGE BEAM ENERGYNo filtration on a 70 kVp tube (0-70) would produce an average energy of 35 kVpHowever, if you filter out the lower energies (30-70 kVp) is 50 kVpInherentAdded_________is required for machines operating at 70 kVp
43HVLHow many HVL’s are required to reduce the intensity of the beam to less that 15% of its original valueA) 2B)3C)4D)5
45READING NOMOGRAMS What kind of info do you need? From Appleton and LangeWhat is the approximate patient ESE from an AP projection of the abd. made at 105 cm, 70 kVp, 300 mA, 0.2 sec (60 mAs)and 2.5 mm AL total filtration
46SCATTER STATSEach time the x-ray beam scatters, its intensity at 1 meter from the scattering object is one thousandth of its original intensityor it decreases 1000 times!!!!Or 1/1000 or0.1%
47FLUOROSCOPY PULSED (DF) X-RAY TUBE OPERATES IN RADIOGRAPHIC MODE WHICH MEANS USING TECHNICAL FACTORS THAT ARE USED FOR OVERHEAD EXAMSHOWEVERTHE TIME REQUIRED TO REACH THE SELECTED MA AND KV (INTERROGATION TIME) AND THE TIME FOR THE X-RAY TUBE TO BE SWITCHED OFF (EXTINCTION TIME) IS LESS THAN 1 MSTHEREFORE IN DR FLUORO A 5 MINUTE STUDY WILL RESULT IN A PATIENT DOSE OF 10 RAD VS 20 RAD FOR A CONVENTIONAL FLUOROSCOPY STUDY
48Conventional fluoroscopy mA less than 5Use of magnification mode increases patient exposure
49All types of fluoro Intermittent fluoro Field size Focus to table distance (15” stationary, 12” mobile
52THE ENVIRONMENT CONTROLLED AREA OCCUPANCY FACTOR UNCONTROLLED AREA USE FACTORWORKLOADBadged personnelWho,what is whereEveryone else!% of time primary beam is directed at a particular wall# of x-ray exams per week
53Primary barrier7 feet, 1/16 inch of leadSecondary barrierExtend to ceiling1/32 inch of lead
54Which of these regulations are accurate? DL for eye is 50 mSv?Cumulative whole body is 10mSv x age?Leakage radiation – 100 mR/hr at 2 meters?Lead aprons at mm pB equivalent?ESE in 10R/min in fluoro?Exposure cord on portable must be 1 meter long?Pregnant radiographer DL for fetus is 500 mrem for period of pregnancy?The public exposure DL is 100 mrem per year?Bucky slot cover and protective curtain, minimum of 0.5 pB equivalent?
56CARDINAL RULES OF PROTECTION PERSONNEL MONITORS ALARACARDINAL RULES OF PROTECTIONPERSONNEL MONITORSTLD’S VS OSL VS. FILM BADGES VS DOSIMETERSLithium fluoride vs aluminum oxide vs x-ray film vs.gasINVERSE SQUARE LAW WITH EXPOSURE RATE
57If a radiographer receives 25 mR standing 3 feet from the source for one hour how much would he receive if he stands 2 feet from the source at 20 minutes?25mR 2 feet squaredX 3 feet squared25 mR feetx feet4 x = 225X = 56 mR per hour20 minutes/60 minutes = .3356 mR x .33 = mR at two feet for 20 minutes
58SEE YA!!! GOOD LUCK TO ALL THE GRADUATES OF 2012!!!!!