RADIATION SAFETY AND PROTECTION

Transcription

1 RADIATION SAFETY AND PROTECTION JASON S. TAVEL, MS, DABR Astarita Associates, Inc. Disclosures to Report: Consultant Medical Physics Consultant in NY area for hospitals and private practices.

2 RADIOLOGICAL UNITS ROENTGEN KERMA RAD GRAY REM SIEVERT

3 ROENTGEN (R) The amount of X or gamma ( ) radiation that produce one electrostatic unit per cubic centimeter of air at STP (0 0 C & 760mmHg) 1 Roentgen = 2.58x10-4 C/kg

4 ROENTGEN OR Exposure measured in AIR

5 KERMA INTERNATIONAL SYSTEM OF UNITS SI Kinetic Energy Released in the Medium Units are J/kg Stands to replace the Roentgen

6 TISSUE WEIGHTING FACTORS f-factor Tissue weighting factor for converting exposure in air to absorbed dose.

7 TISSUE WEIGHTING FACTORS f-factor 100kev photons fat muscle bone

8 RAD Roentgen X f factor = RAD RAD radiation absorbed dose Energy absorbed in material 1 RAD = 100erg/gr

9 GRAY SI UNIT FOR RADIATION ABSORBED DOSE 100 RAD = 1 GRAY (Divide Rad by 100 to get Gray)

10 LET Linear Energy Transfer The energy absorbed by a medium per unit of length (kev/um)

11 RELATIVE BIOLOGICAL EFFECTIVENESS (RBE) DIFFERENT TYPES OF RADIATION HAVE DIFFERENT BIOLOGICAL BURDENS

12 Quality factor (QF) Determined from the LET value of each type of radiation QF x & rays 1.0 beta particles 1.0 neutrons & protons 10 alpha particles 20

13 RADIATION EQUIVALENT MAN REM = RAD X QF REM 1RAD gamma rays = 1REM 1Rad Alpha Particles = 20REM

14 SIEVERT (SV) SI UNIT FOR REM 100REM = 1 SV (divide REM by 100 to get Sv)

15 RADIOLOGICAL UNITS SUMMARY Roentgen (R) exposure in air RAD radiation absorbed dose (R * f) REM radiation equivalent man (RAD * QF) SI units Gray (Gy) Sievert(SV) = 100RAD (absorbed dose) = 100REM (equivalent dose)

16 RADIOLOGICAL UNITS In the diagnostic Nuclear Medicine environment 1R ~= 1Rad ~= 1Rem

17 Effective Dose Equivalent Introduced by the ICRP (International Commission on Radiation Protection) to represent the whole body dose that would result in the same overall risk as a non-uniform dose distribution delivered to the subject. Units are Rem or Sievert. Conversion: 1 Rem = 10 msv, 1 mrem = 0.01 msv.

18 EDE - A Measure of Risk EDE represents the theoretical risk of developing a harmful effect as a result of exposure to radiation. Allows for a comparison of risk between internal exposures for different types/sources of radiation (i.e. exposures from CT, nuclear & fluoroscopy.

19 MIRD Medical Internal Radiation Dose Established by committee of the Society of Nuclear Medicine. Uses Standardized Models of Man and Monte Carlo simulation of radiation transport to estimate dose to internal organs. Provides support for FDA package insert information. Calculates dose to organ from adjacent organs

20 Assumptions and Limitations of the MIRD Method Radioactivity is uniformly distributed in the organ. Organ size assumed for the standard man. Cellular level micro-dosimetry is not modeled.

21 Effective Dose Comparison Tc99m MIBI (40mCi) Tl201 (3mCi) Cardiac Cath CT Angio - 2.2Rem (22mSv) Rem (18mSv) Rem (28mSv) Rem (12mSv)

22 1. The unit for radiation exposure in air is the a. Rad b. Rem c. Roentgen QUIZ 1-units 4. The SI unit for the RAD is a. Sievert b. Gray c. LET 2. With the use of a tissue weighting factor, the Roentgen is converted to a for assessing absorbed dose. a. Rad b. Rem c. Roentgen 3. The REM measures a. Exposure in air b. Air kerma c. Relative Biological Effectiveness 5. The SI unit for REM is a. Sievert b. Gray c. LET 6. What is the conversion from Rad / Rem to Sievert / Gray? a. Multiply Rad / Rem by 100 b. Divide Rad / Rem by 100 c. Multiply by 0.96 for muscle

23 1. The unit for radiation exposure in air is the a. Rad b. Rem c. Roentgen QUIZ 1-units 4. The SI unit for the RAD is a. Sievert b. Gray c. LET 2. With the use of a tissue weighting factor, the Roentgen is converted to a for assessing absorbed dose. a. Rad b. Rem c. Roentgen 3. The REM measures a. Exposure in air b. Air kerma c. Relative Biological Effectiveness 5. The SI unit for REM is a. Sievert b. Gray c. LET 6. What is the conversion from Rad / Rem to Sievert / Gray? a. Multiply Rad / Rem by 100 b. Divide Rad / Rem by 100 c. Multiply by 0.96 for muscle

24 RADIATION EXPOSURE NATURAL BACKGROUND MAN MADE RADIATION DOSE LIMITS NON OCCUPATIONAL OCCUPATIONAL

25 BACKGROUND RADIATION ~360mRem

26 NATURAL BACKGROUND Cosmic Radiation The sun and stars send a constant stream of cosmic radiation to Earth, much like a steady drizzle of rain. Differences in elevation, atmospheric conditions, and the Earth's magnetic field can change the amount (or dose) of cosmic radiation that we receive.

27 NATURAL BACKGROUND Terrestrial Radiation Radioactive materials (including uranium, thorium, and radium) exist naturally in soil and rock. Water contains small amounts of dissolved uranium and thorium. Some of these materials are ingested with food and water, while others (such as radon) are inhaled. The dose from terrestrial sources varies in different parts of the world, but locations with higher soil concentrations of uranium and thorium generally have higher doses.

28 NATURAL BACKGROUND Internal Radiation All people have internal radiation, mainly from radioactive potassium-40 and carbon- 14 inside their bodies from birth and, therefore, are sources of exposure to others. The variation in dose from one person to another is not as great as that associated with cosmic and terrestrial sources.

29 MAN MADE RADIATION Medical Sources (by far, the most significant man-made source) Diagnostic x-ray Nuclear medicine procedures (iodine-131, cesium-137, and others)

30 MAN MADE RADIATION Consumer Products Building and road construction materials X-ray security systems Smoke detectors (americium) Luminous watches (tritium) Lantern mantles (thorium) Tobacco (polonium-210) Some ceramics

31 COMMON DOSES Flight from Los Angeles to London 5 mrem Annual natural background 300 mrem Barium enema 870 mrem Heart catheterization (skin dose) 26,000 mrem Mild acute radiation syndrome 200,000 mrem Radiation therapy (localized & fractionated) 6,000,000 mrem

32 DOSE LIMITS NON OCCUPATIONAL DOSE LIMITS FROM OCCUPATIONAL SOURCES 100mRem per year 1mSv per year

33 NON OCCUPATIONAL DOSE LIMITS INFREQUENT EXPOSURE FROM OTHERS MEDICAL PROCEDURES (i.e. family member ) 500mRem 5 msv

34 NON OCCUPATIONAL DOSE LIMITS We calculate the exposure to the general public and ensure it will be less than 500mRem. We then give instructions to try and reduce the exposure to <100mRem

35 OCCUPATIONAL DOSE LIMITS Whole Body 5 REM (50mSv or 0.05Sv) Skin/extremity 50 REM(0.5Sv) (shallow dose 0.007cm deep averaged over 10cm 2 ) Lens of eye 15 REM(0.15Sv)

36 PREGNANT WORKERS Fetus is a non-occupational worker Limit is 500mRem (5mSv)over gestation period Monitor for <50mRem/month

37 PREGNANT WORKERS Declare pregnancy is option Modify work if possible Monitor to ensure limits are not exceeded

38 QUIZ 2 background radiation & dose limits 1. The average background radiation exposure is. a. 100mRem b. 500mRem c. 1000mRem 5. The whole body occupational dose limit is.. a. 100mRem/yr b. 500mRem/yr c. 5000mRem/yr 2. The largest source of background radiation is from a. Radon b. Cosmic ray c. Terrestrial radiation 3. A round trip flight from NY to LA yields approximately mrem. a. 5mRem b. 50mRem c. 75mRem 4. The non-occupational dose limit is. a. 10mRem/yr b. 100mRem/yr c. 5000mRem/yr 6. The occupational dose limit to an extremity is a. 5000mRem/yr b. 15,000mRem/yr c. 50,000mRem/yr 7. The pregnant worker dose limit is.. a. 100mRem/gestation b. 500mRem/gestation c. 5000mRem/gestation 8. When monitoring a pregnant worker, the monthly exposure should be less than. a. 10mRem/month b. 25mRem/month c. 50mRem/month

39 QUIZ 2 background radiation & dose limits 1. The average background radiation exposure is. a mRem b mRem c mRem 5. The whole body occupational dose limit is.. a. 100mRem/yr b. 500mRem/yr c. 5000mRem/yr 2. The largest source of background radiation is from a. Radon b. Cosmic ray c. Terrestrial radiation 3. A round trip flight from NY to LA yields approximately mrem. a. 5mRem b. 50mRem c. 75mRem 4. The non-occupational dose limit is. a. 10mRem/yr b. 100mRem/yr c. 5000mRem/yr 6. The occupational dose limit to an extremity is a. 5000mRem/yr b. 15,000mRem/yr c. 50,000mRem/yr 7. The pregnant worker dose limit is.. a. 100mRem/gestation b. 500mRem/gestation c. 5000mRem/gestation 8. When monitoring a pregnant worker, the monthly exposure should be less than. a. 10mRem/month b. 25mRem/month c. 50mRem/month

40 PERSONNEL MONITORING Must monitor any occupational worker likely to exceed 500mRem/yr (health code) and/or Those who handle radioactive material (license requirement)

41 PERSONNEL MONITORING TYPES OF DEVICES Film Badges Thermo Luminescent Devices (TLD) Optically Stimulated Luminescence (OSL) Pocket Ion Chamber

42 FILM BADGES Plastic holder with a strip of film that is exposed to radiation. Degree of darkening (density) is proportional to exposure. Lead, copper, aluminum & plastic filters used to assess energy range and penetration power. Affected by heat, moisture, sunlight & time (fades)

43 TLD Uses special crystals (Lithium Fluoride LiF) Absorb energy and electrons are trapped in a higher energy stated. (valence band forbidden band) Use heat to release electrons back to ground state. As they return to ground state, the energy is released in form of light which is proportional to radiation absorbed. Small crystals ideal for ring badge use Can be re-used after reading

44 OSL - Luxel Luxel badges contains a sheet of radiation-sensitive aluminum oxide sealed in a light and moisture proof packet. When atoms in the aluminum oxide sheet are exposed to radiation, electrons are trapped in an excited state until irradiated with a specific wavelength of laser light. The released energy of excitation, which is given off as visible light, is measured to determine radiation dose. Sensitive.Re-usable.uses filters like film badge Good whole body monitor

45 POCKET ION CHAMBER Pen-like chamber that collects radiation by measuring ionizations in the gas chamber Read after each use Leaky Good for monitoring visitors No permanent record

46 FREQUENCY OF MONITORING License Requirements Dictate Recommend Monthly in Nuclear Medicine

47 ALARA As Low As Reasonably Achievable 10% OF OCCUPATIONAL DOSE LIMITS 10% OF LIMIT (5Rem/yr) = 500mRem/yr

48 ALARA time distance shielding

49 ALARA TIME reduce time around radiation source Exposure of 10mR/hr is only 2.5mR for 15min

50 ALARA DISTANCE maintain a distance from a know radiation source INVERSE SQUARE LAW

51 INVERSE SQUARE LAW

52 INVERSE SQUARE LAW I = I/d 2 100mR/hr at 1 meter = 25mR/hr at 2 meters = 11mR/hr at 3 meter

53 SHIELDING Alpha Particles Stopped by a sheet of paper Beta Particles Stopped by a layer of clothing or less than an inch of a substance (e.g. plastic) Gamma Rays Stopped by inches to feet of concrete or less than an inch of lead

54 SHIELDING ALARA

55 Half Value Layer The amount of material needed to reduce the intensity by 1/2 Tc99m F18 Cs137 HVL in Pb 0.03cm 0.4cm 0.6cm

56 Half Value Layer Exp = Exp e -.693t/T1/2 How much would 1mm of lead reduce the exposure to from 10mR/hr of Tc99m?

57 Half Value Layer Exp = Exp e -.693t/T1/2 Exp = 10mR/hr e -.693(0.1cm/.03cm) = 10mR/hr * = 1mR/hr (TVL)

58 QUARTERLY ALARA INVESTIGATIONAL LEVELS I II Whole body 125mRem/q 375mRem/q Extremity 1875mRem/q 5625mRem/q Skin 750mRem/q 2250mRem/q I-notify II-investigate and take action

59 QUIZ 3- Monitoring & ALARA 1. Personnel monitoring is required when a. The annual exposure is likely to exceed 500mRem b. Personnel are handling radioactive material. c. Both a & b 2. In Nuclear Medicine / Cardiology departments, personnel monitors should be evaluated... a. Weekly b. Monthly c. Quarterly 3. Common monitors in Nuclear Medicine / Cardiology labs are.. a. Film Badges b. TLD ring badges c. OSL whole body badges d. All of the above 4. The principle rules of ALARA are,, mR/hr measured at 1 meter would be at 2 meters. a. 10mR/hr b. 25mR/hr c. 50mR/hr 6. Assuming the HVL for Tc99m is 0.3mm in lead. How much lead would be needed to reduce the exposure from 10mR to 5mR. a. 0.1mm b. 0.3mm c. 0.6mm 7. The ALARA I level for the whole body is. a. 25mRem/quarter b. 125mRem/quarter c. 375mRem/quarter

60 QUIZ 3- Monitoring & ALARA 1. Personnel monitoring is required when a. The annual exposure is likely to exceed 500mRem b. Personnel are handling radioactive material. c. Both a & b 2. In Nuclear Medicine / Cardiology departments, personnel monitors should be evaluated... a. Weekly b. Monthly c. Quarterly 3. Common monitors in Nuclear Medicine / Cardiology labs are.. a. Film Badges b. TLD ring badges c. OSL whole body badges d. All of the above 4. The principle rules of ALARA are Time, Distance, and Shielding mR/hr measured at 1 meter would be at 2 meters. a. 10mR/hr b. 25mR/hr c. 50mR/hr 6. Assuming the HVL for Tc99m is 0.3mm in lead. How much lead would be needed to reduce the exposure from 10mR to 5mR. a. 0.1mm b. 0.3mm c. 0.6mm 7. The ALARA I level for the whole body is. a. 25mRem/quarter b. 125mRem/quarter c. 375mRem/quarter

61 RADIATION SURVEYS Instrumentation GM meter pancake attachment Scaler & Well

62 SURVEY INSTRUMENT QC GM meter Annual calibration on all scales with NIST source (Cs137) Constancy check with long lived spot source (Cs137)

63 SURVEY INSTRUMENT QC Scaler & Well Annual efficiency check Daily constancy check

64 SURVEYS FOR CONTAMINATION Using GM meter Survey <1cm from surface Limit 1mR/hr restricted areas 0.2mR/hr unrestricted areas (NYS)

65 WIPE TESTS FOR REMOVABLE CONTAMINATION Using well counter and scaler Wipe 10x10cm area Limit 5000dpm/100cm 2 restricted areas 200dpm/100cm 2 unrestricted areas

66 SURVEY LIMITS May vary by state!!!!!!!!

67 SPILL PROCEDURES Major spill >10mCi Minor spill <10mCi

68 Minor Spill <10mCi NOTIFY all persons in area a spill has occurred PREVENT cover with absorbent paper CLEAN using gloves, tongs,..(remote handling) clean outside to inside place in plastic bag SURVEY check spill and personnel REPORT to RSO

69 Major Spill >10mCi CLEAR AREA all persons to vacate room PREVENT cover with absorbent paper SHIELD only if can be done without further contamination or increasing exposure to staff CLOSE ROOM lock and prevent entry (signs) NOTIFY RSO PERSONNEL survey and decontaminate mild soap.luke warm water surgical sponge CLEAN under RSO supervision

70 WASTE MANAGEMENT Decay in storage Transfer to Authorized Recipient Sewage Atmosphere

71 DECAY IN STORAGE Waste with half life of <120 days (state varies) Store in shielded container Label with date and longest lived isotope Hold for 10 half lives (60 hours for Tc99m) Survey to ensure indistinguishable from background RECORD IN LOG!!!

72 TRANFER TO AUTHORIZED RECIPIENT Spent unit doses may be returned to vendor Un-used doses may be returned to vendor

73 UNUSED / SPENT DOSE RETURN LIMITATIONS Package surface survey <0.5mR/hr Wipe <6600dpm/300cm 2 Quantity Limitations (Total amt. In package) Tc99m-11mCi Tl201-11mCi Package Label Limited Quantity, Excepted Package UN2910

74 TRANFER TO AUTHORIZED RECIPIENT Radioactive waste may also be picked up by an authorized vendor Expensive Must follow DOT regulations

75 WASTE MANAGEMENT Sewage Material may be disposed into the sewer system Concentration limits apply Calculations must be performed

76 WASTE MANAGEMENT Atmosphere Gases and Aerosols may be released into the atmosphere Limits apply (DEC) Calculations performed

77 ORDERING DOSES Individuals pre authorized by RSO/USER Standard Dose Ranges for Diagnostic Imaging Outside range should have written directive Rx for Therapeutic

78 RECEIVING During normal business hours directly to hot lab Off Hours escorted by security to hot lab given key to facility and hot lab

79 DOT Labels

80 Excepted Package, Limited Quantity Max. Amounts for commonly used liquid material Co57-27mCi Tc99m-11mCi Tl201-11mCi Ga67-8.1mCi I mCi I mCi F18-1.6mCi In mCi P32-1.4mCi Mo99-2.0mCi Ba mCi Cs mCi Sr89-1.6mCi Xe mCi gas Note : If a package has more than one isotope, the max quantity defaults to the lower limit. Surface Exposure <0.5mR/hr Surface Wipe Test <6600dpm/300cm 2

81 Type I White Surface exposure <0.5mR/hr 1meter exposure not detectable

82 Type II Yellow Surface Exposure <50mR/hr 1meter exposure <1mR/hr

83 Type III Yellow Surface Exposure <200mR/hr 1meter exposure <10mR/hr

84 RECEIVING Package must be monitored within 3hrs (start of business if before hours) Wear gloves Visually inspect for problems Measure 1meter exposure (report if problem) (>10mR/hr report to DOH)

85 RECEIVING Wipe test if suspect contamination Open outer package and remove packing slip Open inner package and ensure contents agree with slip Check integrity of container wipe if needed If all OK, deface labels (turn plastic labels over) and discard if applicable Record readings in Log!!

86 MEASURING ACTIVITY Measure doses prior to administration using Dose Calibrator. Activity must be within 10% of prescribed Maintain record of patient dose!!!

87 DOSE CALIBRATOR QC Annual accuracy Semi annual / Quarterly linearity Daily constancy

88 MEASURING ACTIVITY by calculation Unit doses are measured by pharmacy Using calibrated activity and time, can calculate activity using formula

89 MEASURING ACTIVITY by calculation A = A 0 e -.693t/T1/2 t=time elapsed T1/2 = half life

90 MEASURING ACTIVITY by calculation What is activity of Tc99m at noon if calibrated for 30mCi at 10am? t=2hrs T1/2 = 6.02hrs

91 MEASURING ACTIVITY by calculation A = 30mCi * e -.693*2hrs/6.02hrs = 30mCi *e -.23 = 30mCi * = 23.8mCi

92 SAFE USE OF RADIOACTIVE MATERIAL 1. Wear lab coat / protective clothing when in radioactive material area 2. Wear gloves whenever handling radioactive material 3. Monitor hands for contamination after each procedure and before leaving radioactive material area NYS Rad Guide 10.1, Rev2

93 SAFE USE OF RADIOACTIVE MATERIAL 4. Always use syringe shields when preparing and administering doses (except when care is compromised) 5. Do not eat, drink, smoke, apply cosmetics in radioactive material areas. Do not store food or personal items in radioactive material areas. 6. Assay all patient doses prior to administration. Ensure dose is within 10% of prescription 7. Check patient ID by two methods (name and D.O.B) NYS Rad Guide 10.1, Rev2

94 SAFE USE OF RADIOACTIVE MATERIAL 8. Always wear monitoring devices when working with radioactive materials (whole body and ring if applicable). Store monitors in a non radiation area when not in use 9. Dispose waste only in designated areas in properly shielded containers 10. Never pipette by mouth. Separate radioactive pipettes from non radioactive pipettes 11. Survey generator, kit prep, and injection areas daily for contamination NYS Rad Guide 10.1, Rev2

95 SAFE USE OF RADIOACTIVE MATERIAL 12. Confine radioactive solutions in clearly labeled shielded containers. Label with compound, isotope, date, time, assay 13. Maintain flood sources, syringes, waste and other material in properly shielded containers 14. Use plastic backed absorbent pads when using radioactive aerosols to prevent contamination of surfaces 15. Use a cart or wheeled device to move radioactive sources. Always transport source in shielded containers NYS Rad Guide 10.1, Rev2

96 SAFE USE OF RADIOACTIVE MATERIAL Mo99/Tc99m Generator Assay eluate for Tc99m in dose calibrator and maintain record for 3 years Test for Mo99 concentration and maintain record for 3 years DO NOT USE if Tc99m eluate contains more than 0.15uCi Mo99 per 1mCi of Tc99m NYS Rad Guide 10.1, Rev2

97 MISADMINISTRATIONS Medical misadministration is defined as the administration of: 1. A radiopharmaceutical or radiation from a source other than the one ordered by the physician. 2. A radiopharmaceutical or radiation to the wrong person. 3. A radiopharmaceutical or radiation by route of administration or to a part of the body other than that intended by the ordering physician. 4. A therapeutic radiation dose from a brachytherapy source such that errors in computation, calibration, treatment time, source activity, source placement, or equipment malfunction result in a calculated total treatment dose differing from the final total dose ordered by more than 10 percent

98 MISADMINISTRATIONS Report to the Department of Health.. > 5 Rem to the whole body >50 Rem to any individual organ the administration of iodine-131 or iodine 125 in the form of iodide in a quantity greater than 30uCi

99 QUIZ 4- Survey, Waste, Receipt, Use 1. When checking for removable contamination with a scaler and well, the correct size area to wipe is. a. 1cmx1cm b. 10cm x 10cm c. 100cmx100cm 2. When dealing with a Tc99m spill, the threshold for major and minor spill is a. 10mCi b. 30mCi c. 50mCi 3. If holding radioactive waste for decay in storage, it must be held at least a. 1 half life b. 10 half lives c. 5 half lives 4. When returning radioactive material as excepted package, limited quantity, the surface exposure must be. a. <0.1mR/hr b. <0.5mR/hr c. <10mR/hr 5. Misadministrations must be reported to the DOH if... a. The patient is a young female b. The dose was not administered by an MD c. Results in a dose to the patient >5Rem whole body 6. Dose Calibrator constancy must be performed a. Daily b. Quarterly c. Annually 7. A dose assayed greater than should not be used. a. 5% of prescribed b. 10% of prescribed c. 15% of prescribed

100 QUIZ 4- Survey, Waste, Receipt, Use 1. When checking for removable contamination with a scaler and well, the correct size area to wipe is. a. 1cmx1cm b. 10cm x 10cm c. 100cmx100cm 2. When dealing with a Tc99m spill, the threshold for major and minor spill is a. 10mCi b. 30mCi c. 50mCi 3. If holding radioactive waste for decay in storage, it must be held at least a. 1 half life b. 10 half lives c. 5 half lives 4. When returning radioactive material as excepted package, limited quantity, the surface exposure must be. a. <0.1mR/hr b. <0.5mR/hr c. <10mR/hr 5. Misadministrations must be reported to the DOH if... a. The patient is a young female b. The dose was not administered by an MD c. Results in a dose to the pt. >5Rem whole body 6. Dose Calibrator constancy must be performed a. Daily b. Quarterly c. Annually 7. A dose assayed greater than should not be used. a. 5% of prescribed b. 10% of prescribed c. 15% of prescribed

101 THE END