1. IAEA International Atomic Energy Agency Lecture 7 – Calibration and Testing of Radiation Protection Instruments Postgraduate Educational Course in radiation protection and the Safety of Radiation sources PART V: ASSESSMENT OF EXTERNAL AND INTERNAL EXPOSURES (OTHER THAN MEDICAL) Module V.1 - Assessment of occupational exposure due to external sources of radiation

2. IAEA Instrument Calibration - lecture objectives The objective of this lecture is to provide an overview of radiation protection instrument calibration and test techniques and requirements. It is intended to provide a review of radiation fields and reference instruments, calibration methods, and instrument test categories and requirements. At the completion of this lecture, the student should understand how instrument calibrations are performed, and what tests should be conducted by a dosimetry service. Module V.1 Lecture 7 - Calibration2

3. IAEA Calibration of Instruments - Module outline l Introduction l Traceability l Calibrations and tests l Calibration fields and sources l Reference dosimetry l Type testing l Performance testing Module V.1 Lecture 7 - Calibration3

4. IAEA Introduction Module V.1 Lecture 7 - Calibration4

5. IAEA The primary objectives of calibration are to: l Ensure that an instrument is working properly and will be suitable for the intended monitoring purpose. l Determine, under a controlled set of standard conditions, the indication of an instrument as a function of the quantity to be measured. l Adjust the instrument calibration, if possible, so that the overall measurement accuracy of the instrument is optimized. Module V.1 Lecture 7 - Calibration5

6. IAEA The process of calibration: l Establishes the relationship between the relevant quantity (dosimetric) to be measured and the response of the instrument or dosimeter. l Assumes that the calibration and measurement conditions are the same within acceptable limits of uncertainty. Module V.1 Lecture 7 - Calibration6

7. IAEA Calibration terminology Conventional true value: The best estimate of the value determined by a primary or secondary standard, or by a reference instrument that has been calibrated against a primary or secondary standard. Reference instrument: A tool to transfer the standard from a higher level to a lower level. It should be secondary standard calibrated with primary standard. Module V.1 Lecture 7 - Calibration7

8. IAEA Calibration terminology Response (for instrument): The quotient of the indication (evaluated value) M of the instrument and the delivered value of the quantity to be measured, H R = M / H Calibration factor N: The delivered value of the quantity which the instrument is intended to measure, H, divided by the reading (or indication, evaluated value) M, given by the instrument N = H / M Note: The symbol, H, refers to any of the operational quantities - H P (d,  ), H * (d) or H’(d,  ) Module V.1 Lecture 7 - Calibration8

9. IAEA Calibration terminology Reference dosimetry: A measurement made with the instrument that has been calibrated against the higher level standard to determine the dose rate or other quantity values at the point of interest. Traceability: The process that provides a documented dosimetric relationship between the reference instrument used for calibration purposes and reference instruments of higher quality, up to the level of the accepted national standard. Module V.1 Lecture 7 - Calibration9

10. IAEA Basic instrument calibration elements 1)Field calibration or reference dosimetry in the appropriate quantity. 2)Irradiation of instrument with reference source at the reference point - Conventional true, H. 3) Compare the indication of the instrument with the reference value of measurement quantity - Instrument Reading, M. 4) Obtain the response R = M/H, or calibration factorN = H/M = 1/R Module V.1 Lecture 7 - Calibration10

11. IAEA Instrument calibration - example l 137 Cs source l Air kerma rate at 2 meters = 0.5 Gy/h l Conversion coefficient for H p (10) = 1.21 Sv/Gy l H p (10) rate at 2 meters = 1.21  0.5 = 0.605 Sv/h l Expose a dosimeter on a slab phantom at 2 m for 10 minutes Module V.1 Lecture 7 - Calibration11

12. IAEA Instrument calibration - example (Cont.) l H p (10) = 0.605 Sv/h  0.167 h = 0.101 Sv l Dosimeter reading, M = 55 units l Response, R = 55/0.101 = 544 units/Sv l Calibration factor, N = 0.101/55 = 0.00184 Sv/unit Module V.1 Lecture 7 - Calibration12

13. IAEA Calibration Factor, Response dimensions l Calibration factor or response should ideally be dimensionless - instrument’s indication has the same unit as the value to be measured. l In some cases a dimension may be involved. ex. TLD reader that indicates “C” can measure Dose Equivalent in “mSv”. The calibration factor, N, carries the unit, mSv/C. Module V.1 Lecture 7 - Calibration13

14. IAEA Traceability Module V.1 Lecture 7 - Calibration14

15. IAEA Hierarchy of instrument standards Primary Standard: A standard with the highest metrological qualities. Secondary Standard: A standard whose value is fixed by direct comparison with a primary standard. Tertiary Standard: A standard whose value is fixed by comparison with a secondary standard Module V.1 Lecture 7 - Calibration15

16. IAEA Traceability and lateral comparability National (primary) Standard Secondary Standard Secondary Standard Local Standard Tertiary Standard Lateral Comparability (Intercomparisons etc.) Instrument Traceability Local Standard Module V.1 Lecture 7 - Calibration16

17. IAEA Traceability: an example National Standard of exposure (Air Kerma) Primary Standard Secondary Standard Practical Standard (Tertiary Standard) Dose Equivalent Standard Operational Instrument Specified Standard Instrument Specified 2nd. Standard Instrument Reference Standard Instrument Practical Standard Instrument Conversion Coefficient Module V.1 Lecture 7 - Calibration17

18. IAEA Calibrations and Tests Module V.1 Lecture 7 - Calibration18

19. IAEA Calibration and Tests Calibration l The quantitative determination, under a controlled set of standard conditions, of the indication given by a radiation measuring instrument as a function of the value of the quantity the instrument is intended to measure. Module V.1 Lecture 7 - Calibration19

20. IAEA Calibrations are conducted to: l Ensure that an instrument is working properly. l Determine, under a controlled set of standard conditions, the indication of an instrument as a function of the value of the measurand (the quantity intended to be measured). l Adjust the instrument indication so that the overall measurement accuracy of the instrument is optimized. Module V.1 Lecture 7 - Calibration20

21. IAEA Calibration and Tests Tests l Measurements intended to confirm that an instrument is functioning correctly, and/or the quantitative determination of the variations of the indication of the instrument over a range of radiation, electrical and environmental conditions. Module V.1 Lecture 7 - Calibration21

22. IAEA Routine calibrations - Intended to determine a calibration factor appropriate to the routine application of the dosimeter or dose rate-meter. Special calibrations - Special cases requiring measurements, similar to a type test, when an instrument may be used under abnormal circumstances. Calibrations Module V.1 Lecture 7 - Calibration22

23. IAEA l Type tests - Tests conducted to determine the characteristics of a particular type or model of a production instrument. l Acceptance tests - Contractual tests on all instruments of a particular type to demonstrate conformance to specifications. l Performance tests - Regular tests conducted to demonstrate maintenance of overall dosimetric performance standards. l QC tests – Part of Quality Management System (QMS) Tests Module V.1 Lecture 7 - Calibration23

24. IAEA There are 4 classes of test for instruments Daily, prior to start-up of dosimeter processing End user or ServiceQC Test: a part of QMS Monthly (or Every monitoring period) End user or ServiceRoutine Test: Verify the sensitivity, precision and accuracy for a single radiation type and energy. AnnuallyOrganization authorized by regulatory authority Approval Test: Demonstrate that overall dosimetric performance standard is maintained. Once, prior to marketing to end-users Manufacturer or authorized type-testing organization Type Test: Test the performance characteristics of the system as a whole. FrequencyPerformed byType Module V.1 Lecture 7 - Calibration24

25. IAEA Some reference conditions for calibration Influence quantitiesStandard conditions Temperature18 – 22 °C Humidity50 – 75 % Air pressure86 – 106 kPa Power supply voltageNominal voltage ± 3 % Electromagnetic field and Magnetic induction Negligible (or less than affecting level) Module V.1 Lecture 7 - Calibration25

26. IAEA Calibration Fields and Sources Module V.1 Lecture 7 - Calibration26

27. IAEA General requirements for calibration fields l Characterize the calibration field uniformity. l Room scatter effects should be investigated for neutron and non-collimated  ray irradiations. l Background levels should be low. l Record and correct background readings of the instrument if necessary. l Correct mixed field instrument calibrations for the influence of accompanying radiation. Module V.1 Lecture 7 - Calibration27

28. IAEA Non-symmetrical dose rate variation of X-ray field -15-10-5051015 Angle - Degrees(Left)(Right) 1.2 1.1 1.0 0.9 0.8 0.7 0.6 0.5 Horizontal variation Phantom Module V.1 Lecture 7 - Calibration28

29. IAEA Symmetrical dose rate variation of X-ray field -15-10-5051015 Angle - Degrees(Down)(Up) 1.2 1.1 1.0 0.9 0.8 0.7 0.6 0.5 Calculated value 60 kV 100 kV 200 kV Vertical variation Phantom Module V.1 Lecture 7 - Calibration29

30. IAEA X-ray machine for instrument calibration Module V.1 Lecture 7 - Calibration30

31. IAEA Machine for production of filtered X-rays Survey instrument Filter wheels Filters Module V.1 Lecture 7 - Calibration31

32. IAEA Example of a panoramic calibrator Module V.1 Lecture 7 - Calibration32

33. IAEA Typical photon calibration sources Gamma sources: 241 Am 59.5keV 137 Cs 662 keV 60 Co1170 keV 1330 keV Fluorescence X-rays:E = 8.6 keV - 98.4 keV Ge, Zr, Cd, W, Au, Sn etc. Filtered X-rays: E = 8 keV - 250 keV Module V.1 Lecture 7 - Calibration33

34. IAEA ISO radiation qualities a 1. Low air-kerma rate 2. Narrow spectrum 3. Wide spectrum 4. High air-kerma rate Good Bad Energy resolution Dose rate High Low There is a trade-off between energy resolution and dose rate. Steps necessary to produce narrow x-ray beams also reduce the x-ray output. a) See ISO reports 4037-1, 4037-2 and 4037-3 Module V.1 Lecture 7 - Calibration34

35. IAEA Comparison of ISO low exposure rate filtered and fluorescence reference radiations Energy - keV 010203040506070 Photons per keV Filtration 55 kV, 1.3 mm Cu + 4.0 mm Al 47.8 keV, 20.6 % Fluorescence Erbium k-X rays, 120 kV, 0.25 mm Gd, 49.1 keV Module V.1 Lecture 7 - Calibration35

36. IAEA ISO reference photon radiations Module V.1 Lecture 7 - Calibration36

37. IAEA ISO reference photon radiations Module V.1 Lecture 7 - Calibration37

38. IAEA Beta calibration stands Module V.1 Lecture 7 - Calibration38

39. IAEA Typical beta sources and characteristics Nuclide E max (keV) Min. E res (keV) 14 C 156 90 147 Pm 225 130 204 Tl 763 530 90 Sr-Y22741800 106 Ru-Rh3541 2800 Beta reference dosimetry is performed with an extrapolation chamber in terms of tissue absorbed dose rate.  Source Reference point Module V.1 Lecture 7 - Calibration39

40. IAEA Beta particle spectra Module V.1 Lecture 7 - Calibration40

41. IAEA Effect of beta beam flattening filters Without filter With filter Module V.1 Lecture 7 - Calibration41

42. IAEA Effect of beta beam flattening filters Without filter With filter Module V.1 Lecture 7 - Calibration42

43. IAEA Neutron irradiation facility Module V.1 Lecture 7 - Calibration43

44. IAEA Accelerator, reactor produced neutrons and graphite moderated neutrons are also used for calibration. Typical neutron sources and characteristics Neutron Source Average Energy f n H P (10) (MeV) pSv· cm 2 D 2 O moderated 252 Cf2.2 110 252 Cf2.4 400 241 Am-B2.8 426 241 Am-Be4.4 411 Module V.1 Lecture 7 - Calibration44

45. IAEA ISO Neutron Reference Spectra Module V.1 Lecture 7 - Calibration45

46. IAEA Neutron calibration using a precision long counter Long counter Survey meter Accelerator target Module V.1 Lecture 7 - Calibration46

47. IAEA Reference Dosimetry Module V.1 Lecture 7 - Calibration47

48. IAEA Reference dosimetry Reference values for calibration can be determined by three different methods: 1) Alternating instrument method 2) Source method 3) Inverse-square law method Module V.1 Lecture 7 - Calibration48

49. IAEA Reference dosimetry Alternating instrument method l Reference dosimetry is made with a reference instrument just before irradiation. l The test instrument is placed at the same point after removal of the reference instrument. l The test instrument is irradiated. After the calibration exposure, a 2 nd measurement is made with reference instrument. Module V.1 Lecture 7 - Calibration49

50. IAEA Reference dosimetry Source method l Reference dose rate measurements are made at pre-selected calibration points. l Instrument calibrations are then made at these points with comparison to the reference values. Module V.1 Lecture 7 - Calibration50

51. IAEA Reference dosimetry Inverse square law method: l The dose rate at a reference point is made by calculation using source activity and distance. l This is imprecise and suitable only for rough instrument checks. Module V.1 Lecture 7 - Calibration51

52. IAEA Type Testing Module V.1 Lecture 7 - Calibration52

53. IAEA Dosimetry system type testing Conducted to characterize the performance of the dosimetry system, including: l Calibration in various irradiation and storage conditions. l Quantification of the sources of uncertainty. Quantify sources of random and systematic error. Module V.1 Lecture 7 - Calibration53

54. IAEA Dosimetry system type testing Investigation of dosimeter response variation with: u energy u angle of radiation incidence u linearity of dosimeter response, and Minimum and maximum measurable doses Module V.1 Lecture 7 - Calibration54

55. IAEA Dosimetry system type testing Additional type test parameters include: u effect of temperature and humidity. u response to high dose rate and pulsed radiation fields. u effect of electric and magnetic fields. u ability to withstand mechanical shock and vibration. Module V.1 Lecture 7 - Calibration55

56. IAEA Basic calibration sequence 1) Calibrate radiation field in terms of a physical transfer quantity (air kerma, etc.) at the point where instruments are irradiated. 2) Characterize the field (dose rate) in terms of the suitable protection quantity at this point. 3) Expose dosimeters or instruments for a pre-determined time (dose) and record the readings. 4) Compare the readings with the reference value to obtain the response or calibration factor. Module V.1 Lecture 7 - Calibration56

57. IAEA Four methods of calibration Module V.1 Lecture 7 - Calibration57

58. IAEA Calibration in the Operational Quantities l Reference dosimetry is made with Air Kerma, for photons, Fluence for neutrons and Tissue (or Air) Absorbed Dose for beta rays. l The field is then characterized in terms of the suitable operational quantity suitable using conversion coefficients (f ) provided. ex. H * (d) = K air × f a for photons H P (d) =  × f n for neutrons, where K air is air kerma and  is fluence Module V.1 Lecture 7 - Calibration58

59. IAEA Calibrations - Geometrical considerations l Instruments and dosimeters should be at least 2 m from the source. l Exceptions: (1) Irradiation with non-collimated point source causes larger scattering component than for collimated sources. Module V.1 Lecture 7 - Calibration59

60. IAEA Calibrations - Geometrical considerations 2) Most neutron calibrations are made with irradiation distances less than 1 m to minimize the scatter contribution. 3) Beta irradiations are made at distances of 20 – 50 cm because of the short range of the electron. Module V.1 Lecture 7 - Calibration60

61. IAEA The ISO has specified three phantoms that should be used for dosimeter calibration. A water filled PMMA phantom represents the human torso. The water filled pillar phantom is recommended as an arm or wrist phantom. ISO rod phantom serves as a finger phantom. Calibration of individual dosimeters Module V.1 Lecture 7 - Calibration61

62. IAEA ICRU tissue substitute cannot be produced exactly, so l 30 cm x 30 cm x 15 cm PMMA phantom may be used. l Photon backscatter from PMMA is similar to tissue. l ISO has also proposed a thin wall, water filled slab (water is preferred for neutrons). l Interpret dosimeter response in terms of the tissue equivalent slab conversion coefficients. Module V.1 Lecture 7 - Calibration62

63. IAEA Perform type testing of dosimeters on a slab phantom l Energy response l Angular dependence l 30 cm x 30 cm x 15 cm l Conversion coefficients for ICRU tissue substitute u Monoenergetic photons u ISO photon reference radiations Module V.1 Lecture 7 - Calibration63

64. IAEA ISO calibration phantoms Slab: 30 × 30 × 15 cm with 2.5 mm PMMA front wall Pillar: 73 mm diameter × 30 cm with 2.5 mm PMMA wall Rod: Solid PMMA rod, 19 mm diameter × 30 cm Module V.1 Lecture 7 - Calibration64

65. IAEA Dosimeter placement Single dosimeters should be placed on the center of the phantom surface. Multiple dosimeters should be arranged to avoid radiation interaction between dosimeters. Avoid placing dosimeters closer than 7 cm from the slab phantom edge.  7 cm Module V.1 Lecture 7 - Calibration65

66. IAEA Reference point for dosimeter calibration l It should be stressed that the proper response of the dosimeter depends on scattering from the body. l The body-dosimeter combination is the instrument. l In principle, the reference point of calibration is the point of depth d from the surface of the slab phantom, because the H P (d,0) is calculated and defined at that point. Module V.1 Lecture 7 - Calibration66

67. IAEA Reference point for dosimeter calibration l In practice, the center (sensitive point) of dosimeter is used as the reference point for calibration. l If the source separation distance is  2m, the exposure surface of the phantom may be used as the reference. Module V.1 Lecture 7 - Calibration67

68. IAEA Photon Energy - keV All PMMA RS-1 ISO Water Backscattering ratio of slab phantom for various materials Module V.1 Lecture 7 - Calibration68

69. IAEA Energy response of a individual dosimeter: Measurements should be with reference radiations as specified in ISO standards within the energy ranges, l 15 keV to 1.5 MeV for photons l 0.2 MeV to 3.5 MeV (E max ) for beta rays, and l thermal to 15 MeV for neutrons Module V.1 Lecture 7 - Calibration69

70. IAEA individual dosimeter tests - Phantom needed Tests that require placement on a phantom l Energy dependence l Angular dependence ( – 75º to + 75º )  Module V.1 Lecture 7 - Calibration70

71. IAEA l Energy response curves may be established for H P (0.07) and H P (10) at incident angles of the radiation of 0° and 20°, 40° and 60° from normal. l For the angles 20°, 40° and 60°, data is obtained for both horizontal and vertical rotation planes. Angular response of a individual dosimeter: Module V.1 Lecture 7 - Calibration71

72. IAEA Angular dependence For whole-body dosimeters, calibrations should be made up to  75 degrees. A weighted angular response has been used for type testing. R E = 0.25 (R E,0 + R E,20 + R E,40 + R E,60 ) Module V.1 Lecture 7 - Calibration72

73. IAEA Weighted angular response considerations l In isotropic radiation fields the results for each angle should be weighted by the solid angle at the dosimeter. l In practice irradiations are probably rotationally isotropic. l Therefore, the response at each angle should have equal weighting. Module V.1 Lecture 7 - Calibration73

74. IAEA Weighted angular response considerations For each radiation type, a combined (E,  ) response curve can be constructed for each energy R E = 0.25 (R E, 0 + R E, 20 + R E, 40 + R E, 60 ) Where R E, , the ratio of true to measured dose equivalent, is the relative response at energy E and incident angle . Module V.1 Lecture 7 - Calibration74

75. IAEA Angular dependence of photon conversion coefficients for H P (10) in an ICRU slab Module V.1 Lecture 7 - Calibration75

76. IAEA Angular dependence of photon conversion coefficients for H P (0.07) in an ICRU slab Module V.1 Lecture 7 - Calibration76

77. IAEA Conversion Coefficients - pSv/n cm -2 Angular dependence of neutron conversion coefficients for HP(10) in an ICRU slab Module V.1 Lecture 7 - Calibration77

78. IAEA 1 1.2 1.0 0.8 0.6 0.4 0.2 0.0 Angular dependence of neutron conversion coefficients for HP(10) in an ICRU slab Module V.1 Lecture 7 - Calibration78

79. IAEA Individual monitor tests - no phantom needed Tests that don’t require a phantom l Dose rate dependence and response to pulsed radiation fields l Response dependence to atmospheric conditions (Pressure, temperature, humidity, dust, electric and magnetic fields, etc.) l Fading Module V.1 Lecture 7 - Calibration79

80. IAEA Recommended type testing procedure 1. Choose the photon energy from the ISO reference radiations. 2. Set up the radiation beam and a monitorchamber. 3. The monitor chamber, phantom and dosimeters must be completely enveloped by the beam at a distance of at least 2 m. 4. Measure air kerma (Ka) at the position to be occupied by the front surface of the phantom, but without the slab present, for a given indication on the monitor chamber. Module V.1 Lecture 7 - Calibration80

81. IAEA Dosimeter type testing in terms of H P (d) Module V.1 Lecture 7 - Calibration81

82. IAEA 1. Multiply the air kerma by the appropriate conversion coefficient (f). 2. Dose equivalent is then given by (K a ·f) for a monitor indication of D. 3. Each unit on the monitor chamber thus corresponds to a dose equivalent of (K a ·f) / D. 4. Place the slab phantom and dosimeter(s) with the beam incident on the dosimeters at angle  ° and the center of the phantom front face on the beam axis at the position at which the air kerma was measured in step 4. Recommended type testing procedure Module V.1 Lecture 7 - Calibration82

83. IAEA Dosimeter type testing in terms of H P (d) Module V.1 Lecture 7 - Calibration83

84. IAEA Recommended type testing procedure 9.Choose the dose equivalent (H) to be delivered to the dosimeters. 10. Irradiate the phantom until the monitor chamber indicates the desired value of (H·D) / (K af ). 11.Process the dosimeters and compare their readings with the conventional true doseequivalent, H. Module V.1 Lecture 7 - Calibration84

85. IAEA Scatter corrections are important for neutron calibrations Instruments and dosimeters respond to direct and scattered neutrons. Neutrons are scattered from walls, floor, objects in the room, and even air. Scatter contribution depends on distance to the source, room size and other factors. Scatter contribution can be estimated from calibration room geometry, or measured with a shadow cone. Module V.1 Lecture 7 - Calibration85

86. IAEA Shadow cone for scatter correction R 1 (r) = R o (r) + R s (r) Without shadow cone R 2 (r) = R s (r)With shadow cone R o (r) = R 1 (r) - R 2 (r) Iron Borated wax filling Solid polyethylene Neutron Source Shadow Cone Detector 50 cm 20 cm Module V.1 Lecture 7 - Calibration86

87. IAEA Effect of scatter with a bare 252 Cf source Module V.1 Lecture 7 - Calibration87

88. IAEA Effect of scatter with a moderated* Cf source * 15 cm D 2 O Module V.1 Lecture 7 - Calibration88

89. IAEA Type testing for workplace monitors l Procedures type testing of workplace monitors are similar to those for individual dosimeters. l However, exposures in workplace monitoring would normally be free-in-air (no phantom). Test H*(d) or H’(d) meters through 360°. l IEC issues standards for most radiation protection monitoring equipment. Module V.1 Lecture 7 - Calibration89

90. IAEA Photon dose conversion coefficients for E and H* Energy - keV 1010 2 10 3 10 4 10 1 10 -1 10 -2 10 -3 Conversion coefficients - Sv/Gy Module V.1 Lecture 7 - Calibration90

91. IAEA Neutron dose conversion coefficients for Ambient Dose Equivalent, H*(10) Neutron energy - MeV Conversion coefficients - pSv cm -2 Module V.1 Lecture 7 - Calibration91

92. IAEA Performance Testing Module V.1 Lecture 7 - Calibration92

93. IAEA Three categories of performance testing l Approval performance testing l Routine testing or calibration l Quality Management (QM) program testing Module V.1 Lecture 7 - Calibration93

94. IAEA Approval performance testing Subdivided into different irradiation categories to suit different classes of dosimeter design, i.e. l Radiation types and energy ranges covered by the dosimeters, l Range of energies and angles of incidence, and Dose distribution from 0.20 mSv to at least 100 mSv to test the overall performance of the system. Module V.1 Lecture 7 - Calibration94

95. IAEA Approval performance testing l Carried out at regular intervals, l In agreement with the regulatory requirements, l By an external test facility. l Test results should comply with the overall accuracy requirements specified by ICRP. Module V.1 Lecture 7 - Calibration95

96. IAEA Routine performance testing l Carried out u At one radiation energy and u Under a given set of irradiation conditions l To normalize or standardize the sensitivity of the system l Should not be confused with type testing Module V.1 Lecture 7 - Calibration96

97. IAEA Routine performance testing l Tests the accuracy and precision of the dosimetry system for measurement of doses. l The calibration source has a single energy usually, e.g., 137 Cs or 60 Co for photon dosimeters. l Precision and accuracy should be tested at different dose levels. Module V.1 Lecture 7 - Calibration97

98. IAEA Routine performance testing l Test results should at least fulfill the accuracy requirements. l Test also normalizes the overall system sensitivity. l Should be repeated, normally by the service, at regular intervals, preferably monthly. Module V.1 Lecture 7 - Calibration98

99. IAEA Routine performance testing l Routine check of the calibration factor of the system does not always need a phantom. l Make free-in-air dosimeter irradiations and obtain the with/without phantom ratios. l Apply the ratio for each free air irradiation results to get the H P (d) values. l A panoramic type irradiator may be used. Module V.1 Lecture 7 - Calibration99

100. IAEA Quality Management System l Internal system of procedures to ensure quality. l On-going QC program, tests equipment, calibration facilities, materials and processes. One overall quality testing method - a dummy client. Module V.1 Lecture 7 - Calibration100

101. IAEA Quality control testing l Dummy user dosimeters are processed normally, except some dosimeters receive radiation doses. l Dosimeters exposed to known doses either in the laboratory or by some external test facility. l Measured values are compared with conventional true values and results interpreted using prescribed methods. Module V.1 Lecture 7 - Calibration101

102. IAEA Quality control testing l Measured values should be compared with the conventional true values. l One alternative is to establish a procedure “surprise” visit procedure. l Another alternative - participation in national or international intercomparison programmes. Module V.1 Lecture 7 - Calibration102

103. IAEA References BOEHM, J., Exchange of sources, beam flattening filters and jigs of a secondary standard for absorbed dose rates of beta radiation, PTB Mitt. 96 (1986) 317. BOEHM, J., Standardization and Calibration in Beta Dosimetry, Rep. NUREG-CP-0050, Nuclear Regulatory Commission, Washington, DC (1984). EHRLICH, M., PRUITT, J.S., SOARES, C.G., Standard Beta-Particle and Monoenergetic Electron Sources for the Calibration of Beta-radiation Protection Instrumentation, Rep. NUREG-CR-4266, NBSIR-85-3169, Nuclear Regulatory Commission, Washington, DC (1985). EISENHAUER, C.M., SCHWARTZ, R.B., "The effect of room ‑ scattered neutrons on the calibration of radiation protection instruments", Neutron Dosimetry in Biology and Medicine (Proc. 4th Symp. Neuherberg, 1981), Vol. I (BURGER, G., EBERT, H.G., Eds), Rep. EUR-7448 EN, CEC, Luxembourg (1981) 421-430. Module V.1 Lecture 7 - Calibration103

104. IAEA References EISENHAUER, C.M., SCHWARTZ, R.B., JOHNSON, T., Measurement of neutrons reflected from the surface of a calibration room, Health Phys. 42 (1982) 489-495. INTERNATIONAL ATOMIC ENERGY AGENCY, Calibration of Radiation Protection Monitoring Instruments, Safety Series No. 16 (2000). INTERNATIONAL ATOMIC ENERGY AGENCY, Compendium of Neutron Spectra and Detector Responses for Radiation Protection Purposes, Technical Reports Series No. 318, IAEA, Vienna (1990). INTERNATIONAL ATOMIC ENERGY AGENCY, Compendium of Neutron Spectra and Detector Responses for Radiation Protection Purposes Supplement to TRS 318, Technical Reports Series No. 403 (2002). Module V.1 Lecture 7 - Calibration104

105. IAEA INTERNATIONAL COMMISSION ON RADIATION UNITS AND MEASUREMENTS, Measurement of Dose Equivalents from External Photon and Electron Radiations, Rep. ICRU 47, Bethesda, MD (1992). INTERNATIONAL COMMISSION ON RADIATION UNITS AND MEASUREMENTS, Fundamental Quantities for Ionizing Radiation, Rep. ICRU 85, Bethesda, MD (2011). INTERNATIONAL COMMISSION ON RADIATION UNITS AND MEASUREMENTS, Determination of Operational Dose Equivalent Quantities for Neutrons, ICRU Report 66, [Journal of the ICRU Volume 1, No 3, 2001 (20021). INTERNATIONAL COMMISSION ON RADIOLOGICAL PROTECTION/ INTERNATIONAL COMMISSION ON RADIATION UNITS AND MEASUREMENTS, Conversion Coefficients for Use in Radiological Protection Against External Radiation, ICRP Publication 74, Pergamon Press, London and New York (1997) or ICRU Publication 57, ICRU, 7910 Woodmont Ave., Bethesda, MD 20814 USA (1998). Module V.1 Lecture 7 - Calibration105 References

106. IAEA INTERNATIONAL ELECTROTECHNICAL COMMISSION, Alpha, Beta and Alpha-Beta Contamination Meters and Monitors, EEC Publication 325, Geneva (198 1). INTERNATIONAL ELECTROTECHNICAL COMMISSION, Portable Neutron Ambient Dose Equivalent Ratemeters for Use in Radiation Protection, IEC Standard 1005, Geneva (1990). INTERNATIONAL ORGANIZATION FOR STANDARDIZATION, Reference Beta Radiations for Calibrating Dosemeters and Doseratemeters and for Determining their Response as a Function of Beta Radiation Energy, ISO Standard 6980 (E), Geneva (1984). INTERNATIONAL ORGANIZATION FOR STANDARDIZATION, Reference Photon Radiations - Dosimetry of X and Gamma Reference Radiations for Radiation Protection over the Energy Range from 8 keV to 1.3 MeV and from 4 MeV to 9 MeV, ISO/DIS 4037-2, Geneva (1995). INTERNATIONAL ORGANIZATION FOR STANDARDIZATION, Reference Photon Radiations ‑ Calibration of Area and Personnel Dosemeters and the Determination of their Response as a Function of Energy and Angle of Incidence, ISO/DIS 4037-3, Geneva (1995). Module V.1 Lecture 7 - Calibration106 References

107. IAEA INTERNATIONAL ORGANIZATION FOR STANDARDIZATION, Reference Sources for the Calibration of Surface Contamination Monitors – Beta-Emitters (Maximum Beta Energy Greater than 0. 15 MeV) and Alpha Emitters, Draft Standard, ISO/DIS 8769, Geneva (1986). INTERNATIONAL ORGANIZATION FOR STANDARDIZATION, X and Gamma Reference Radiations for Calibrating Dose Meters and Dose Rate Meters and for Determining Their Response as a Function of Photon Energy ‑ Characteristics of the Radiations and their Methods of Production, ISO Standard 4037-1, Geneva (1995). INTERNATIONAL STANDARDS ORGANIZATION, Neutron Reference Radiations for Calibrating Neutron Measuring Devices Used for Radiation Protection Purposes and for Determining their Response as a Function of Neutron Energy, Draft Standard ISO/DIS 8529, Part 1: ISO, Geneva (1086). INTERNATIONAL STANDARDS ORGANIZATION, Procedures for Calibrating and Determining the Energy Response of Neutron Measuring Devices Used for Radiation Protection, Draft Standard ISO/TC 85/SC2/GT2 N200, ISO, Geneva (1987). Module V.1 Lecture 7 - Calibration107 References