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Radiation Safety Training for Fluoroscopy in Research Radiation Safety Office Indiana University Purdue University Indianapolis and Associated Facilities.

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Presentation on theme: "Radiation Safety Training for Fluoroscopy in Research Radiation Safety Office Indiana University Purdue University Indianapolis and Associated Facilities."— Presentation transcript:

1 Radiation Safety Training for Fluoroscopy in Research Radiation Safety Office Indiana University Purdue University Indianapolis and Associated Facilities

2 2 Radiation Safety Concerns in Fluoroscopy MMMMonitor radiation exposure of operators KKKKeep exposures “as low as reasonably achievable” (ALARA) MMMMinimize deleterious effects to subjects from radiation exposure

3 3 Radiation Quantities & Units Traditional Units SI Units Exposure (Air Kerma) R or mR c/kg Absorbed Dose rad or mrad Gy or mGy Dose Equivalent rem or mrem Sv or mSv

4 4  Conversions - Traditional to SI Units  1 R = 2.58 x 10 -4 c/kg  1 rad = 0.01 Gy  1 rem = 0.01 Sv  Conversions - SI to Traditional Units  1 c/kg = 3876 R  1 Gy = 100 rad  1 Sv = 100 rem  1 R ≈ 1 rad ≈ 1 rem  1 Gy ≈ 1 Sv Radiation Quantities & Units

5 5 Sources of Ionizing Radiation  Natural Sources Radon gas Radon gas Uranium and Thorium in rock and stone Uranium and Thorium in rock and stone Galaxy & Sun Galaxy & Sun  Man-Made Sources Medical x-rays Medical x-rays Nuclear medicine studies Nuclear medicine studies Consumer products Consumer products (e.g., smoke detectors, exit signs)

6 6 Average Dose Equivalent ~360 mrem/yr Radon 54% Cosmic 8% Terrestrial 8% Internal 11% Medical X-rays 11% Nuclear Medicine 4% Other 1% Consumer Products 3% Naturally Occurring

7 7 Dose Comparisons “Typical” Doses Flight from Los Angeles to London 5 mrem (.05 mSv) Chest X-Ray 10 mrem (0.1 mSv) Average annual background dose 360 mrem (3.6 mSv) “Comparative” Dose Skin erythema (reddening) ~300,000 mrad (~3000 mGy)

8 8 Radiation Dose Limits  Occupational limits  Effective dose equivalent limit - 5,000 mrem/yr  Skin, organs, or extremities - 50,000 mrem/yr  Lens of the eye - 15,000 mrem/yr  “Declared pregnant woman” - 500 mrem to embryo/fetus  Member of the public - 100 mrem/yr

9 9 ALARA LocationLimit(mrem/yr) ALARA I (mrem/qtr) ALARA II (mrem/qtr) Whole body 5000125375 Lens of the Eye 15,0003751125 Extremities/Skin50,00012503750

10 10 Personnel Monitoring  Two body badges  One badge should be worn under all leaded apparel.  Second badge should be worn at the collar level outside all leaded apparel. DO NOT INTERCHANGE THESE BADGES

11 11  Ring badges should be worn by operators whose hands are very near the primary beam Personnel Monitoring

12 12 Minimizing Operator Dose  ↑ Subject dose ↑ Operator Dose  ↑ Clarity or detail of image ↑ Operator Dose

13 13 Subject Dose Measurement  Indicators of Dose  Fluoroscopy time  DAP (Dose Area Product)  Cumulative dose at IRP  Limitations  Field sizes  Movement of x-ray tube

14 14 Cataract originating in the posterior pole of the lens of an interventionalist, consistent with radiation-induced cataract Biological Effects of Radiation to Operator

15 15 Biological Effects of Radiation to Subject  Skin injury to animal  Can range from skin reddening to tissue necrosis  May take weeks to months for skin problems to occur

16 16 Correlation of Dose Operator and Subject  With the exception of magnification, “scatter” radiation dose to operator is affected by the same parameters as the radiation dose to the subject  Low dose to subject = Less scatter = Low dose to operator


18 18 Decrease Radiation Field Size   Collimate to the smallest practical field size  Reduces exposure to subject  Reduces scatter to operator  Improves image

19 19 Increase Tube Potential (kVp)  Lowers scatter since fewer photons will be needed to penetrate the subject  In automatic mode, the mA decreases as the kVp increases  Therefore, higher kVp generally results in a lower skin dose to the subject and less scatter to the operator

20 20 Subject Thickness  ↑ Thickness ↑ Photons to get to II  Large subjects and oblique beam angles may result in significantly higher skin doses and scatter  May not be negotiable

21 21

22 22 Use Magnification Sparingly  Machine automatically reduces the field size  Higher “Mag” modes result in higher doses to smaller areas of the skin  May negatively affect your research results  Instead, reduce field size to the extent practical when in “normal” mode

23 23 Lower Pulse Rate  Lower pulse rates result in lower exposure to the subject and less scatter to the operator  Dynamic image quality will be reduced (image may appear “jerky”)  Operate in “pulse rate” mode whenever possible

24 24

25 25 Minimize High Dose Rate Mode (Cine)  A high dose rate mode (“cine”) is used to capture digital images  20 times the dose rate from standard fluoroscopy  A minimum number of these runs should be used consistent with obtaining adequate information

26 26  Maximize distance between tube & subject  Minimize distance between subject and II Subject Distances to Tube and II

27 27 “Danger” Zone between X-ray Tube and Subject

28 28 “Danger Zone” Analogy

29 29 Reducing Exposures “TDS”  Time  Distance  Shielding

30 30 Reducing Exposures Time  Minimize fluoro time to reduce subject dose and scatter dose to operator  Use “image hold” capabilities to reduce need for additional fluoro time  Personnel should not be in the room unless their presence is necessary to the procedure.

31 31 Reducing Exposures Distance  Radiation follows the “inverse square law” 8 R/min32 R/min2 R/min ½ meter 1 meter 2 meters

32 32 Reducing Exposures Shielding  Pb aprons (at least 0.5 mm Pb equivalent) should be worn by all personnel involved in fluoro/cine procedures  Thyroid collars and Pb glasses may also be recommended or required

33 33 Reducing Exposures Shielding  Portable/pull- down shields may be utilized  Pb drapes on table and image intensifier

34 34 Dose Reduction Summary  Use pulsed fluoroscopy or other low-dose- rate modes of operation  Keep tube current low and tube potential high  Optimum kVp – below gives better contrast at expense of dose increase and above decreases subject dose and image quality  Use heavy beam filtration to increase kVp  Use “image hold” to avoid repetitive exposure  Use magnification modes sparingly

35 35  Do not remove devices designed to maintain adequate distance between x-ray tube & subject (beam separator device)  Collimate to the smallest reasonable field size  Utilize dose monitoring equipment (e.g., radiation badge)  Keep x-ray tube as far from subject as possible and image intensifier as close to subject as possible  Avoid prolonged exposures over the same skin area, especially through thick body masses Dose Reduction Summary

36 36 Radiation Safety Office Clinical Building – Room 159 274-4797 After hours pager 312-1519

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