1. RC325C Personnel Protection during Fluoroscopic Procedures
(Title slide)
Beth Schueler, PhD, Mayo Clinic Rochester, MN

2. Learning Objectives
For staff performing fluoroscopically-guided interventional procedures:
Summarize typical radiation exposure levels
Understand issues related to lens exposure
Learn about new shielding devices and techniques
Review practical rules for occupational dose reduction
I’m going to focus our discussion particularly to staff performing fluoro-guided interventional procedures
And protection of the eye
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3. Operator Exposure During Interventional Fluoroscopy Procedures
Procedure Type
Mean Dose per Procedure (µSv)
Neck
Lens
Effective
Mixed general IR1
50-325
300
1-5
Cerebral angiography/embolization1
10-30 15
0.5-2
Vertebroplasty1
220 80 10
PCI2
10-130
10-170
0.2-11
Cardiac ablation2
8-200
50-320
0.2-6
First, let’s take a look at typical dose levels for this group.
This table lists data from several publications where operator dose was measured for a sample to individual procedures. Areas monitored are the neck or collar over a lead apron and lens of the eye not accounting for use of lead protective eyewear.
Mean doses per procedure can reach as high as 325 microSv for the neck and lens.
Effective doses, which account for shielding provided by a lead apron, are generally 1-10 microSv
NCRP 168: Table 5.1 p. 118
1. NCRP 168. Radiation Dose Management for Fluoroscopically-guided Interventional Procedures, 2011.
2. Kim KP, et al. Health Physics 2008; 94:211–227.

4. Typical Operator Exposure Levels
Annual doses for a workload of 1000 procedures per year:
Mean Annual Dose (mSv)
Lens
Effective
Published Occupational Doses
10-325
0.2-11
Annual Dose Limit (US) 1
150 50
Annual Dose Limit (International) 2
20 (averaged over 5 years)
Potential for doses exceeding regulatory dose limits exists
To translate these individual procedure doses into annual dose, let’s assume a busy workload for an interventionalist of 1000 procedures in a year. We can see that the potential exists for very high dose levels. Even exceeding regulatory limits for the lens if no additional shielding is used.
1. NCRP 116. Limitation of Exposure to Ionizing Radiation, 1993.
2. ICRP

5. New ICRP Guideline on Lens Exposure*
Lower threshold for cataract formation: 0.5 Gy (previous threshold 2-5 Gy)
Lower occupational eye dose limit is recommended: 20 mSv/yr averaged over 5 years with no year > 50 mSv
*International Commission on Radiological Protection (ICRP) Statement on tissue reactions. April 21,
Lens dose is of particular concern. Not only are the levels potentially exceeding current regulatory limits but. The International commission on radiological Protection has recently released a new guideline on lens exposure, published in April of this year. New research suggests a lower threshold
Significantly lower than current regulatory dose limit of 150 mSv/yr
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6. Lowered Radiation-Induced Cataract Threshold Dose
Problems found with earlier cataract studies:
Short follow-up period – latency period is longer for low doses
Insufficient sensitivity to detect early lens changes
Few subjects with low lens dose
Recent additional significant studies indicate lower threshold:
Chernobyl nuclear reactor accident clean-up workers1
US radiologic technologists2
1. Worgul BV, et al. Radiat Res 2007; 167:233–243.
2. Chodick G, et al. Am J Epdiemiol 2008; 168:620–631.
To lo
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7. Cataracts in Fluoroscopy Operators
In a survey of 59 interventional radiologists, 5 had posterior subcapsular cataracts (PSCs) 1
In a survey of 42 interventional cardiologists, 17 had PSCs 2
1. Junk A. et al, RSNA 2004 Annual Meeting
2. Information and Preliminary results of the IAEA Cataract Study Retrospective Evaluation of Lens Injuries and Dose (RELID) 2009,
Study detailed in June 2004 issue of RSNA News
PSCs are thought to be more likely to be caused by radiation exposure. Cataract formation is typically seen in the anterior pole of the lens.
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8. Lens Dose Estimation
Potential high dose levels require lens exposure monitoring or accurate estimation
Monitoring at or near the eye is difficult
Estimation from a neck dosimeter dose reading is a more practical solution
Published occupational dose studies utilized TLDs or other dosimeters placed on an operators forehead or glasses. Compliance is problematic on a daily basis
Photo reference: Harstall Spine 2005
Harstall R, et al. Spine 2005; 30:
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9. Lens Dose Estimation Under-table X-ray Tube: Lens:Neck 0.5 – 0.74 2 1
0.5
0.25 mGy/hr
Under-table X-ray Tube:
Lens:Neck 0.5 – 0.7
Over-table X-ray Tube:
Lens:Neck 1.0 – 1.2
For a typical configuration with the x-ray tube under the table, the lens dose will be lower than the collar badge reading. For the config shown here, lens: collar dose is about However, if the x-ray tube is placed overhead, the lens dose can actually be higher than the collar reading.
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10. Lens Dose Estimation
Actual Lens:Neck dose ratio varies with C-arm angulation and operator position
For typical under-table x-ray tube configurations, the collar dosimeter reading provides conservative estimate of the lens dose
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11. Lens Exposure Reduction
Shielding specific to eye and head protection:
- Leaded eyewear
- Ceiling-mounted shields
So, now we’ve settled on a way to estimate the lens dose, what can be done to lower the dose when it is too high. Overall any dose reduction technique will also reduce lens exposure. Ed has already reviewed this earlier this morning. Techniques available to specifically shield the eyes and head include
Shield photo – mavig website
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12. Leaded Eyewear
Typical lead equivalent thickness of radiation protective eyewear is 0.75 mm
98% attenuation or attenuation factor = 50
Actual lens dose is higher due to
Backscatter from head
Exposure from the side and from below the protective lenses
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13. Eye Exposure Conditions
Photo – SIR web page
Operator is looking as display monitor during fluoroscopy. Head is at an angle to scatter source. Exposure to the lens is from the side and below and not directly through the front of the lenses
Therefore, the effectiveness of leaded eyewear at reducing lens exposure depends not only on the lead equivalent thickness of the lenses, but also on the eyewear design and the position of the operator
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14. Leaded Eyewear Effectiveness Comparison
Traditional style
0.75 mm lead-equivalent
120 g
28 cm2 surface area
Sport-wrap style
0.75 mm lead-equivalent
59 g
16 cm2 surface area
A study was conducted to compare the attenuation factor of 3 styles of leaded eyewear
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15. Leaded Eyewear Effectiveness Comparison
Panoramic Shield
0.07 mm lead-equivalent acrylic
43 g
50 cm2 surface area
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16. Leaded Eyewear Effectiveness Comparison
Lens dose measured on a head phantom angled at 0, 45 and 90 to the scatter source
to mimic the range of operator locations possible
0 deg angle is for the head phantom oriented directly toward the scatter source
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17. Leaded Eyewear Effectiveness Comparison
Style
Attenuation Factor
0 Angle
45 Angle
90 Angle
Traditional 10 5 4
Sport-wrap 8
4.5
1.5
Panoramic Shield
2.5 2 10 8
2.5 4
1.5
Animate colors
Here are the results. the attenuation factor is the ratio of the lens dose without glasses / lens dose with glasses
First note that At 0 angle, note that attenuation factor is well below expected for 0.75 mm lead equivalent which is about 50. This shows the contribution from backscatter from the head. The reduced attenuation factor of the Sport-wrap style is expected due its smaller lens size and the reduced attenuation factor for the pan shield is due to its lower lead content only 0.07 mm. But 0 angle is not relevant clinically since the head is angled to the source of x-rays. At a 45 and 90 angle, attenuation drops due to the contribution from side exposure. The styles with larger side shields provide sufficient coverage up to 90 deg but the sport wrap style provides only minimal coverage at 90 deg
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18. Leaded Eyewear Recommendations
Adequate side shields or wrap-around design is essential
Radiation attenuation factor for typical configuration is between 2 and 5
Leaded eyewear alone may be insufficient for high exposure conditions if 20 mSv/yr lens dose limit is implemented
Recall highest dose procedures up to mSv annually
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19. Ceiling-Mounted Shields
Overhead lead shields provide head and neck protection in addition to lens protection
May be cumbersome for certain procedures:
C-arm angulation
Biliary/transjugular access
Another option for lens dose reduction is ceiling mounted shields
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20. Ceiling-Mounted Shield Effectiveness
When it is possible to use them, it is worth the added exam complexity to position and adjust?
Up to factor of 6-9 dose reduction is possible with optimal placement. Poor placement provides less than a factor of 2 protection
Taking into account potentially poor shield placement, lens doses may still exceed regulatory limits, especially if they are reduced to 20 mSv/yr
Fetterly KA, et al. JACC Intv 2011;4:
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21. Lens Exposure Reduction
Leaded
Eyewear
Ceiling-
Mounted
Shield
Eyewear +
Shield
But, a Combination of both eyewear and shield is recommended for maximum dose reduction is the best approach resulting in a 20 fold lens dose reduction
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22. Learning Objectives
For staff performing fluoroscopically-guided interventional procedures:
Summarize typical radiation exposure levels
Understand issues related to lens exposure
Learn about new shielding devices and techniques
Review practical rules for occupational dose reduction
11/29/2011
Schueler RC325C

23. Orthopedic Complications from Lead Apron Use
Back pain was reported by 50-75% of interventional physicians surveyed *
Compare to incidence of 27% in US adults
25-30% reported that back problems had limited their work
Options for relief
Lightweight aprons
Vest/kilt design
We all know lead aprons are heavy and when worn all day, every day back problems commonly result
* Klein LW, et al. J Vasc Interv Radiol 2009; 20:147–152.
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24. Lightweight Protective Aprons
Weight reduction
of 20-30%
possible
McCaffrey JP, et al.
Med Phys 2007;34:530-7.
Multiple lead composite and lead-free materials have been developed using other high atomic number shielding materials such as barium, tin, or tungsten, bismuth
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25. Radiation Protection Cabin
Provides whole-body shielding from an external support system
Include head and neck protection
Eliminates need for
lead apron
thyroid shield
leaded eyewear
other ceiling-mounted or mobile shields
Another device that is now being sold is the radiation protection cabin
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26. Radiation Protection Cabin
ZeroGravity
Apron: 1.25 mm lead equivalent lead front, 0.5 mm sides and arm flaps
Lead plex face shield: 0.5 mm lead – protects eyes and head
Suspended from ceiling mount or mobile column and boom – shown here
Sterile drapes shown
Operator can move and disengage from cabin as needed
Marichal DA, et al. J Vasc Interv Radiol 2011; 22:
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27. Radiation Protection Cabin
Marichal DA, et al.
J Vasc Interv
Radiol 2011;
22:
Operator dose for a Simulated procedure compared to use of a 0.5 mm lead apron. Factor of dose reduction to eyes
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28. Radiation Protection Cabin
Here is a different cabin design
Cathpax
2 mm lead plex walls
Mobile on wheels
Dragusin O, et al. Eur Heart J 2007; 28:183–189.
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29. Radiation Protection Cabin
Protective Garment
Mean Dose per Procedure (µSv)
Face
Waist
Lead Apron Only
102 3
Protection Cabin 2 1
Dragusin O, et al. Eur Heart J 2007; 28(2),183–189.
Mean dose for 40 ablation procedures
similar dose reduction amounts
These devices can provide an effective alternative for physicians who have problems with wearing a lead apron
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30. Radiation Protective Drapes
Placed on patient surface, sterile, disposable
Various sizes, shapes and cut-outs for different procedures
Exposure reduction factors measured:
Eyes: 12, Thyroid: 25, Hands: 29
King JN, et al.
AJR 2002; 178:153–157.
Photos – BW: King
Color: Radpad website – ID covered
Particularly useful for procedures where a ceiling-mounted shield cannot be used
Also useful for hand dose reduction for procedures where hands need to be near the exposure field
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31. Learning Objectives
For staff performing fluoroscopically-guided interventional procedures:
Summarize typical radiation exposure levels
Understand issues related to lens exposure
Learn about new shielding devices and techniques
Review practical rules for occupational dose reduction
11/29/2011
Schueler RC325C

32. Practical Rules for Dose Reduction
Minimize fluoroscopy time and number of fluorographic images acquired
Last-image-hold
Fluoroscopy loop recording
Reduced acquisition frame rates
Virtual collimation
All these will also reduce patient dose
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33. Practical Rules for Dose Reduction
Minimize fluoroscopy time and number of fluorographic images acquired
Use available patient dose reduction technologies
Pulsed fluoroscopy at low frame rates
Low dose rate settings
Spectral beam filtration
Increased minimum kVp
Grid removal
All these will also reduce patient dose
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34. Practical Rules for Dose Reduction
Minimize fluoroscopy time and number of fluorographic images acquired
Use available patient dose reduction technologies
Use good imaging-chain geometry
All these will also reduce patient dose
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35. Practical Rules for Dose Reduction
Minimize fluoroscopy time and number of fluorographic images acquired
Use available patient dose reduction technologies
Use good imaging-chain geometry
Use collimation to the area of interest
All these will also reduce patient dose
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36. Practical Rules for Dose Reduction
Minimize fluoroscopy time and number of fluorographic images acquired
Use available patient dose reduction technologies
Use good imaging-chain geometry
Use collimation to the area of interest
Use all available information to plan the interventional procedure
CT, MR, US to define anatomy
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37. Practical Rules for Dose Reduction
Position yourself in a low-scatter area
Schueler RC325C
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38. Practical Rules for Dose Reduction
Position yourself in a low-scatter area
Use protective shielding
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39. Practical Rules for Dose Reduction
Position yourself in a low-scatter area
Use protective shielding
Use appropriate fluoroscopic imaging equipment
Optimized for the procedure and body part
High dose procedures should utilize fluoroscopy equipment with dose reduction technologies and dose display
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40. Practical Rules for Dose Reduction
Position yourself in a low-scatter area
Use protective shielding
Use appropriate fluoroscopic imaging equipment
Obtain appropriate training
Operators should be thoroughly familiar with the particular equipment used
Residents and fellows should be trained in safe operating procedures
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41. Practical Rules for Dose Reduction
Position yourself in a low-scatter area
Use protective shielding
Use appropriate fluoroscopic imaging equipment
Obtain appropriate training
Wear radiation monitoring dosimeters and review your dose reports
Wear badges assigned to them to monitor their radiation dose
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