Post on 05-Jun-2018
transcript
Secondary Risks in Radiation Protection in Interventional Cardiology and Radiology:
Solving one problem without creating another
Paddy Gilligan, Dublin, Ireland
Occupational Radiation Dose
• Modern interventional units have become more powerful allowing more complex lengthy procedures. Higher staff doses
• Radial techniques allow greater throughput and quicker recovery
Higher staff doses • Radiation Dose Limit to the eyes has lowered by
a factor of 7 under new EU directive (59/13) -clinical workload restrictions by 2018 ?
y = 0,0856x + 0,0193 R² = 0,832
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0 20 40 60 80 100 120 140 160
LHS
Co
llar
Do
se (
mSv
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Total # procedures in a given month
Collar TLD Dose/ Month vs Activity
Cardiologist Workload 2015
Solutions • Do less procedures
– Patient suffers, poor access to clinical procedures increased waiting lists
Solutions • Replace existing technology & Equipment
with better dose performance equipment – Capital investment, Equipment life cycle ,lower
radiation dose and clinical performance
Dose Reduction • Increase protection in lead aprons:
- extra weight, lead aprons, increased spinal problems.
• Engineered Solutions
- Zero Gravity ,Catphax: high level of protection with no weight for operator, workflow and capital cost
• Eye Protection
- Lead glasses: compliance & uncertainty over level of protection (dose reduction factor 2-6) .
Aprons Weights and Transmission
Apron Weight Sacttered Transmission % @ weakest point, no copper, 80 KVp
Vendor 1 ,0.25 mm lead free, coat and skirt, thyroid collar
3.75 Kg 9.9 %
Vendor 2 ,0.25 mm lead free, coat and skirt
4.01 Kg 10 %*
Vendor 2,0.25 mm lead free single apron
4.75 Kg 10 %*
Vendor 2 , 0.25 mm lead composite single apron
7 kg 4 %*
Solutions
• Reduce scatter at source: –Concerns about automatic exposure control
• Lead aprons reduce operator dose but increase dose three fold
– Interference with procedure
– Infection Control Musallam A, et al. A randomized study comparing the use of a pelvic lead shield during trans-radial interventions: Threefold decrease in radiation to the operator but double exposure to the patient. Catheter Cardiovasc Interv. 2015 Jun;85(7):1164-70
Current Shielding Arrangements
• Upper body protection developed for femoral access
• Lower body shield
• Drapes not used locally due to concern over automatic exposure control
Objective:
• To clinically evaluate novel MAVIG shield/ drape combination against a number of end points:
– Staff Dose reduction
– Effect on Patient Dose
– Clinical Utility
– Infection control
Novel Shield from MAVIG, Germany
• 0.5 mm Pb lead acrylic
• Larger with better eye protection
• Clip on lamellae depending on whether access is radial or femoral
Conventional New shield
On-Patient Drape
• 0.5 mm Pb flexible shield
• Designed differently for each access type
• Disposable sterile cover
• Washable material
• Placed under or over cloth/ paper sterile patient drape
• Protective effect was modeled using Monte Carlo simulation
• Modeling results were correlated with Rando Phantom Measurements
• Estimated reduction :
– Shield alone : 84%
– Combined shield and pad: 90%
Eder H, Seidenbusch MC, Treitl M, Gilligan P. A New Design of a Lead-Acrylic Shield for Staff Dose Reduction in Radial and Femoral Access Coronary Catheterization. Rofo. 2015 Jun 17.
Materials and Methods
• Siemens Artis zee large detector interventional System
• Angios, Chronic Total Occlusion, PCI’s
• Data collected in September, October, November 2013
• Shield/ Pad placed in October 2013
• Collected collar EPD exposure per case for Cardiologist, Nurse , Radiographer, Technician
• Excluded where mobile phone was present
• Training and evaluation
• Statistical analysis using Mann Whitney U Test
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Angio PCI CTO
Pooled Cardiologist Exposure Reading Per Procedure (µSv)
Without Shield
With Shield
OVERALL
No of Procedures Median EPD exposure
in µSv /procedure p
Without With Without With
Cardiologists Pooled
165 132 15.7 7.3 <0.0001
Nurse Pooled 125 133 1 0.1 <0.0001
Tech Pooled 203 137 3.2 2.7 ns
Rad Pooled 177 137 4.2 2.5 <0.0001
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Pooled Cardiologist 1 Cardiologist 2 Cardiologist 3
Cardiologist EPD reading per Angiographic Procedure (μSv)
Without Shield
With Shield
OVERALL
No of Procedures Median Dose in µSv
/procedure
p
Without With Without With
Cardiologist 1 23 25 22.2 7.5 0.0164
Cardiologist 2 49 42 13.7 5.05 0.00068
Cardiologist 3 43 20 14.8 12.25 ns
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RRA RFA
Pooled Cardiologist Doses for radial and femoral Access Type (Angio)
Without Shield
With Shield
Discussion
• Shield and drape do reduce exposure to cardiologists by a factor of two to three with reductions for other staff
• Similar exposure reduction equivalent to doubling of lead apron weight
• Reduction similar or better than that reported for drapes alone in the literature
• Operator and procedure effect is significant
Dose reduction achieved with
• No increase in patient dose area product
• No evidence of infection issues
• No interference with clinical workflow
Results Clinical
• Cardiologists found shield easy to use
• Differing approaches to placement of shield and pad
• Sterile covers were tight : scrub issue
Conclusion
“A novel shield/ drape design has led to occupational exposure reduction without increasing patient exposure in interventional cardiology”.