Transcript Instrumentation Quality Control

Managing Patient
Fluoroscopy
Dose
Christopher B. Martel, CHP
Director, Health Physics
Radiation Safety Officer
© 2010 University at Buffalo
Brigham and Women’s Hospital
Harvard Medical School
--Headline and photograph accompanying article published in USA Today [2] reporting jury
award of $1 million to 57-year-old man who sustained serious skin injury after two coronary
artery angioplasties that occurred 5 months apart
Berlin, L. Am. J. Roentgenol. 2001;177:21-25
Radiation Damage to Skin
Radiation Dermatitis
Radiation damage. There is loss of
dermal appendages.
Blood vessels are telangiectatic. (H&E)
Fluoroscopy Uses
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Anesthesia (Pain management)
Urology
Otolaryngology (Ear, nose, throat)
Orthopedics
Interventional Radiology
Emergency Room
Cardiac Catheterization
Electrophysiology
Interventional Neuroradiology
Radiation Oncology
Neurosurgery
Surgery
Gastroenterology (Endoscopy)
Image Intensifier
X-Ray Tube
Who is getting involved?
• CRCPD
– State Regulations
– Committee established to develop a list of reportable
events (including fluoroscopy)
• JCAHO Sentinel Event
– Prolonged exposure to single field resulting in >1500
rads
• NCRP Report 160
– Number of Interventional fluoroscopy procedures
increased eight fold over past 25 years
Typical Regulatory
Requirement
• Conduct Patient Dose Evaluations
• Report patient cumulative doses in
single procedure > 1 Gy to
Radiation Safety Committee
• Dose must be entered into the
patient’s medical record
• Perform follow up with patients
likely to have deterministic injury
• Physician must have fluoroscopy
priviliges
What’s Important?
Peak Skin Dose
The likelihood and severity of radiationinduced skin injury to the patient as a
whole are functions of the highest
radiation dose at any point on that
patient’s skin—the PSD.
Interventional Reference Point
For C-arm–type fluoroscopic systems with
an isocenter, the IRP is located along the
central ray of the x-ray beam at a distance
of 15 cm from the isocenter in the direction
of the focal spot.
Backscatter
• Backscattered radiation contributes 2745% to the measurement.
C J Martin 1995 Phys. Med. Biol. 40 823
• Backscattered radiation contributes 25 40% to the measurement.
S Balter 2010 Radiology 254 326-341
What methods are currently
being used?
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Time
GAFchromic film
Dose Mapping
Landauer Dots
Cumulative Air KERMA
Time
• Fluoroscopy time, although still used in
many healthcare institutions as an
indicator for skin dose, it is widely known
that there is little correlation between
fluoroscopy time and skin dose.
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GAFChromic Film
• Measures surface
peak skin dose
• Sensitive to dose
range 1cGy to
10Gy and energy
range 30KeV to
30MeV.
• Visually identify
areas of overlap
Landauer Nanodots
• Range is 10 mrad to
1500 rads
• +/- 5%
• Radiotranslucent
Graphical display of Caregraph
(Siemens Medical Solutions)
Chida, K. et al. Am. J. Roentgenol. 2006;186:774-778
Cumulative AIR Kerma
The air kerma accumulated at a specific
point in space relative to the fluoroscopic
gantry (the interventional reference point)
during a procedure. CD does not include
tissue backscatter and is measured in Gy.
CD is sometimes referred to as cumulative
air kerma.
J Vasc Interv Radiol 2004; 15:423–429
Which method should you use?
• What are you trying to do?
• According to ACR:
– Identify area to avoid in future procedures
– Identify patients likely to develop a radiationinduced skin injury – provide follow up
Brigham & Women’s Hospital
(BWH) Fluoro Dose Management
Goals
– Develop a tool that will facilitate:
• Compliance with regulations
• Allow monitoring of physician
“performance” to guide best practices and
identify opportunities for quality
improvement
• Allow monitoring of procedures to compare
with other institutions and published data
BWH Results
• Groups that perform fluoroscopically
guided procedures with potential to
exceed 1 Gray.
– Electrophysiology
– Cardiac Catheterization
– Interventional Radiology
– Interventional Neuro-radiology
– Neurosurgery
Physician
Patient undergoes
fluoroscopic guided
procedure
< 1000 mGy
No further
action required
>1000 mGy
MD notes dose
in patient’s
medical record
Procedure info
added to database
by MD designee
HP
< 5,000 mGy
Health Physics
reviews
database daily
HP Reports all
>1Gy exposures
to RSC in
bimonthly report
>5,000 mGy
> 15,000 mGy
MD gives patient
discharge
instructions
No further
action required
Health Physics
sends letter to
attending requiring
follow up
HP notifies Risk
Management of
potential Sentinel
Event
Physician
schedules
follow up visit
in 2 to 4 weeks
Physician follows up
with patient and if
injury present provides
referral to Dermatology
Risk Management
reviews and makes
determination
Patient Fluoroscopy Dose
Management and Reporting
Desirable Features for BWH
Patient Dose Tracking Program
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Web-based
Secure
Editing/tracking
Searchable
Statistical Analysis
Reporting
(Inventor of the Internet)
What we are doing
• Track ALL fluoro procedures in EP, CC, IR
and INR
– Cumulative Air Kerma
– Fluoroscopy Time
– Attending Physician
– MRN
– Referring Physician
Other Features
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Median dose for every procedure
Statistics for each physician by procedure
Sum fluoro doses for each patient
Record patient dose and follow-up
information
• Cross referenced with physician
credentialing database
• Drop down menus tailored to groups
based on their log in
Dashboard
By Physician
Physician Name Here
By Procedure
Physician
Names
Here
By Multiple Procedures
for Individual Patients
Patient
MRNs
Here
Summation of
Patient Cumulative Air Kerma
MRN Here
Physician
Names
Here
Make notes on cases
Interventional Reference Levels
IRL = 75th Percentile
AHD = (1.5 * IQR) + 75th Percentile
Looking at the Data
• Median CAK for 38 of 39 procedures is
below 500 milliGray
• 75th percentile of CAK for 36 of 39
procedures is below 1,000 milliGray
• Outlier CAK for 34 of 39 is below 2,000
milligray
Conclusions
• For most interventional procedures at
BWH, a CAK greater than 2,000 mGy
should be rare. Exceptions are:
– Percutaneous Coronary Interventions
– Device upgrade ICD-CRT
– Ventricular Epicardial Ablations
Conclusions (cont)
Individual Cases
>1 Gray – reported
to RSC and noted
in EMR
>5 Gray – Follow up
with patient
>15 Gray –
Investigation for
SE
Physician Data
Median for
procedure > 1
Gray – reported to
Dept Chair for
evaluation
Conclusions (cont)
What gets measured,
gets managed!
• Over 8,000 cases in database so far
(January 1, 2009 to present)
• Developed BWH-specific Interventional
Reference Levels (IRLs)
• Provide quarterly reports of physician fluoro use
to Department Chairs, Chief Medical Officer,
individual physicians