Transcript 137Cs Blood Irradiator

Radiation protection review for
credentialed fluoroscopy operators @ BWH
Dept. of Health Physics and Radiopharmacology
Brigham and Women’s Hospital
Radiation protection review for
credentialed fluoroscopy operators @
BWH
Purpose:
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Review safe practices of fluoroscopy, including
radiation protection strategies for patients and staff
Review occupational dosimetry program
Comply with Massachusetts regulations
Stimulate dialogue amongst fluoroscopy users and
radiation oversight committees
Radiation protection review for
credentialed fluoroscopy operators @
BWH
Who is responsible for fluoroscopy oversight?
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Government
US FDA
guidance/advisories for manufacturers, users, and public
Massachusetts Dept. of Public Health
inspects and enforces regulations in Massachusetts
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Accreditation organizations: JCAHO, ACR
BWH Radiation Safety Committee
Medical Directors of Radiology, Cardiology, etc.
Radiation protection regulations
105CMR120- Mass. Regulations for the Control of Radiation
120.400:
X-RAYS IN THE HEALING ARTS
120.405:
Fluoroscopy
Describes:
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Shielding requirements
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Tube output, beam filtration and limitation
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Exposure and dose rate limits
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Recording of fluoroscopy time and dose
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Protection from scattered x-rays
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Operator qualifications………
Radiation protection regulations
120.405:
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X-RAYS IN THE HEALING ARTS
Operator Qualifications.
(1) A facility shall ensure that only a licensed physician or
a radiologic technologist who is trained in the safe use of
fluoroscopic x-ray systems licensed in accordance with 105
CMR 125.000 shall be allowed to operate these systems. All
persons using fluoroscopic x-ray systems shall have, at a
minimum, documented training in the topics specified 105
CMR 120.405(K)(2).
Radiation protection regulations
120.405:
X-RAYS IN THE HEALING ARTS
Describes: Operator training:
(2) Training to meet requirements of 105 CMR 120.405(K)(1) shall
include, but not be limited to the following:
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and
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(a)
(b)
(c)
(d)
(e)
(f)
Principles and operation of the fluoroscopic x-ray system;
Biological effects of x-ray;
Principles of radiation protection;
Fluoroscopic outputs;
High level control options;
Dose reduction techniques for fluoroscopic x-ray systems;
(g) Application requirements of 105 CMR 120.000.
Radiation protection regulations
120.405:
X-RAYS IN THE HEALING ARTS
Describes: Operator training:
(3) The facility shall maintain all records relating to compliance with
the training requirements for five years.
(4) The facility shall establish policies and procedures for restricting
the use of fluoroscopic systems to only those physicians who
have been granted privileges for the use of fluoroscopy based
on a determination of adequate training and knowledge of the
curriculum of 105 CMR 120.405(K)(2).
(5) The facility shall ensure that all non-radiologist physician using
fluoroscopy equipment obtain annual training in Radiation
Safety/Radiation Protection and maintain all records relating to
compliance with this training requirement for five years.
Fluoroscopy safety training @ BWH
Since 1990:
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All new fellows, residents, and attending physicians
undergo a training course with take-home reading
materials, exam, and fluoroscopy competency
assessment.
Upon successful completion, are issued a certificate
and entered into BICS as holding Fluoroscopy
privileges
Ad hoc retraining/radiation safety in-services
presented
Fluoroscopy safety training @ BWH
As of 2008 (non-radiologist physicians):
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BICS Fluoroscopy privileges will expire annually
Recertification takes place by viewing study materials
and retuning quiz to Health Physics
Ad hoc retraining/radiation safety in-services
presented
Somatic and genetic damage
depends on exposure parameters
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the quantity of ionizing radiation to which the subject
is exposed
the rate of exposure
the ionization ability of the radiation
the volume of tissue exposed
the types of tissues exposed
Radiation Units
Activity
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Disintegration/sec=1 Becquerel (Bq)
37 billion Bq = 1 curie
Dose (Absorbed)
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1 joule/kg=1 Gray(Gy)
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1Gray=100 rad =100,000 mrad
Dose (Equivalent)
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Gray x quality factors= Sievert (Sv)
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1 Sievert =100 rem =100,000 mrem
U.S. Dept. of Energy
Biologic Effects of Ionizing Radiation (IOM) BEIR VII, 2005
Radiation risks
Stochastic effects
(= non-threshold, increasing probability with dose)
genetic mutation
genomic instability
cancer induction
DNA is the most important molecule
that can be changed by radiation
Effects of DNA Damage
A gene may
respond to the
radiation by
changing its signal
to produce
protein. This may
be protective or
damaging.
Cell Killing
Chromosome
Aberrations
Gene Expression
Gene Mutation
Sometimes a
specific gene is
changed so that it is
unable to make its
corresponding
protein properly
Sometimes the
damage effects the
entire chromosome,
causing it to break or
recombine in an
abnormal way.
Sometimes parts of
two different
chromosomes may be
combined
Genomic
Instability
Sometimes DNA
damage produces
later changes which
may contribute to
cancer.
Damaged DNA
may trigger
apoptosis, or
programmed cell
death. If only a
few cells are
affected, this
prevents
reproduction of
damaged DNA
and protects the
tissue.
Studies have shown that most radiation-induced DNA
damage is normally repaired by the body
U.S. Dept. of Energy
Review for credentialed fluoroscopy
operators @ BWH
Risks of radiation exposure:
In 2004, ionizing radiation classified as a known carcinogen by the
US. National Toxicology Program.
The category "known to be a human carcinogen" is reserved for
those substances for which there is sufficient evidence of
carcinogenicity from studies in humans that indicates a causal
relationship between exposure to the agent, substance, or
mixture and human cancer."
Radiogenic cancer = stochastic risk
E. Picano, BMJ 2004
Radiation risks
(non-stochastic)
Commonly referred to as deterministic effects:
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threshold-related symptoms
worsen with dose
includes:
Skin changes
(erythema /hair loss/ulceration)
Cataracts
Teratogenesis
Doses in interventional procedures
Effect
Threshold
dose (Gy)
Minutes fluoro Minutes fluoro
at 0.02 Gy/min at 0.2 Gy/min
Transient erythema
2
100
10
Permanent epilation
7
350
35
Dry desquamation
14
700
70
Dermal necrosis
18
900
90
Telangiectasia
10
500
50
Cataract
>5
>250 to eye
>25 to eye
Not known
Not known
Not known
Skin cancer
from ICRP 85, Interventional procedures-avoiding radiation injuries
Radiation – dose limits, patients?
Even with increased utilization of imaging procedures
and image-guided interventions, there is no maximum
permissible dose or procedure volume for medically
indicated procedures.
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Weigh risk vs. benefit
Advise patient if deterministic effect possible
If patient is pregnant, consider limited exam, or alternative
(MRI, sonography)
Utilize dose-saving protocols
Fluoroscopy dose-saving protocols
Whenever and wherever possible:
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Limit beam-time on (use last image hold)
Reduce tube current (mA)
Use lower pulse sequence fluoroscopy
Limit magnification
Maintain adequate x-ray source-skin distance
Keep Image intensifier as close as possible to patient
Apply positive beam limitation (collimators)
Record* and minimize fluoroscopy time
Fluoroscopy dose reporting
105 CMR 120 (as of 6 OCT 2006)
Each facility performing fluoroscopically-guided
interventional procedures shall conduct patient dose
evaluation for any procedure that has a reasonable
probability of resulting in a deterministic injury as
further defined in 105CMR120.405(L)(5). *
* Any cumulative absorbed dose to the skin equal to or
greater than 1 Gy (100 rads)
Review for credentialed fluoroscopy
operators @ BWH
* Record and minimize fluoroscopy time
Fluoroscopy procedures in which the dose exceeds
1,000 mGy are reported to Medical Physics for dose
calculations which are then sent to the:
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Radiation Safety Officer
Radiation Safety Committee
In some instances, the patient’s primary care physician
will be notified for deterministic effect surveillance and
patient follow-up.
Sample dose
calculation,
Medical Physics
Why limit exposure to pregnant
patients (and staff)?
Law of Bergonié and Tribondeau = rapidly dividing, less
differentiated cells more sensitive to radiation effects
…..therefore the conceptus is at higher risk.
Pregnant females should not be irradiated unless
absolute medical necessity
Pregnant radiation workers restricted to much lower
doses.
Probability of bearing healthy children as
a function of radiation dose
from ICRP 84, Pregnancy and radiation
Dose to
conceptus (mGy)
above natural
background
Probability of no
malformation
Probability of no
cancer (0-19 years)
0
97
99.7
1
97
99.7
5
97
99.7
10
97
99.6
50
97
99.4
100
97
99.1
>100
Possible, see text
Higher
Conceptus dose, interventional procedures
(mGy)
For BWH-specific protocols, please see:
http://brighamrad.harvard.edu/education/fetaldose/
Part III-Occupational
exposures and radiation
protection program
Schematic provides a graphical representation of definitions of radiation safety
terms as they are used in radiation protection (with an x-ray tube as the radiation
source)
Brateman, L. Radiographics 1999;19:1037-1055
Copyright ©Radiological Society of North America, 1999
Scattered radiation fields
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Various studies have shown scattered radiation in a
fluoroscopy procedure
room will range from 0.03 to 0.5 R per hour of
actual x-ray beam time.
D. Allard, CHP; Health Physics Society
Radiation – dose limits for staff
Maximum permissible dose, annual limits:
Occupational workers:
Whole body = 5,000 mrem/yr (= 50 mSv)
Eyes = 15,000 mrem/yr (= 150 mSv)
Skin = 50,000 mrem/yr (= 500 mSv)
Radiation – occup.dose limits
If declared pregnancy
= 500 mrem/gestational period (5.0 mSv)
= not to exceed 50 mrem/month
(0.5 mSv)
Radiation safety strategies
Decrease time around source
Increase distance from source
Use appropriate shielding
Contamination control (PPE)
Monitor badge reports - ALARA
Intensity of the radiation dramatically
drops off with distance, due to the inverse square
law:
I1/I2 = D2 2/D12
Sample: exposure rate @ 0.5 m = 50 mR/hr
What is the exposure rate @ 1.5 m
(50mr/hr)/( ? mr/hr) = (1.5 m)2 /(0.5 m)2
50/x = 2.25/0.25
50/x = 9.0
50 = 9x
x = 50/9
=
5.56 mR/hr @ 1.5 m
Staff and trainees working with ionizing
radiation are issued monthly radiation
dosimeters. You may be issued:
- a single collar badge, with red icon (WORN ABOVE Pb APRON)
- a single whole body badge, with black icon (WORN BELOW Pb
APRON)
- both badges, if you regularly operate the fluoroscope during
interventional studies.
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a ring badge, if you handle > 1.0 mCi of radionuclides
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a fetal dose monitor, if pregnancy declared
- an Area monitor badge will be placed in your workspace if little to no
exposure is anticipated
Dosimeter exposure estimates calculated
several ways
EDE 1 – 2 dosimeters; one worn at waist (under Pb
apron), the other at collar level (outside of Pb apron)
Assigned deep dose
=[1.5 (waist) + 0.04 (collar)]
most commonly done with routine fluoroscopy
Dosimeter exposure estimates
EDE 2 – one whole body dosimeter worn at collar level
(outside of Pb apron)
Assigned deep dose
= 0.3 x (whole body badge)
most commonly used for occasional fluoroscopy
users
BWH Deep dose equivalent
(~ 99% < 500 mrem)
2009 BWH Deep dose equivalent
N = 1530 (98.5% < ALARA I)
900
ALARA I
(10% MPD)
807
800
700
605
# of staff
600
500
400
300
200
100
28
35
50-99
100-199
15
17
16
7
200 -299
300 -499
500 -999
1000 -1999
0
<1.0 mrem
1-49
DDE (mrem)
2000+
As Low as Reasonably Achievable
(ALARA) – staff notified if dose
exceeds 10% of MPD
Sample ALARA notification/response
BWH Radiation Safety Contacts
Health Physics & Radiopharmacology
Main # = 617 732 6056
24 hr emergency pager = 33330
Christopher Martel, MS, DABHP
Director & Radiation Safety Officer
= 617 732 6057
A. Robert Schleipman, RT, CNMT, MSc
IRB, Occupational Dosimetry, Training
= 617 732 5963
Medical Physics, Radiology
Richard Nawfel, MS
Dose calculations, equipment testing, training
= 617 732 7201
Radiation Safety Liaisons have been established
for each area to assist you with badges, PPE,
etc.
CDIC = Kelley Grassi, RT
EP Lab = Jim McConville, RT, CNMT
Endoscopy = Sandra Cialfi, RN
Pain Management = Diane Palombi, RN
Interventional Radiology = Carol Upson, RT
Diagnostic (L1) Radiology = Charles David Healy, RT
Emergency Dept. = Angela McLaughlin, RT
Nuclear Medicine = Victor Gerbaudo, PhD
O.R. Nursing = Mike Bickerstaff, RN
O.R. Radiology equipment = Steve Kenary, RT
Radiation protection review for
credentialed fluoroscopy operators @
BWH
Process:
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BICS fluoroscopy credential expires annually*
Participant reviews slide show
Participant contacts RSO with any questions
Participant completes and returns quiz
BICS Fluoroscopy credentials renewed for 12 months
*Radiologists, by nature of their continuing education
requirements, are exempt from annual radiation
safety/fluoroscopy retraining