What is cataract?
Radiation & Cataract: A New Challenge
Clouding or opacification of the natural lens of the
eye and obstructing the passage of light
Madan Rehani, PhD
Radiation Protection of Patients Unit, IAEA, Vienna, Austria
Lawrence Dauer, PhD
Medical Physics, Memorial Sloan-Kettering Cancer Center
M.Rehani@iaea.org
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Cataract


Lenticular Opacification
Risk Factors:
 Corticosteroids
 Diabetes Mellitus
 Sunlight exposure (UVB)
 Trauma
 Infections
 Nutritional deprivation
 Age (~ 50% >65 yrs)
 Heredity
 Radiation
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What is treatment?
Phacoemulsification
• Eye's internal lens is emulsified with an
Easily treatable condition -surgery
ultrasonic handpiece
• Aspirated from the eye.
• Aspirated fluids replaced with irrigation of
balanced salt solution
Nothing to match natural
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Radiation & Cataract


Dot Opacities
Latency depends on rate at
which damaged epithelial
cells undergo fibrogenesis
and accumulate.
HOT Topic in Occupational Radiation
Protection
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Unlike Patients where……..
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Capsule
Epithelium
Epithelium
nucleus
CORNEA
LENS
ANTERIOR
CHAMBER
PSC
Cataract
Capsule
a.
b.
3
Major Cataract Subtypes
• Cortical
• Nuclear
• Posterior SubCapsular (psc)
• Mixed
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History of radiation cataract
History of radiation cataract-II
• However, cataract was long thought to result
• Documented within 1 year of Roentgen’s
from only high doses of radiation to the lens of
the eye.
• This was based on data from early cyclotron
workers with cataract after substantial
neutron doses and
• with early Japanese A-bomb studies that
reported excess cataracts among those who
received over 2–3 Gy.
discovery of X rays
• H. Chalupecky, Ueber die wirkung der
Roentgenstrahlen. Centralblatt fuer
praktische Augenheilkunde (J. Hirschberg
Ed.), pp. 386–401. Veit, Leipzig, 1897.
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Up to early 1950’s
• W. Rohrschneider, Beitrag zur entstehung und
morphologie der ro¨ntgenstrahlenkatarakt. Klin.
Monatsbl. Augenheilkd. 81, 254–259 (1928).
• A. U. Desjardins, Action of Roentgen rays and radium
on the eye and ear. Am. J. Roentgenol. 26, 643–679
(1931).
• P. J. Leinfelder and H. D. Kerr, Roentgen-ray cataract:
An experimental, clinical, and microscopic study. Am. J.
Ophthalmol. 19, 739–756 (1936).
• D. G. Cogan and K. K. Dreisler, Minimal amount of xray exposure causing lens opacities in the human eye.
AMA Arch. Ophthalmol. 50, 30–34 (1953).
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Beliefs based on data in late 1950’s
• G. R. Merriam and E. Focht, A clinical study of
radiation cataracts and the relationship to dose.
Am. J. Roentgenol. Radium Ther. Nucl. Med. 77,
759–785 (1957).
• G. R. Merriam and E. F. Focht, A clinical and
experimental study of the effect of single and
divided doses of radiation on cataract
production. Trans. Am. Ophthalmol. Soc. 60, 35–
52 (1962).
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• Cataract has a dose threshold
• The severity increased and the latency decreased
as the radiation dose increased above that
threshold
• Latent period was strongly inversely correlated
with dose and that there was no cataract
induction below 2 Gy.
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Other major papers that influenced
ICRP 60 and 103
• M. D. Nefzger, R. J. Miller and T. Fujino, Eye
findings in atomic bomb survivors of Hiroshima
and Nagasaki: 1963–1964. Am. J.Epidemiol. 89,
129–138 (1969).
• M. Otake and W. Schull, Radiation-related
posterior lenticular opacities in Hiroshima and
Nagasaki atomic bomb survivors based on the
DS86 dosimetry system. Radiat. Res. 121, 3–13
(1990).
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NCRP
• Visually disabling cataracts of 2–10 Sv
for single brief exposures, and 0.8 Sv for
protracted exposures
…However, new data on the radiosensitivity of the eye with
regard to visual impairment are expected.
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What is New?
Odds Ratio
• Is a measure of effect size, describing the
Lens opacities being reported at
dose levels below the currently
mentioned threshold in ICRP,
NCRP
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A-Bomb Survivors
Neriishi et al, Rad Research
168:2007
strength of association or non-independence
between two binary data values.
• Odds ratio treats the two variables being
compared symmetrically, and can be estimated
using some types of non-random samples
• Ratio of the odds of an event occurring in one
group to the odds of it occurring in another group
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A-Bomb Survivors
Minamoto et al, Int. J Rad Biol
80(5):2004
• Operative Cataract odds
• Prevalence of cortical and
ratio of
~1.4 at 1 Gy
• Dose threshold seen at
0.1 Gy (upper bound of
0.8 Gy).
posterior subcapsular
opacities showed significant
correlation with radiation dose
• Odds ratios of
~1.3 at 1 Gy
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Chernobyl
Airline Pilots
Rafnsson et al, Arch
Ophthalmol. 123:2005
Worgul et al, Rad Research
167:2007
• Dose effect threshold
• Cosmic radiation may
< 1 Gy
• UN Chernobyl Forum 2006
be a causative factor in
nuclear cataracts.
• Note – some have
disagreed with this
assertion
• Even low doses of
0.25 Gy may also be
cataractogenic.
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Astronauts
Aviators / Astronauts
Jones et al, Aviat Space
Environ Med 78:2007
• Military aviators with
cataracts were found to have
a younger average age at
onset compared with
astronauts.
• Prevalence of cataracts was
found to be higher in
astronauts than aviators.
Cucinotta
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2001
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Astronauts
Infancy Exposures
Hall et al, Rad Research
152:1999
Cucinotta et al, Rad Research
156:2001
• Children exposed to lenticular
• Relatively low doses of space
doses during skin hemangioma
treatments 1920-1959
• Odds ratio for developing
posterior subcapsular cataract
1.5 at 1 Gy
• Odds ratio for developing
cortical opacity
1.35 at 1 Gy
radiation are causative of an
increased incidence and early
appearance of cataracts
• Increased risk with higher
lens doses > 8 mSv
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Chronic Low Dose Exposures
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Interventional Radiologists
Haskal & Worgul,
RSNA News 2004:14
• Radiologists
• 5/59 posterior
subcapsular cataracts
• 22/59 small dot-like
Chen et al, Rad Research 156:2001
• Contaminated buildings in Taiwan
• Minor lenticular changes in lenses of young subjects
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opacities (early signs
of radiation damage)
• 1/59 had undergone
cataract surgery in one
eye
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Schueller et al, Radiographics 2006
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Strength of newer studies over earlier ones
• Negative aspects of earlier studies:
• Inspection of the Merriam and Focht papers
• short follow-up periods,
• failed to take into account increasing latent periods
shows that the observation periods after
irradiation were mostly quite short (average of 8
years)
• They studied only 20 individuals who had
estimated lens doses under 2 Gy,
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with decreasing doses,
• relatively few subjects with doses below a few Gy.
• Positive aspects of newer studies: Long followup, larger numbers, lower doses
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Why longer follow-up?
• The latent period is dependent on the rate at
which damaged epithelial cells undergo aberrant
differentiation (fibergenesis) and accumulate in
the PSC region of the lens cortex .
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Active collaborators
Eliseo Vano
Ariel Duran
Norman Kleiman
KH Sim
IAEA Cataract
A Minanoto
Olivera Ciraj Raul Ramirez
A Nader
Plus a team ofRehani
local
ophthalmologists
& Dauer
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Objective
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Background
• Since we are concerned with
determination of effect, we need
doses incurred in past, not
prospective
• Non-availability of records of
measured values from routine
individual monitoring
• Non-availability of widely accepted
methods for retrospective
estimation
To examine the prevalence of radiationassociated lens opacities among interventional
cardiologists and technical staff and correlate
with occupational radiation exposure
• Not purely a doismetry or effect study
• Dose and effect
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Interventional procedures
• Limited occupational dose data, USA/Canada??
• 20-30% of cardiologists do not use dosimeter
Vano et al, Radiology, 2008:
routinely (Vano et al, BJR, 2006, 79:383-388)
• In developing countries 40-90%
• Errors in use of dosimeters:
• Identification
• Interchange
• Use of protective devices??
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Dose information for various studies (I)
Model
Value
Unit
Source
Remark
n/a
59
µSv/proc
Tsapaki ate all, PMB, 2004
CA, 5 countries, shoulder
dose
n/a
89
µSv/proc
Tsapaki ate all, PMB, 2004
PTCA, 5 countries,
Shoulder dose
Philips Optimus M
200 Poly C
260
mSv/y
Vano, et al, BJR, 2006
5000 procedure/y
Philips
Integris HM 300
31
mSv/y
Vano, et al, BJR, 2006
5000 procedure/y
Philips
Integrtis N-5000
18
mSv/y
Vano, et al, BJR, 2006
5000 procedure/y
Philips
Integrtis Allura
Philps
Polydiagnost C2
3.5
0.21-0.37
mSv
mSv/proc
Kuipers et al, Cardiovas Int
Rad, 2008
Steffino, et al BJR 1996
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Dose information for various studies (II)
4 weeks, TLD above the
apron
Ceiling screen in place
Model
Value
Unit
Source
Remark
Philips Integris Allura
3.85
mSv/4 weeks
Kuipers et al, J
Inte Card, 2008
TLD dose above the apron, mean value for 7
radiologists
Average 35 institutions
48
mSv/y
Niklason at al,
Radiolgy, 1993
972 procedures/y, dose above the apron
Philips Integris 3000, II
GE L-U, II
6.55
mSv/month
Williams, BJR,
1997
46 procedures/month, neck dose
Not available
Figure 2.b
µGy/min
Whitby, et al,
BJR, 2005
PTCA
Different types of systems,
average values
0.5 (IC)
0.15 (nurses)
mSv/proc
Vano et al, BJR ,
1998
Without protective tools
Philips Integris V 3000
Figs 3.4,6,7
µGy/min
Whitby, BJR,
2003
Diagrams for PA, RAO, LAO projections
Not available
0.11
mSv/proc
Pratt and Shaw, BJR, 1993
Ceiling screen and
Goggles in place
CGR DG 300
0.014
mSv/proc
Marshall et al, BJR 1995
Eye dose, lead shield
Siemens
Angioskop D
0.28
mSv/proc
Calkins et al, circulations,
1991
Eye, Ceiling screen in place
Different units
Table 3
µ Sv/proc
Vano, et al, BJR,
1998
TLD dose, eyes, with and without protective screen
Philips Alura
10FD/20FD. GE
Advantix, Philips
Intergris 3000/5000,
Siemens Axiom bip A
Table 1
Sv//h
Vano et al. Radiology 2008.
Dose rate at 1 m. h=1.6 m
for different modes (fluoro.
cine..)
Philips Integris HM 3000
Figs 4.5. 711
µGy/min
Morrish et al
BJR, 2008
Scatter dose rate for fluoroscopy and acquisition for
different projections
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Remarks
Our Decision
• Reported eye lens doses:
• Typical doses if protective devices are not used
• 0.3-11 mGy/study (without use of protective devices)
• 0.011-0.33 mGy/study (with protective devices)
• 0.5 mGy/procedure for interventional cardiologists
• 0.15 mGy/procedure for and nurse
• This exposure corresponds to a typical procedure
of 10 min of fluoroscopy and 800 cine frames
• Multiple dosimetry quantities: air kerma, H*(10),
Hp(10), Hp(3)…)
• Inaccuracy in dose assessment for nurses due to large
variability of location and multiple tasks performed
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Radiation dose assessment
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Materials and methods
• Interventional
Typical doses if protective devices are not used:
•0.5 mGy/procedure for interventional cardiologists
•0.15 mGy/procedure for and nurse
Workload:
•number of procedures per week
•fluoroscopy time
•number of cine series per procedure
•number of frames per series
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cardiologists
and nurses
• Control group
Use of protective devices:
•ceiling suspended screens (factor: 0.1)
•leaded glass eyewear (factor: 0.1)
Angulations (factor: 1.8)
Radial access (factor: 2.0)
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Dose related parameters (I)
Parameter
Dose related parameters (II)
Source
Number of years in interventional cardiology
form
Model of fluoroscopy system used (in the past/now)
form
Use of ceiling suspended screens (in % of time period), S
form
Use of goggles (in % of time period), G
form
Workload: number of procedures/week
form
Fluoroscopy time/procedure
form
No of frames/procedure
(no of frames/series and series/ procedure)
form
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Parameter
Source
Value
Attenuation of goggles, A
literature
90%
Attenuation of ceiling suspended screen, B
literature
90%
Distance from isocenter
literature
75 cm
For particular procedure. for different models
of interventional systems at eye level scatter
dose:
• Dose rate [Sv/h]
• Normalized dose rate [Sv/mAs]
• Total dose for typical procedure [Sv/study]
literature;
different
sources to
match the
model of the
system
Angulations
literature:
Vano, 2006
Batsou, 1998
Morrish, 2008
Radial access
literature:
IAEA, 2004
Vano, 2008
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Calculation
100
ISL
1.8
2
54
Betsou et al.
BJR, 1998
Vano et al.
Radiology, 2008.
Average
TIME (%)
mSv/h
mSv/h
PA
11.50
1.00
0.12
PA CD
0.50
1.00
0.01
PA CR
5.90
1.00
0.06
RAO
7.50
1.00
0.08
RAO CD
15.80
1.00
0.16
RAO CR
4.20
1.00
0.04
LAO
26.30
2.00
0.53
LAO CD
11.90
2.50
0.30
LAO CR
15.10
3.00
0.45
L LAT
1.30
5.00
0.07
PROJECTION
•Typical exposure parameters from the
literature for a particular or similar type if
system (10 min fluoroscopy time and 800
cine frames)
•Same a previous
100.00
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S (1  B )
Angulation for typical procedure (CA)
Information about model of the
•Scattered dose rate
unit, workload and typical
•Correction for distance, use of protective
procedure parameters are available devices, angulation, radial access
•Dose ate eye level for typical procedure
•Annual dose/dose for the whole period use
of a particular system
Information about model and
workload is available
(procedure parameters are not
available)
G (1  A )
1
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Dose assessment
Scenario
Factor
1
55
1.8
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14
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Assessment of lens change
• Dilatated slit lamp
examination
• Merriam-Focht scoring
system
• Scores: 0-3.0
• Scores >2.0 correlate
with visual acuity
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Results
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PSC changes (score > 0.5)
CCI has the highest impact factor of all journals
focusing on interventional/invasive therapies.
IF≈ 2.5
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Interventional
cardiologists
Nurses
Control group
No
56
11
22
No of years in
interventional
cardiology
Age*
(y)
42 ± 7
(31-64)
38 ± 11
(25-53)
44 ± 9
(29-57)
9.2 ± 6.9
(1.0-33)
6.0 ± 4.6
(1.0-14)
n/a
66
Dose response for posterior lens changes in cardiologists and
nurses and associated odds ratios (OR). relative risk (RR)
and 95% confidence intervals (CI)
Subjects and cumulative radiation dose
to the lens of the eye
Subjects
Nurses:
• Prevalence 45% (5/11. 95%
CI: 15-100)
• Significance (Fisher exact
test): p<0.05
• Relative risk: 5.0 (95% CI:
1.2-21)
Interventional cardiologists:
• Prevalence 52% (29/56. 95%
CI: 35-73)
• Significance (Fisher exact
test): p<0.001
• Relative risk: 5.7 (95% CI:
1.5-22)
Cumulative dose
to the lens (Gy)*
3.7 ± 7.5
(0.02-43)
1.8 ± 3.1
(0.01-8.5)
Number of subjects
with posterior lens
changes*
OR
22
2 (9%)
31
12 (39%)
1<2
11
2-<3
9
≥3
16
Dose (Gy)
Number of
subjects
0 (Control)
<1
95% CI
RR
95% CI
1.0
n/a
1.0
n/a
6.3
1.2-32
4.3
1.0-17
5 (45%)
8.3
1.3-54
5.0
1.1-22
5 (55%)
12.5
1.7-89
6.1
1.4-26
12 (75%)
30
4.7-189
8.3
2.1-32
34 (51%)
10.3
2.2-48
5.6
1.4-21
n/a
*mean ± standard
deviation;
values
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*cataract grade 0.5 or higher in one eye 68
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Number of interventional cardiologists with posterior lens changes graded by
severity of lens changes with associated cumulative doses to the lens of the eye
Dose (Gy)
Score
N
(%)
mean
median
min
max
0 in both eyes
27
48
1.6
0.94
0.02
7.4
0.5 in one eye
8
14
2.4
1.8
0.04
8.4
0.5 in both eyes
18
32
7.4
1.3
0.02
43
>1 in one eye
(0.5 or more in the other eye)
3
5
3
2.8
0.24
4.5
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Vano, E., Kleiman, N.J., Duran, A, Rehani MM, D Echeverrie,
M Cabreraf. Radiation cataract risk in interventional
cardiology personnel. Radiat. Res. 174, 490-5 (2010).
IF≈3.1
• 116 exposed individuals and 93 similarly aged
non-exposed controls
• Relative risk of psc opacities in IC was 3.2 (38%
compared to 12%; p<0.005).
• 21% of nurses and technicians
• Cumulative median values of lens doses were
estimated at 6.0 Sv for cardiologists and 1.5 Sv
for associated medical personnel.
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Conclusions from IAEA studies
Limitations
• Threshold value, if any, is much lower that
• Opacities that had not progressed to cause
current guidelines indicate
• Dose-response relationship between
occupational exposure and the prevalence of
radiation-associated posterior lens changes
• There is a need to find better means for eye
lens dosimetry
• First ever report among this group
significant visual disability
• Preliminary investigation of the dose response
relationship
• A study of a larger cohort is needed
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Shielding & Positioning
Use Barrier Shielding for Body and Eye Protection
Be aware of Staff Location
• Lens of the eye, threshold in absorbed dose is
now considered to be 0.5 Gy (against 0.5 to 2 for
detectable opacities and 5 for visual impairment) .
• Occupational Exposure Lens of Eye Limit
• 20 mSv in a y (against 150), averaged over
defined periods of 5 y, with no single y exceeding
50 mSv
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Shielding & Positioning
Eye Shielding Imperative
• Leaded Ceiling Shield
98% reduction.
• Leaded Glasses Shield
~74-91%
• Differences in
performance related to
operator position,
likely representing
interplay of design and
fit.
• Sports wraparound or
side shields important.
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Mitigation Efforts
Training & Self-Evaluations
(Training, Behavior Modification & Shielding)
• Operators and Staff should be trained in the
~45% drop in 3 years
machine operation and radiation protection.
• Free Training Programs:
• IAEA has free training program
Average IR LDE by Year
60
50
• http://rpop.iaea.org/RPOP/RPoP/Content/40
LDE (mSv)
AdditionalResources/Training/1_TrainingMaterial/Radiology.htm
• MARTIR (Multimedia and Audiovisual
Radiation Protection Training in Interventional
Radiology)
20
10
• http://ec.europa.eu/energy/wcm/nuclear/cd_rom_martir_project.zip
• Perform frequent Self-Evaluations / Audits
30
0
2003
Lieto and Jackson, 2000.
2004
2005
2006
2007
2008
Years
Dauer, 2008
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Additional Resources
Additional Resources
CVIR-JVIR, 2010
• http://rpop.iaea.org = IAEA Radiation Protection of Patients
• http://rpop.iaea.org/RPOP/RPoP/Content/Documents/TrainingRadiolo
gy/Lectures/RPDIR-L16.2_Fluoroscopy_doses_WEB.ppt
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Learning Objectives
d
IAEA
1. To understand the basic information about
radiation cataractogenesis
2. To understand the efficacy of protective tools
3. To become aware about the most recent changes
in recommendation by the ICRP on reduction in
eye lend dose limit
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