Transcript IAEA Training Material on Radiation Protection in Cardiology

International Atomic Energy Agency
Radiation risks in paedriatic
interventional cardiology
L 10
Educational Objective
1. Unique considerations in paediatric
patients having bearing on patient dose
2. How can dose be managed in paediatric
patients
Radiation Protection in Cardiology
Lecture 10: Radiation risks in paediatric interventional cardiology
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Unique Considerations for Radiation
Exposure in Children
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There are two unique considerations in children:
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Children are considerably more sensitive to radiation than adults
Children also have a longer life expectancy, resulting in a larger
window of opportunity for expressing radiation damage.
As an example, compared with a 40-year old, the same radiation
dose given to a neonate is several times more likely to produce a
cancer over the child's lifetime.
Great attention to not optimised procedures in CT examinations:
•
•
the same exposure parameters used for a child and an adult will result
in larger doses to the child
there is no need for these larger doses to children. Currently,
adjustments are not frequently made in the exposure parameters
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Lecture 10: Radiation risks in paediatric interventional cardiology
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Unique Considerations for Radiation
Exposure in Children
CT as a Diagnostic Tool
It will address the following issues:
• CT as a diagnostic tool
• Unique considerations for radiation
• Radiation risks from CT in children: a public health issue
• Immediate strategies to minimize CT radiation exposure to
children
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Lecture 10: Radiation risks in paediatric interventional cardiology
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Risk probability for stochastic effects as a
function of age at exposure
0.20
Death per 0.16
Sievert
(Sv)
0.12
Female
Male
0.08
0.04
0.00
0
15
30
45
60
75
90
Age at Exposure
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Lecture 10: Radiation risks in paediatric interventional cardiology
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Epidemiology evidences (I)
Ionizing radiation and cancer risk: evidence from
epidemiology
Ron E. Radiat Res. 1998 Nov;150(5 Suppl):S30-41
• ….. For all solid cancers combined, cancers of the
thyroid, breast and lung, and leukemia, risk
estimates are fairly precise, and associations have
been found at relatively low doses (<0.2 Gy).
• Associations between radiation and cancers of the
salivary glands, stomach, colon, bladder, ovary,
central nervous system and skin have also been
reported, but the relationships are not as well
quantified. …..
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Lecture 10: Radiation risks in paediatric interventional cardiology
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Epidemiology evidences (II)
Radiation-induced skin cancer in humans
Shore RE. Med Pediatr Oncol. 2001
May;36(5):549-54
• ... The Japanese atomic bomb study indicates
that doses of radiation under about 1 Gy
confer less risk per unit dose than higher
doses do.
• … skin cancer risk is greater from radiation
exposure at young ages than at older ages…...
• … available evidence indicates that the excess
risk of skin cancer lasts for 45 years or more
following irradiation …
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Lecture 10: Radiation risks in paediatric interventional cardiology
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Epidemiology evidences (III)
• Cancer risks from medical radiation
Ron E. Health Phys. 2003 Jul;85(1):47-59
• Because doses from diagnostic examinations
typically are low, they are difficult to study using
epidemiological methods, unless multiple
examinations are performed…
• An excess risk of breast cancer has been reported
among women:
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with tuberculosis who had multiple chest fluoroscopies
scoliosis patients who had frequent diagnostic x rays
during late childhood and adolescence.
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Lecture 10: Radiation risks in paediatric interventional cardiology
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Frequency of cardiac intervention in
pediatrics
Spanish Registry on Cardiac Catheterization and
Coronary Interventions. (1990-2002)]
Data from 101 centers …6 carried out only pediatric procedures. … a
total increase of 5.1% in comparison to 2001.
• The population-adjusted rate:
• 2,053 coronary angiograms per million inhabitants
• 850 coronary interventions per million inhabitants
• Coronary interventions increased by 11% in comparison to
2001
• Stenting accounted for 91.7% of all procedures
• Direct stenting was done in 13 768 procedures (43.2%).
Multivessel percutaneous in 9,830 patients (28%), and ad hoc
interventions in 26,341 patients (76%).
• … and the slight increase in pediatric interventions (3.7%).
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Indications for interventions in
pediatric cardiology
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Interventional catheterization in pediatric cardiology:
tools and indications
Boudjemline Y., Arch Pediatr. 2004 Mar;11(3):276-84.
During the last decade, a remarkable number of
transcatheter methods were developed:
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balloon dilatation to treat vascular or valvular obstructive
lesions,
intravascular stents to manage obstructive lesions that
cannot be satisfactorily balloon-dilated,
transcatheter closure of atrial septal defects, patent
ductus arteriosus,
and ventricular septal defect.
More recently, pulmonary valve replacement has become
possible through a percutaneous technique
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Indications for interventions in pediatric
cardiology
Future of interventional cardiology in pediatrics
Levi DS, Alejos JC, Moore JW. Curr Opin Cardiol. 2003
Mar;18(2):79-90.
• A trend toward use of less invasive, non-surgical
approaches to the treatment of congenital heart disease has
developed
• Additionally, fetal catheter-based interventions are being
developed for the treatment of severe congenital heart
disease in utero
• Trend toward catheter-mediated treatment is certain to
continue, care must be taken to regulate safely the
introduction of novel techniques and devices into clinical
use
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Lecture 10: Radiation risks in paediatric interventional cardiology
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Radiation Exposure to Children
during various interventions (I)
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Procedure
No.
patients
Fluoroscopy
time (min)
Cine
time
(sec)
Total cumulative skin
dose (mGy)
PDA
8
10.1 ±1.8
11.5±1.8
97±25
PBV
5
19.3 ±2.3
10.9±2.3
86±32
Amplatzer
14
23.5 ±2.1
19.9±3.3
102±34
DC
12
13.2 ±1.5
18.7±1.5
108±21
DC=diagnostic catheterization, PDA=Coil occlusion of the patent ductus arteriosus,
PBV=pulmonary balloon valvuloplasty
Coil occlusion of the patent ductus arteriosus (PDA) as well as other more
complex pediatric interventions has raised concern regarding radiation exposure
No correlation between fluoroscopy time and measured entrance dose
Strongest correlation cumulative dose vs. patient weight and BSA
J. Donald Moore, David Shim, John Sweet, Kristopher L. Arheart and Robert H. Beekman III,Catheterization and
Cardiovascular Interventions 47:449–454 (1999)
David Shim, Thomas R. Kimball, Erik C. Michelfelder, Lisa Koons, RN and Robert H. Beekman, Catheterization and
Cardiovascular Interventions 51:451–454 (2000)
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Radiation Exposure to Children
during various interventions (II)
• Cumulative skin
dose is well
correlated with
patient size and
not with
fluoroscopy time
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Lecture 10: Radiation risks in paediatric interventional cardiology
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Radiation Exposure to Children
during various interventions (III)
1400
1200
1000
800
Entrance dose
(mGy)
600
400
200
0
A
B
C
D
E
F
Comparison of surface entrance doses of radiation.
A: Present study (Amplatzer atrial septal defect closure).
B: Moore et al. [6] (patent ductus coil occlusion).
C: Moore et al. [6] (pulmonary valvuloplasty).
D: Wu et al. [8] (pulmonary valvuloplasty).
E: Park et al. [10] (arhythmia ablation).
F: Rosenthal et al. [11] (arhythmia ablation).
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Occupational exposure in pediatric
interventions
• Although pediatric cardiologists have
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been performing cardiac catheterizations
in infants and children for over 30 years,
data regarding their occupational
exposure are sparse
Radiation exposure during arrhythmia
ablation procedures in children, as
measured by fluoroscopy duration, has
been shown to be comparable to adults
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Summary
• Increased radiation risks for pediatric patients
• Evidence of increased number of pediatric
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interventional procedures
Radiation doses can be high
Very few dosimetric studies
Radiological technique must be optimised and
tailored to small body sizes:
• Re-consider the need of antiscatter grid (doserate x 2)
• Avoid electronic magnifications
• Use collimations (reduce imparted energy, organ and
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effective dose)
Image intensifier close to patient skin
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