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International Atomic Energy Agency
Example of Practice of Radiation
Protection
L 9.2
Educational Objectives
1. How awareness of radiation
protection and close
cooperation with medical
physics / radiation safety
staff helps
2. Avoidance of skin injuries
Radiation Protection in Cardiology
Lecture 9.2: Example of practice of radiation protection
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Introduction
• The evaluation of maximum local skin dose from an
interventional procedure is difficult:
•
•
On-line evaluation: dosemeter or computer code
Off-line methods more accurate: use of large area detectors,
time consuming (adopted for a limited number of patients)
• It should be important to periodically evaluate
•
incidence of skin injuries in cardiac centres
A follow-up protocol has been developed in Dimond
European research project (www.dimond3.org):
•
•
Purpose to identify patients with an high probability of an
high localised skin dose to be submitted to a follow-up.
The protocol adopts a trigger value in terms of dose-area
product (DAP) as a dose quantity indicator of possible
localised high skin dose.
Radiation Protection in Cardiology
Lecture 9.2: Example of practice of radiation protection
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Retrospective evaluation of skin injuries on
patients of Udine cardiac centre
•
•
Patient can be submitted to repeated cardiac
procedures in short period of time
Methodology:
•
•
•
•
Analyse database of patients submitted to diagnostic and
therapeutic procedures in a 4 years period
Detect patients with highest cumulative DAPs (due to
repeated procedures) selecting an appropriate DAP trigger
value
Evaluate maximum local skin dose
Submit selected patients to a clinical evaluation to detect
possible skin injuries
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Lecture 9.2: Example of practice of radiation protection
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Patient database: CA and PTCA in Udine
hospital from 1998 to 2002
SAMPLE COLLECTION
21 April 1998 - 17 April 2002
NUMBER OF PROCEDURES
5517
N. OF PTCA PROCEDURES
1843
N. OF CA PROCEDURES
3674
N. OF PATIENTS
3332
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Lecture 9.2: Example of practice of radiation protection
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CA and diagnostic procedures
500
3674
Mean DAP
37.5
Gycm2
Median DAP
31.2
Gycm2
400
Frequency
No. of procedures
300
200
100
0
No. of procedures
with
DAP>300Gycm2
0
50
100
1
150
200
250
Gy cm^2
DAP distribution of CA procedures
Radiation Protection in Cardiology
Lecture 9.2: Example of practice of radiation protection
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300
No. of
procedures
1843
Mean DAP
66.1
Gycm2
Median DAP
48.3
Gycm2
No. procedures
with
DAP>300Gycm2
13 (0.7%)
Frequency
PTCA procedures
160
140
120
100
80
60
40
20
0
0
50 100 150 200 250 300 350 400 450 500
Gy cm^2
DAP distribution of PTCA procedures
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Lecture 9.2: Example of practice of radiation protection
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Frequencies of repeated procedures
and cumulative dose
No. of procedures per
patient
1
2
3
4
5
6
7
>7
No. of patients
1967
940
194
138
41
29
14
9
600
3332
Mean DAP
78.6
Gycm2
Median DAP
50.6
Gycm2
No. of patients with
DAP>300Gycm2
87 (2.6%)
Frequency
No. of patients
500
400
300
200
100
0
0
100
200
300
400
500
600
Gy cm^2
Radiation Protection in Cardiology
Lecture 9.2: Example of practice of radiation protection
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700
Sample of patients
extracted for the follow-up study
79 patients with a cumulative DAP>300
Gycm2 extracted from the database
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Number of procedures/patient
Radiation Protection in Cardiology
40
35
30
25
20
15
10
5
0
35
0
40
0
45
0
50
0
55
0
60
0
65
0
70
0
75
0
80
0
85
0
90
0
95
10 0
00
18
16
14
12
10
8
6
4
2
0
No. of patients
No. of patients
Distribution of number of procedures performed and cumulative DAP
Lecture 9.2: Example of practice of radiation protection
DAPtotal (Gycm2)
9
Sample of patients
extracted for the follow-up study
No. of patients
Maximum local skin dose evaluated for the
79 patients
18
16
14
12
10
8
6
4
2
0
1.5
Radiation Protection in Cardiology
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2.5 3 3.5 4 4.5 5 5.5 6
Maximum Local Skin Dose (Gy)
Lecture 9.2: Example of practice of radiation protection
6.5
7
10
Maximum local skin dose (MSD)
assessment
• Correlation between DAP and MSD has been
evaluated: operator and installation dependent
• Skin dose distributions measured on a sample
of patients with radiochromic films
Maximum local skin dose versus DAPfor PTCA
 MSD= 0.0141*DAP
PSD (Gy)
4.0
PSD= 0.0141*DAP
3.0
2.0
1.0
0.0
0
Radiation Protection in Cardiology
50
100
150
DAP (Gycm2)
Lecture 9.2: Example of practice of radiation protection
200
11
250
Skin dose assessment (patient no. 1)
•
Patient no. 1: Total maximum local skin dose 6,7 Gy
Procedure type
DAP per
procedure(Gycm2)
Maximum local skin dose
(Gy)
Diagnostic
86.9
0,416
Diagnostic
86.3
0,413
Diagnostic
26.8
0,128
Ad hoc PTCA
57.1
0,509
Diagnostic
108.6
0,520
Diagnostic
73.8
0,354
135.6
1,208
Diagnostic
28.4
0,136
Ad hoc PTCA
33.8
0,301
Election PTCA
84.7
0,755
Diagnostic
58.4
0,280
115.3
1,027
Diagnostic
27.2
0,130
Diagnostic
33.5
Ad hoc PTCA
39.2
Ad hoc PTCA
Ad hoc PTCA
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Conclusions
• 56 patients received medical examination with
•
•
particular focus on the more exposed skin
area.
None of visited patients presented skin lesions
that could be attributed to high dose X-ray
irradiation
The result assures cardiologists and medical
physicists that, if proper quality assurance and
radiation protection programme is established,
the frequency of skin injuries can be very low
also when repeated procedures are taken into
account
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