Transcript IAEA Training Material on Radiation Protection in Cardiology

International Atomic Energy Agency
Examples of Good & Bad
Practice:
Effect of the wedge filter
and field size in the skin dose
distribution
L 9.1
Educational Objectives
1. How wedge filter & field
size affect the skin dose
2. When and how to use
wedge filter
Radiation Protection in Cardiology
Lecture 9.1: Examples of good and bad practice
2
Philips systems
Radiation Protection in Cardiology
Lecture 9.1: Examples of good and bad practice
3
Series 14:
KVP: 88
Distance source to
detector: 1048
Exposure time 8
X-ray tube current 467
Intensifier size 169.9 mm
Positioner primary angle
5.2 (LAO)
Positioner secondary angle
28.3
13 Sep 04; 40414
Example of lack of wedge filter use in a left projection. Image quality is not
good (too bright in the upper left corner of the image) and in addition, more
dose per frame than necessary. Bad practice!.
Radiation Protection in Cardiology
Lecture 9.1: Examples of good and bad practice
4
Series 21:
KVP 87
Distance source to detector
995
Exposure time 8
X-ray tube current 472
Positioner primary angle
- 41.1 (RAO)
Positioner secondary angle
28.8
13 Sep 04; 40414
Example of lack of wedge filter use in a right projection. Image quality is not
good (too bright in the upper right corner of the image) and in addition, more dose
per frame than necessary. . Bad practice!.
Radiation Protection in Cardiology
Lecture 9.1: Examples of good and bad practice
5
Example of appropriate use of the wedge filter.
(flat panel). Good practice!.
Radiation Protection in Cardiology
Series : 6
(0008,0020) : Study Date
: 21/09/2004
(0008,0080) : Institution Name
: HOSPITAL SEVERO OCHOA
(0008,1090) : Manufacturer's
Model Name : INTEGRIS Allura
Flat Detector
(0018,0060) : KVP
: 78.0
(0018,1110) : Distance Source to
Detector : 1.08
(0018,1111) : Distance Source to
Patient : 0.765 (?)
(0018,1150) : Exposure Time
:6
(0018,1151) : X-ray Tube Current
: 812
(0018,1510) : Positioner Primary
Angle
: -31.2
(0018,1511) : Positioner
Secondary Angle : 32.2
Lecture 9.1: Examples of good and bad practice
6
No wedge
filter used.
Image
partially
saturated.
Bad
practice!.
Radiation Protection in Cardiology
Lecture 9.1: Examples of good and bad practice
7
0.5 mGy/fr
Radiation Protection in Cardiology
0.8 mGy/fr (60% more)
Lecture 9.1: Examples of good and bad practice
8
International Atomic Energy Agency
Use of wedge filter
in right
projections
Effect of the wedge filter in skin dose distribution (right projections).
Saving skin dose and improving image quality. Good practice!.
Radiation Protection in Cardiology
Lecture 9.1: Examples of good and bad practice
10
Radiation Protection in Cardiology
Lecture 9.1: Examples of good and bad practice
11
Areas in red are saturated in the slow film. Skin dose more than 1.2 Gy.
Radiation Protection in Cardiology
Lecture 9.1: Examples of good and bad practice
12
International Atomic Energy Agency
Philips Integris: Use of wedge
filter in left projections
Effect of the wedge filter in skin dose distribution (left projections).
Saving skin dose and improving image quality. Good practice!.
Radiation Protection in Cardiology
Lecture 9.1: Examples of good and bad practice
14
Radiation Protection in Cardiology
Lecture 9.1: Examples of good and bad practice
15
Areas in red are saturated in the slow film. Skin dose more than 1.2 Gy.
Radiation Protection in Cardiology
Lecture 9.1: Examples of good and bad practice
16
International Atomic Energy Agency
Use of wedge filter
in right and left
projections
Radiation Protection in Cardiology
Lecture 9.1: Examples of good and bad practice
18
Radiation Protection in Cardiology
Lecture 9.1: Examples of good and bad practice
19
Areas in red are saturated in the slow film. Skin dose more than 1.2 Gy.
Radiation Protection in Cardiology
Lecture 9.1: Examples of good and bad practice
20
International Atomic Energy Agency
Geometry with
small field size
Radiation Protection in Cardiology
Lecture 9.1: Examples of good and bad practice
22
68 cm2
28 cm2
26 cm2
Radiation Protection in Cardiology
Lecture 9.1: Examples of good and bad practice
23
Areas in red are saturated in the slow film. Skin dose more than 1.2 Gy.
Radiation Protection in Cardiology
Lecture 9.1: Examples of good and bad practice
24
International Atomic Energy Agency
Geometry with big
field size
Radiation Protection in Cardiology
Lecture 9.1: Examples of good and bad practice
26
1.2 Gy
113 cm2
0.6 Gy
41 cm2
Radiation Protection in Cardiology
Lecture 9.1: Examples of good and bad practice
27
Areas in red are saturated in the slow film. Skin dose more than 1.2 Gy.
Radiation Protection in Cardiology
Lecture 9.1: Examples of good and bad practice
28
International Atomic Energy Agency
No wedge filter used.
Geometry with big
radiation field size.
Overlapping of radiation
fields could occur.
Radiation Protection in Cardiology
Lecture 9.1: Examples of good and bad practice
30
319 cm2
234 cm2
91 cm2
Radiation Protection in Cardiology
Lecture 9.1: Examples of good and bad practice
31
Areas
in red are saturatedLecture
in the
slow film. Skin dose more than321.2 Gy.
9.1: Examples of good and bad practice
Radiation Protection in Cardiology
• Patients who had multiple coronary
angiographies and who underwent more than four
PTCAs. 7824 PTCAs performed during 14 years
was analysed.
• 14 patients were included in the study. Each
patient had undergone between 4 and 14 coronary
angiographies and between 5 and 10 PTCAs,
performed over a period of 2-10 years.
Radiation Protection in Cardiology
Lecture 9.1: Examples of good and bad practice
33
• Mean values of maximum skin dose per
procedure were 217 mGy for the diagnostic
studies and 391 mGy for the PTCAs.
• Only a slight radiation skin injury was
clinically demonstrated in one patient with a
history of 10 coronary angiographies and 10
PTCAs (estimated maximum skin dose 9.5 Gy).
Radiation Protection in Cardiology
Lecture 9.1: Examples of good and bad practice
34
CONCLUSION:
IC procedures performed on modern X-ray
systems under QA programmes and by
cardiologists trained in RP, repetition of
procedures is not the main cause of possible
skin radiation injuries.
Radiation Protection in Cardiology
Lecture 9.1: Examples of good and bad practice
35