Erasmus MC Health Academy
Practical radiation protection level 5R
Course information
Erasmus MC Health Academy
Content
General information………………………………………………………………………..2
Learning objectives for self-study………………………………………………………3
Information regarding the practical……………………………………………………..5
Practical manual……………………………………………………………………………6
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Practical radiation protection 5R – course
Erasmus MC Health Academy
may 2016
Erasmus MC Health Academy
General information
Target group
The course is designed for workers who are involved with (clinical) use of X-ray
equipment. Our participants are for example dentists, medical assistants,
anesthesiologists and anesthesiology assistants.
The Erasmus MC Health academy provides a range of radiation protection courses.
Please contact us, if you are not sure which level is required for your work field.
Aspects
The course consists of self-study, a practical and an exam. In the practical part you
will work with an X-ray apparatus to determine the influence of different parameters
on the amount of scattered irradiation and you will demonstrate the influence of
distance on the measured dose. The course is concluded with a multiple choice test.
Study information
Please make sure you are prepared for both the practical and the exam by studying
the prescribed literature (learning objectives are given below) and reading the
practical manual in advance. Please read the given instructions in this document
before attending the practical.
Literature
Practical Radiation Protection
J. van den Eijnde / M. Schouwenburg
ISBN 978-94-91764-01-1
Syllabus Internal regulations Erasmus MC
Contact information
Erasmus MC Health Academy
Unit MBR
010-7043860
[email protected]
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Practical radiation protection 5R – course
Erasmus MC Health Academy
may 2016
Erasmus MC Health Academy
Learning objectives for self-study
Syllabus Internal regulations Erasmus MC: the learning objectives are described in
the syllabus. Please study all information, except 2.5.
The following learning objectives are described per relevant chapter of the book
”Practical radiation protection”.
Structure of the atom and decay
By the end of the course, you will be able to:
•
describe the structure of an atom (chapter 1.1)
Sources, X-ray equipment and neutron radiation (chapter 2.4)
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describe the generation of X-rays;
explain the continuous spectrum of Bremsstrahlung;
describe the concepts: photons, anode, diverging beams, kV, mAs, filtering;
describe the concepts: natural radiation, cosmic radiation, artificial radiation;
describe the most naturally occurring radioactive materials and their
contribution to the annually exposure of individuals in the Netherlands;
Quantities and units in radiation protection
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describe the concepts: absorbed dose, dose rate, equivalent dose, radiation
weighting factor, effective dose, tissue weighting factor;
make dose calculations;
Biological effects and risk of radiation
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describe the effect of radiation at molecular and cellular levels;
describe somatic and genetic effects, harmful tissue reactions (deterministic),
stochastic effects, early and late effects;
describe dose-effect relations;
describe the effects of radiation on the unborn child;
cite the probability /risk coefficient for a fatal cancer for radiation workers
name the risk numbers for fatal cancer and genetic effects;
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Practical radiation protection 5R – course
Erasmus MC Health Academy
may 2016
Erasmus MC Health Academy
Regulations
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describe the role and tasks of the ICRP;
describe the structure of national guidelines for the use of radiation sources;
describe the main starting points in radiation protection: justification,
optimization and limitation;
explain the ALARA concept;
name the different dose limits;
Safety precautions for sealed sources and X-ray equipment (chapter 8.3)
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describe the main principles of practical radiation protection: distance, time
and shielding;
make simple dose calculations based on the inverse square law;
describe the concepts primary beam and leakage radiation;
describe ways to protect yourself against radiation;
describe which position in the room is best, while working with radiation
equipment;
name the most common thicknesses of lead aprons;
describe the way to use and handle lead aprons;
Dosimetry in practice
•
perform calculations using the inverse square law
Additional information regarding chapter 3 Interaction of radiation with matter
and shielding of radiation
•
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Basic principles of interaction and shielding of photon radiation must be
comprehended. It is not necessary to learn the different ways of interaction
and the formula’s.
Regarding the half value layer: when shielding photon radiation with a certain
material, the amount of matter that reduces the intensity of the photon beam
with 50% is called the half value layer (in centimeters or millimeters). The
second half value layer (that reduces the intensity to 25%) will be larger than
the first one, because of the “hardening of the beam”. Low energy photons
will be filtered by the first half value layer, higer energy photons remain.
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Practical radiation protection 5R – course
Erasmus MC Health Academy
may 2016
Erasmus MC Health Academy
Information regarding the practical part
The training is conducted at the Rijndam Rehabilitation center in Rotterdam
The directions will be send to you after signing up for the course.
The experiments can only be carried out if you are familiar with the basics of
radiation protection as is described in the learning objectives above.
Instructions
Please bring along this course book and a pocket calculator.
You have to be in time; otherwise you cannot attend the practical.
Content of the practical
1. Scattered Radiation;
2. Effect of distance on the entry dos: the inverse square law.
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Practical radiation protection 5R – course
Erasmus MC Health Academy
may 2016
Erasmus MC Health Academy
Practical Manual
X-rays
5R
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Practical radiation protection 5R – course
Erasmus MC Health Academy
may 2016
Erasmus MC Health Academy
How to use the equipment
Make adjustments to the diaphragm
Move the X-ray tube
KV en mAs
Preparation first, then expose
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Practical radiation protection 5R – course
Erasmus MC Health Academy
may 2016
Erasmus MC Health Academy
1. Scattered radiation
Aim
To get insight into into the effect of X-ray tube voltage and field size on scattered
radiation and into the direction and the intensity of scattered radiation
Materials
A bucket of water, a Solidose dosemeter, measuring tape and a stool.
Method
Place the bucket on the stool. Direct the X-ray beam horizontally towards the bucket
so that the central ray goes through the centre of the water phantom (Figure 1).
The distance between the focus and the centre of the bucket is 1 metre.
Connect the R100/Code8 detector to the Solidose dosemeter and plug the green
plug in the dosemeter.
Figure 1 Side view
X-ray tube
Bucket of water on a chair
Task 1
Measure the dose due to the scattered radiation at a 1 m distance from the phantom
in the directions as indicated in Figure 2 and apply the following exposure settings.
50 kV and 20 mAs with a small field size
100 kV and 20 mAs with a small field size
The measuring positions are on the same height as the central ray of the incident
beam.
Task 2
Apply a large field size and repeat the measurements as described in Task 1.
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Practical radiation protection 5R – course
Erasmus MC Health Academy
may 2016
Erasmus MC Health Academy
Task 3
Repeat this task for one of the directions at a 2 meter distance. Use a large fieldsize.
Figure 2: View from above
Bucket of water
X-ray tube
measuring position 1
measuring position 2
measuring
position 5
measuring position 3
measuring position 4
At 1 meter distance
Position
50 kV
Small
field size
Large
field size
100 kV
Small
field size
Large
field size
1
2
3
4
5
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Practical radiation protection 5R – course
Erasmus MC Health Academy
may 2016
Erasmus MC Health Academy
At 2 meters distance, large fieldsize
Position
…
50 kV
100 kV
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Practical radiation protection 5R – course
Erasmus MC Health Academy
may 2016
Erasmus MC Health Academy
1. At which position the highest dose is measured ?
2. What is the relation between the scatter direction and the amount of scattered
radiation?
3. What is the relation between tube voltage and the fraction of scattered
radiation?
4. What is the relation between the field size and the fraction of scattered
radiation?
5. What is the relation between the measuring distance and the fraction of
scatterd radiation?
6. If you are working with X-ray equipment can you reason which position in the
room is preferred for you to stay in terms of radiation protection.
7. Which position of the X-ray tube is preferred in terms of radiation protection:
under the table or above the table?
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Practical radiation protection 5R – course
Erasmus MC Health Academy
may 2016
Erasmus MC Health Academy
2. Effect of distance on the entry dose: the inverse
square law
Aim
To get insight into the inverse square law.
Materials
Dosemeter with detector
Phocus H/DN-2x
Measuring tape
Logaritmic paper
Instruction
The initial focus-detector distance is 60 cm. Position the ionisation chamber
completely in the beam. Note that no collimation is applied.
Task 1
The exposure settings are 102 kV and 32 mAs. Take an exposure with the detector
at each of the four focus-detector distances as indicated in the table underneath.
Distance
Measured dose
60 cm
mGy
80 cm
mGy
100 cm
mGy
120 cm
mGy
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Practical radiation protection 5R – course
Erasmus MC Health Academy
may 2016
Erasmus MC Health Academy
Task 2
Plot the obtained data on a logarithmic graph.
Task 3
Explain the differences between the measured entry doses.
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Practical radiation protection 5R – course
Erasmus MC Health Academy
may 2016