IAEA Training Material on Radiation Protection in Radiotherapy

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IAEA Training Material on Radiation Protection in Radiotherapy
Radiation Protection in
Radiotherapy
Part 1
Aim and Role of Radiotherapy
Introductory Lecture
Radiotherapy
One of the main treatment
modalities for cancer (often in Siemens Oncology
combination with chemotherapy and
surgery)
 It is generally assumed that 50 to 60%
of cancer patients will benefit from
radiotherapy
 Minor role in other diseases

Radiation Protection in Radiotherapy
Part 1: Introductory lecture
2
Objectives of the Module

To become familiar with
the principles of radiotherapy
 the role of radiotherapy in cancer
management
 the cost effectiveness of radiotherapy


To appreciate the importance of
radiation dose in radiotherapy
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Part 1: Introductory lecture
3
Contents of the Lecture
1.Cancer management and radiotherapy
2.Approaches for dose delivery
External beam radiotherapy
Brachytherapy
3.Features of a radiotherapy department
4.Self test at the end of the lecture
”Quick test”
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Part 1: Introductory lecture
4
Cancer incidence (WHO)
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Part 1: Introductory lecture
5
Major indications for radiotherapy







Head and neck cancers
Gynaecological cancers (e.g. Cervix)
Prostate cancer
Other pelvic malignancies (rectum, bladder)
Adjuvant breast treatment
Brain cancers
Palliation
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Approaches
Palliative radiotherapy to reduce pain
and address acute symptoms – e.g.
bone metastasis, spinal cord
compression, ...
 Radical radiotherapy as primary
modality for cure – e.g. head and neck
 Adjuvant treatment in conjunction with
surgery – e.g. breast cancer

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Patient
Aim


Critical
organs
To kill ALL viable
cancer cells
To deliver as much
dose as possible to
the target while
minimising the dose
to surrounding
healthy tissues
Radiation Protection in Radiotherapy
Beam
directions target
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Prognostic Factors
Cancer type and stage
 Patient performance
 Radiation dose
 ...
survival

Bad prognosis
Radiation Protection in Radiotherapy
Part 1: Introductory lecture
Good prognosis
time
9
Prognostic Factors
Cancer type and stage
 Patient performance
 Radiation dose
 ...

Accurate dose delivery
matters!
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Dose
response
100% response
means the tumour
is cured with
certainty (TCP) or
unacceptable normal
tissue damage (e.g.
paralysis) is
inevitable
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Dose
response
Therapeutic window:
Maximum probability
of Complication Free
Tumour Control
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Dose should be accurate

To target:


5% too low - may result in clinically
detectable reduction in tumour control (e.g.
Head and neck cancer: 15%)
To normal tissues:

5% too high - may lead to significant
increase in normal tissue complication
probability = morbidity = unacceptable side
effects
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“Deviations from Prescribed Dose”
May involve severe or even fatal
consequences.
 IAEA Basic Safety Standards (SS 115):
”…require prompt investigation by
licensees in the event of an accidental
medical exposure…”

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Options for dose delivery
External beam radiotherapy = dose is
delivered from outside the patient using
X Rays or gamma rays or high energy
electrons (refer to part 5 of the course)
 Brachytherapy = dose delivered from
radioactive sources implanted in the
patient close to the target (brachys =
Greek for short distance; refer to part 6
of the course)

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External beam radiotherapy
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External Beam Radiotherapy

Typically fractionated - e.g. 30 daily fractions
of 2Gy up to a total dose of 60Gy
 Superficial/orthovoltage photons (50 to
400kVp) for skin or superficial lesions
 Megavoltage photons (60-Co or linear
accelerators = linacs) for deeper lying
tumours.
 Megavoltage electrons from linacs for more
superficial lesions
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Superficial/orthovoltage unit
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Modern Cobalt 60 unit
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Linear accelerator with
electron cone
Electron
applicator
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Brachytherapy
Interstitial implant for breast
radiotherapy
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Intracavitary
gynecological implant
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Brachytherapy
Implant of radioactive materials (e.g.
137-Cs, 192-Ir) close to the target area
 Intracavitary, interstitial and mould
surface applications
 Low dose rate, LDR, (60Gy in about 5
days) and high dose rate, HDR, (several
fractions of several Gy in few minutes
each) applications

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Example for HDR Brachytherapy
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A radiotherapy department is
part of a health system
Radiotherapy
Department
Oncology
National
Cancer System
Host hospital
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Patient
Flow in
Radiotherapy
…not necessarily a straightforward process
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Patient flow in radiotherapy

Depends on:
disease site and stage
 departmental protocols
 treating clinician
 resources available

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Components of a
Radiotherapy Department

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Diagnostic facilities (CT, MRI, …)
Simulator (refer to part 5 of the course)
Mouldroom
Treatment planning
External beam treatment units (parts 5 and
10)
Brachytherapy equipment (part 6)
Clinic rooms, beds, ...
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Layout of a Department
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Part 1: Introductory lecture
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Layout of a Department
Physics &
workshops
Planning
Clinics
Offices
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Simulator
Two linac
bunkers
Patient
waiting
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Professionals in radiotherapy
Radiation oncologists
 Other clinicians
 Medical radiation physicists
 Radiation therapists
 Nursing staff
 Radiation safety officer
 Information technology officer
 Administrative staff

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Features of Radiotherapy
High and potentially lethal absorbed
dose is required to cure cancer
 High technology environment
 Individualized treatment approach
 Complex treatment set-up

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Features of Radiotherapy
High and potentially lethal absorbed
dose is required to cure cancer
 High technology environment
 Individualized treatment approach
 Complex treatment set-up
 Quality assurance, treatment verification
and radiation protection essential

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Summary
Radiotherapy is an important cancer
treatment modality
 Accuracy of dose delivery is essential
for good outcomes
 The complex and high tech environment
requires attention to quality assurance
and radiation protection

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Where to Learn More
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
Other parts of the course, handouts
References:
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Radiotherapy physics textbooks (as per reference
list)
IUCC Cancer Statistics
Radiotherapy textbooks (e.g. Perez and Brady
1998)
Site visit of a radiotherapy department (day
xxx of the course)
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Any questions?
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Question:
What is the main cancer treated with
radiotherapy in your country and what
would be a typical treatment approach?
(Number of fractions? Total dose?)
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