Transcript IAEA Training Material on Radiation Protection in Radiotherapy

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

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Objectives of the Module
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To become familiar with
the principles of radiotherapy
 the role of radiotherapy in cancer
management
 the cost effectiveness of radiotherapy
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To appreciate the importance of
radiation dose in radiotherapy
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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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Cancer incidence (WHO)
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Major indications for radiotherapy
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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
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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
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Beam
directions target
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Prognostic Factors
Cancer type and stage
 Patient performance
 Radiation dose
 ...
survival
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Bad prognosis
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Good prognosis
time
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Prognostic Factors
Cancer type and stage
 Patient performance
 Radiation dose
 ...
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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
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To target:
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5% too low - may result in clinically
detectable reduction in tumour control (e.g.
Head and neck cancer: 15%)
To normal tissues:
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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
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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
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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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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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