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 Radiation Protection in Radiotherapy 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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Cancer incidence (WHO)

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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 Radiation Protection in Radiotherapy Part 1: Introductory lecture 6

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 Radiation Protection in Radiotherapy Part 1: Introductory lecture 7

Aim

Patient 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

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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Radiation Protection in Radiotherapy Part 1: Introductory lecture

Dose response

100% response means the tumour is cured with certainty (TCP) or unacceptable normal tissue damage (

e.g.

paralysis) is inevitable 11

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 Radiation Protection in Radiotherapy Part 1: Introductory lecture 13

“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…” 14 Radiation Protection in Radiotherapy Part 1: Introductory lecture

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) Radiation Protection in Radiotherapy Part 1: Introductory lecture 15

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 superficial lesions from linacs for more Radiation Protection in Radiotherapy Part 1: Introductory lecture 17

Superficial/orthovoltage unit

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Modern Cobalt 60 unit

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Linear accelerator with electron cone

Radiation Protection in Radiotherapy Part 1: Introductory lecture Electron applicator 20

Brachytherapy

Interstitial implant for breast radiotherapy Radiation Protection in Radiotherapy Part 1: Introductory lecture Intracavitary gynecological implant 21

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 Radiation Protection in Radiotherapy Part 1: Introductory lecture 22

Example for HDR Brachytherapy

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A radiotherapy department is part of a health system

Radiotherapy Department Oncology Host hospital Radiation Protection in Radiotherapy Part 1: Introductory lecture National Cancer System 24

Patient Flow in Radio therapy

…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 Radiation Protection in Radiotherapy Part 1: Introductory lecture 26

Components of a Radiotherapy Department

 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 Simulator Clinics Two linac bunkers Offices Patient waiting 29 Radiation Protection in Radiotherapy Part 1: Introductory lecture

Professionals in radiotherapy

 Radiation oncologists  Other clinicians  Medical radiation physicists  Radiation therapists  Nursing staff  Radiation safety officer  Information technology officer  Administrative staff Radiation Protection in Radiotherapy Part 1: Introductory lecture 30

Features of Radiotherapy

 High and potentially lethal absorbed dose is required to cure cancer  High technology environment  Individualized treatment approach  Complex treatment set-up Radiation Protection in Radiotherapy Part 1: Introductory lecture 31

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 Radiation Protection in Radiotherapy Part 1: Introductory lecture 32

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 Radiation Protection in Radiotherapy Part 1: Introductory lecture 33

Where to Learn More

 Other parts of the course, handouts  References:  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) Radiation Protection in Radiotherapy Part 1: Introductory lecture 34

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?) 36 Radiation Protection in Radiotherapy Part 1: Introductory lecture