training module 3 – version 1.1 for internal use only ® radiation therapy
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Training Module 3 – Version 1.1
For Internal Use Only
®
Radiation Therapy
The basic idea behind radiation therapy is to destroy the tumour through high doses of radiation:
Training Module 3 – Version 1.1
For Internal Use Only
®
Radiation Therapy
The Royal College of Radiologists (UK) estimates that, of those cancer patients who are cured:
49% are cured by surgery
40% are cured by radiotherapy
11% are cured by chemotherapy
Training Module 3 – Version 1.1
For Internal Use Only
®
Radiation Therapy - Basics
Radiation Therapy - External
Radiation Therapy - Internal
Radiation Therapy
Training Module 3 – Version 1.1
For Internal Use Only
®
Radiation Therapy - Basics
Radiation Therapy - External
Radiation Therapy - Internal
Radiation Therapy
Training Module 3 – Version 1.1
For Internal Use Only
®
Radiation Therapy – Basics
Gamma Rays have a energy high enough to displace an electron from its orbital path.
This creates an unstable or ionized atom, leading to a changed and dysfunctional molecule.
Wavelength [m]
low energy
high energy
Training Module 3 – Version 1.1
For Internal Use Only
®
Radiation Therapy – Basics
The main target is the DNA which, when hardly damaged, can lead to cell death and therefore tumour necrosis.
Training Module 3 – Version 1.1
For Internal Use Only
®
Radiosensitivity and cell cycle
The greatest amount of damage occurs during the period of mitosis where one cell divides into two individual cells
Radiation Therapy – Basics
Training Module 3 – Version 1.1
For Internal Use Only
®
Radiation Therapy - Basics
Radiation Therapy - External
Radiation Therapy - Internal
Radiation Therapy
Training Module 3 – Version 1.1
For Internal Use Only
®
Radiation Therapy – External
The radiation is artificially produced by a linear accelerator.
The energy of up to 30MeV and more can be 600-fold higher than this of a conventional x-ray machine.
Training Module 3 – Version 1.1
For Internal Use Only
®
Radiation Therapy – External
As the tumour is normally surrounded by normal tissue and often far away from the body surface, collateral damage of this tissue by external radiation cannot be avoided.
Training Module 3 – Version 1.1
For Internal Use Only
®
Radiation Therapy – External
The success depends on the difference between the sensitivity of tumour and surrounding tissue.
A BC
Training Module 3 – Version 1.1
For Internal Use Only
®
Radiation Therapy – External
Radiosensitivity of normal and malignant tissue
Training Module 3 – Version 1.1
For Internal Use Only
®
Radiation Therapy – External
Like chemotherapy, external radiation therapy is often given in fractions over a certain time period.
For breast cancer for example, a total dose between 40Gy and 60Gy is given in 15-30 fractions over a period of 6 weeks.
Training Module 3 – Version 1.1
For Internal Use Only
®
Radiation Therapy – External
Radical external beam irradiation often requires a multi-field technique employing three or four fields
This technique allows to apply higher doses to the tumour without to much collateral damage
Training Module 3 – Version 1.1
For Internal Use Only
®
Radiation Therapy - Basics
Radiation Therapy - External
Radiation Therapy - Internal
Radiation Therapy
Training Module 3 – Version 1.1
For Internal Use Only
®
Radiation Therapy – Internal
specific radiation to tumour tissue
less collateral damage
higher doses possible
Advantages of internal radiation methods:
To bring the radiation dose as close as possible to the tumour, several internal radiation methods are used where applicable.
Training Module 3 – Version 1.1
For Internal Use Only
®
Radiation Therapy – Internal
131I – carcinoma of the thyroid
32P – bone marrow radiation
137Cs – needle for local treatment
125I – brachytherapy seeds
Examples of internal radiation therapies:
Training Module 3 – Version 1.1
For Internal Use Only
®
Radiation Therapy – Internal
125I – Brachytherapy seeds
Training Module 3 – Version 1.1
For Internal Use Only
®
Radiation Therapy - Basics
Radiation Therapy - External
Radiation Therapy - Internal
Radiation Therapy