Training Module 3 – Version 1.1

For Internal Use Only

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Radiation Therapy

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

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®

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

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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

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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

Training Module 3 – Version 1.1

For Internal Use Only

®

What is most important to remember?

Principles of Radiation Therapy

Tissue radiosensitivity

Differences internal/external

Radiation Therapy