Training Module 3 – Version 1.1 For Internal Use Only ® 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 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 B C 

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 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  131 I – carcinoma of the thyroid  32 P – bone marrow radiation  137 Cs – needle for local treatment  125 I – brachytherapy seeds Examples of internal radiation therapies: 

Training Module 3 – Version 1.1 For Internal Use Only ® Radiation Therapy – Internal 125 I – 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 

Training Module 3 – Version 1.1 For Internal Use Only ® Further Readings R.Souhami & J.Tobias: Cancer and its Management 2005 Radiation Therapy