Radiotherapy Techniques Introduction

Study Notes

The Department of Diagnostic Radiology and Imaging aims to be nationally outstanding in the discipline of diagnostic radiology and imaging for the best treatment prescription and prognosis.

Introduction to radiotherapy and types of radiation used in radiotherapy
Radiotherapy equipment and utilization
Physics and main accessories used in radiotherapy
Radiotherapy plan (clinical, physical, and technical)
Staging of cancer patients
Techniques and planning of cancer patients
Selective cases: Head and neck tumours, Chest, Female Breast, Uterus and Cervix, Ovary, and testicular tumour
Emergency in radiotherapy
Advanced radiotherapy techniques: Brachytherapy, Gamma Knife, and IMRT

Radiation therapy: medical use of ionizing radiation to control or kill malignant cells directly or indirectly
Types of radiation for treatment: Photons beam (x-ray and gamma ray), Particles (Electron, protons, neutron, alpha..)
Sources of radiation for treatment: Linear accelerators, Radioactive sources (Co-60 teletherapy unit, Cs-137 teletherapy unit, Brachytherapy units, Sr-90, Xenon, Iridium)

Radiation therapy is the medical use of ionizing radiation to manage malignant/benign tissues

Procedure to implement radiotherapy plan (Clinical, physical, and technical) for malignant/benign tissue patients, considering anatomy, physiology, and patient position

External beam (Teletherapy)
Internal irradiation (Brachytherapy): Intra-cavitary, Interstitial, Surface molds, Inhalation

Damaging DNA of cancerous cells through direct ionization or indirect ionization
High-energy radiation directed to area of interest, forming free radicals that damage DNA and cause cell death and tissue injury

Free radicals cause single-strand DNA damage (cell repair) or double-stranded DNA (cell death)

Radical radiotherapy is treatment delivered with the intention to produce a high rate of local tumour control
Most radical treatments are given over 4-6 weeks, in 1.8-2 Gray fraction/day to a total dose of 55-74Gy

Radiation therapy may be used alone or in combination with other treatments: Surgery, Chemotherapy, Immunotherapy

Palliative radiotherapy is given over a shorter period of time with larger fraction of dose but in single dose or short period
Treatment may be given as a single fraction or short fractions: 8-10 Gy or 20 Gray /5 fractions, 30Gy /10 fractions

Allows for loco-regional treatment of cancer without direct removal of organs/tissues
Can allow for organ preservation
Better cosmesis
Less restricted by pre-existing medical conditions

Almost impossible to avoid some damage to normal tissues
May involve multiple daily treatments over several weeks, especially for curative treatment
Psychological aspects of “not removing” cancer

Immediate relief of symptom or pain does not occur
Significant improvement may require a couple of weeks or more after radiotherapy
Etiology of the symptoms needs to be clear before giving radiation
Diffuse/extensive involvement of critical organs by cancer not treatable