Radiotherapy Techniques Introduction

Introduction to Radiotherapy Techniques

• 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.

Course Content

• 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

Objectives

• Know the types of radiation used in therapy
• Define radiation therapy and radiotherapy technique
• Describe the team of radiation therapy

Introduction to Radiotherapy

• 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)

Definition of Radiotherapy

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

Radiotherapy Technique

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

Goals/Aims of Radiotherapy

• Radical treatment
• Palliative treatment
• Adjuvant therapy
• Enhancing the chance of operation

Types of Radiation Therapy

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

Mechanism of Radiation Therapy

• 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

Photon Therapy

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

Radical Treatment

• 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

Combination Treatment

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

Palliative Treatment

• 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

Advantages of RT

• 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

Disadvantages

• 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

Limitations of Radiotherapy

• 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

Teamwork of Radiotherapy

• Radiation Oncologist
• Medical Radiation Physicists
• Radiation Therapist
• Medical Dosimetrist
• Radiation Oncology Nurses
• Social Workers
• Dieticians