aim of radiotherapy

1. Radiotherapy introduction
Dr/ Saeed Albehairy
Lecturer of clinical oncology
MD of clinical oncology
Beni-Suef University

2. Definition of radiotherapy
• The use of high-energy radiation from x-rays,
gamma rays, neutrons, protons, and other
sources to kill cancer cells and shrink tumors
• Radiotherapy is a local treatment as surgery
• Radiotherapy is either external ( as cobalt or
linear) or internal as brachytherapy)

3. Aim of radiotherapy
1. Definitive:
• alternative to surgery( equal results with better
QOL or unresectable), with
• advantages of organ preservation and less
morbidity
• example early cancer larynx, prostate and
nasopharynx
• Alone or with systemic ttt(chemo-hormonal)
• Usually high total dose compared to
neo(adjuvant) or palliative.

4. 2-Neo(Adjuvant) radiotherapy:
• Aim: improve local control+/- overall survival
• Exapmples:
Neoadjuvant radiotherapy in rectal cancer, STS
Adjuvant in breast, brain, STS, head neck,,,,,,

5. 3- Palliative:
• Pain control
• Relieve symptoms as cord compression and
increased ICT
• Either single dose or higher can be given
• Ex: bone and brain metastases

6. External radiotherapy
• Use external machines for radiation
• Examples: Cobalt, linear and proton machines
• The most common method used in
radiotherapy
• Either natural or artificial sources

7. Cobalt 60 machine
• Simple machine
• Release gamma ray (photon)
• SSD: 80 cm
• Mean energy: 1.25 MeV
• Natural source with half life 5 years
• Source size about 2 cm
• Dmax: 0.5 cm
• Source must change every 5 years
• Advantages: simple, less cost
• Disadvantages: mono-energic with low energy compared to
linear, not fit for deep lesion > 10 depth, large source size
so wider penumbra

8. Linear accelerator
• Complicated machine
• Artificial
• SSD: 100 cm
• Small source
• Relases x-ray(photon) or electron
• Mono-energic or multienergic with 4-20mv range
• Dmax: vary according to energy, the higher energy the
deeper Dmax( 4mv: Dmax at 1 cm, 20mv: Dmax 3 cm)
• Advantages: can treat deep tumors, narrow penumbra
• Disadvantages: expensive and complicated

9. Linear
Cobalt60

10. Brachytherapy
• Def: use radioactive source for radiotherapy
ttt from short distance
• May be: