Podcast
Questions and Answers
Who discovered X-rays?
Who discovered X-rays?
Roentgen
Which type of radiotherapy unit initially gained prominence after the invention in the early 1950s?
Which type of radiotherapy unit initially gained prominence after the invention in the early 1950s?
What are the two groups of X-ray photons produced during radiotherapy?
What are the two groups of X-ray photons produced during radiotherapy?
All modern radiotherapy uses cobalt units exclusively.
All modern radiotherapy uses cobalt units exclusively.
Signup and view all the answers
In which energy range do clinical X-ray beams typically operate?
In which energy range do clinical X-ray beams typically operate?
Signup and view all the answers
What event leads to the production of characteristic X-rays?
What event leads to the production of characteristic X-rays?
Signup and view all the answers
Characteristic X-rays are emitted when an _____ electron fills an orbital vacancy.
Characteristic X-rays are emitted when an _____ electron fills an orbital vacancy.
Signup and view all the answers
What is the fluorescent yield (w)?
What is the fluorescent yield (w)?
Signup and view all the answers
Study Notes
Introduction to Radiotherapy Technology
- Radiotherapy began shortly after X-ray discovery by Roentgen in 1895, initially focusing on increasing photon and electron beam energies.
- Early technological advancements were slow, primarily using X-ray tubes, van de Graaff generators, and betatrons.
- The 60Co teletherapy unit, invented by H.E. Johns in the 1950s in Canada, significantly advanced radiotherapy by providing higher photon energies.
- Medical linear accelerators (linacs) replaced cobalt units, evolving through five generations and becoming the primary radiation source in modern therapy.
- Linacs are compact, efficient, versatile, and can deliver both electron and megavoltage X-ray therapy with a wide energy range.
- Alternative accelerators such as betatrons and microtrons are also used, along with special particles like protons and heavy ions, though linacs and cobalt units dominate.
X-ray Beams and X-ray Units
- Clinical X-ray beams vary in energy from 10 kVp to 50 MV, produced by decelerating electrons in metallic targets.
- The majority of the electron's kinetic energy converts to heat in the target, with a small portion emitted as X-ray photons.
- X-ray photons can be categorized into two main types: characteristic X-rays and bremsstrahlung X-rays.
Characteristic X-rays
- Characteristic X-rays originate from Coulomb interactions between incident electrons and target material’s atomic orbital electrons.
- When an incident electron collides with an orbital electron, it ejects the orbital electron, creating a vacancy.
- Another electron from a higher energy shell fills this vacancy, leading to the emission of energy in the form of a characteristic photon or an Auger electron.
- The fluorescent yield (w) quantifies the number of characteristic photons emitted per vacancy (0 < w).
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
Test your knowledge on treatment machines for external beam radiotherapy as discussed in Chapter 5. This chapter covers the advancements in technology since the discovery of X-rays and their impact on radiotherapy practices. Engage with the material and solidify your understanding of the subject.
