Capitulo 38
1. Who discovered x-rays?
Wilhem Conrad Roentgen discovery in 1895
2. Who was the first person to make practical use of x-rays in dentistry?
C. Edmund kells
3. What is ionization?
Ionization is the process by which electrons are removed from electrically stable atoms through collisions with x-
ray photons.
4. What are the primary components of a dental x-ray machine?
Tubehead, extension arm and control panel.
5. Name the negative electrode inside the x-ray tube.
The cathode is the negative electrode inside the x-ray tube.
6. Name the positive electrode inside the x-ray tube.
The anode is the positive electrode inside the x-ray tube.
7. What does the control panel contain?
Master switch, indicator light, selector buttons and exposure button.
Nota: Select button is used: select exposure time Milliamperage (mA) and kilovoltage (kV) regulating the x-ray
beam.
8. Name the three types of radiation.
1era radiation (primary or useful beam): Made up of the x-rays coming from the target of the x-ray tube.
2condary radiation: Create when the primary beam interacts with matter or the persons tissue. Is less penetrating
than primary and is not useful radiation because produce fog on the x-ray damaging the quality of diagnostic.
3er radiation (Scatter radiation): Scatter radiation: Secondary radiation from x-rays deflected by matter, harmful
to patients and operators in the dental office.
9. Describe the difference between radiopaque and radiolucent.
Radiolucent: dark dark appearance of a structure on a processed radiograph.
Radiopaque: white or light gray image, not easily penetrated.
10. Give examples of structures that appear radiolucent on a radiograph.
Air, soft tissue, abscess, decay, dental pulp.
11. Give examples of structures that appear radiopaque on a radiograph.
Enamel, dense areas bone, metal restauration.
12. What are the three characteristics of the x-ray beam?
Quality, quantity and intensity.
13. Which exposure factor controls contrast?
The range of shades of gray to black to white.
Nota: ideal contrast is radiopaque white: metal restoration
14. What is meant by density on a dental radiograph?
Is the overall blackness or darkness of a film.
(black areas: air space, white areas: enamel, dentin and bone, gray areas: soft tissues.)
15. What is the name of the process that results in the harmful effects of x-rays?
Ionization radiation
16. What is the name of the time period between x-ray exposure and the appearance of symptoms?
Latent period
17. What is meant by genetic effects of radiation?
Genetic effects of radiation damage genetic cells (sperm and ova) and are passed on to
future generations.
