Radiation Physics
Who discovered x-rays?
Wilhelm Roentgen
What does ALARA stand for?
As Low As Reasonably Achievable
What is the overall blackness or darkness of a radiograph called?
Density
What is the preferred periapical technique?
Paralleling technique
What radiolucent area lies between maxillary central incisors?
Incisive foramen
What part of the x-ray tube generates electrons?
The cathode
What protects the patient’s thyroid from scatter radiation?
Lead apron with thyroid collar
What term describes the difference in shades of gray?
Contrast
In the bisecting technique, where is the beam directed?
Perpendicular to the imaginary bisector
What radiopaque U-shaped structure is seen above maxillary molars?
Zygomatic process
What controls the energy (penetrating power) of x-rays?
Kilovoltage (kVp)
At what angle should the operator stand during exposure?
90–135 degrees from the beam
Name the three geometric characteristics of a radiographic image.
Sharpness, Magnification, Distortion
What error results from too little vertical angulation?
Elongation
What radiolucent opening appears near mandibular premolars?
Mental foramen
What controls the number (quantity) of x-rays produced?
Milliamperage (mA)
What device restricts the size of the x-ray beam?
Collimator
What causes magnification?
Increased object–receptor distance
What error results from incorrect horizontal angulation?
Overlapping contacts
What structure forms the inverted “Y”?
Nasal cavity and maxillary sinus
What is the process called when x-rays cause atoms to lose electrons?
Ionization
What material filters out long, non-penetrating wavelengths?
Aluminum filter
What factor most affects sharpness?
Focal spot size
What error appears when the PID does not cover the entire receptor?
Cone cut
What radiopaque structure is seen on Maxillary 3rd molar region?
Tuberosity