Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
CH 38
| Term | Definition |
|---|---|
| ALARA concept | Concept of radiation protection that states all exposures should be kept "as low as reasonably achievable." |
| amperes (A) | A unit of electric current. |
| anode | Positive electrode in the x-ray tube (+). |
| atom | Basic unit of matter. |
| bremsstrahlung radiation | "Braking radiation"; the sudden deceleration of electrons as they interact with highly positively charged nuclei. |
| cathode | Negative electrode in the x-ray tube (-). |
| central ray | X-rays at the center of the beam. |
| contrast | Differences in degrees of blackness on an image. |
| control panel | Portion of the x-ray unit that contains the master switch, indicator light, selector buttons, and exposure button. |
| density | Overall darkness or blackness of an image. |
| dental radiography | Process of recording images of the teeth and adjacent structures by exposure to x-radiation. |
| digital imaging | Filmless method of capturing an image and displaying it by using an image receptor, an electronic signal, and a computer to process and store the image. |
| distortion | Change in the size or shape of an image caused by improper vertical or horizontal angulation. |
| dose (of radiation) | Amount of energy absorbed by tissues. |
| dosimeter | Device used to detect and measure an accumulated dosage of radiation. |
| electron | Negatively charged particle in the atom. |
| energy | Ability to do work. |
| extension arm | Flexible arm that is attached to the x-ray tubehead; encloses wires and aids in positioning. |
| genetic effects | Effects of radiation that are passed on to future generations through genetic cells. |
| image | Film-based or digitally produced recordings of anatomical structures. |
| image receptor | Recording medium for an image, normally film, phosphor storage plate, or digital sensor. |
| intensity | Total energy of the x-ray beam. |
| ion | Electrically charged particle. |
| ionization | Process by which electrons are removed from atoms, causing the harmful effects of radiation in humans. |
| ionizing radiation | Radiation that produces ionization, resulting in harmful effects. |
| kilovoltage peak (kVp) | Highest voltage of x-ray tube used during an exposure; controls beam quality and contrast. |
| latent period | Time between exposure to ionizing radiation and appearance of clinical symptoms. |
| lead apron | Device used to protect the reproductive and blood-forming tissues from scatter radiation. |
| magnification | Proportional enlargement of an image. |
| matter | Anything that occupies space and has form or shape. |
| milliampere (mA) | One one-thousandth (1/1000) of an ampere; unit of measurement used to describe the intensity of an electrical current/quantity of x-rays. |
| penumbra | Blurred or indistinct area that surrounds an image. |
| personal radiation monitoring badge | Device that measures exposure of personnel to ionizing radiation. |
| photon | Minute (tiny) bundle of pure energy that has no weight or mass. |
| primary beam | Most penetrating beam produced at the target of the anode (same as primary radiation). |
| primary radiation | X-rays that come directly from the target of the x-ray tube. |
| quality (of x-ray beam) | Mean energy or penetrating ability of the x-ray beam, controlled by kilovoltage. |
| quantity (of x-ray beam) | Number of x-rays produced in the dental unit; controlled by milliamperage. |
| radiation | Forms of waves of energy emission through space or material. |
| radiograph | Image produced on photosensitive film or digital receptor by exposing it to radiation and processing it. |
| radiology | Science or study of radiation as used in medicine. |
| scatter radiation | Form of secondary radiation that occurs when an x-ray beam has been deflected from its path by interaction with matter. |
| secondary radiation | X-radiation that is created when the primary beam interacts with matter. |
| sensor | Solid-state image receptor that contains a silicon chip with an electric circuit. |
| sharpness | Measure of how well an image reproduces the fine details or outline of an object. |
| somatic effects | Effects of radiation that cause illness and are responsible for poor health, but are not passed on to offspring. |
| thyroid collar | Flexible lead shield that is placed securely around the neck to protect the thyroid gland. |
| tubehead | Part of the x-ray unit that contains the x-ray tube, high-voltage and low-voltage transformers, and insulating oil. |
| tungsten target | Focal spot in the anode hit by electrons to produce x-rays. |
| x-radiation | High-energy ionizing electromagnetic radiation. |
| Position Indicator Device (PID) | Lead-lined extension on the tubehead used to aim the x-ray beam at the image receptor in the patient's mouth. |
| What is the primary importance and use of dental imaging? | It enables the dentist to see conditions not visible in the oral cavity (e.g., detecting early caries, bone loss, abnormalities, and evaluating growth). |
| How does ionization take place? | When an x-ray photon collides with an orbiting electron of a stable atom, knocking it out of orbit and creating an unstable positive ion and a free electron. |
| What produces a dental image? | X-rays pass through structures of varying density in the oral cavity and strike an image receptor (film or sensor), which is then processed. |
| What are the primary characteristics of x-rays? | They are invisible, weightless, high-energy electromagnetic waves that travel at the speed of light, penetrate matter, cause ionization, and produce images on receptors. |
| Where in the x-ray machine are x-rays produced? | Inside the sealed glass x-ray tube, located within the heavy metal tubehead. |
| What is the makeup of the x-ray tube? | A glass vacuum envelope housing a negative cathode (with a tungsten filament) and a positive anode (with a tungsten target and copper stem). |
| How is the Position Indicator Device (PID) used? | It is attached to the tubehead and open-ended to aim and direct the x-ray beam directly toward the patient's face and image receptor. |
| What is the importance of the extension arm in positioning the tubehead? | It encloses the wiring, swivels side-to-side, and extends/folds to allow precise positioning of the tubehead without drifting. |
| What is the difference between radiolucent and radiopaque? | Radiolucent structures allow x-rays to pass through (appearing dark/black); Radiopaque structures absorb/block x-rays (appearing light/white). |
| How do kilovoltage (kVp) and milliamperage (mA) affect the x-ray beam? | Kilovoltage (kVp) controls the QUALITY and penetrating power; Milliamperage (mA) controls the QUANTITY or amount of x-rays produced. |
| How is the ampere used to operate an x-ray unit? | It measures the electrical current; in dental units, milliamperes (mA) regulate the temperature of the cathode filament to produce the electron cloud. |
| What are density and contrast, and how are settings adjusted to change contrast? | Density is overall darkness; Contrast is the difference between dark and light areas. High kVp (90 kVp) lowers contrast (more shades of gray), while lower kVp (70 kVp) increases contrast. |
| What are the biologic effects of radiation exposure on the human body? | Ionization causes cellular and tissue damage, which can lead to somatic effects (damage to individual) or genetic effects (damage passed to offspring). |
| Which critical organs are most sensitive to dental radiation? | Skin, thyroid gland, lens of the eye, and bone marrow. |
| How is radiation measured, and what is the Maximum Permissible Dose (MPD)? | Measured in Traditional (rem/mrem) or SI units (Sv/mSv). The MPD for occupationally exposed personnel is 5000 mrem (5.0 rem or 50 mSv) per year. |
| What items on the x-ray unit are essential for patient protection? | Aluminum filters (remove long wavelengths), lead collimators (restrict beam size), and lead-lined PIDs. |
| What measures are taken to protect the patient from excess radiation? | Use of lead apron/thyroid collar, fast-speed film/digital sensors, proper exposure technique (avoiding retakes), and receptor-holding devices. |
| What measures must the operator take to protect themselves from excess radiation? | Never stand in the direct primary beam, stand behind a lead barrier or at right angles to the beam, and stay at least 6 feet away during exposure. |
| What is ALARA and why is it important? | ALARA stands for "As Low As Reasonably Achievable." It ensures every safety precaution is taken to keep radiation exposure to patients and staff at absolute minimums. |
Created by:
Cocoalover