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x ray physics
exam 1
| Question | Answer |
|---|---|
| what is an x-ray? | light energy |
| Describe electromagnetic energy in terms of mass? charge? velocity? | mass= no mass charge = no charge velocity = speed of light |
| Define ionize | the ability to totally remove an electron from its orbit around a nucleus |
| Which of the types of energies in the electromagnetic spectrum have the ability to ionize? | x-rays, gamma ray and possibly some short wavelength UV rays are the only ones |
| What makes an x-ray photon higher energy than a microwave? | the wavelength |
| State the wavelength equation | speed of light= wavelength x frequency |
| What is a gamma ray? | high energy ray that comes from inside the nucleus |
| What is the difference between gamma rays and x-rays? | their origin; gamma rays come from the nucleus |
| Is a gamma ray always high energy than an x-ray? | no |
| will you, as a chiropractor, ever use gamma rays in your practice? | no |
| will exposure to x-radiation leave matter radioactive? | no |
| to avoid being exposed to x-rays, how long must you wait before entering the x-ray room after the exposure is terminated? | immediately |
| Why is a free electron in human tissue a worry? | because they are highly reactive and are believed to be involved in degenerative diseases and cancers |
| What is the relationship between x-ray wavelength and energy? | inversely related; shorter wavelength, higher energy |
| what is the mechanism of cell damage from diagnostic x-ray exposure? | ionization |
| What is the most biologically damaging type of ionizing radiation? | particulate (from radioactive elements) |
| in bremsstrahlung production, x-rays are produced that range from zero to ----- kVp in energy | peak |
| ---- characteristic x-rays of tungsten are the only ones energetic enough to be useful | K characteristics |
| At least ---- kVp must be set on the console to produce K characteristic x-rays in tungsten | 70 kVp |
| What type of x-ray provides the least amount of exposure to the patient and is affordable? | high frequency |
| What type of x-ray allows for the shortest exposure time? | high frequency |
| Which side of the x-ray beam has the least number of x-rays? | anode |
| How much of the electric and kinetic energy of the projectile electrons is converted to heat? x-ray? | heat- 99% x-ray - 1% |
| is heat production an excitation interaction or is it an ionization interaction? | excitation interaction |
| x-rays are produced by what two methods? | 1. characteristic 2. bremsstrahlung |
| Which method of x-ray production occurs when electrons shift energy levels/ shells within the atom? | characteristic |
| Tungsten is used as a target material, it has electron shells from "k" near the nucleus out to -- | P |
| at least -- kVp is required to produce useful energy k-characteristic x-rays of tungsten? | 69 kVp |
| the vast majority of x-rays in the beam are a result of what production process? | bremsstrahlung |
| what is the highest energy x-ray in a beam dependent on? | kVp |
| describe bremsstrahlung x-ray production. | occurs when an electron is slowed down due to a nuclear force field |
| what is the average of an x-ray mean produced at 80 kVp? | 26.67 kVp |
| describe characteristic x-ray production. | occurs when outer shell electrons fill inner shell vacancies due to the projectile electron hitting an electron and ejecting it from an inner shell |
| what is radiographic density? | the blacks on the film |
| which side of a radiograph will exhibit the least radiographic density? | the anode |
| T/F - the high atomic number of the tungsten target absorbs low energy x-rays | false |
| where should the anode side of the tube be placed when performing a lateral thoracic spine radiograph? | down |
| where should the anode side of the tube be placed when performing an AP thoracic spine radiograph? | up |
| where should the anode side of the tube be placed when performing a full spine radiograph on a 14 x 36 film? | up |
| where should the anode side of the tube be placed when performing a lateral cervical spine radiograph? | it doesnt matter on a 10 x 12" film at 40" |
| How does placing the anode/cathode side in the proper affect the radiograph's overall density? | it produced uniform density |
| besides using the anode heel effect properly there are two other options that may help to produce a more uniform film density. They include; | slow speed (where are is thin), faster speed (where area is thick) |
| How should you have your tube installed? | anode side up |
| Which side of the radiograph will be the sharpest? | anode side |
| The --- side of the x-ray tube emits x-rays that are relatively perpendicular to the film | anode |
| what type of current is required to produce x-rays? | DC (direct current) |
| does the power company provide DC current? | no, they only provide AC |
| What is the purpose of the rectifier? | changes AC to DC |
| what does kVp do inside the tube to produce x-rays? | it is the technical factor that controls energy of the electron |
| do all of the electrons have the same velocity as they pass from cathode to anode? why? | no when electrons from the cathode hit the tungsten anode they suddenly stop and give up their energy |
| What type of rectifiers produce a beam with the highest energy x-rays? | high frequency rectification |
| what type of rectifier reduced patient exposure by at least 30%? | high frequency rectification |
| what type of rectifiers is the most consistent with the concept of ALARA? | full wave rectification |
| what type of rectifiers will extend the tube life? | high frequency rectification |
| what type of rectifiers produce the highest contrast radiograph? | full wave rectification |
| unit of x-ray intensity in air? | Roentgen (R) ; classical |
| unit of radiation absorbed dose? | RAD ; classical |
Created by:
tlh003