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RAD 106 Exam 2
| What is amplitude? | It measures the height of the wave and represents the brightness, intensity, or power of the radiation. |
| True or False: Higher amplitude means more x-ray photons are present, making the x-ray beam stronger. | True |
| What is wavelength? | It is the physical distance between two crests or troughs of a wave. It determines the type of radiation and its penetrating power. |
| True or False: Longer wavelengths have lower-energy radiation such as radio waves and shorter wavelengths have high-energy, highly penetrating radiation such as gamma rays. | True |
| What is frequency? | It is the number of complete wave cycles that pass a fixed point in one second and is measured in Hertz (Hz). |
| What is the wave equation? | c = f(wavelength symbol). c represents the speed of light and f represents frequency. |
| What is velocity? | It is the speed of light which is 3.0 x 10^8 m/s |
| What is the relationship between frequency and wavelength? | It is an inverse relationship. As frequency increases, wavelength decreases and vice versa. |
| What is the relationship between energy and frequency? | It is a direct relationship. As energy increases, frequency increases and vice versa. |
| What are x-ray identified by? | Their energy |
| What is visible light identified by? | Their wavelength |
| What is the smallest unit of electromagnetic radiation? | Photon |
| True or False: High frequency -> short wavelength -> high energy | True |
| What is a photon in radiation physics? | It is the fundamental quantum of electromagnetic energy. It behaves as both a wave and particle, does not have mass, travels at the speed of light in a vacuum, and acts as an energy carrier. |
| What is the Planck's equation (photon energy)? | E = hf. h is Planck's constant which can be expressed in either Joule-seconds (6.62607015 x 10^-34 Js) or Electron-volt seconds (4.135667696 x 10^-15 eVs). |
| True or False: Photons interact with matter bigger than their wavelength size | False, photons interact with matter similar to their wavelength size |
| What is the formula for Inverse Square Law? | I1 x (d1)^2 = I2 x (d2)^2. I1 is the original radiation intensity, d1 is the original distance, I2 is the new radiation intensity, and d2 is the new distance |
| True or False: As your distance doubles, intensity decreases to 1/4 of its original strength | True |
| What is electrostatics? | It is the study of electric charges at rest/stationary |
| What is electrodynamics? | It is the study of electric charges in motion |
| What types of charges repel vs attract? | Like charges (- and - or + and +) repel while unlike (- and +) charges attract |
| What type of electric charge is the fundamental source of all magnetic fields? | Moving electric charge |
| What is ferromagnetic? | They are strongly attracted to magnets and can easily become permanently magnetized themselves |
| What is paramagnetic? | They are weakly attracted to magnets and only show magnetic properties when an external magnetic field is present |
| What is diamagnetic? | They are weakly repelled by magnets. An example is water. |
| What is Ohm's Law? | It states that the electric current flowing through a conductor is inversely proportional to the resistance and directly proportional to the voltage across it |
| What is the formula for Ohm's Law? | V = I x R or I = V/R. I is the current (amperes), V is the voltage (volts), and R is the resistance (ohms). |
| What is the x-ray tube power equation? | P = V x I. P is power (watts), V is voltage (kVp), and I is current (mA) |
| What is an autotransformer? | It is a single-winding transformer in an x-ray circuit that allows the radiologic technologist to select the voltage sent to the high-voltage step-up transformer, aka kVp selector |
| Define conductors vs insulators | Electrons flow easily in conductors, while insulators resist electron flow |
| Define AC vs DC | AC's wave shape is sinusoidal and electrons constantly change direction, flowing forward and backward through the circuit. DC's wave shape is constant (straight flat line) and electrons continuously flow in one direction only. |
| What is Bremsstrahlung radiation? | Aka braking radiation where the positive charge of the nucleus slows down the incoming electron and deviates it from its original path. The kinetic energy lost by slowing down is converted into a Bremsstrahlung x-ray photon. |
| What is Characteristic radiation? | An electron traveling from the cathode hits an inner-shell electron (usually K-shell) of a target atom and knocks it out of its orbit. An electron from an outer shell drops down to fill the vacancy and releases its excess energy. |
| How do electrons travel in an x-ray tube? | From cathode to anode |
| True or False: 99% of energy is turned into heat and only 1% is turned into x-rays | True |
| What is continuous spectrum radiation? | It is produced when free charged particles change velocity. The most common is Bremsstrahlung, where a high-speed electron is deflected by a target nucleus, emitting photons of any energy up to the electron's maximum kinetic energy |
| What is discrete spectrum radiation? | It is produced when a bound particle changes quantum states. The most common is Characteristic x-ray emission where an inner-shell vanacy is filled by an outer-shell electron, releasing a photon equal to the exact energy difference. |
| What does mAs control? | The amplitude (quantity) only. |
| What does kVp control? | The amplitude (quantity) and position (quality/energy) of the x-ray emission spectrum |
| What does filtration do? | It removes low-energy photons, decreases amplitude since the total photon quality drops and the spectrum curve is lowered, and shifts the spectrum right as the average energy of the remaining beam increase, this moves the peak towards the higher-energy |
| Where does most heat come from in the x-ray tube? | Outer-shell interactions and electron deceleration |
| What is the difference between quantity and quality? | Quantity is the number of photons (mAs) and quality is the penetration/energy (kVp) |
| What is attenuation? | The reduction in the intensity of a radiation beam as it passes through a material. The incoming photons are either absorbed or scattered by the atoms of the medium. Photons interactions also depend on energy and material density. |
| What is the diagnostic x-ray range? | 30-150 kVp |
| A 15% kVp increase is the equivalent of what? | Doubling mAs |
| Bremsstrahlung accounts for what percentage of x-ray beam? | About 80%+ |
Created by:
naomi_taylorrr
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