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64 Cards in this Set
- Front
- Back
What two main parts make up the x-ray tube? |
Cathode and anode קתודה ואנודה |
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What two types of radiation are produced in an x-ray? |
קרינת בלימה וקרינת אופיינית |
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What is the "fuse" הארה in קרינת בלימה וקרינת אופיינית? |
מתח וזרם חשמלי |
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ייצור קרינת X הוא תוצר של המרת אנרגיה ____ לקרינת ____? |
קינטית, אלקטרומגנטית |
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Which three conditions have to occur (in order) to make x-rays? |
1. ענן אלקטרונים חופשיים 2. מתח גבוה בין הקתודה לאנודה 3. בלימה פתאומית של אלקטרודים באנודה 1. Free electron cloud 2. High מתח tension between cathode and anode 3. Stopping the electrons suddenly in the anode |
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From what material is the interior of the x-ray tube made? |
זכוכית ממנה שאבו את האוויר ליצירת ריק vacuum |
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What is the purpose of the vacuum in an x-ray tube? |
To enable free electrons |
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Which part of the x-ray tube has a negative charge and shoots electrons? |
Cathode |
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Which part of the x-ray tube has a positive charge and serves as the target for the electrons? |
Anode |
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Why are the electrons attracted to the anode? |
It has a positive charge |
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??? What does the anode do to create the electromagnetic energy that makes the x-rays? |
??? The anode suddenly stops spinning and electrons are released (or energy?). בלימה??? |
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What are the two important components of the cathode? |
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Why is tungsten used in the cathode and on the target of the anode? |
Releases large number of photons in a short time, withstands heat |
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How does the filament get electricity? |
From the electric מתח and זרם from a special power line, up to 10 volts. |
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How does the filament give electrons? |
When lit up, the filament heats up and the electrons in the outer rings are freed in an electron cloud. |
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What types of חוט is in the filament and why? |
Long מוקד קטן and short מוקד גדול--the length designates the size of the target area in the anode. |
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What is the typical shape of the anode? |
Round (disc) |
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How does the cathode release the electrons? |
The plates in the filament are negative--reject the electrons in the direction of the anode. |
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What type of metal may be used in a mammogram machine and why? |
Molybdenum, bc mammogram x-rays are low voltage (about 25v instead of 40) |
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Why is the שטח הפגיע at an angle? |
So the x-ray beams can be directed toward the opening of the tube. |
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What is the advantage of a round anode that spins? |
Lasts longer bc the electrons hit a different spot each time. |
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What is קרינת בלימה or bremsstahlung (or קרינה שבירה)? |
Electrons with high kinetic energy are released from the cathode and hit the tungsten atoms of the anode. The nuclei in the tungsten have a strong bond and cause the electrons to change direction and lose energy, in the form of x-rays. |
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What % of קרינת בלימה energy is x-ray? |
1% (99% is heat) |
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What are the three different ways an electron shot from the cathode can create קרינת בלימה and which are x-rays? |
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What is the spectrum of קרינת בלימה? |
0 - 90 kVp |
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What is the highest possible energy in קרינת בלימה and why? |
90 kVp, electrons get as close as possible to nucleus without hitting it |
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What are the three parameters of an x-ray? |
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Why are x-rays heterogenic? |
The electrons are stopped in stages, so their losses of kinetic energy results in photons of different levels of energy, and rays of different wavelengths. |
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Electrons with more kinetic energy result in x-rays that are more ___ ? |
penetrating |
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The shortest wavelength in results in the weakest/strongest ray. |
Strongest |
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The shortest wave emits photons in accordance with the ____ selected. |
מתח |
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קרינת בלימה results in relatively a lot of _____ and a little_____. |
קרינה רקה קרינה קשה |
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קרינה רקה What is ? |
Waves under 40, doesn't penetrate. Body absorbs all of it, so does damage but has not benefit. |
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What is קרינה אופיינית? |
Energy created when electrons shot from the cathode hit electrons in the K ring (of the tungsten) and knock them out of place. An electron from L must fill it's place, losing energy in the move, released in the form of an x-ray. (To remove an electron from tungsten (atomic # 69.5), the electrons shot at it must be at least 70 kev) |
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Characteristic radiation is called that bc it is characteristic of the _____ used. |
Material |
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Most mammograms use _____ radiation. |
Characteristic |
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_____ radiation appears as spikes and ____ appears as a wide wave. |
Characteristic בלימה |
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Characteristic radiation is easier/harder to make in molybdenum than in tungsten, because it has a lower electron binding energy. |
Easier |
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A target area mafe of tungsten in an x-ray tube will most likely use what type of radiation? |
בלימה |
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What type of imaging uses characteristic radiation and need energy of only 20 KEV? |
Mammogram |
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Ma= KV= S= |
זרם חשמלי מתח חשמלי זמן |
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True or false?: Both processes of radiation (characteristic and בלימה) occur inside the x-ray tube. |
True |
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מתח= זרם= |
Strength of current # of electrons |
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True or false?: in an electric current, the electrons flow and the protons do not move. |
True |
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What is the measurement of an electric current זרם and to what does it refer? |
A (amperes), refers to the number of electrons that flow |
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MA= S= MAS= KV= |
MA=Miliampere S=Second MAS=Miliampere per second (represents flow) KV=מתח, strength, speed of electrons from cathode to anode |
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The זרם that passes through the x-ray tube is measured in what units? |
MA (miliampere) |
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The ____ is what decides the number of electrons hitting the target area of the anode and affects the amount of radiation. |
זרם |
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The זרם of the filament ____ the filament to create electrons. |
heats |
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מתח חשמלי: |
The difference in the electric potential between two points, measured in volts (V) |
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Electric current in an x-ray tube is measured in ___ ? |
Kv (how fast the electrons flow toward the anode) |
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The Kv chosen equals the ____ highest level of energy in the x-ray spectrum. |
highest |
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The higher the מתח, the faster the free electrons will move toward the anode, the higher the ____ energy. |
kinetic |
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Time in an x-ray refers to the length of exposure and is measured in ___ or ___. |
seconds, milliseconds |
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More time exposure means more ___ and more ____. |
electrons, radiation |
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If, for example, 400 MA for .25 seconds, produces 5000 x-rays, how many x-rays are produced if we change the time to .5 seconds? |
10,000 |
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200 MA × .1 S = 20 MAS. How can we raise the MAS to 40? |
400 MA × .1S 200 MA × .2S |
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400 MA × .1S = 40 MAS200 MA × .2S = 40 AND Which option is better? |
Higher MA (# of electrons) at less time, to reduce chance of movement |
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Today, the radiography only chooses the ___? |
KVP |
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MAS ⬇️ FOCUS AREA ❔ RESOLUTION ❔ |
MAS ⬇️ FOCUS AREA ⬇️ RESOLUTION ⬆️ |
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What are the 5 steps that happen in the cathode? |
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What are the 4 steps that happen in the anode? |
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קרינה x הוא תוצר של: א. המרת אנרגיית חום לאנרגיה קינטית ב. המרת אנרגיית קינטית לקרינה אלקטרומגנטית ג. המרת אנרגיית חשמלית לאנרגיה כימית ד. המרת אנרגיה כימית לאנרגיה חשמלית |
ב |
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היחס בין חום לקרינת רנטגן בזמן יצירת הארה בשפופרת אבחון הוא: |
99:1 |