Discussion topic:
There are two mechanisms by which x-rays are produced...bremsstrahlung and characteristic. Use Khan and other resources (even youtube.com) to help yourself understand these processes. Pick one or the other and describe this process to your classmates in as simple terms as you can. These terms will be used throughout the program, so if you can find a way to remember them now, it may help you in the long run.
Discussion post:
Bremsstrahlung radiation is the result of a high speed electron interacting with the nucleus of an atom. As a high speed electron travels near the nucleus of an atom the negative charge of the electron interacts with the positive charge of the atom’s nucleus. The coulomb force from the positive nucleus alters the course of the electron’s travel and causes it to lose energy. The path of the electron is bent and the electron is whipped around the nucleus.1 For a mental picture you could imagine the path of a comet as it passes near the Earth, if the comet enters the Earth’s gravitational field the comet’s course can be altered and the gravitational field can slingshot the comet off in another direction. Although very different forces are at play in my example it may help you picture how bremsstrahlung interactions work.
In a bremsstrahlung interaction as the electron path is altered by the nucleus some electron energy is lost. This lost energy is given off in the form of an x-ray. A few things can affect the amount of energy given off as an x-ray. The closer an electron travels to a nucleus the stronger the electromagnetic interaction and the greater the resulting bremsstrahlung x-ray.2 The amount of energy given off as an x-ray also depends on the initial energy of the electron. A bremsstrahlung x-ray can have up to as much energy as the initial interacting electron. However, an electron traveling very fast may have one bremsstrahlung interaction and produce an x-ray and then continue on to have several more bremsstrahlung interactions.1
Another interesting facet about bremsstrahlung radiation is that as electron energy increases the direction of the x-rays produced changes. Higher energy electron interactions produce bremsstrahlung x-rays moving forward in the same direction as the interacting electron was traveling. This is why linear accelerators use transmission targets in radiation therapy and diagnostic x-ray uses an angled target. Additionally, higher energies and high atomic number targets are more efficient at producing bremsstrahlung interactions.1
References
1.Khan FM, Gibbons JP. The Physics of Radiation Therapy. 5th Philadelphia, PA: Lippincott Williams and Wilkins. 2014.
2. Goaz, Pharoah. Production of X-Rays and Interactions of X-Rays with Matter. Columbia.edu. http://www.columbia.edu/itc/hs/dental/sophs/material/production_xrays.pdf. Accessed on September 13, 2016.
There are two mechanisms by which x-rays are produced...bremsstrahlung and characteristic. Use Khan and other resources (even youtube.com) to help yourself understand these processes. Pick one or the other and describe this process to your classmates in as simple terms as you can. These terms will be used throughout the program, so if you can find a way to remember them now, it may help you in the long run.
Discussion post:
Bremsstrahlung radiation is the result of a high speed electron interacting with the nucleus of an atom. As a high speed electron travels near the nucleus of an atom the negative charge of the electron interacts with the positive charge of the atom’s nucleus. The coulomb force from the positive nucleus alters the course of the electron’s travel and causes it to lose energy. The path of the electron is bent and the electron is whipped around the nucleus.1 For a mental picture you could imagine the path of a comet as it passes near the Earth, if the comet enters the Earth’s gravitational field the comet’s course can be altered and the gravitational field can slingshot the comet off in another direction. Although very different forces are at play in my example it may help you picture how bremsstrahlung interactions work.
In a bremsstrahlung interaction as the electron path is altered by the nucleus some electron energy is lost. This lost energy is given off in the form of an x-ray. A few things can affect the amount of energy given off as an x-ray. The closer an electron travels to a nucleus the stronger the electromagnetic interaction and the greater the resulting bremsstrahlung x-ray.2 The amount of energy given off as an x-ray also depends on the initial energy of the electron. A bremsstrahlung x-ray can have up to as much energy as the initial interacting electron. However, an electron traveling very fast may have one bremsstrahlung interaction and produce an x-ray and then continue on to have several more bremsstrahlung interactions.1
Another interesting facet about bremsstrahlung radiation is that as electron energy increases the direction of the x-rays produced changes. Higher energy electron interactions produce bremsstrahlung x-rays moving forward in the same direction as the interacting electron was traveling. This is why linear accelerators use transmission targets in radiation therapy and diagnostic x-ray uses an angled target. Additionally, higher energies and high atomic number targets are more efficient at producing bremsstrahlung interactions.1
References
1.Khan FM, Gibbons JP. The Physics of Radiation Therapy. 5th Philadelphia, PA: Lippincott Williams and Wilkins. 2014.
2. Goaz, Pharoah. Production of X-Rays and Interactions of X-Rays with Matter. Columbia.edu. http://www.columbia.edu/itc/hs/dental/sophs/material/production_xrays.pdf. Accessed on September 13, 2016.