RAD 1126 CHAPTER 11 Flashcards

Question

MAJOR ROLE

Answer 1

CREATION OF SUBJECT CONTRAST -CAPTURE OF IMAGE BY IR MOST OF THE PRIMARY BEAM CONSIST OF PHOTOELECTRIC INTERACTION

Answer 2

THE INCOMING PHOTON MUST BE JUST ABOVE THE BINDING ENERGY OF THE INNER SHELL ELECTRON HAS A SLIGHTLY HIGHER ENERGY THAN THE BINDING ENERGY

Answer 3

EP= EB+EKE

Answer 4

PHOTOELECTRIC INTERACTION

Answer 5

This is an interaction with an incoming high-energy photon hitting the electron in the outer shell whose binding energy is weak, the electron in the outer shell absorbs some energy from the incoming photon and gets ejected as a recoil electron, and a slight lower energy photon is created and shots out at a different angle

Answer 6

- The incoming photon loses a small amount of energy and changes direction, and angle based on initial energy -Takes place in outer shell -Incoming photon energy much higher than binding energy The electron ejected becomes a recoil electron/secondary electron/Compton scattered electron

Answer 7

EP= ES+EB+EKE

Answer 8

Can be in remnant beam but reduces contrast, Represents 97% of all scatter Represents occupational dose

Answer 9

SCATTER OCCURS IN ALL DIRECTIONS, AND THE ANGLE IS BASED ON THE ORIGINAL ENERGY OF INCOMING PHOTON SCATTER THAT COMES DIRECTLY BACK TO THE TUBE (180 DEGREES) KNOWN AS BACK SCATTER

Answer 10

As kvp increases the energy of the initial photon as well increases. As the energy increases more scatter is likely to hit the IR. THIS SCATTER IS LIKE A FOG OBSCURING THE DETAILS IN THE WITHIN THE IMAGE AND IS KNOWN AS NOISE

Answer 11

KVP INCREASE, INTIAL/INCOMING PHOTO ENERGY INCREASE, SCATTER INCREASE, THEN FOG AND THEN NOISE

Answer 12

IT REDUCES CONTRAST

Answer 13

An incoming low-energy photon interacts with the tightly bound electron, but instead of knocking it out, the energy is absorbed by the electron, existing the electron and causing a release of a new photon in a different direction but with the same energy as the initial photon 80KV IN AND 80KV OUT, END PRODUCT IS A SCATTERED PHOTON

Answer 14

Here the electrons are exited, the initial photon energy was absorbed by the orbital electrons NEW PHOTON CREATED

Answer 15

Here the entire atom is exited, the initial photon energy was absorbed by the entire atom NEW PHOTON CREATED

Answer 16

Represents only 3 % scatter to IR, Very little effect on image

Answer 17

After an (Ionizing event) in a tissue atom such as Compton or photoelectric interaction an electron will be pulled ( from the inside or outside) to fill the vacancy. This can result in an extremely low photon (1kv) or ultraviolet light and will not have an effect on the x-ray image

Answer 18

- Occurs after the atom is ionized by Compton or PE -Happens in any shell with vacancy -New electron from inside or outside falls causing a loss of potential energy and emission IT IS THE ONLY INTERACTION THAT TAKES PLACE IN THE X. RAY TUBE AND WITHIN THE PATIENT -An ionizing effect can cause a characteristic event

Answer 19

After an ionizing event (like Compton or photoelectric interaction) happens in an atom, it knocks an electron out, creating a vacancy. To fill that vacancy, another electron from a different part of the atom (inside or outside) moves in. When this happens, a small amount of energy is released, but it’s so low (around 1 kV or ultraviolet light) that it doesn’t affect the X-ray image. These low-energy photons are too weak to contribute to the image you see on the X-ray.

Answer 20

The energy created is so slow there is no effect on image and energy created is likely to be light or ultraviolet EM Radiation

Answer 21

This is the partial absorption of X-ray in the patient's body based on the thickness or atomic density of a tissue, which is the basis for contrast known as attenuation. So without Contrast we wont be able to see differences in tissues

Answer 22

Attenuation refers to the partial absorption of X-rays as they pass through the patient's body. The amount of absorption depends on the thickness and atomic density of the tissue. Dense tissues, like bone, absorb more X-rays, while less dense tissues, like muscle or fat, absorb fewer X-rays. This difference in absorption creates contrast on the X-ray image, allowing different tissues to be seen clearly.

Answer 23

The contrast created by attenuation in an X-ray image refers to the differences in brightness (shades of gray) between various tissues. This contrast helps distinguish between different structures in the body based on how much X-ray each tissue absorbs. For example: Dense tissues like bone absorb more X-rays, so they appear white or very light on the image. Less dense tissues like muscle or fat absorb fewer X-rays, so they appear in shades of gray. Air-filled areas like the lungs absorb the least X-rays, so they appear black or very dark.

Answer 24

Without contrast, it would be difficult to distinguish between different tissues in an X-ray image. All the tissues would appear the same shade, making it impossible to tell apart structures like bones, muscles, fat, or organs. Contrast is what allows us to see the differences in density and make the various tissues visible in the image. Without it, the X-ray image would lack detail and clarity.

Answer 25

In a homogeneous object (made of the same material throughout), the attenuation of the X-ray beam depends only on the thickness of the object. Here's what happens: Thinner areas cause less attenuation because there is less material for the X-rays to pass through. More X-rays reach the detector, making those areas appear darker on the radiograph. Thicker areas, like the right side of a stepwedge, cause more attenuation because there is more material, so fewer X-rays make it through. This results in those areas appearing lighter (brighter) on the radiograph. In summary, the thicker the tissue or material, the more X-rays are absorbed (attenuated), leading to brighter areas on the image. Thinner areas absorb less, resulting in darker areas.

Answer 26

The intensity of the X-ray beam is reduced by 50% (cut in half) for every 4 to 5 cm of tissue it passes through. To maintain a consistent image, the exposure technique must be doubled for each increase of 4 to 5 cm in tissue thickness. This can be done in two ways: Doubling the mAs (milliamperage-seconds), which increases the total amount of X-rays produced. Increasing the kVp (kilovolt peak) by approximately 15%, which makes the X-rays more penetrating. This principle reflects the normal rate of attenuation, where 50% of the beam's intensity is lost for every 4 to 5 cm of tissue, and adjustments in technique ensure the image quality remains consistent despite changes in tissue thickness

Answer 27

Each type of tissue in the body has a unique molecular structure and atomic number (Z#), which influences how it interacts with X-rays. Combined with varying thicknesses, different tissues will attenuate (absorb) the X-ray beam to different degrees. Dense tissues like bone have a higher atomic number and absorb more X-rays, so they appear lighter (whiter) on the image. Less dense tissues like muscle or fat absorb fewer X-rays, resulting in darker shades of gray. These differences in attenuation create various shades of gray in the X-ray image, forming the gray scale. In digital imaging, the gray scale can be further adjusted or manipulated using digital processing to enhance the image and make the details clearer

Answer 28

It is the total reduction in number of x-rays in beam after passing through tissue

Answer 29

Secondary Photon: This is a photon that is produced as a result of interactions with matter, specifically when the primary photon interacts with atoms in the body or material. Coherent Scattering: In this interaction, the primary photon can change direction without a loss of energy, leading to the emission of a secondary photon of the same energy. Both the scattered photon and the original photon can coexist after the interaction, but they are not the same photon

Answer 30

Digital imaging relies on atomic interactions between the remnant beam and the various phosphors contained in different image receptors. Much more on this in future lectures.