MindMap Gallery X-ray
It summarizes the properties and dose of X-rays, the generation of X-rays, the interaction between X-rays and matter, the formation and detection of images in X-ray projection imaging, etc.
Edited at 2024-03-26 20:04:09This Valentine's Day brand marketing handbook provides businesses with five practical models, covering everything from creating offline experiences to driving online engagement. Whether you're a shopping mall, restaurant, or online brand, you'll find a suitable strategy: each model includes clear objectives and industry-specific guidelines, helping brands transform traffic into real sales and lasting emotional connections during this romantic season.
This Valentine's Day map illustrates love through 30 romantic possibilities, from the vintage charm of "handwritten love letters" to the urban landscape of "rooftop sunsets," from the tactile experience of a "pottery workshop" to the leisurely moments of "wine tasting at a vineyard"—offering a unique sense of occasion for every couple. Whether it's cozy, experiential, or luxurious, love always finds the most fitting expression. May you all find the perfect atmosphere for your love story.
The ice hockey schedule for the Milano Cortina 2026 Winter Olympics, featuring preliminary rounds, quarterfinals, and medal matches for both men's and women's tournaments from February 5–22. All game times are listed in Eastern Standard Time (EST).
This Valentine's Day brand marketing handbook provides businesses with five practical models, covering everything from creating offline experiences to driving online engagement. Whether you're a shopping mall, restaurant, or online brand, you'll find a suitable strategy: each model includes clear objectives and industry-specific guidelines, helping brands transform traffic into real sales and lasting emotional connections during this romantic season.
This Valentine's Day map illustrates love through 30 romantic possibilities, from the vintage charm of "handwritten love letters" to the urban landscape of "rooftop sunsets," from the tactile experience of a "pottery workshop" to the leisurely moments of "wine tasting at a vineyard"—offering a unique sense of occasion for every couple. Whether it's cozy, experiential, or luxurious, love always finds the most fitting expression. May you all find the perfect atmosphere for your love story.
The ice hockey schedule for the Milano Cortina 2026 Winter Olympics, featuring preliminary rounds, quarterfinals, and medal matches for both men's and women's tournaments from February 5–22. All game times are listed in Eastern Standard Time (EST).
X-ray
1. Nature and dose of X-rays
Properties of X-rays
X-rays are electromagnetic waves with wave-particle duality
Particleity: Interaction with matter.
Wave nature: can propagate in space and undergo reflection, interference, and diffraction.
X-ray particle properties
physical effects
Penetration
Fluorescence
ionization
chemical effect
photosensitivity
Coloration
Biological effects
Cells undergo ionization, causing inhibition, damage, and even necrosis to biological cells.
Disadvantages: hair loss, reduction of white blood cells, redness and inflammation of tissues.
Benefits: Used in clinical treatment, commonly used in radiotherapy, such as X-ray surgery.
X-ray intensity definition
The total energy of x-ray photons passing through the unit surface per unit time
Exposure dose definition
The absolute value of the total charge of a symbolic particle produced when all electrons ejected by unit mass x-ray photons in the air volume circle come to a complete stop in the air
Absorbed dose definition
The radiation causing ionization is transmitted to a volume of mass dm. The average energy of matter within the circle D=(dε/dm)
Ionization properties in biological tissues
Kinetic energy transferred to charged particles by indirect ionizing radiation per unit mass of matter. In a unit mass of biological tissue, when X-rays pass through, how much energy can be transferred to the ionization characteristic kinetic energy released in the tissue?
Define measurement equivalent
H=DQN
D-absorbed dose
N-Correction Factor
Q-quality factor
3. The role of X-rays and matter
definition
Macroscopically, three results may occur when a photon enters a certain medium:
Penetrates the medium without interacting with the medium
Scattered during one or more interactions
absorbed in the course of one or more interactions
X-ray attenuation
The intensity of mercerized light after passing through a board with thickness d is Id
Incident x-ray intensity Io
Board thickness d
Linear attenuation coefficient μ
Depends on the energy of the photons of the x-ray beam, the atomic number of the elements in the transmitted material, and the density of the transmitted material
Id/Io=e-μd d infinity Id is infinitely close to zero
The main chain reactions between X-rays and matter
Compton scattering
Production process: collision of photons with outer electrons of medium atoms
Some energy is transferred to the recoil electron
The remaining energy is carried by scattered photons
Geometric relations
Incident photon: Eo=hv=h(c/λo)
Scattered photons: Esc=hv=h(c/λ)
Scattering angle: θ
Recoiling electrons: binding energy T, kinetic energy Et
Recoil angle:Φ
Conservation of energy:Eo=Esc TEt
Conservation of momentum
Scattering probability
Compton scattering mainly occurs when the number of electron atoms in the outermost layer is greater and the number of electrons outside the nucleus increases, the probability of scattering increases.
The higher the energy of the incident photon, the smaller the probability of scattering under the feet.
photoelectric absorption
production process
Photons collide with atoms, causing orbiting electrons to be ejected
Photon energy is completely absorbed
Part of the energy is used by the electrons to overcome the binding energy of the atoms
The remaining energy is converted into kinetic energy of the ejected electrons
Atoms are in an ionized state
Electrons rearrange to fill gaps
May result in emission of fluorescence photons and Auger electrons
Loss of some absorbed binding energy
Geometric relations
Incident photon: kinetic energy: Eo=hv Momentum: Po
Ejected electron: kinetic energy: Et Binding energy: T Momentum:P Injection angle: Θ
Atom:Kinetic energy:Ta Momentum: Pa
Conservation of energy: Eo=T Ta Et
Conservation of momentum:Po=P Pa
Snow Compton Scattering Contrast
photoelectric absorption
The photon is completely absorbed
interact with tightly bound electrons
Atoms participate in reactions as a whole. Photons do not need to maintain momentum to satisfy the conservation law.
Compton scattering
Photons cannot be completely absorbed
Interact with loosely bound free electrons
Photons must maintain a certain amount of energy to satisfy the conservation law
electron pair effect
production process
So it reaches the inside of the atom and collides with the atom
The photon energy is absorbed, producing an electron pair: one positron, one negative electron
Usually occurs near the nucleus
The photon energy requires at least the sum of the energies of two stationary electrons: p p-=(2mo)²=1.022MeV
Geometric relations
Incident photon: kinetic energy: Eohv Momentum: Po
Electron pair: positron Kinetic energy: T Negative electron kinetic energy: T-
Energy conservation: Eo=T T- 1.022MeV
Conservation of momentum: Po=P P- Pa
coherent scattering
photonuclear reaction
4. Image formation and detection in X-ray projection imaging
Three elements of imaging
Target to be imaged
energy emitted by target
Detection device
Composition of hospital radiology department
scan doctor
medical physicist
radiologist
X-ray photography
The patient is located between the x-ray tube and detector
Unlike the gray value of the pixel above, which reflects the degree of x-ray attenuation, different tissues show different brightness.
Characteristics of conventional x-rays
The lungs and intestines of the human body contain more air, have the lowest density, and absorb the least X-rays; the bones have the highest calcium salt content, the highest density, and absorb the most X-rays.
The density difference of soft tissue materials such as fat is small, making it a good exposure condition. There are only subtle differences in the image
Various soft tissues and body fluids have similar densities, resulting in minimal image differences.
Four-ray contrast agent, injecting contrast agent and introducing density difference
Positive contrast agent: large atomic number, high material density, strong absorption of x-rays
Negative contrast agent: small atomic number, low material density, low absorption of x-rays
X-ray image converter
Analog x-ray imaging
film
Intensifying screen-film system
advantage
Shooting film alone absorbs only 10% of the incident X-rays and wastes 90%
Improve x-ray absorption rate
For each x-ray absorbed, hundreds of visible light photons are produced to expose the film, increasing efficiency
Reduce radiation time, reduce X-ray radiation amount, and reduce image blur caused by patient movement
X-ray image intensifier-TV system
step
X-ray photons are converted into fluorescent electrons at the photocathode
Fluorescent electrons accelerate to gain kinetic energy
The output bottle reduces electron energy to light energy
advantage
Radiation dose can be reduced to 1/10
Image brightness is greatly increased, eliminating the need for a darkroom
New fluorescent substances and processes improve image resolution and can distinguish subtle lesions
Imaging speed is fast, suitable for real-time imaging
Compared with traditional digital x-ray imaging
traditional x-ray imaging
advantage
High spatial resolution and low price
Low equipment cost and low maintenance cost
shortcoming
Small dynamic range
Requires chemical treatment, affects image quality, and pollutes the environment
Difficult to post-process High fragmentation rate
The functions of image acquisition, display, storage and transmission are all based on film and cannot be copied.
Need to consume to win Ag
digital x-ray imaging
advantage
Large dynamic range
Direct imaging without film
Powerful image post-processing technology eliminates the need to re-image
The functions of image acquisition, display storage and delivery are separated from each other, showing that storage, copying and delivery are very convenient for telemedicine
shortcoming
Resolution and image quality are relatively poor
High equipment and maintenance costs
DR and CR
CR
Similar to the TrueSense screen film system, the latent image in the IP version is an artificial template image
Image quality: both spatial resolution and density resolution CR are low
Imaging time: Conventional 7.5 minutes per person Cr 6 minutes per person.
Software function: Use different exposure indexes for different parts
Radiation dose: The exposure dose is 1/2~2/3 of the traditional one.
DR
After X-ray exposure, the absorbed energy is quickly converted directly into a digital signal
DR 25min/person
Automatic exposure control technology enables subsequent digital image processing
Reduce dose by at least 2/3 or more
digital subtraction imaging
definition
Obtaining two or more images under different circumstances, and then performing some processing and subtracting the resulting images can highlight the interesting parts and eliminate the occlusion of the uninteresting parts to obtain better diagnostic information.
Different energy subtraction
definition
Perform subtraction on two images of the same part exposed with different energies
Subtraction at different times
Features
The subtracted image signal is proportional to the thickness of the contrast agent
The image is also proportional to the difference in attenuation coefficient between the contrast agent and the background soft tissue. The larger the difference, the better.
The subtracted image is independent of the structure of bone and soft tissue
shortcoming
Imaging quality is affected by patient movement, heartbeat, swallowing, intestinal motility, etc.
No selective injection, blood vessels overlap
2.Generation of X-rays
X-ray imaging system structure
control platform
high pressure generating system
X-ray tube
Detector
Generation of tube voltage
Structure of X-ray tube
Cathode: tungsten wire
Anode: copper
Tungsten target
Electron beam
vacuum tube
high voltage power supply
Energy conservation: Energy of high-speed electrons Qe = collision heat energy loss Qt Radiation x-ray energy Qx
Radiated x-ray energy accounts for less than 1% of the total energy of electrons, and more than 99% is heat loss.
The actual focal length depends on the length of the filament. The longer the length of the filament, the greater the actual focal length and the better the heat dissipation. The effective focal length depends on the target inclination angle. The smaller the target inclination angle, the smaller the effective focal length and the better the clarity.
Anode-fixed x-ray tube: lower X-ray energy
application
mammography
dental imaging
The anode rotates a ray tube: black rays have higher energy
application
Chest X-ray
CT
Fluorescence imaging
small animal imaging
Development of X-ray tubes
X-ray tube is also called a tube or tube. Its function is to generate x-rays and is the core component of the x-ray generating device. The technical barrier of the tube is relatively high
Manufacturer
domestic
Ruineng Medical
Kunshan Yiyuan Medical Technology Co., Ltd.
Maimo Vacuum Technology Wuxi Co., Ltd.
foreign
Siemens
Philips
IAE
characteristic radiation
definition
Produced by the shooting and emission of particles in an electromagnetic field
feature
It's intermittent
Bremsstrahlung
definition
Radiation produced by electrons moving unaccelerated in an electromagnetic field
feature
is continuous
Total radiation energy of L rays - tube voltage, tube current and filament current
Factors affecting the generation of a ray
proportional coefficient
Atomic number of target material
tube current
tube voltage
Filament current