General introduction- fundamental principles X ray & CT Radiology Dept. 1st Hospi. of Peking University 唐光健 Radiology Dept. 1st Hospi. of Peking University 唐光健

Questions to think of with the lecture What is X ray? What kinds of the features of it are useful or harmful? What are the two steps of X ray imaging? How is the grey scale of bone, muscle and air in the X ray film? What is the main difference between the CT imaging and the image of X ray film? What are same and what are different between the processes of CT imaging and imaging of X ray projection? Is the meaning of a CT axial imaging and a section of a body specimen in same location identical? What is X ray? What kinds of the features of it are useful or harmful? What are the two steps of X ray imaging? How is the grey scale of bone, muscle and air in the X ray film? What is the main difference between the CT imaging and the image of X ray film? What are same and what are different between the processes of CT imaging and imaging of X ray projection? Is the meaning of a CT axial imaging and a section of a body specimen in same location identical?

Black box?

Wilhelm C Röntgen Black box?

Wilhelm C Röntgen

Generation and features of X ray High speeding electrons  Anode target  sudden slow down  special X ray – sequence spectrum narrow  consecutive X ray – sequence spectrum wide X ray e e  special X ray – sequence spectrum narrow  consecutive X ray – sequence spectrum wide

electromagnetic waves-ionizing radiation -wave length of medical use: 0.08 ~ 0.71Å -feature of wave; feature of particle Features-Effects electromagnetic waves-ionizing radiation -wave length of medical use: 0.08 ~ 0.71Å -feature of wave; feature of particle Features-Effects Physical effect Chemical effect Biotic effect Physical effect Chemical effect Biotic effect Generation and features of X ray

electromagnetic waves-ionizing radiation -wave length of medical use: 0.08 ~ 0.71Å -feature of wave; feature of particle Features-Effects electromagnetic waves-ionizing radiation -wave length of medical use: 0.08 ~ 0.71Å -feature of wave; feature of particle Features-Effects Physical effect Chemical effect Biotic effect Physical effect Chemical effect Biotic effect Generation and features of X ray Penetrability Fluorescent effect Thermal effect Ionizing effect interference ， diffraction, reflection, refraction Penetrability Fluorescent effect Thermal effect Ionizing effect interference ， diffraction, reflection, refraction

Features-Effects Physical effect Chemical effect Biotic effect Physical effect Chemical effect Biotic effect Generation and features of X ray Penetrability Fluorescent effect Thermal effect Ionizing effect interference ， diffraction, reflection, refraction Penetrability Fluorescent effect Thermal effect Ionizing effect interference ， diffraction, reflection, refraction -be able to penetrate ma. of dif. density while attenuated I0I0 I0I0 I I µ µ l l I = I 0 · e - µl

Features-Effects Physical effect Chemical effect Biotic effect Physical effect Chemical effect Biotic effect Generation and features of X ray Penetrability Fluorescent effect Thermal effect Ionizing effect interference ， diffraction, reflection, refraction Penetrability Fluorescent effect Thermal effect Ionizing effect interference ， diffraction, reflection, refraction - making some compounds fluoresce -Fluoroscopy, image intensifier - making some compounds fluoresce -Fluoroscopy, image intensifier

Features-Effects Physical effect Chemical effect Biotic effect Physical effect Chemical effect Biotic effect Generation and features of X ray Penetrability Fluorescent effect Thermal effect Ionizing effect interference ， diffraction, reflection, refraction Penetrability Fluorescent effect Thermal effect Ionizing effect interference ， diffraction, reflection, refraction - making some compounds fluoresce -Fluoroscopy, image intensifier - making some compounds fluoresce -Fluoroscopy, image intensifier

Features-Effects Physical effect Chemical effect Biotic effect Physical effect Chemical effect Biotic effect Generation and features of X ray Penetrability Fluorescent effect Thermal effect Ionizing effect interference ， diffraction, reflection, refraction Penetrability Fluorescent effect Thermal effect Ionizing effect interference ， diffraction, reflection, refraction -Subject absorb the energy of X ray  ionized  ionized voltage -ionizing cell  auto-exposure X ray detector -Subject absorb the energy of X ray  ionized  ionized voltage -ionizing cell  auto-exposure X ray detector

Features-Effects Physical effect Chemical effect Biotic effect Physical effect Chemical effect Biotic effect Generation and features of X ray Penetrability Fluorescent effect Thermal effect Ionizing effect interference ， diffraction, reflection, refraction Penetrability Fluorescent effect Thermal effect Ionizing effect interference ， diffraction, reflection, refraction -  penumbra, interferential signal  image blued

Features-Effects Physical effect Chemical effect Biotic effect Physical effect Chemical effect Biotic effect Generation and features of X ray sensitization effect coloration effect  fundament of X ray filming sensitization effect coloration effect  fundament of X ray filming

Features-Effects Physical effect Chemical effect Biotic effect Physical effect Chemical effect Biotic effect Generation and features of X ray radiated tissue cells restrained, damaged, necrosing  X ray protection radiated tissue cells restrained, damaged, necrosing  X ray protection

X ray Imaging X ray penetrate the subject （ body) while attenuated attenuate signal recorded by the accepting medium X ray penetrate the subject （ body) while attenuated attenuate signal recorded by the accepting medium

X ray Imaging X ray penetrate the subject （ body) while attenuated attenuate signal recorded by the accepting medium X ray penetrate the subject （ body) while attenuated attenuate signal recorded by the accepting medium I0I0 I0I0 I I µ1µ1 µ1µ1 l1l1 l1l1 I = I 0 · e - µ 1 l 1 · e - µ 2 l 2 · e - µ 3 l 3 · e - µ 4 l 4 I = I 0 · e- e- µ1l1 µ1l1 · e- e- µ2l2 µ2l2 · e- e- µ3l3 µ3l3 · e- e- µ4l4µ4l4 µ2µ2 µ2µ2 l2l2 l2l2 µ3µ3 µ3µ3 l3l3 l3l3 µ4µ4 µ4µ4 l4l4 l4l4

X ray Imaging X ray penetrate the subject （ body) while attenuated attenuate signal recorded by the accepting medium X ray penetrate the subject （ body) while attenuated attenuate signal recorded by the accepting medium getting special distribution of different density overlapping of anterio- posterior images

X ray Imaging X ray penetrate the subject （ body) while attenuated attenuate signal recorded by the accepting medium X ray penetrate the subject （ body) while attenuated attenuate signal recorded by the accepting medium film-silver bromide decomposed positive correlation with dosage of X ray negative correlation with degree of attenuation flu. screen detectors flu. screen detectors

X ray Imaging X ray penetrate the subject （ body) while attenuated attenuate signal recorded by the accepting medium X ray penetrate the subject （ body) while attenuated attenuate signal recorded by the accepting medium grey of spots ∽ thickness & density of the mat. in the path way of X ray beam distribution of the spots ∽ anatomic form in the path way of X ray beam difference between the sports - contrast  image natural contrast artificial contrast grey of spots ∽ thickness & density of the mat. in the path way of X ray beam distribution of the spots ∽ anatomic form in the path way of X ray beam difference between the sports - contrast  image natural contrast artificial contrast

X ray Imaging X ray penetrate the subject （ body) while attenuated attenuate signal recorded by the accepting medium X ray penetrate the subject （ body) while attenuated attenuate signal recorded by the accepting medium grey of spots ∽ thickness & density of the mat. in the path way of X ray beam distribution of the spots ∽ anatomic form in the path way of X ray beam difference between the sports - contrast  image natural contrast artificial contrast grey of spots ∽ thickness & density of the mat. in the path way of X ray beam distribution of the spots ∽ anatomic form in the path way of X ray beam difference between the sports - contrast  image natural contrast artificial contrast

X ray Imaging X ray penetrate the subject （ body) while attenuated attenuate signal recorded by the accepting medium X ray penetrate the subject （ body) while attenuated attenuate signal recorded by the accepting medium grey of spots ∽ thickness & density of the mat. in the path way of X ray beam distribution of the spots ∽ anatomic form in the path way of X ray beam difference between the sports - contrast  image natural contrast artificial contrast grey of spots ∽ thickness & density of the mat. in the path way of X ray beam distribution of the spots ∽ anatomic form in the path way of X ray beam difference between the sports - contrast  image natural contrast artificial contrast

X ray Imaging

X ray equipment X ray source X ray tube High voltage generator X ray imaging devices X ray film / image intensifier / plate detector X ray mechanical device exam table frame …… X ray source X ray tube High voltage generator X ray imaging devices X ray film / image intensifier / plate detector X ray mechanical device exam table frame ……

X ray tube filament - cathode anode target tube shell X ray tube filament - cathode anode target tube shell X ray equipment

X ray tube filament - cathode anode target tube shell X ray tube filament - cathode anode target tube shell

Protection from X ray X ray protection Cancel X ray exam unnecessary Reduce radiation dosage Distance from X ray source Protective device X ray protection Cancel X ray exam unnecessary Reduce radiation dosage Distance from X ray source Protective device

Principles of imaging diagnosis familiar with imaging methods and body position familiar with the normal imaging anatomy and variations sequential observation imaging manifestations and relationship with neighboring structures of the lesion clinical and laboratory materials understanding the meaning and limitations of the imaging methods familiar with imaging methods and body position familiar with the normal imaging anatomy and variations sequential observation imaging manifestations and relationship with neighboring structures of the lesion clinical and laboratory materials understanding the meaning and limitations of the imaging methods

fundamental principles of CT

CT-Computerized Tomography real tomography ， without any overlapping CT-Computerized Tomography real tomography ， without any overlapping fundamental principles of CT

I0I0 I µ1µ1 µ1µ1 l1l1 l1l1 I = I 0 · e - µ 1 l 1 · e - µ 2 l 2 · e - µ 3 l 3 · e - µ 4 l 4 I = I 0 · e- e- µ1l1 µ1l1 · e- e- µ2l2 µ2l2 · e- e- µ3l3 µ3l3 · e- e- µ4l4µ4l4 µ2µ2 µ2µ2 l2l2 l2l2 µ3µ3 µ3µ3 l3l3 l3l3 µ4µ4 µ4µ4 l4l4 l4l4 I0I0 I µ1µ1 µ1µ1 l1l1 l1l1 I = I 0 · e - µ 1 l 1 · e - µ 2 l 2 · e - µ 3 l 3 · e - µ 4 l 4 µ2µ2 µ2µ2 l2l2 l2l2 µ3µ3 µ3µ3 l3l3 l3l3 µ4µ4 µ4µ4 l4l4 l4l4 l 1 = l 1 = l 1 = l 1 = 1 I = I 0 · e - ( µ 1+ µ 2 + µ 3 + µ 4 ) · 1 fundamental principles of CT

Godfrey Hounsfield First laboratory CT scanner 1968 fundamental princ. of CT

First clinical head CT scanner Atkinson Morley‘hosp. ， London

fundamental principles of CT

measurement fundamental principles of CT

DAS － data acquisition system -detector -bumper -integrator -amplifier -A/D converter detector fundamental principles of CT measurement

Reconstruction fundamental principles of CT

backprojective method Iterative method Factorial method Fourier method Filt. backprojective method backprojective method Iterative method Factorial method Fourier method Filt. backprojective method fundamental principles of CT Reconstruction

Filt. function (Kernol) High filt. (bone algorithm) low filt. (soft tissue algorithm) Filt. function (Kernol) High filt. (bone algorithm) low filt. (soft tissue algorithm) fundamental principles of CT Reconstruction

Filt. function (Kernol) High filt. (bone algorithm) low filt. (soft tissue algorithm) Filt. function (Kernol) High filt. (bone algorithm) low filt. (soft tissue algorithm) fundamental principles of CT Reconstruction

[(μ obj. - μ water )/μ water ]× 1000 CT value - relative magnitude to water may be used qualitatively but not quantitively fundamental principles of CT Reconstruction

image display fundamental principles of CT

200/30=7HU muscle 50HU- fat -50HU=100 ~13 grey scale 200/30=7HU muscle 50HU- fat -50HU=100 ~13 grey scale 1000/30=33HU muscle 50HU- fat -50HU=100 ~3 gray scale 1000/30=33HU muscle 50HU- fat -50HU=100 ~3 gray scale image display ability of identify grey scale eyes ： 24~30 CT ： 2000 ability of identify grey scale eyes ： 24~30 CT ： 2000 fundamental principles of CT

Voxel and pixel voxel – 3D, pixel – 2D CT value of a voxel represent all messages of the elements in the voxel Voxel and pixel voxel – 3D, pixel – 2D CT value of a voxel represent all messages of the elements in the voxel fundamental principles of CT image display

partial volume effect fundamental principles of CT image display

enhancement CT high density contrast agent injected into vein  intro-vascular/-tissue （ extracellular space)  CT scan  density contrast hypersensitiveness nephrotoxitity enhancement CT high density contrast agent injected into vein  intro-vascular/-tissue （ extracellular space)  CT scan  density contrast hypersensitiveness nephrotoxitity fundamental principles of CT

enhancement CT high density contrast agent injected into vein  intro-vascular/-tissue （ extracellular space)  CT scan  density contrast hypersensitiveness nephrotoxitity enhancement CT high density contrast agent injected into vein  intro-vascular/-tissue （ extracellular space)  CT scan  density contrast hypersensitiveness nephrotoxitity fundamental principles of CT

enhancement CT high density contrast agent injected into vein  intro-vascular/-tissue （ extracellular space)  CT scan  density contrast hypersensitiveness nephrotoxitity enhancement CT high density contrast agent injected into vein  intro-vascular/-tissue （ extracellular space)  CT scan  density contrast hypersensitiveness nephrotoxitity fundamental principles of CT

Indications No absolute contraindication, suitable for emergency and serious cases exam Single imaging factor ， image interpretation easily ， anatomy clear and detailed deformation 、 infection 、 trauma 、 neoplasm… Limitations Low soft tissue resolution ， difficult to detect lesion with small density difference from neighbor structure Low sensitivity for the lesion with slight gross change Contrast agent using Indications No absolute contraindication, suitable for emergency and serious cases exam Single imaging factor ， image interpretation easily ， anatomy clear and detailed deformation 、 infection 、 trauma 、 neoplasm… Limitations Low soft tissue resolution ， difficult to detect lesion with small density difference from neighbor structure Low sensitivity for the lesion with slight gross change Contrast agent using fundamental principles of CT

Questions to think of with the lecture What is X ray? What kinds of the features of it are useful or harmful? What are the two steps of X ray imaging? How is the grey scale of bone, muscle and air in the X ray film? What is the main difference between the CT imaging and the image of X ray film? What are same and what are different between the processes of CT imaging and imaging of X ray projection? Is the meaning of a CT axial imaging and a section of a body specimen in same location identical? What is X ray? What kinds of the features of it are useful or harmful? What are the two steps of X ray imaging? How is the grey scale of bone, muscle and air in the X ray film? What is the main difference between the CT imaging and the image of X ray film? What are same and what are different between the processes of CT imaging and imaging of X ray projection? Is the meaning of a CT axial imaging and a section of a body specimen in same location identical?