Bioimaging - EEC 476 PDF

Bioimaging –EEC 476 Team code: fgq054j Recommended Textbook Stewart C. Bushong, Radiologic Science for Technologists: Physics, Biology, and Protection, 10th ed., Mosby, 2012. (ISBN 978- 0323081351) The Essential Physics of Medical Imaging by Jerrold T. Bushberg, J. Anthony Seibert, E...

Bioimaging –EEC 476 Team code: fgq054j Recommended Textbook Stewart C. Bushong, Radiologic Science for Technologists: Physics, Biology, and Protection, 10th ed., Mosby, 2012. (ISBN 978- 0323081351) The Essential Physics of Medical Imaging by Jerrold T. Bushberg, J. Anthony Seibert, Edwin M. Leidholdt Jr, John M. Boone (ISBN 978-0-7817-8057-5) Course Outline X-ray imaging Mammography CT Fluoroscopy MRI What is medical imaging? Definition: ‘Medical imaging is the visualisation of body parts, tissues, or organs, for use in clinical diagnosis, treatment and disease monitoring. Imaging techniques encompass the fields of radiology, nuclear medicine and optical imaging and image- guided intervention.’ Why use medical imaging techniques? By using methods which provide an insight within the human body without the need to undergo invasive, medical procedures such as surgery. This could prevent the risk of a patient becoming infected after surgery and/or suffering unnecessary surgery. Overall Concept  SPECT Medical Imaging Modalities MEDICAL IMAGING MODALITIES X-ray CT – Computed Tomography 1. X-ray MRI – Magnetic Resonance 2. CT – Computed Tomography Imaging (also called MR) PET/CT 3. MRI – Magnetic Resonance Imaging Ultrasound (also called MR) CT General 4. Ultrasound Nuclear Medicine Gamma 5. General Nuclear Medicine Cameras MRI Cardiac Cameras a) Gamma Cameras SPECT – Single b) Cardiac Photon Emission Cameras Computed Tomography c) SPECT – Single Photon Emission Computed Tomography PET – Positron Emission 6. PET – Positron Emission Tomography Tomography  Differences between Imaging Modalities DIFFERENCES BETWEEN1.IMAGING MODALITIES X-ray: Uses x-rays from a stationary source to create 2D image 1. X-ray: Uses x-rays from a stationary source to create 2D 2. image CT: Uses x-rays in a circular source to create 3D images in slices 2. CT: Uses x-rays in a circular source to create 3D images in slices 3. MRI: Uses changes in magnetic fields to create 3D images 3. MRI: Uses changes in magnetic fields to create 3D 4. images Uses sound waves to create 2D& 3D images Ultrasound: 4. Ultrasound: Uses sound waves to create 2D& 3D images 5. Nuclear Medicine: Uses radiation from gamma ray emitting 5. Nuclear Medicine: radioisotopes Uses injected into radiation patient from gamma to generate 2D andray3D emitting radioisotopes injected into patient to generate pictures 2D and 3D pictures a) Gamma a) Gamma Camera: Camera: Generates Generates 2D pictures 2D pictures b) Cardiac Cameras: Specifically designed for generating 3D b) Cardiac Cameras: Specifically designed for generating 3D pictures of the heart pictures of the heart c) SPECT: Generates 3D pictures c)6.SPECT: Generates PET: Uses 3D radiation pictures from positron emitting radioisotopes injected into the patient to generate 3D pictures 6. PET: Uses radiation from positron emitting radioisotopes injected into the patient to generate 3D pictures Imaging modalities Ionizing modalities Non ionizing modalities Plain x ray MRI CT US & Doppler Nuclear imaging PET and PET CT  PET-MR Multi-modality Scanners Some scanners use 2 different modalities in MULTI-MODALITY the same scanner. SCANNERS PET/CT Some scanners use 2 different modalities in the same scanner. PET-MR PET/CT SPECT/CT PET-MR SPECT/CT These take 2 images either sequentially These take 2 images either sequentially (PET/CT & SPECT/CT) (PET/CT & SPECT/CT) or simultaneously or simultaneously (PET- MR) and fuseand (PET-MR) the fuse images together the images together Virtual medicine  History of Medical Imaging 1895 Roentgen discovers x-rays 1896 First medical applications of x-rays in diagnosis and therapy are made. 1901 The Nobel Prize in Physics is awarded to Roentgen for his discovery. 1922 Compton describes the scattering of x-rays. 1929 The rotating anode x-ray tube is introduced. 1930 Tomographic devices are shown by several independent investigators. 1932 Blue tint is added to x-ray film (DuPont). 1951 Multidirectional tomography (polytomography) is introduced. 1955 Ultrasound for medical diagnosis 1960 – First use of endoscope  1973 Hounsfield completes development of first computed tomography (CT) imaging system (EMI). 1973 Damadian and Lauterbur produce the first magnetic resonance image (MRI). 1973 first use of PET scan by Phelps 1979 The Nobel Prize in Physiology or Medicine is awarded to Allan Cormack and Godfrey Hounsfield for CT. 1990 Helical CT is introduced (Toshiba). 1991 Twin-slice CT is developed (Elscint). 1998 Multislice CT is introduced (General Electric). 2002 Positron emission tomography (PET) is placed into routine clinical service. 2003 The Nobel in Physiology or Medicine is awarded to Paul Lauterbur and Sir Peter Mansfield for MRI. Anatomic versus Functional Imaging Medical imaging planes Axial (transverse) plane: perpendicular to the body long axis Sagittal: bisects the left from the right side Coronal: bisects the front from the back Medical Imaging Coordinates The anatomical terms of location Superior / inferior, left / right, anterior / posterior: Note: left / right is seen from the view of the patient!  Patient coordinate system Coordinate system positive direction conventions 3 letters are used to indicate sequence and orientation of the (x, y, z ) axes, e.g. “LSA” coordinates used in computed tomography (CT). Abbreviation letter codes: “ LSA” thus indicates: –x axis goes from left (L) to right –y axis goes from superior (S) to inferior –z axis goes from anterior (A) to posterior Intrinsic Coordinate System The intrinsic coordinate system describes the spatial dimensions of the patient coordinate system. Intrinsic coordinates are in units of voxels, while patient coordinates have real-world dimensions and are usually in units of millimeters. The origin of the intrinsic coordinate system is located at the center of the first pixel (2-D image) or voxel (3-D volume), represented by the black circle. The i-axis corresponds to (rows), the j-axis corresponds to (columns), k-axis corresponds to the third dimension of a medical image or volume. This image grid shows the i-axis corresponding to the anatomical z-axis and the j-axis corresponding to the anatomical x-axis, whereas this image grid shows the i-axis corresponding to the anatomical x-axis and the j-axis corresponding to the anatomical z- axis  Picture Archiving and Communication System (PACS) A PACS system is an efficient way to securely transport private patient medical imaging information, in contrast, to manually filing, retrieving, or physically transporting film jackets Medical Imaging Standards 1-Digital Imaging and Communications in Medicine (DICOM) every imaging device used in radiology — including CT, MRI, Ultrasound, and RF — is equipped to support the DICOM standard  2-The Neuroimaging Informatics Technology Initiative (NIfTI) One of the most significant challenges neurosurgeons faced with older image formats, was the lack of information about the orientation of image objects. Orientation was ambiguous and unclear, forcing anyone attempting to analyze an image to add detailed notes about the orientation of objects within images. In particular, there was often confusion as to which side of the brain a doctor was looking at, a significant problem that needed a solution. Why DICOM? DICOM files allow medical professionals to store more information across multiple layers. You can create structured reports and even freeze an image so that other clinicians and healthcare data scientists can clearly see what an opinion/recommendation is based on. So, although DICOM files are sometimes harder to handle, the information stored is more sophisticated and applicable across a wider range of medical use cases. X-Ray Imaging (Radiography) Outline X-Ray Production X-Ray System Circuit Diagram X-Ray Interaction with Matter Radiologic Units and Safety X-Ray Production X-Ray Production Bremsstrahlung x-rays are produced when a projectile electron is slowed by the nuclear field of a target atom nucleus In the diagnostic range, most x-rays are bremsstrahlung x-rays Characteristic x-rays are emitted when an outer-shell electron fills an inner-shell void This type of x-radiation is called characteristic because it is characteristic of the target element Only the K-characteristic x-rays of tungsten are useful for imaging  Anode Heat Approximately 99% of the kinetic energy of projectile electrons is converted to heat X-Ray Production  A K-shell electron is removed from a tungsten atom and is replaced by an L-shell electron. What is the energy of the characteristic x-ray that is emitted? Answer: K-shell electrons have binding energies of 69 keV, and L-shell electrons are bound by 12 keV. Therefore, the characteristic x-ray emitted has energy of 69 − 12 = 57 keV  Kα refers to an electron transition from the L to the K shell, Kβ refers to an electron transition from the M, N, or O shell to the K shell.  In an x-ray imaging system operating at 70 kVp, each electron arrives at the target with a maximum kinetic energy of 70 keV. Because there are 1.6 × 10−16 J per keV, this energy is equivalent to the following: (70 keV) (1.6 × 10−16 J/keV) = 1.12 × 10−14 J When this energy is inserted into the expression for kinetic energy and calculations are performed to determine the velocity of the electrons, the result is as follows: 1 𝐾𝐸 = 𝑚𝑣 2 2 2 2𝐾𝐸 𝑣 = 𝑚 v = 1.6 ×108 m/s The distance between the filament and the x-ray tube target is only approximately 1 cm. It is not difficult to imagine the intensity of the accelerating force required to raise the velocity of electrons from zero to half the speed of light in so short a distance X-Ray Production  The filtered spectrum of bremsstrahlung and characteristic radiation from a tungsten target with a potential difference of 90 kV illustrates specific characteristic radiation energies from Kα and Kβ transitions. ε0 𝑖𝑠 𝑡ℎ𝑒 𝑝𝑒𝑟𝑚𝑖𝑡𝑡𝑖𝑣𝑖𝑡𝑦 𝑜𝑓 𝑓𝑟𝑒𝑒 𝑠𝑝𝑎𝑐𝑒 𝑚𝑒 𝑖𝑠 𝑡ℎ𝑒 𝑚𝑎𝑠𝑠 𝑜𝑓 𝑎𝑛 𝑒𝑙𝑒𝑐𝑡𝑟𝑜𝑛 𝑞𝑒 𝑖𝑠 𝑡ℎ𝑒 𝑐ℎ𝑎𝑟𝑔𝑒 𝑜𝑓 𝑎𝑛 𝑒𝑙𝑒𝑐𝑡𝑟𝑜𝑛 𝑞𝑧 𝑖𝑠 𝑎𝑛 𝑒𝑓𝑓𝑒𝑐𝑡𝑖𝑣𝑒 𝑐ℎ𝑎𝑟𝑔𝑒 𝑜𝑓 𝑡ℎ𝑒 nucleus expressed as Z − b 𝑞𝑒 𝑛𝑓 𝑖𝑠 𝑡ℎ𝑒 𝑞𝑢𝑎𝑛𝑡𝑢𝑚 𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑡ℎ𝑒 𝑓𝑖𝑛𝑎𝑙 𝑒𝑛𝑒𝑟𝑔𝑦 𝑙𝑒𝑣𝑒𝑙 𝑛𝑖 𝑖𝑠 𝑡ℎ𝑒 𝑞𝑢𝑎𝑛𝑡𝑢𝑚 𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑡ℎ𝑒 𝑖𝑛𝑖𝑡𝑖𝑎𝑙 𝑒𝑛𝑒𝑟𝑔𝑦 𝑙𝑒𝑣𝑒𝑙