To help answer those questions we have put together our protocols as well as adding ct scan protocols from other institutions that we thought might prove useful. Dose and imaging quality mtmi skip to main content. Ct physics lecture 2 spiral ct ct scan medical equipment. A more serious problem may arise from motions, since adjacent structures in the patient are physics of ct scanners. Instead, the slice is reconstructed by averaging ct projections taken 180 degrees apart which are separated along the scan axis based on the value of the pitch. It is aimed at beginners in possession of only a minimal level of technical expertise. Basic principles of computed tomography physics and. Xray ct physics the detectors are basically similar. Ct scanner uses a motorized xray source that rotates around the circular opening of a donutshaped structure called a gantry. To complete the cardiac ct, we need to cover the entire heart, which is typically around 1215 cm. In addition, detector resolution is poorer due to the detector physics.
Ct physics lecture 2 spiral ct free download as powerpoint presentation. In cat scanning, an electronic device called a detector array absorbs. Computed tomography ct donut shaped machine uses xray energy and computer generation of images advantages sensitive to slight density difference cross sectional anatomy attenuation. Basic principles of computed tomography physics and technical considerations kyongtae t. Aug 31, 2017 this feature is not available right now. Introduction to magnetic resonance imaging techniques lars g. For two objects to be seen as separate the detectors must be able to identify a gap between them. The centre for medical, health and environmental physics, queensland university of. Imaging and detectors for medical physics lecture 1. Scribd is the worlds largest social reading and publishing site. It is highly recommended that you download and experiment with these programs, which are available at no charge.
Associate professor and head of physics department of nuclear medicine and pet research vu university medical centre. For the love of physics walter lewin may 16, 2011 duration. The radon transform allows us to create \ lm images of objects that are very similar to those actually occurring in xrays or ct scans. Ct scans are generally used for studying the chest, abdomen and. During the accompanying lectures, software that illustrates important aspects of basic mr physics, including popular sequences, contrast and imaging, was used. The image quality is mainly determined by 3 factors. Free radiology books download ebooks online textbooks tutorials. Physics and imaging methods spect and pet yao wang polytechnic institute of nyu, brooklyn, ny 11201 based on j.
The quiz below is designed to help you revise what you know about ct physics and instrumentation. Computed tomography ct is a widely used imaging method. Download as ppt, pdf, txt or read online from scribd. However, there may be significant variability in the quality of ct imaging performed at different sites. Xray computed tomography based on chapter 5 of suetens, but not in order. Compared to ct and mr images, pet images appear much blurrier and or noisier, due to the relatively limited number of photons that can be collected during an imaging study. Xray ct scanners can easily resolve points less than 1 mm in size, while pet scanners cannot reliably. Previously, it was hypothesized that there may be a threshold below. An appreciation of the potential of ct and its limitations can be obtained with an. Mathematics of medical imaging 3 essentially, the mathematics of ct scanning involves two problems. Imaging and detectors for medical physics lecture 3. Abdominal organs can also be categorized as to whether are retroperitoneal. While image quality has always been a concern for the physics community. This text serves as an introduction to magnetic resonance imaging techniques.
Apr 26, 2014 ultrasound vs xray photography and ct scans advantages and disadvantages gcse physics duration. Computed tomography ct scanning, also known as, especially in the older literature and textbooks, computerized axial tomography cat scanning, is a diagnostic imaging procedure that uses xrays to build crosssectional images slices of the body. Crosssections are reconstructed from measurements of attenuation coefficients of xray beams in the volume of. The wires are immersed in liquid helium at superconducting. Basic principles of computed tomography physics and technical. This lecture note includes a series of lectures with a parallel set of recitations that provide demonstrations of basic principles.
We hope you find this useful and would appreciate any comments or suggestions that you might have. Since the first ct scanner was developed in 1972 by sir godfrey hounsfield, the modality has become established as an essential radiological technique applicable in a wide range of clinical situations. Lecture notebasic principles of xray computed tomography. The increasing prevalence of chronic diseases and improving healthcare infrastructure in developing countries are also driving the growth of the global computed. Figures are from the textbook except otherwise noted. Imaging and detectors for medical physics lecture 7. Sep 09, 2010 welcome to part 2 in my series of the physics of medical imaging. Fishman, md, this website has an expansive library of content ranging from ct scan protocols, lectures, and case studies to medical illustrations and a monthly quiz. Complex clinical decisions about treatment of oncologic patients are largely guided by imaging. When compared with a conventional radiograph, which is an image of many planes superimposed on each other, a ct image exhibits signi.
The basics of ct ct imaging chain system components acquisition methods image quality applications 632014 hareesha n g, dept of aero engg, dsce 2 3. Modern ct technology can be understood as a natural progression of improvements and innovations in response to both engineering problems and clinical requirements. A computer program then computes the brightness of each pixel from all of these separate recordings. Free radiology books download ebooks online textbooks. Since computed tomography ct has entered the industrial environment around thirty year ago. There are 2 kinds of sampling radial sampling along the projection in r and angular sampling q. Lecture outline objectives relevance of material imaging modalities clinical approach to abdominal anatomy 4 quadrants. We also enhance the ct protocols with select instructive cases. This chapter focuses on the techniques of ct imaging and covers equipment used to acquire an image, how the image is formed and displayed, the factors affecting the quality of the image and how dose is measured.
In plain xray imaging, the film directly absorbs penetrated x rays. Introduction to ct physics image generation what is computed tomography ct. Ct image quality a summary image noise image noise, in its most simple definition, is measured as the standard deviation of voxel values in a. Whiting introduction slightly more than three decades old, computed tomography ct continues to advance rapidly in both imaging performance and widening clinical applications. Resolution is the measure of how far two objects must be apart before they can be seen as separate details in the image. Computed tomography ct scanning is an extremely common imaging modality in modern medicine. Tomographic imaging, ieee press, 1988 a free pdf copy. Xray computed tomography mathematics and physics of emerging biomedical imaging.
Page 1 computed tomography notes, part 2 practical considerations in ct sampling ct the c meaning computed relies on the sampling of projection data for processing on a computer. Knowledge of the physics and imaging technology involved in the production of ct scans is vitally important for medical imaging specialists. With advancements in technology, it is rapidly replacing many diagnostic radiographic procedures. An introduction to pet ct imaging1 vibhu kapoor, md barry m. Ct scans performed annually in usa courtesy mike partridge oxford computed tomography ct. Welcome to part 2 in my series of the physics of medical imaging. Jul 01, 2005 the main magnetic field of an mr system comes from a large electric current flowing through wires that are formed into a loop in the magnet of the imaging system, fig 3. A reconstruction made from projections at neighboring scan axis positions in helical ct, the scanner never images a single slice. Both ionizing and nonionizing radiation are covered, including xray, pet, mri, and ultrasound. Introduction to magnetic resonance imaging techniques. Physics of imaging systems basic principles of magnetic resonance imaging ii prof. Since the ct scan requires so many xray exposures, the amount of radiation used to make a ct scan is typically greater that used to make a traditional xray.
In this article, we will outline the basic science behind ct scans, describe the principles of interpretation, and highlight their advantages and drawbacks compared to other. Mar 18, 2019 a computerized tomography is an xray imaging procedure in which a narrow beam of xrays is aimed at a patient and quickly rotated around the body. Physics of imaging systems basic principles of magnetic. The technological improvements in the first 20 years of ct can best be characterized by a comparison of typical scan parameters from 1972 and 1994, as shown in table 3. The ct scanner computed tomography is an imaging technique that produces crosssectional images, representing in each pixel the local xray. The term computed tomography, or ct, refers to a computerized xray imaging procedure in which a narrow beam of xrays is aimed at a patient and quickly rotated around the body, producing signals that are processed by the machines computer to generate crosssectional imagesor slicesof the body.
Ct physics lecture 2 spiral ct ct scan radiology scribd. Vodcasts, podcasts, ct topics, quiz, discussions, interesting case discussion, ct scan protocols, organ specific lectures, hot topics in ct all sections journal club lectures pearls protocols case studies medical illustrations search. Introduced in the early 1970s, ct scanning gained rapid acceptance in clinics and. Resolution is measured in line pairs per centimeter lpcm i. Achieving the full potential of ct requires careful attention to quality assurance qa, both in regard to equipment performance as well as the execution of imaging studies. Imaging and detectors for medical physics dr barbara camanzi barbara. Physics of mri yao wang polytechnic university, brooklyn, ny 11201 based on j. Thus, with wider detectors more rows, the heart is captured in fewer beats. Positron emission tomography pet offers several unique advantages compared with other imaging modalities.
An understanding of the quadrant anatomy allows you to identify relevant pathology. Each scan has a certain zaxis coverage, which is determined by the width of the ct detector and pitch. The ct scan format consists of many cells,each assigned a no. The integration of ct scanners in multi modality imaging applications, for example by integration of a ct scanner with a pet scanner or a spect scanner. Cts ca nep third generation ct rotating fan beam 0.
Jun 26, 2011 ct physics lecture 2 spiral ct free download as powerpoint presentation. A typical clinical mr system will have a magnetic field strength of 1. Lothar schad 1292008 page 1 physics of imaging systems roe, ct, mri. In the medical community they simply call them ct scans, because axial, as youll find out, is unnecessary in the title. Links, medical imaging signals and systems, and lecture notes by prince. Ct scanning ct protocols ctisus ct scan, protocols. Xray imaging joint cijai advanced accelerator lecture series. In the forward problem, we model the data obtained from realworld ct scans using the radon transform. Computed tomography notes, part 2 practical considerations in ct.
Xray computed tomography ct is a medical imaging technique that produces images of transaxial planes through the human body. History 1924 mathematical theory of tomographic image. Emphasis on the physics and engineering of image formation. Torok, md cancer is one of the leading causes of morbidity and mortality in developed countries such as the united states.