Basic interpretation of ct scans most of the ct pictures are nonspecific ct pictures are depending on the density of the structures. This book provides an overview of the evolution of ct, the mathematical and physical aspects of the technology, and the fundamentals of image reconstruction using algorithms. If you are in a group, let us know the number of people that are watching. Tissue density differences as low as 1% or less can be detected with ct. Since there is a definite benefit of ct scan in diagnosis and planning therapeutic procedures, a riskbenefit assessment should be done in each individual. Feb 26, 2019 please use one of the following formats to cite this article in your essay, paper or report. Helical imaging is used for ct angiograms of the head neck and. Compared to singledetector helical ct, this technique offers three significant advantages. Ct instrumentation and principles of ct protocol optimisation. The interslice distance can be negative for overlapping scans which in helical ct means a. The basic principles of fdgpetct imaging request pdf. A pet scan for brain tumors can identify brain tumors and will give you an idea of what exactly is happening and how it can be treated. Computed tomography ct scan is a type of medical examination that uses xrays and computer processing to create sectional images of the body to provide more efficient results than xrays. Ct scans can be used to identify disease or injury within various regions of the body.
In recent years, mri scans have become increasingly common, as costs decrease. If the patient stays reasonably immobile between the scans, the pet and ct data are aligned and can be accurately fused. In 2010, the technologist committee decided that the next three guides would be dedicated to the topic of hybrid pet ct imaging. Ct scans and mris are both used to capture images within your body.
Although bones show up clearly on such xray images, soft tissues do not show up as well. Pet imaging is now combined with ct, as the pet camera provides high sensitivity for the distribution of the tracer, and the ct provided precise anatomic localization and attenuation correction. A ct scanner makes many measurements, from different rotational angles, of xray attenuation weakening in force or intensity through the crosssectional plane of the thorax. Ct scans interpretation principles basics teachmeanatomy. Physics of imaging systems basic principles of magnetic.
To familiarize the student with ct scanning principles, acquisition and reconstruction. Mathematics of medical imaging 3 essentially, the mathematics of ct scanning involves two problems. It examines image display from traditional methods through the most recent. Ct the pitch factor is the ratio of the couch increment per rotation to the nominal slice thickness at the axis of rotation. In this article, we will outline the basic principles behind mri scans, how to orientate and interpret a scan, and address some of their advantages and. A pictorial essay galal omami, 1 dania tamimi, 2 and barton f. In singlephoton emission computed tomography spect photons emitted from the radiotracer in the body are detected by the system as independent. Ct scans are created using a series of xrays, which are a form of radiation on the electromagnetic spectrum. Basic principles of ct each ct slice represents a specific plane in the patients body, referred to as the z axis. Basic principles of computed tomography flashcards quizlet.
Basic principles of ct ct imaging system moves around the body part at a fixed location attenuation information obtained in multiple planes reconstruct of this attenuation information into a simple grid. Basic principles of computed tomography physics and technical considerations kyongtae t. Produced with the kind support of principles and practice of petct part 1 a technologists guide publications brochures european sa sociation of nuclear m e d. Whiting introduction slightly more than three decades old, computed tomography ct continues to advance rapidly in both imaging performance and widening clinical applications. A hybrid device that includes a single patient table for acquiring a pet scan and ct scan in sequential fashion. Principles and practice of pet ct part 1 a technologists guide publications brochures. Basic principles of ct scanners and image reconstruction indico. Understanding computed tomography ct dose reduction. Basic principles of ct scanners and image reconstruction. Here, only the xray tube rotates around the patient.
Computed tomography ct is a technique that uses an xray beam to generate images. In addition to the difficulty in differentiating and classifying tissue. This course is based on the textbook, computed tomography physical principles, clinical applications, and quality control 4 th edition, authored by euclid seeram, phd, msc, bsc, fcamrt. The biggest difference is that mris magnetic resonance imaging use radio waves and ct computed tomography scans use xrays.
Jun 06, 2018 computed tomography ct computed tomography ct uses xrays to produce multiple images of the inside of the body, and provides thin, crosssectional slices for viewing. The historical background, developments, and innovations in ct are presented from the general perspective of medical imaging. Basic principles of computed tomography physics and technical. What is needed is a crosssection view that displays a thin slab of the body. Clinicians need to be aware of the potentially harmful radiation that patients are exposed to, with each individual ct scan that is performed.
Computed tomography ct, helical computed tomography ct, technology computed tomography. Ct uses multiple pencil or fan beams of kilovoltage photons that pass through a desired volume from multiple angles usually over 180 degrees. Magnetic resonance imaging mri scanning principles. On the opposite side of the volume is a dosimeter which measures the amount of ionising radiation reaching it. In this article, we will outline the basic science behind ct scans, describe the principles of interpretation, and highlight their advantages and. The scanner emits xrays towards the patient from a variety of angles and the detectors in the scanner measure the difference between the xrays that are absorbed by the body, and xrays that are transmitted through the body. Basic principles in computed tomography ct thoracic key.
This first article covers the fundamental principles of ct, including the basic geometry of the ct scan process, the nature of the measurements made by ct detectors, a qualitative explanation of the image reconstruction process, the evolution of ct technology the 4 generations of ct from the emi firstgeneration scanner through modern slip. For example, ct has become a useful screening tool for detecting possible tumors or lesions within the abdomen. 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. Basic principles of ct scanners and image reconstruction ct scanning and imaging parameters dr slavik tabakov slavik. Moreover, since threedimensional body parts are projected onto twodimensional film, much information is lost. Principles of operation ct scanners use slipring technology, which was introduced in 1989. Magnetic resonance imaging mri is arguably the most sophisticated imaging method used in clinical medicine. History, technical feasibility, mechanism of action, normal biodistribution, and diagnostic performance in bone metastasis detection compared with other imaging modalities. It then uses these data to reconstruct a digital representation of the crosssection with each pixel of the image representing a measurement of the mean attenuation through the thickness of the predetermined segment. Ct mri ct transmission tomography mri direct tomography xray tube detector. In singlephoton emission computed tomography spect photons emitted from the radiotracer in the body are detected by the system as. Moderncttechnology canbe understood as a natural progression of improvements and in novations in response to both engineering problems and clinical requirements. Computed tomography available for download and read online in other formats.
This directed reading article describes the physical principles and instrumentation of computed tomography ct and outlines several recent advances in ct technology. Together, the tube and the detector scan across the subject, sweeping the narrow xray beam through the slice 6. Adapt scan protocol to the clinical situation and indication sample neuro protocols routine head cta head perfusion ct temporal bone ct paranasal sinuses ct ct angiography spine ct tailor protocol to clinical question, e. Sep 29, 2014 ct uses xrays to generate crosssectional, twodimensional images of the body. Computerised tomography, ct, is an ideal form of tomography yielding sequence images of thin consecutive slices of the patient and providing the opportunity to localise in three dimensions. Click to view this presentation from the impact course. When to get a brain scan even in the case of health conditions where internal symptoms in the body are not visible, a pet scan will tell you whether there are internal tumors and what is the extent of the internal tumors. We are comprised entirely of cells which all contain water principally made of hydrogen ions h 2 o. Background and terminology the main advantages of ct over conventional radiography are in the elimination of superimposed structures, the ability to differentiate small differences in density of anatomic structures and abnormalities, and the superior quality of the images. Ct can detect tissue density differences as low as what. This presentation gives an information about basic principles of ct scanning covering the. The basic principles of computed tomography and magnetic. Physical principles, clinical applications, and quality control, 4th edition.
Principles of ct diagnosis precontrast study postcontrast study change in adjacent structures clinical information. Physics of imaging systems basic principles of magnetic resonance imaging ii prof. Written to meet the varied requirements of radiography students and practitioners, this twocolor text provides comprehensive coverage of the physical principles of ct and its clinical applications. It uses a combination of xrays and a computer to create pictures of your organs, bones, and other tissues. Mri scans work as an imaging method due to the unique makeup of the human body. The transmitted radiation is then measured by a ring of sensitive radiation detectors located on the gantry around the patient. Produced with the kind support of principles and practice of pet ct part 1 a technologists guide publications brochures e ur o p e an a sociati on f n u c l e r m. Make sure each scan is justified even a lowdose ct is too much dose when inappropriately ordered check with physician if. During a ct scan, the table moves the patient into the gantry and the xray tube rotates around the patient. Hyperdensity in ct comparison with bone isoor higher than bone. Please use one of the following formats to cite this article in your essay, paper or report.
Basic principles and applications of 18ffdgpetct in. Slipring scanners can perform helical ct scanning, in which. Ct uses xrays to generate crosssectional, twodimensional images of the body. Acrspr practice parameter for performing fdgpetct in. Physical principles of computed tomography quizlet. This is an illustration of a patient moving into the bore of a ct scanner. This presentation gives an information about basic principles of ct scanning covering the syllabus of non destructive testing slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. The image by the ct scanner is a digital image and consists of a square matrix of elements pixel, each of which represents a voxel volume element of the tissue of the patient. In the forward problem, we model the data obtained from realworld ct scans using the radon transform. Basic principles and applications of 18 ffdgpet ct in oral and maxillofacial imaging. The basics of ct ct imaging chain system components acquisition. With a recent increase in gantry speed from one to two revolutions per second, multisection ct scanners are now up to eight times faster than conventional. Ct scan computerized tomography is a procedure that uses xrays to scan and take images of crosssections of parts of the body. Branstetter 3 1 department of oral diagnosis and polyclinics, faculty of dentistry, the hong kong university, hong kong.
Part 1 of the pet ct series focussed on the principles and practice of pet ct and included topics ranging from practical radiation protection, quality assurance and quality control to pa tient care. This article discusses ct radiation dose, the measurement of ct dose, and ct image quality. Unlike conventional, classical tomography, computerised tomography does not suffer from interference from struc. Images are acquired by rapid rotation of the xray tube 360 around the patient. Ct scan cat scan, computerized tomography imaging procedure. Computed tomography ct and magnetic resonance imaging mri are the most widely used crosssectional imaging methods used in medicine. Ct scans of internal organs, bone, soft tissue and blood vessels provide much more detail than conventional xrays. The radon transform allows us to create \ lm images of objects that are very similar to those actually occurring in xrays or ct scans. Scan ning techniques and clinical applications1 jonas rydberg, md kenneth a. In conclusion, a measurement made by a detector ct is proportional to the sum of the attenuation coefficients.
The book offers a comprehensive and useroriented description of the theoretical and technical system fundamentals of computed tomography ct for a wide readership, from conventional singleslice acquisitions to volume acquisition with multislice and conebeam spiral ct. Tabakov, 1999 planar xray sinogram rotate around object reconstructed image advantages. With advancements in technology, it is rapidly replacing many diagnostic radiographic procedures. Basic principles of ct ct imaging system moves around the body part at a fixed location attenuation. A computed tomography ct or cat scan allows doctors to see inside your body. Xray computed tomography ct has experienced tremendous growth in recent years, in terms of both basic technology and new clinical applications. Conceptually, the ct numbers of three materials of known composition and density are plotted on a graph, where the yaxis is the ct number at low energy eg, 80 kv and the xaxis is the ct number at the high energy eg, 140 kv fig 9. Pdf computed tomography download full pdf book download. The z axis determines the thickness of the crosssectional slice. Original ct images were an 80x80 matrix, matrix size is chosen by the technologist before the ct, scan fov is set by the technologist before the ct, during scanning and reconstruction a matrix is placed over the sfov to cover the slice imaged, the radiation beam passes through each voxel and a ct number is, generated for each pixel in the displayed image, the display fov can be equal to or.
In clinical practice the interslice distance generally lies in the range between 0 and 10mm, and the pitch factor between 1 and 2. Guiding principles of radiation protection there are three guiding principles for radiation protection in. Computed tomography ct scanning is an extremely common imaging modality in modern medicine. The most commonly used dose descriptor is ct dose index, which represents the dose to a location e. Computed tomography, more commonly known as a ct or cat scan, is a diagnostic medical imaging test. Ct scan can help diagnose broken bones, tumors or lesions in areas of the body, blood clots in the brain, legs, and lung, and lung infections or diseases like pneumonia or. Computed tomography national institute of biomedical imaging. 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. A ct scan of the heart may be ordered when various types of heart disease or abnormalities are suspected. It then uses these data to reconstruct a digital representation of the crosssection with each pixel of the image representing a measurement of the mean attenuation through the thickness of. Ideally, the three basis materials should be sufficiently different as to create a broad triangle in this plot. Computed tomography ct scans can detect pathology that may be missed on a conventional chest radiograph. First, the history of ct is presented with emphasis on the contributions of two pioneers who earned the nobel prize for the development of the first clinically useful ct scanner.
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