Basic Radiology PDF

Basic Radiology By. Tsegaye K. (MRT)  Content’s Introduction of medical physics Sub-types of radiological physics Introduction of radiology Types of imaging modalities Radiological Physics 1.1 What is Medical physics? Is branch of physics concerned with the a...

Basic Radiology By. Tsegaye K. (MRT)  Content’s Introduction of medical physics Sub-types of radiological physics Introduction of radiology Types of imaging modalities Radiological Physics 1.1 What is Medical physics? Is branch of physics concerned with the application of medicine, it deals mainly the use of ionizing radiation and non-ionizing radiation in diagnosis and treatment of human disease Other application of physics to medicine There are four important sub-specialties in medical physics Cont.. A. Diagnostic radiology physics B. Nuclear medicine physics C. Radiation oncology physics D. Health physics Diagnostic Radiology physics -concerned with the application of physical energy to the diagnosis and treatment of human disease -medical diagnostic imaging instruments include x-ray, MRI, CT scan, ultrasound. Definition of Radiology  Radiology is a medical specialty using medical imaging technologist to diagnose and treatment of patients. Medical imaging Radiology department Radiographer Radiography Technologist Radiologist What is radiation Radiation can be thought of as the transmission of energy through space Classification of radiation A. ionizing radiation B. Non-ionizing radiation Both forms can interact with matter and transfer their energy to the matter Cont.  Radiology Modalities A. Conventional radiographs (“x-rays”) Fluoroscopy Mammography B. Computed Tomography= (CT scan) C. Nuclear Medicine =(NM) D. Ultrasound= (US) E. Magnetic resonance imaging =(MRI) A. Conventional Radiograph Conventional radiograph ( X-Rays) = an x-ray is beam generated and passed through a patient to a piece of film or radiation detector producing an image. Wilhelm Conrad Röntgen. While working with a Crookes tube, a plate of Barium Platino-Cyanide (fluorescent crystals) on a table six feet away in his workroom glowed when he activated the tube. Even after covering the tube with black cardboard it kept glowing. He concluded that a new type of ray emitted from the tube, passed through the covering, and casted shadows of solid objects. The rays passes through most substances, including the soft tissues of the body, but left the bones and most metals visible. One of his earliest photographic plate from his experiments was a film of his wife, Bertha's hand with a ring, was produced on Friday, November 8, 1895 The news of Roentgen’s discovery spread quickly throughout the world. Scientists everywhere could duplicate his experiment because the cathode tube was very well known during this period. In early 1896, X-rays were being utilized clinically in the United States for such things as bone fractures and gun shot wounds. Internal structures of the body could be made visible without the necessity of surgery. What are x-rays? No mass No charge Energy X-rays are a type of electromagnetic energy How do x-rays passing through the body create an image? X-rays that pass through the body render the image dark (black) X-rays that are totally blocked render the image light (white) Air = low atomic # = x-rays get through = image is dark (black) Metal = high atomic # = x-rays blocked = image is light (white) 5 Basic Radiographic Densities 1. 1. Metal 2.Fat 4. 3. Bone /mineral 4. Air 5. Soft tissue/fluid 2. 5. 3. Name these radiographic densities. X-rays characteristics Highly penetrating, invisible rays Electrically neutral Travel in straight lines. Travel with the speed of light in vaccum: 300, 000 km/sec or 186, 400 miles/sec. Ionize matter by removing orbital electrons Induce fluorescense in some substances. Fluorescent screen glow after being stricken with photons. Can't be focused by lenses nor by collimators. CONVENTIONAL RADIOGRAPHY PRODUCES STATIC IMAGES FLUOROSCOPE WAS INVENTED BY THOMAS EDISON Radiology Modalities Fluoroscopy “Live” imaging Contrast agents often given Fluoroscopy - is an imaging technique commonly used by physicians to obtain real-time moving images of the internal structures of a patient through the use of a fluoroscope. In its simplest form, a fluoroscope consists of an x-ray source and fluorescent screen between which a patient is placed. However, modern fluoroscopes couple the screen to an x-ray image intensifier and video camera allowing the images to be recorded and played on a monitor.  X-rays are highly penetrative rays that can ionize matter by removing electrons from the atoms. Are they harmful? Yes, they are. Nevertheless, radiography is considered a safe profession? Despite the fact that x-rays are harmful radiography is considered a safe profession. In order to understand this we must explain principles of the ALARA( as low as reasonable achievable) concept Personnel protection Time=minimized Distance =maximized Shielding=apply i.e gonad, thyroid , eye google Mammography Mammography is the radiographic examination of the breast tissue (soft tissue examination). Used for screening procedure for asymptomatic women Known history or suspected abnormality for symptomatic women Uses low amount of radiation Cont.. Breast or mammary gland Location Composition of breast Size and shape d/t Factors influence the development of breast cancer 29 X-ray equipment 31 32 Advantages of CT, MRI and Ultrasound These modalities are cross sectional imaging Cross sections are like slices X-ray studies are a 2 dimensional representation of 3 dimensional structures can result in undesirable overlapping densities and artifacts  CT(computed Tomography) Advantages Disadvantages Eliminates overlapping More expensive than x- densities ray and ultrasound Excellent resolution Much more radiation Excellent for detecting Metal cause severe intracranial bleeding artifacts Excellent for evaluating fractures 7/27/2024 36 Cont.. Computed Tomography Lingo: Attenuation Density Enhancement Hounsfield Units -1000 air *** -100 fat 0 water *** 20-80 soft tissues 100’s bone/Ca/contrast >1000’s metal Large radiation dose Magnetic Resonance Imaging(MRI) MRI Lingo: Signal intensity T1 T2 Enhancement No radiation Strong magnetic field No pacemakers No electronic implants Small, loud tube and patients must be able to hold still Relatively expensive  Main MRI Components Console Electronics Magnetics 40 Cot.. Key features biologically relevant element candidates for producing MRI images include Influence of external magnetic field … Cont… 42 Cont..  Contrast administration NB. contrast media- a substance administered to enhance the visibility of structures (increasing the contrast) MRI Advantages Disadvantages No overlapping artifact Very expensive Excellent resolution Patients cannot have a Very good at detecting pacemaker or fluid ferromagnetic material Excellent for imaging Slower to acquire the brain, spine and images joints (approximately 45 No radiation minutes) Multiple imaging tests within the same study (T1, T2, IR, GE) Ultrasound ( US ) Ultrasound Lingo Echogenicity Shadowing Doppler for flow No radiation Can be portable Relatively inexpensive Ultrasound Advantages Disadvantages No radiation Does not work well in large or obese Portable patients Instantaneous (real time) Resolution less than CT and MRI Excellent for cysts and fluid Air or bowel gas prevents visualization of structures Doppler ultrasound is excellent to assess blood flow Excellent for newborn brain, thyroid, gall bladder, female pelvis, scrotum, pregnancy Ultrasound terms Echogenicity Anechoic Hypoechoic Hyperechoic Isoechoic Ultrasound of the gall bladder showing a gall stone X-rays, CT, MRI and ultrasound help us see into the body Internal body structures are composed of varied material (fat, muscle, bone, gland) or contain air, water or minerals that “show up” differently on each type of imaging test. Each modality has its own advantages allowing us the choose the best one for each medical circumstance. What an excellent medical student at your level can do: Be able to describe how x-rays can create an image of internal body structures Recognize and label the 5 basic densities on an x- ray Be familiar with the advantages for CT, for MRI and for ultrasound 10 Q