Radiology (Basics and Image Interpretations) Lecture Notes PDF

Course Instructor Dr.Ali Hayder ALi Topics:  Course objectives.  Course contents.  Sources of Radiation.  Radiation in medicine.  Types of Radiographic Imaging.  Bioliogical effects of radiation.  Radiation protection and safety.  By the end of the radiology courses, and...

Course Instructor Dr.Ali Hayder ALi Topics:  Course objectives.  Course contents.  Sources of Radiation.  Radiation in medicine.  Types of Radiographic Imaging.  Bioliogical effects of radiation.  Radiation protection and safety.  By the end of the radiology courses, and for the practice, you should be able to:  Understand the concept of Radiology.  Learn the terminology specific to Radiology and how to use it in verbal and written communication with patients, family, staff and peers.  Understand the relationship between the basic and clinical sciences as it applies to Radiology.  Apply their knowledge in the basic and clinical sciences to the determination of which imaging studies are most appropriate to the care of their patients.  Understand which study would be most important and helpful versus which studies are less useful or helpful for diagnoses of a wide spectrum of specific diseases.  Demonstrate and discuss radiation safety including radiation biology, dosimetry, and exposure limits, radiation protection and waste disposal.  Introduction to Radiology.  Medical applications of radiology.  Radiologic Imaging Modalities.  Biological Effect of Radiation.  Radiation Protection and Safety.  Standards for the Reporting And Interpretation of Imaging Investigations  Image quality , artifacts , hanging radiograph , projection terminology.  Approach to the CXR, AXR, and skull x.ray interpretations: Technical and clinical Aspects.  The basics of MRI and CT chest ,abdomen, and skull.  The different options for MRI and CT imaging of the chest , abdomen , and skull..  A few disease patterns that will help you impress.  Clinical scenarios and competitions.  Definition:  Radiology is the branch of medical science dealing with medical imaging. It may use x-ray machines or other such radiation devices.  It also uses techniques that do not involve ionize radiation, such as MRI and ultrasound.  Radiology, as a field is still advancing, helping & participating in the steady progress of modern medicine.  Today it is difficult to imagining clinical medicine without the diagnostic support from radiology.  “Radiation is an energy in the form of electro- magnetic waves or particulate matter, traveling in the air.”  Sources of radiation can be divided into two categories: Natural Man-Made Backgroud Radiation Radiation  Cosmic Radiation Terrestrial Internal Radiation Radiation  The earth, and all living things on it are constantly bombarded by radiation from outer space in all directions.  Charged particles from the sun and stars interact with the earth’s atmosphere + + - + - +_ _ and magnetic field to __ ++__ produce a shower of radiation typically beta and gamma radiation. EARTH Path of incoming solar radiation Albedo: a measure of how well a surface reflects insolation  Radioactive material is also found throughout nature in: soil – water – vegetation  Some of these materials are ingested with food and water, while others, such as radon, are inhaled.  The dose from natural background varies in different parts of the world.  In addition to the cosmic and terrestrial sources, all people also have radioactive 40K, 14C, 210Pb, and other isotopes inside their bodies from birth.  People are exposed to radiation from radioactive material inside their bodies.  Besides radon, the most important internal radioactive element is naturally occurring 40K but U and Th are also present.  Radionuclides Found in the Body Total Mass of Total Activity of Daily Nuclide* Nuclide Found Nuclide Found in Intake of in the Body the Body Nuclides Uranium 90 mg 0 1.1 Bq 1.9 mg Thorium 30 mg 0.11 Bq 3 mg 40K 17 mg 4.4 kBq 0.39 mg Radium 31 pg 1.1 Bq 2.3 pg 14C 95 mg 15 kBq 1.8 mg *Uranium, Thorium and Radium are elements  Radiation produced in devices, such as x-ray machines,  Produced radioisotopes made in a reactor or accelerator.  Medical Radiation  Consumer Products  Industrial Applications  Nuclear power  Radioactive Fall out  Examples on Non-ionizing Radiation Sources GAMMA Visible light Microwaves ULTRA V Radios VISIBLE INFRARED MICROWAVE Video Display Terminals TV AM Power lines RF Radiofrequency Diathermy (Physical Therapy) Lasers  These two groups are: 2/Occupationally 1/ Members of exposed the public individuals  Tobacco (polonium-210)  Televisions  Medical x-rays  Smoke detectors (americium)  Nuclear medicine  Building materials  Airport X-ray systems Of lesser magnitude, to radiation from the nuclear fuel cycle  Shipment of radioactive materials ▪ Residual fallout from nuclear weapons testing and accidents, such as Chernobyl. Radiography Radiation oncology departments Nuclear medicine departments University research laboratories Nuclear power plants Fuel cycle  are exposed according to their occupations and to the sources with which they work.  Some of the isotopes of concern would be uranium and its daughter products, 60Co, 137Cs, 241Am, and others  Fallout is a term used to describe radioactive material which has become airborne as a result of nuclear weapons testing in the atmosphere or as a result of large scale accidents such as that which occurred at the Chernobyl nuclear reactor  The airborne material is carried into the atmosphere and is deposited (falls out of the sky) on remote locations.  0 10 20 30 40 50 60 70 Smoking 25 (perWeek) Medical 60 Building 7 Material Phosphate 4 Fertilizer 2 Natural Gas Nuclear Plant 0.4 Lantern 0.2 Mantles Coal Plant 0.15  Treatment  Diagnosis  Sterilization  2. Therapeutic 1.Diagnostic imaging imaging. (Radiotherapy).  Diagnostic Radiology is the branch of medical science dealing with medical imaging and diagnosing purposes.  It may use x-ray machines or other such radiation devices.  It also uses techniques that do not involve radiation, such as MRI and ultrasound  Radiation therapy uses ionizing radiation to treat cancer i.e. to destroy cancerous cells.  There are two techniques in radiation therapy that are used to treat cancer using ionizing radiation:  1/Teletherapy  2/Brachytherapy  Cancerous tumors can be treated using the following main methods: 1/ Chemotherapy (drugs). 2/ Radiation therapy (radiotherapy and brachytherapy). 3/ Surgery.  The aim of radiation therapy is to cause damage to the cancerous cells whilst minimizing the risk to surrounding healthy tissue.  The damage inflicted by radiation therapy causes the cancerous cells to stop reproducing and thus the tumor shrinks.  Unfortunately, healthy cells can also be damaged by the radiation.  Radiation is classified into:  Ionizing radiation  Non-ionizing radiation Ionizing Radiation – Higher energy electromagnetic waves (gamma) or heavy particles (beta and alpha). – High enough energy to pull electron from orbit. Non-ionizing Radiation – Lower energy electromagnetic waves. – Not enough energy to pull electron from orbit, but can excite the electron.  NON- IONIZING IONIZING RADIATION RADITION  Paper Plastic Lead Concrete Alpha Helium nucleus (2 protons, 2 neutrons): +2 charge Beta Electron: +1 or -1 charge Gamma and X-rays Photon: 0 charge Neutron Neutron: 0 charge X-rays were discovered by Roentgen (1845–1923) in 1895 while studying cathode rays (stream of electrons) in a gas discharge tube. Roentgen received the first Nobel Prize in Physics in 1901. This radiation could penetrate opaque substances, produce fluorescence, blacken a photographic plate, and ionize a gas. He named the new radiation x-rays.  Radiation in Medicine X-ray Diagnostics First X-ray photograph made by Röntgen in 1895, shows ring on his wife’s hand (left) Modern X-ray picture obtained by means of digitized data and image processing (right) From: National Geographic 171/1(1987)2-41 48  X-Rays X-ray of Bertha Roentgen's Hand Roentgen soon found that photographic plates were sensitive to the newly discovered rays.  Roentgen placed his hand on a cassette loaded with a photographic plate. He then aimed the activated cathode ray tube at her hand for fifteen minutes. An x ray of the hand requires an exposure of about 1/25 to 1/50 of a second today Scientist filled the room at the University of Wurzburg, Germany, in 1896, when Wilhelm Conrad Roentgen demonstrated his newly discovered x-rays  Characteristics of X rays And all ionizing radiation 1. Electromagnetic spectrum 2. Penetration 3. Radiographic effect 4. Biological effect 5. Ionization 6. Fluorescence 7. Chemical effect 8. Thermal effect  The production of X rays X-ray production typically involves bombarding a metal target in an x-ray tube with high speed electrons (kV). The bombarding electrons can eject electrons from the inner shells of the atoms of the metal target. Those vacancies will be quickly filled by electrons dropping down from higher levels, emitting x-rays with sharply defined frequencies associated with the difference between the atomic energy levels of the target atoms. Genetic appears in latter generations due to cell damage of the reproductive organs Somatic appears in the irradiated individual immediate or delayed effects 54 Cells were most sensitive to radiation when they are: Rapidly dividing Undifferentiated Have a long mitotic future The more often they divide, the more chances for DNA damage to result in cell death. 56 No change Mutation and repair Permanent change with limited effect Changes leading to cancer or other effects Death of cell / organism (mins - years) 57 1/Direct 2/Indirect Action Action H 2O H 2O + + e -  Radiation ionizes a water molecule H2O+ H+ + OH  The positive ion dissociates  The electron attaches H 2O + e- H2 O- to a neutral water molecule H2O- H + OH-  The negative ion then dissociates H + H H2  The H radicals combine to form hydrogen gas OH + OH H2O2  Hydrogen peroxide is produce through two mechanisms H + O2 HO2  *OH and peroxide are very reactive HO2 + H H2O2  Damage cell membranes, proteins, and DNA  Possibility of antioxidants as treatment 1/Stochastic 2/Non-stochastic (Random) (Deterministic) Effects. Effects Occur by chance Occur in both exposed and unexposed individuals Are not unequivocally related to the radiation exposure Become more likely as dose increases Severity is independent of the dose  1 Assumes that any Probability of amount of radiation has a detrimental effect 0.5 Is not a predictive model Is used to establish 0 regulatory dose limits Dose Cancer Mental Retardation Genetic Effects Radiation induced tumors most frequent in the hemopoietic system, thyroid, and skin. Cancer induction is well documented at doses of 100 rad or more Induction at lower doses is inconclusive (possible exceptions are leukemia and thyroid cancer) Tumor induction has a latent time of 5-20 years Radiation induced leukemia in Atomic bomb survivors has been documented at doses above 40 rad Bone Cancer induction has been documented in laboratory animals for large injection of “bone seeking” radionuclide Radiation induced lung cancer is seen mainly in underground miners exposed to high Radon concentrations Most pronounced in those exposed between the 8th and 17th week of pregnancy Brain cells divide rapidly during this period Has been observed in children exposed in-utero to radiation from the atomic bombs in Japan No radiation induced genetic effects have been observed in humans Genetic effects have been observed in animal studies  A certain minimum dose must be exceeded before the effect occurs  The severity of the effect increases as dose increase  There is a clear causal relationship between exposure and occurrence  100  No response is seen until the threshold Present Response dose is exceeded  At some dose all 50 individual experience the effect  Applies to non- 0 stochastic effects Dose  Sterlity  Cataracts  Skin Erythema  Hemopoietic Syndrome  Gastrointestinal (GI) Syndrome  Central Nervous System Syndrome  Temporary sterility had been observed  In men at dose as low as 30 rads in women at does as low as 300 rads  In women at doses as low as 300 rads  The higher the dose the longer the period of sterility.  Cataracts  Threshold eye dose of about 200 rads of beta or gamma radiation.  Threshold may be as low as 60 rads for neutron radiation.  Long latent period.  Reddening of the skin (erythema) occurs at photon or beta doses of about 300 rads  Higher doses may cause epilation, blistering, necrosis, and ulceration  Blood changes may be seen at doses as low as 14 rads  Blood changes almost certain at doses above 50 rads  Hemopoietic Syndrome appears at about 200 rads  Characterized by depression or ablation of the bone marrow  May be accompanied by nausea, vomiting, fatigue, and increased temperature  Death occurs within 1-2 months unless medical treatment is successful  Occurs at a whole body dose of 1000 rads or greater  Characterized by the destruction of the intestinal epithelium and complete destruction of the bone marrow  Accompanies by severe nausea, vomiting, and diarrhea soon after exposure  Death occurs within a few weeks  Occurs at whole body doses of 2000 rads or more  Damages the central nervous system as well as all other organs and systems  Unconsciousness occurs within minutes  Death follows in a matter of a few hours to a few days  Biological effects of concern in the occupational setting do not appear until several years after radiation exposure if they appear at all  The probability of these effects increases with dose  In any individual case it can never be determined with 100% confidence that radiation was the cause  Radiation protection and radiation safety: Protection is “reactive” while “safety” is proactive and indicating positive gain.  Radiation cannot merely be controlled but preferably managed.  RSMS is a system approach to managing radiation hazards and risks.  RSMS involves the interaction of five major elements to achieve set goals.  The five major elements are: a. policy; b. organizing; c. planning and implementation; d. evaluation; and e. action for improvement  Justification of practice  Optimization of protection  Individual dose limits As Low As Reasonably Achievable  Primary Methods of Radiation Protection Three basic factors Time Distance Shielding 1. To protect the patient from deterministic effects, e.g., skin burns 2. To optimize X ray exposure to minimize risk of stochastic effects, e.g., development of cancer 88  ICRP Publication 85. Avoidance of radiation injuries from medical interventional procedures  LK Wagner. Radiation injury is a potentially serious complication to fluoroscopically-guided complex interventions. Biomed Imaging Interv J 2007; 3(2): http://www.biij.org/2007/2/e22/  IAEA http://www.rpop.org Radiation protection of patients 89 3.5p 90