11 - dasar diagnostik radiologi (eng)

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BASIC PRINCIPLES OF BASIC PRINCIPLES OF RADIOLOGY RADIOLOGY Bachtiar Murtala Bachtiar Murtala

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11 - Dasar Diagnostik Radiologi (Eng)

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  • BASIC PRINCIPLES OF RADIOLOGYBachtiar Murtala

  • BASIC PRINCIPLES OF RADIOLOGYBachtiar Murtala

  • General objective To provide a basic understanding of ionizing radiation and other sources as a tool of diagnosis

  • Specific objectives :

    - Types of radiation sources- Equipments- Basics of interpretation- Biologic effects- Radiation protection

  • History in briefRadiology started when Prof.Wilhelm Conrad Roentgen discovered of a new kind of rays (x-rays) in November 8,1895 in GermanyHe made a first photograph of his wifes (Bertha) hand in Dec 22, 1895 using the rays, signed the true birthday of radiology as a medical specialty.He was awarded Nobel Prize in Physics in 1901Later, CT (Computed Tomography) and US (Ultrasonography) introduced in the seventies dan MRI ( Magnetic Resonance Imaging ) in the eighties.CT was discovered by Sir Godfrey Hounsfield, and together with Allen Cormack , awarded Nobel Prize in 1979.

  • Radiology can be categorized as :Diagnostic radiologyRadiations (ionizing and nonionizing ), used as a tool to make diagnosis of diseases.Radiotherapy or radiation oncology --radiation used as an agent to eradicate tumor/cancer

  • Types of radiation sourceRadiations can be categorized into two main forms :(1) ElectromagneticX-rays,gamma-rays, uv, infra red, visible light, radio waves. (2) ParticlesElectron, positron,etc

  • X-rayTo develop of x-ray beam, we need :A vacuum tubeElectronsFocusing cupMetal filamentTarget

  • In conventional radiography, after passing the body, x-ray will create an image directly on photographic film.

    The film is covered by a thin emulsion of Silver Bromide (AgBr), which is very sensitive to x-rays and visible light, blackening the film after having developed in liquid developer ( washing processing )

  • Terms in conventional radiographyDarkness to brightness

    Hyperradioluscent : free-airRadioluscent : lung, fat tissueIntermediate : soft tissues,water/fluidRadiopaque : Calsium, boneHyperrariopaque : metal

  • CT-Scan(Computerized Tomography Scan )The greatest step forward since the discovery of X-rays. First CT-Scan was introduced in 1972.X-rays pass the patient and reach detectors ( not on the film )Only thin tissue slices are exposed by X-rays high contrast resolution, no superimposition/ blurring of structuresTissue and water/fluid can be distinguished ( in conventional radiography can not be )

  • Terms in CTHyperdense : blood, calcification, boneIsodense/normodense : normal soft tissues such as; brain, liver, spleen,etcHypodense : fluid, edema, fat, abscess, tumor, etc

  • HU=Hounsfield Unit

  • Radionuclide Imaging( Nuclear medicine )Radioactive introduced into the body of the patients orally or intravenouslyDetection of radiation emitted from radioactive tracer inside the patientRadioactive tracers, termed radiopharmaceuticals emit gamma rays.Gamma camera is used to detect the rays and produce image.

  • Two major tomographic methods :(1) SPECT ( single photon emission computed tomography)(2) PET ( positron emission tomography )

  • UltrasonographyUltrasound (US) sound wave freq >20 KHz (above the human hearing range)Commonly used : 2-10 MHzNo biologic effects

  • ComponentsTransducer/probe which contain piezo-electrical crystals ( the main component ) These crystals act as both transmitter/produce ultrasound and receiver (of echo)Computer and dysplayPrinter

  • The most important part is transducerTransducer contains piezoelectric crystals with two functions : transmitter of US and receiver of echoEcho returning to transducer generates electrical signalscomputer image

  • Terms in USHyperechoic = echorich brightness : calcification, stone, gasIsoechoic= normoechoic : normal soft tissue; liver, spleen, etcHypoechoic = echopoor : tumor, abscessFree-echoic = unechoic : fluid ;water,etc

  • MRI( Magnetic Resonance Imaging )The latest newcomer of radiological modalitiesExploits hydrogen nuclei (proton) of the human body to develop signalImages in any plane of any part of the bodyNo ionizing radiation No biologic effectsContraindication for patients with using ferromagnetic material such as pacemakerMore expensive, theoretically more difficult, and technically more advanced

  • Main ComponentsA very strong magnet ( 0.1-1.5 Tesla or > )A radio transmitterA radio frequency receiver coilA computer

  • Terms in MRIT1WI, T2WI, DWI, etc(T1 Weighted Image)Hyperintense : brightnessIsointense : same with normal adjacent tissue Hypointense : darkness

  • T2WIT1WI

  • Positioning in radiographyIn conventional radiography, we should familiar with the routine positionsPA : Postero-anteriorAP : Anterio-posteriorRLD : Right lateral decubitusLLD : Left lateral decubitusetc

  • Foto2

  • Biologic effectsCome from X-rays and gamma-rays since they can ionize atoms/molecules of human tissueCan be grouped into : immediately effects, latent somatic effects, and manifest genetic damage

  • Principles of radiation protectionShould be apply to : patient, personnel, and environment / around peopleWork with : - shorten time, - appropriate distance, - use protective toolsAvoid and reduce somatic and genetic doses to as low as possible ( ALARA, As Low As Reasonably Achievable )

  • Thank you