Diagnostic_radiology_ppt_for_public_heal
- 1. Gambella University College of NCS Diagnostic radiology(DiRa4134) for public health 4th year students By: Nega Cheru (Msc. In Medical Physics) December 2024
- 2. Overview of Diagnostic Radiology ⚫Radiology is a medical specialty that employs the use of imaging to both diagnose and treat disease visualized within the human body. ⚫Radiologists use an array of imaging technologies. ⚫It may use x-ray machines or othersuch radiation devices. ⚫Or It also uses techniques that do not involve radiation, such as MRI and ultrasound.
- 3. ⚫Radiology can refer to two sub-fields, diagnostic radiology and therapeutic radiology. ⚫Diagnostic radiology is concerned with the use of various imaging modalities toaid in thediagnosis of disease. ⚫Therapeutic radiology or, as it is now called, radiation oncology uses radiation to treatdiseases such as cancer using a form of treatment called radiation therapy.
- 4. ⚫Commonly used techniques for diagnostic radiology includes ➢X-rays ➢Computed tomography (CT - scan ) ➢Mammography ➢Magnetic resonance imaging (MRI) ➢Ultrasound ➢Nuclear medicine imaging techniques
- 5. Radiation ➢Radiation is the energy that travels through space either in the form of wave or particle ▪ Particulate radiations are: alpha particle, beta particle ▪ Electromagnetic radiations are: x-ray and gamma rays ➢ The radiation that we are exposed to can be ▪ Ionizing – high energy electromagnetic wave ▪ Non-ionizing-low energy electromagnetic wave
- 6. X-rays: A Historical Journey ▪ In 1895, Wilhelm Conrad Röntgen, a German physicist, stumbled upon X- rays while experimenting with cathode rays. ▪ He observed an unseen radiation passing through opaque objects, creating the first X-ray image of his wife's hand, revealing the bones beneath the skin ▪ Röntgen's discovery quickly revolutionized medicine, providing a non-invasive tool for diagnosing fractures, tumors, and other internal ailments. X-RAYS
- 7. X-RAYS ⚫X-rays are basically electromagnetic radiations which are used to create images of inside our body. ⚫The images show the parts of your body in different shades of black and white due to different level of absorption of x-rays by different tissues ⚫Calcium in bones absorbs x-rays the most, so bones look white. Fatand othersoft tissues absorb less, and look gray. ⚫Airabsorbs the least, so lungs look black.
- 9. X-ray applications ❖X-rays are particularly effective in diagnosing ▪ fracture detection: used to check for broken bones or fracture ✓ It provide clear image of bone structures, allowing doctors to see the location, type and the severity of the break ▪Joint problems: Detecting Arthritis and joint dislocation ▪Lung condition: Diagnosing pneumonia, tuberculosis, lung cancer and other pulmonary diseases ▪Dental issues: Assessing tooth decay, impacted teeth and jawbone abnormalities ▪Digestive track issues: used to Identify issues in the digestive tract such as blockage, perforations or swallowed foreign objects
- 10. X-ray Production ➢ X-rays are produced when high energy electrons interact with matter and convert their kinetic energies into electromagnetic radiation. ➢ The production of an x-ray beam in a clinical imaging system is performed by the x-ray tube. ➢ Inside the x-ray tube, an electron beam is generated by liberating electrons from the filament via thermionic emission (heating of the filament). ➢ Electrons are accelerated towards the anode by applying potential difference between Anode and Cathode.
- 11. Electrons are first emitted from a heated filament, by a process called thermionic emission. They are then accelerated across the evacuated X-ray tube, under the action of a large voltage across the tube, the filament forming the negative cathode and the target being positive anode. On striking the target, the electrons lose most (about 99%) of their energy in low-energy collisions with target atoms, resulting in a substantial heating of the target. The rest of the electron energy (usually less than 1%) reappears as X-ray radiation. Production Of X-Rays.. (continued) Production_of_X_Rays(360p).mp4
- 12. x-ray Image formation ▪X-ray imaging utilizes the ability of high frequency electromagnetic waves to pass through soft parts of the human body largely unimpeded ▪In X-ray radiography images are produced by casting an X- ray shadow onto a photographic film or digital detector
- 13. Advantage and disadvantages of x-rays Advantages ➢Non-invasive: x-rays allow doctors to view the interior of the body without surgery ➢Quick and painless: The process of taking an x-ray is fast and doesn’t cause any pain ➢Cost-Effective: Compared to other imaging techniques like MRI’s, x-rays are generally more affordable ➢Widely available: x-ray machines are commonly found in hospitals and clinics Disadvantages ➢ Radiation exposure ➢Limited soft tissue imaging ➢Risk of misinterpretation
- 14. Computed Tomography ❖ Computed Tomography, CT for short (also referred to as CAT, for Computed Axial Tomography), utilizes X-ray technology and sophisticated computers to create images of cross-sectional “slices” through the body. ❖ CT exams and CAT scanning provide a quick overview of pathologies and enable rapid analysis and treatment plans. ❖ Tomography is a term that refers to the ability to view an anatomic section or slice through the body. ❖Anatomic cross sections are most commonly refers to transverse axial tomography.
- 15. ❖This x-ray based system created projection information of x-ray beams passed through the object from many points across the object and from many angles (projections). ❖CT produces cross-sectional images and also has the ability to differentiate tissue densities, which creates an improvement in contrast resolution
- 16. Label 1. gantry aperture (720mm diameter) 2. microphone 3. sagittal laser alignment light 4. patient guide lights 5. x-ray exposure indicator light 6. emergency stop buttons 7. gantry control panels 8. external laser alignment lights 9. patient couch 10. ECG gating monitor
- 17. CT Scan ◼ CT scan produces axial sections/cuts /Slices ◼ The CT image is recorded through a SCAN. ◼ Scan? ◼ A scan is made-up of multiple X- Ray attenuation measurements around an objects periphery X-ray tube Detector
- 18. Slice / Cut ◼ The cross -sectional portion of the body which is scanned for the production of CT image is called a slice. ◼ The slice has width and therefore volume. ◼ The width is determined by the width of the x-ray beam
- 19. http://www.themesotheliomalibrary.com/ct-scan.html ▪ The x-ray tube and detectors rotate around the patient and the couch moves into the machine. ▪ This produces a helical sweep pattern around the patient. ▪ The patient opening is about 70cm in diameter. The basics of image formation by CT
- 20. ▪ The data acquired by the detectors with each slice is electronically stored and mathematically manipulated to compute a cross- sectional slice of the body. ▪ Three-dimensional information can be obtained by comparing slices taken at different points along the body. ▪ Or the computer can create a 3D image by stacking together slices. ▪ As the detector rotates around many cross-sectional images are taken and after one complete orbit the couch moves forward incrementally.
- 21. ❑ Pixel– picture element – a 2D square shade of gray. ❑ Voxel– volume element – a 3D volume of gray. ❖ This is a result of a computer averaging of the attenuation coefficients across a small volume of material. ❖ This gives depth information. ❖ Each voxel is about 1mm on a side and is as thick as 2 –10mm depending on the depth of the scanning x- ray beam.
- 22. Computed Tomography Image Quality Contrast Resolution – The ability to differentiate between different tissue densities in the image • High Contrast - Ability to see small objects and details that have high density difference compared with background. ➢ These have very high-density differences from one another. ➢ Ability to see a small, dense lesion in lung tissue and to see objects where bone and soft tissues are adjacent Low Contrast - Ability to visualize objects that have very little difference in density from one another. ➢ Better when there is very low noise and for visualizing soft- tissue lesions within the liver. ➢ Low contrast scans can differentiate gray matter from white matter in the brain.
- 23. ❖Artifacts can degrade image quality and affect the perceptibility of detail. • Includes Streaks – due to patient motion, metal, noise, mechanical failure. Rings and bands – due to bad detector channels. Shading - can occur due to incomplete projections. Computed Tomography Image artifacts Streaks Rings and bands Shading
- 24. Computed Tomography Advantages & Disadvantages Advantages: ✓ Desired image detail is obtained ✓ Fast image rendering ✓ Filters may sharpen or smooth reconstructed image ✓ Raw data may be reconstructed post-acquisition with a variety of filters Disadvantages ✓ Multiple reconstructions may be required if significant detail is required from areas of the study that contain bone and soft tissue ✓ Need for quality detectors and computer software ✓ X-ray exposure
- 25. Mammography ▪ Mammography is specialized medical imaging that uses a low-dose x-ray system to see inside the breasts ▪ A mammography exam, called a mammogram, aids in the early detection and diagnosis of breast diseases in women ▪ In the mid 1950’sJacob Gershon uses mammography to screen healthy women for breast cancer. ▪ Late 1950’s-Robert Egan developed new method of screening mammography and he published his results in journal and book in 1964. ▪ In1960’s mammography become a widely used diagnostic tool
- 26. How is a mammogram taken? ▪ During a mammogram, a patient’s breast is placed on a flat support plate and compressed with a parallel plate called a paddle ▪ An x-ray machine produces a small burst of x-rays that pass through the breast to a detector located on the opposite side ▪ The detector can be either a photographic film, which captures the x-ray image on film, or a solid-state detector, which transmits electronic signals to a computer to form a digital image ▪ The image produced are called mammograms ▪ On a film mammogram, low density tissues, such as fat, appear translucent (i.e. darker shades of gray approaching the black background) ▪ whereas areas of dense tissue, such as connective and glandular tissue or tumors, appear whiter on a gray background
- 28. ▪ A mammogram showing a healthy breast (left), and a mammogram showing cancer (right). ▪ Breast x-rays (mammography) can detect breast lumps or changes long before they can be felt. ▪ The information provided by a mammogram can lead to proper follow-up care. Healthy Cancerous
- 30. Mammography views ▪ Mammography image views are:- ✓Craniocaudal(CC) ✓Mediolateral oblique (MLO) ▪ In craniocaudal, the x-ray beam is directed from top to bottom (superior to interior) ▪ It provides a top-down image of the breast, enabling visualization of the medial(inner)and lateral (outer) parts of the breast ▪ In mediolateral oblique, the x-ray beam is directed at an angle(30,45 and 60) from the upper side of the breast toward the lower inside
- 32. ➢The three recent advances in mammography includes ▪ Digital mammography ▪ Computer-aided detection & ▪ Breast tomosynthesis. ❖Digital mammography,(full-field digital mammography (FFDM)), is a mammography system in which the x-ray film is replaced by electronics that convert x-rays into mammographic pictures of the breast ▪ These images of the breast are transferred to a computer for review by the radiologist and for long-term storage ▪ The patient’s experience during a digital mammogram is similar to having a conventional film mammogram
- 33. ❖Computer-aided detection (CAD): gives digitized mammographic images for abnormal areas of density, mass or calcification that may indicate the presence of cancer. ❖The CAD system highlights these areas on the images, alerting the radiologist to carefully assess this area. ❖Breast Tomosynthesis: also called three-dimensional (3-D) mammography and digital breast tomosynthesis (DBT), is an advanced form of breast imaging where multiple images of the breast from different angles are captured and reconstructed ("synthesized") into a three-dimensional image set. ▪ In this way, 3-D breast imaging is similar to computed tomography (CT) imaging in which a series of thin "slices" are assembled together to create a 3-D reconstruction of the body ▪ The radiation dose for some breast tomosynthesis systems is slightly higher than the dosage used in standard mammography, it remains within the FDA-approved safe levels for radiation from mammograms.
- 34. What are the types of mammograms? ▪ Mammograms are used as a screening tool to detect early breast cancer in women experiencing no symptoms. ▪ They can also be used to detect and diagnose breast disease in women experiencing symptoms such as a lump, pain, skin dimpling or nipple discharge. ❖Screening Mammography: A screening mammography is an x-ray of the breast used to detect breast changes in woman who have no sign or symptoms of the breast cancer ❖Diagnostic mammography: is used to evaluate a patient with abnormal clinical findings such as a breast lump or nipple discharge that have been found by the woman or her doctor. ▪ Diagnostic mammography may also be done after an abnormal screening mammogram in order to evaluate the area of concern on the screening exam
- 35. What are the benefits and risks of mammography Benefits ▪ Radiation exposure: There is always a slight chance of cancer from excessive exposure to radiation ▪ Sensitivity in dense breast tissue: may not be as effective in detecting in breast cancers in women with dense breast tissue. • Dense breast appears white on mammograms, and tumor also appear white making it difficult to distinguish them. This can result false negatives, where cancer is present but not detected ▪ False-positive: mammogram can also lead to false-positive results, where abnormalities that are not cancerous are identified as potential tumors risks ▪ Screening mammography reduces the risk of death due to breast cancer. ▪ It is useful for detecting all types of breast cancer, including invasive ductal and invasive lobular cancer ▪ Screening mammography improves a physician's ability to detect small tumors. ▪ The use of screening mammography increases the detection of small abnormal tissue growths confined to the milk ducts in the breast, called ductal carcinoma in situ (DCIS).
- 36. Magnetic Resonance Imaging (MRI) ▪ MRI is a medical imaging technique that utilizes strong magnetic field and radio-waves to produce detailed image of the internal structure of the body. ▪ Unlike x-rays or CT scans , MRI doesn’t use ionizing radiation, making it safer for repeated use. ▪ MRI makes use of the property of Nuclear magnetic resonance (NMR) to image nuclei of atoms inside the body. ▪ It is particularly useful for imaging soft tissues , such as the brain, muscles and ligaments ▪ Images produced by an MRI scan can show organs, bones, muscles and blood vessels. • MRI is a type of diagnostic test that can create detailed images of nearly every structure and organ inside the body. • MRI uses magnets and radio waves to produce images on a computer. MRI does not use ionizing radiation. • Images produced by an MRI scan can show organs, bones, muscles and blood vessels.
- 37. Components of Magnetic Resonance Imaging ▪ Magnet • The magnet generates a strong magnetic field that aligns the protons in the body • It is typically made of superconducting materials to maintain efficiency • The strength of the magnet is measured in Tesla, with most MRI machines using 1.5 to 3 Tesla magnets.
- 38. ▪ Radiofrequency Coil • The radiofrequency coil transmits radio waves into the body and receives the signals emitted back • Different coil designs are used to target specific body parts for better image quality ▪ Gradient Coils • Gradient coils create varying magnetic fields that spatially localize the MRI signals • They allow for the differentiation of tissues by adjusting the magnetic field strength
- 39. Computer System • The computer system processes the raw data collected from the MRI machine • Software algorithms convert the signals into images that can be interpreted by radiologists • Advanced computing techniques enhance image clarity and detail.
- 40. What kinds of nuclei can be used for NMR? Nucleus needs to have 2 properties: Spin charge Nuclei are made of protons and neutrons Both have spin ½ Protons have charge Pairs of spins tend to cancel, so only atoms with an odd number of protons or neutrons have spin Good MR nuclei are 1H, 13C, 19F, 23Na, 31P
- 41. Hydrogen atoms are best for MRI Biological tissues are predominantly 12C, 16O, 1H, and 14N Hydrogen atom is the only major species that is MR sensitive Hydrogen is the most abundant atom in the body The majority of hydrogen is in water (H2O) Essentially all MRI is hydrogen (proton) imaging
- 42. A Single Proton + + + There is electric charge on the surface of the proton, thus creating a small current loop and generating magnetic moment . The proton also has mass which generates an angular momentum J when it is spinning. J Thus proton “magnet” differs from the magnetic bar in that it also possesses angular momentum caused by spinning.
- 43. How do protons interact with a magnetic field? Moving (spinning) charged particle generates its own little magnetic field Such particles will tend to line up with external magnetic field lines (think of iron filings around a magnet) Spinning particles with mass have angular momentum Angular momentum resists attempts to change the spin orientation (think of a gyroscope)
- 45. How does it work? The MRI machine is a large, cylindrical (tube-shaped) machine that creates a strong magnetic field around the patient and sends pulses of radio waves from a scanner. This magnetic field created by the MRI scanner causes the atoms in our body to align in the same direction. Radio waves are then sent from the MRI machine and move these atoms out of the original position. As the radio waves are turned off, the atoms return to their original position and send back radio signals. These signals are received by a computer and converted into an image of the part of the body being examined
- 47. What is MRI used for? MRI scanners are particularly well suited to image the non-bony parts or soft tissues of the body. They differ from computed tomography (CT), in that they do not use the damaging ionizing radiation of x-rays. The brain, spinal cord and nerves, as well as muscles, ligaments, and tendons are seen much more clearly with MRI than with regular x-rays and CT; for this reason MRI is often used to image knee and shoulder injuries. In the brain, MRI can differentiate between white matter and grey matter and can also be used to diagnose aneurysms and tumors. Because MRI does not use x-rays or other radiation, it is the imaging modality of choice when frequent imaging is required for diagnosis or therapy, especially in the brain. However, MRI is more expensive than x-ray imaging or CT scanning
- 48. Risk of magnetic resonance imaging ▪ Because radiation is not used, there is no risk of exposure to radiation during an MRI procedure. However, due to the use of the strong magnet, MRI cannot be performed on patients with o People with implants, particularly those containing iron-pacemakers, vagus nerve stimulators, implantable cardioverter- defibrillators, loop recorders, insulin pumps and soon • Contrast agents-patients with severe renal failure who require dialysis may risk a rare but serious illness called nephrogenic systemic fibrosis that may be linked to the use of certain gadolinium-containing agents, such as gadodiamide and others • Certain prosthetic devices • Implanted drug infusion pumps • Neurostimulators • Bone-growth stimulator. • Pregnancy
- 49. 49 Ultrasound
- 50. Ultrasound ▪ Ultrasound or ultrasonography is a medical imaging technique that uses high frequency sound waves and their echoes to look at organs and structures inside the body. ▪ These frequencies are between 1 MHz and 10 MHz (mega, M, is one million or × 106) and such frequencies cannot be heard by humans ▪ The technique is similar to the method of location used by bats, whales and dolphins, as well as SONAR used by submarines
- 51. 51 When and why ultrasound used? There are many occasions when ultrasound is a favourable method of viewing inside the body An obstetrician can use ultrasound to check the development of an unborn baby Doppler ultrasound can be use to view blood flow through the heart and diagnose circulation problems Ultrasound is a ‘non-invasive’ imaging method with instant results, relatively inexpensive, with little or no health risks Recent advances, including 4D with surface rendering have increased the resolution and detail of ultrasound scans
- 52. 52 Physics principles: Waves Frequency (f) – number of waves per second (in Hz) crest trough mean or zero position Wavelength () – distance between any point on one wave and the corresponding point on the next wav Velocity v = f Amplitude
- 53. Physics Principles ▪ Ultrasounds are sound waves whose frequency is above the range of normal human hearing. Audible sound frequencies extend from about 20 to 20,000 hertz (1 Hz = 1 cycle per second). ▪ SONAR stands for Sound Navigation and Ranging; it was developed during World War I for submarine detection. ▪ It relies on the reflection of ultrasonic pulses bouncing off an object. By timing how long it takes for the signal to return, the depth of the object can be calculated. It has been used to map the ocean floor, as well as finding shoals of fish by fishermen. 53
- 54. 54 How does an ultrasound machine work? ➢ The ultrasound machine transmits high-frequency (1 to 5 megahertz) sound pulses into the body using a probe. ➢ The sound waves travel into the body and hit different tissue, fluid or bone ➢ Some of the sound waves get reflected back to the probe, while some travel on further until they reach another boundary and then get reflected. ➢ The reflected waves are picked up by the probe and relayed to the machine. ➢ Using speed = distance x time the machine calculates the distance from the probe to the tissue or organ. ➢ The machine displays the distances and intensities of the echoes on the screen, forming a two dimensional image
- 55. 55 How is an ultrasound machine operated? ➢ The patient must remove clothing around the area to be examined. ➢ A gel is applied to the area-this removes any air which would affect the signal. ➢ The probe or transducer is placed on the skin. ➢ A computer monitor displays the image which can be stored or printed
- 56. 56 Ultrasound Treatments ▪ Ultrasound is the best form of heat treatment for soft tissue injuries. It is used to treat joint and muscle sprains, and tendonitis. Ultrasound treatment is used to: relieve pain and inflammation speed healing reduce muscle spams increase range of motion ❖Ultrasound uses high frequency sound waves. The sound waves vibrate tissues deep inside the injured area. This creates heat that draws more blood into the tissues. The tissues then respond to healing nutrients brought in by the blood and the repair process begins.
- 57. 57 Lithotripsy LITHO = Stone , TRIP = To Break Lithotripsy (also called ESWL- Extra-Corporeal Shock Wave Lithotripsy) is a method of breaking up kidney stones in the kidneys or tract ,using ultasound shock waves. A kidney stone(2cm diameter)formed from build up of calcium A Lithotripter machine
- 58. 58 Lithotripsy - Advantages ▪ Lithotripsy was developed in the early 1980s. Before this, surgery was the usual treatment. It is estimated that more than one million patients are treated annually in the USA alone. VIRTUALLY NO PAIN! NO ANESTHESIA! NO SURGERY! NO HOSPITAL STAY
- 59. Radiation hazard and monitoring Excessive exposure to radiation may damage living tissues and organs, depending on the amount of radiation received (i.e. the dose). The extent of the potential damage depends on several factors, including: ➢The type of radiation; ➢The sensitivity of the affected tissues and organs; ➢The route and duration of exposure; ➢the individual characteristics of the exposed person (such as age, gender and underlying health condition). ➢Health effects from radiation doses can be grouped into two categories: deterministic and stochastic
- 60. Stochastic effect: occurs by chance, usually without a threshold level of dose. ➢ The probability of a stochastic effect is increased with increasing doses, but the severity of the response is not proportional to the dose (e.g., two people may get the same dose of radiation, but the response will not be the same in both people). ➢ Genetic mutations and cancer are the two main stochastic effects. Deterministic effect: health effects that increase in severity with increasing dose above a threshold level. ➢ Usually associated with a relatively high dose delivered over a short period of time. ➢ Skin erythema (reddening) and cataract formation from radiation are two examples of deterministic effects.
- 61. Dose-Response Curves ➢ Dose-Response curves represent the relationship between the dose of radiation a person receives and the cellular response to that exposure. ➢ These responses may be linear or non-linear and may, or may not, have a threshold dose; the responses (effects) may be stochastic or deterministic. (See next two slides for definitions of these terms). threshold linear non-linear non-threshold Response Dose
- 62. DNA ➢Radiation effects at the cellular level result from changes in a critical or “target” molecule. ➢This target molecule is DNA (deoxyribonucleic acid), which regulates cellular activity and contains genetic information needed for cell replication. ➢Permanent changes in this molecule will alter cell function and may result in cell death.
- 63. Direct vs. Indirect Effect ➢If an x-ray or some type of particulate radiation interacts with the DNA molecule, this is considered a direct effect. ➢ Particulate radiation, because of its mass, is more apt to cause damage to the DNA by this direct effect. ➢Other molecules that contribute to cell function, such as RNA, proteins, and enzymes, may also be affected by the direct effect.
- 64. ➢Most of the damage to DNA molecules from x-rays is accomplished through the indirect effect. ➢When x-rays enter a cell, they are much more likely to hit a water molecule because there are a large number of water molecules in each cell. ➢When the x-ray ionizes the water molecule, ions and free radicals are produced which in turn bond with a DNA molecule, changing its structure. ➢Since the x-ray interacted with the water molecule before the DNA was involved, this is considered an indirect effect.