Radiology.pdf

TYPE OF IMAGING TECHNIQUES Basic film interpretation - X- ray Specialised radiological investigation - Ultrasound - CT scan - MRI scan - X-RAYS - X-radiation (composed of X-rays) is a form of electromagnetic radiation. -...

TYPE OF IMAGING TECHNIQUES Basic film interpretation - X- ray Specialised radiological investigation - Ultrasound - CT scan - MRI scan - X-RAYS - X-radiation (composed of X-rays) is a form of electromagnetic radiation. - Röntgen discovered X-rays 1895 and received the first Nobel Prize 1901. - X-rays have a wavelength in the range of 10 to 0.01 nm. - X-rays are used is to take images of the inside of an object in diagnostic radiography and crystallography E.g. Arthritis, pneumonia, bone tumours and fractures anterior compression ❑ Hard X-rays can penetrate solid objects. ❑ Equipment typically used for bone x-rays consists of an x-ray tube suspended. over a table on which the patient lies. ❑ A drawer under the table holds the x-ray film or image recording plate. ❑ High contrast image is formed on silver- impregnated film. ❑ Dense bone absorbs much of the radiation while soft tissue, such as muscle, fat and organs, allow more of the x-rays to pass through them. ❑ As a result, bones appear white on the x-ray, soft tissue shows up in shades of grey and air appears black. CONVENTIONAL CHEST X-RAYS FLUOROSCOPY ❑ Is an imaging technique that uses x-rays to obtain real-time moving images of the internal structure and function of a patient ❑ Augmented with a radiocontrast agent Barium Sulphate Radio-Iodine ❑ Radio-contrast agents administered by swallowing or injecting into the body of the patient ❑ To describe the anatomy and functioning of the blood vessels, the genitourinary system, or the gastrointestinal tract (GI tract) INTERVENTIONAL RADIOLOGY ❑ Subspecialty of radiology performed using image guidance of the catheters and needles insertion ❑ Minimally invasive technique ❑ Used for: ▪ Diagnostic (e.g. angiogram) ▪ Treatment (e.g. angioplasty) ▪ Such as: ▪ peripheral vascular disease, renal artery stenosis, inferior vena cava filter placement, gastrostomy tube placements, stents and hepatic interventions ANGIOGRAM ❑ An angiogram is a special form of x-ray that permits the diagnosis of blockages (occlusions) or narrowings (stenosis) in the arteries of the body ❑ During the test, a tube (catheter) is inserted into an artery at the groin ❑ A special radio-opaque dye (contrast medium) is injected down the tube and x-ray pictures are taken as the solution passes along the blood vessels. ANGIOPLASTY ❑ An angioplasty is a procedure where a balloon is passed into your artery on the end of a tube (catheter) and is inflated (blown up) to treat a narrowed or blocked artery. ❑ This technique means that surgery may be avoided in many cases. VENOGRAM ❑ A venogram is an x-ray test that takes pictures of blood flow through the veins in a certain area of the body. ❑ During a venogram, a special dye (contrast material) is put into your veins so they can be seen clearly on an x-ray picture. ❑ A venogram looks at the condition of your veins and the valves in your veins. COMPUTER TOMOGRAPHY (CT) ❑ Ring-shaped apparatus – x-ray tube opposite a detector → computer generated cross- sectional image (tomogram) ❑ Coronal and sagittal images are produced by computer reconstruction ❑ Such as: sliced images of the skull bone and brain ❑ The radio-contrast material is used to enhances clarity of the image e.g. abscess in brain outlined well v/s a tumor ❑ Spiral multi-detector use 16, 64 or 254 detectors → fine detailed images in quick time and produce multi- detector CT reconstructions ULTRASOUND ❑ Ultrasound are high-frequency sound waves used to visualize soft (biological) tissue in the body in real time. ❑ No ionizing radiation (ultrasound contrasting agents) ❑ Hence very safe in pregnancy and fetal anatomy ❑ Useful in solid organ trauma, tumours, cysts, soft tissue injury ❑ Cannot image through air (lungs and bowel loops) or bone. ❑ The first ultrasound images (2D), however now 3D reconstructions can be observed in real time, effectively becoming "4D". MAGNETIC RESONANCE IMAGING. ❑ Magnetic field around patient ❑ The magnetic field excites hydrogen atoms in water, energized, move out of their field when magnet on ❑ Gives off a signal when magnet off and hydrogen atom returns. ❑ The contrast between different tissues signals when the magnet switches on or off gives different quality signals and that is processed to for man image. ❑ Very good for distinguishing all the soft tissues in the body, from organs to ligaments and, the different densities of fluids such as water, blood, pus and infective material.