Radiology in anatomy brief detailed ppt.pptx

Radiology

1. Radiology Dr. Rajesh Pradhan

2. PRINCIPLES OF RADIOGRAPHY Ability to  create  to the electromagnetic radiation at the wavelength required Ability to  focus  the radiation on a particular area Ability to  detect  the radiation once it has passed through the patient Positioning the patient Detecting the type of radiographic tool required. I nterpretation of through radiograph.

3. Classifications X-ray Computed tomography (CT) Magnetic resonance imaging (MRI) Ultrasonography (USG) Mammography

4. X-ray X-rays or electromagnetic waves: These waves pass through the person’s body, with some rays being absorbed by the tissues and others reaching the radiographic film behind. Thus creating a 2 dimensional (flat) image called a radiograph. Dense tissues (bone) will absorb most of the rays and come out on the radiograph as white, while air doesn’t block any rays and comes out as black.

5. CT scan Computed tomography (CT) , earlier referred to as computed axial tomography (CAT), is another non-invasive imaging procedure. CT works by using x-rays too but the machine is more advanced. It rotates around a stationary person creating multiple cross-sectional images, which can then be rendered into a 3D image. This gives us a cross-sectional slice of the specific body region. As CT uses x-rays, the image also depends on tissue density. Density is expressed in  Hounsfield unit (HUs) , which spans from +1000 for bones (bright), 0 for water (gray), to -1000 for air (dark). Every tissue in the body has its normal density familiar to radiologists.

6. MRI MRI is an imaging modality that, besides anatomy, can also show physiological processes in the body MRI works by using magnetic fields and radiofrequency pulses to excite protons (hydrogen ions) in our body. Excited hydrogen ions emit signals toward the MRI scanner which, based on the intensity of the signal, creates a gray-scale image. As we’re made mostly of fat and water, there’s plenty of hydrogen to detect. The density of these protons in our tissues is related to signal magnitude, i.e. increased density = increased signal. High signal intensity is shown as white, intermediate signal intensity as gray and low signal intensity as black. When a structure is brighter than it should be, we say it’s hyperintense. If it’s darker, then it’s hypointense. Proton density is increased in some types of lesions; edema, infection, inflammation, demyelination, hemorrhage, some tumors and cysts, and decreased in other types of lesions; scar tissue, calcification, some tumours , capsule and membrane formation

7. Ultrasonography Ultrasonography uses high frequency sound waves emitted from a transducer through a person's skin. These sounds echo from the contours of the inner body structures bouncing back to the transducer, which then translates them into a pixelated image displayed on the connected monitor. The density of the tissues here defines how echogenic they are, meaning what amount of sound will they resonate back (echo) or pass through themselves. Very solid tissues (bones) are  hyperechoic  and are shown as white, loose structures are  hypoechoic  and shown gray, while fluid is  anechoic  and is shown as black.

8. PET Scan Nuclear medicine imaging is used to visualize the function rather than the structure of specific body parts. A radiopharmaceutical (radioactive pharmaceutical) is administered to the patient (intravenously) and images are created of the passage, accumulation or excretion of that product. This provides information on the function of the organ/s in question. One common nuclear medicine imaging technique is positron emission tomography (PET) scan. PET can be used for functional examination of basically every body system - skeletal, cardiovascular, nervous, endocrine.

9. X-ray radiography An imaging technique which uses beams of electromagnetic waves (x-rays) to produce radiographs that depict the tissues in two dimensions based on their density. Commonly used for assessment of chest, abdominal and skeletal anatomy. Computed tomography (CT) An imaging technique which uses X-ray beams to produce images that depict the tissues in two and three dimensions based on their density. Commonly used for assessment of musculoskeletal system, parenchyma of solid organs, distribution of body fluids. Magnetic resonance imaging (MRI) An imaging technique which uses radio-waves and magnetic fields to produce images based on the tissue’s proton (hydrogen) levels. Commonly used for examination of soft and nervous tissues. Ultrasonography (U/S) An imaging method which uses high frequency sound waves to depict tissues based on their density. Wide array of indications (e.g. Doppler U/S, breast U/S, obstetric U/S) Nuclear medicine Spectrum of imaging methods used for examining the function of specific body parts by using gamma-radiation emitting radiopharmaceuticals (radioactive pharmaceuticals) Common method: PET scan 

10. Factor CT (CT abdo used as example) MRI X-ray (CXR used as example) Ultrasound Duration 3-7 minutes 30-45 min 2-3 min 5-10 minutes Cost Cheaper Expensive Cheap Cheap Dimensions 3 3 2 2 Soft  tissue Poor detail Excellent detail Poor detail Poor detail Bone Excellent detail Poor detail Excellent detail Poor detail

11. Mammography Mammography (also called mastography :) is the process of using low-energy X-rays to examine the human breast for diagnosis and screening. The goal of mammography is the early detection of breast cancer, typically through detection of characteristic masses or microcalcifications.