Introduction to Radiology PDF

Introduction to Radiology Radiology  The use of imaging to make diagnoses and guide treatment.  Diagnostic Imaging – Radiographs, Ultrasound, CT, MRI, nuclear medicine. X-rays  Form of radiation which involves the transfer of energy or energetic particles from one place to another.  Ionizing rad...

Introduction to Radiology Radiology  The use of imaging to make diagnoses and guide treatment.  Diagnostic Imaging – Radiographs, Ultrasound, CT, MRI, nuclear medicine. X-rays  Form of radiation which involves the transfer of energy or energetic particles from one place to another.  Ionizing radiation – energy that causes electrons to leave an atom, thus creating ions. PROPERTIES OF X-RAYS OR PHOTONS  Travel at the speed of light.  Cannot be refracted or reflected like light.  No electrical charge and remain unaffected by magnetic or electrical fields.  Travel in a straight line.  Can penetrate matter to some degree.  Can cause florescence.  Can interact with photogenic emulsion.  Can cause ionization  Cannot be felt  Invisible. Hazards of Radiation  Sufficient energy can be transferred to living tissue and cause ions to be created within those tissues.  Changes in molecular structure.  Changes in cells.  Loss of cell function or abnormal cell function.  Genetic or somatic abnormalities: mutations, cataracts and leukemia/cancer, death. Hazards of Radiation  Cell Sensitivity  Most sensitive cells are ones that have a high division rate.  Gonads and embryonic tissue:  Damaged sperm and eggs can carry on defects to the next generation.  1st trimester: embryonic death, congenital abnormalities or growth defects. SHIELDING  Use of personal shielding: lead or lead equivalent impregnated clothing  Lead aprons and gloves – 0.5 mm Pb equivalent  Thyroid shields – 0.25 mm or 0.5 mm Pb equivalent  Eye glasses – 0.75 mm Pb equivalent SHIELDING  The use of structural shielding such as screens and lead impregnated doors and walls. Image Formation  Black – all the x-rays hit the receiver (digital plate or cassette and film).  White – all the x-rays have been absorbed by the patient.  Various shades of gray – some x-rays hit the receiver, some absorbed by the patient. RADIOPACITIES Normal abdomen Metal opacity – all x-rays are absorbed by the metal Water/soft tissue opacity – some x-rays absorbed Air opacityall x-rays in contact with the plate Mineral/bone opacity –most x-rays absorbed Fat opacity – some x-rays absorbed Radiopacity vs Radiolucency  Radiopacity – relative inability of structures to be penetrated by xrays. Metals of high atomic number prevent x-ray penetration.  Radiolucency – describes substances that are of low atomic number that allow x-rays to penetrate them leaving darkened images on the radiographs. Air is the most radiolucent substance on the radiograph. Radiographic opacities  These opacities are not tied to specific structures.  Thickness plays a role in the appearance of tissues. Os penis superimposed over the right wing of the ilium. Naming the views  The radiographic views are named for the direction of the primary beam.  The name starts with the point of entry followed by the point of exit of the primary beam.  Ventrodorsal view of the thorax – the patient is in dorsal recumbency, the beam enters the ventral portion and exits via the dorsum.  Right lateral view of the thorax – the patient is right lateral recumbency, lying down on the right side. True name – Left to right lateral view. Naming the views Dorsoventral view of the thorax Right lateral thorax Descending aorta Right crus of diaphragm Left crus of diaphragm Trachea Left pulmonary artery Left pulmonary vein Right pulmonary artery Right pulmonary vein Caudal vena cava Ventrodorsal thorax Left cranial pulmonary vein Left cranial bronchus Tracheal bifurcation Cranial mediastinum Left cranial pulmonary artery Cardiac silhouette Right lateral abdomen Decsending colon Urinary bladder Ventral liver Spleen Loops of small intestines Ventrodorsal abdomen Liver Pylorus of stomach Air in the descending duodenum Fundus of the stomach Head of the spleen Left kidney Descending colon The views  Radiographs are named by the direction through which the photons transverse the patient. Dorsal Lateral Medial Palmar Dorsopalmar radiograph of the carpus