2 How X-rays are made X-ray tube produces ionizing radiation Ionization can be damaging to tissues, especially when gonads, thyroids, and eyes are irradiatedConsider that the fetus is most radiosensitive during organogenesis (2nd-8th week) when ordering abdominal exams on femalesDifferent tissue types attenuate/absorb radiation differently (air-dark, fluid/soft tissue-gray, bone-white)
3 Chest X-rays Most frequently performed exam Provides important information about soft tissues, bones, lung tissue, pleura and mediastinumStandard patient position is PA and left lateral (both of these place heart closest to the film)Upright for air-fluid levels72” distance to reduce heart magnification
4 Normal Chest x-rays Costophrenic and cardiophrenic angles Right hemidiaphragm will be 1-2 cm higher than leftCompare lung size and radiolucencyFull inspiration – should see 10 posterior ribs with thoracic vertebrae faintly visible through mediastinumTrachea in the midline
5 Normal Chest x-rays Various soft tissue densities are present Pectoral muscles overlie and extend beyond lung fieldsBreast shadows are in mid chest region (females may overlie costophrenic angles)Nipple shadows may be visible (can do chest obliques with nipple markers to discern whether nipple or nodule)Mediastinum – heart occupies large portion – transverse diameter < ½ thorax diameter
6 Chest Pathologies Normal Chest – heart size < ½ thorax diameter Cardiomegaly with CHF – pulmonary edema around hila with hilar vessels engorged. Heart > ½ thorax diameterPneumothorax – presence of air in the pleural cavity leading to complete or partial lung collapse. Hyperradiolucent area without lung markings. Due to obstruction, penetrating trauma or spontaneous. If entire lung collapses, mediastinum may shift toward affected side.
7 Chest PathologiesAtelectasis – collapse of alveoli ->diminished air in an area of the lung. Shown as a plate-like area of increased density usually. Caused by air or fluid in the pleural space, bronchial obstruction, tumor outside lung, improper placement of ET tubeET tubes, if incorrectly placed, are likely to go into the right primary bronchus, so it blocks the left primary bronchus, causing its collapse
8 Chest PathologiesPleural effusion (fluid in the pleural cavity) or Pulmonary edema (fluid accumulation in lungs)Can be seen during upright cxr, also is shown on lateral decubitus views (a must for patients who cannot sit up or stand)EmphysemaBarrel chest, flattened diaphragm, elongated lung fields.
9 Chest Pathologies Pneumonia – Primary Lung CA – (bronchogenic carcinoma – most common primary lung malignancy in US)If you see a chest nodule:Look for old films ( > 1 yr) for comparisonLook for calcifications (calcifications generally are benign)Look for irregular marginsCT chest w/wo contrast is the next imaging step
10 Chest Pathologies Metastatic Lung CA – can have “cottonball” effect. Hyaline Membrane Disease (IRDS – idiopathic respiratory distress syndrome) – “ground glass” appearance caused by underaeration, uninflated alveoli. Lungs appear dense due to lack of airET tube should be at level of clavicle
11 Chest PathologiesHistoplasmosis – fungal infections from dust of bird droppings, seen in older, rural patientsSarcoidosis – may look similar to histoplasmosis1. perihilar density – lymph nodes enlarged2. diffuse interstitial pattern, coarse lung markings throughout both lungs, sometimes with small, larger widely scattered granulomatous nodules.
12 Chest PathologiesSilicosis – a pneumoconiosis from inhaling silica sand, leads to fibrosis
13 AbdomenKUB – taken prior to contrast exams to rule out pathology/improper exam prepSee liver, kidneys, bowel gas, abnormal masses, calcification, and foreign bodies
14 Abdomen An acute abdominal series includes: Supine KUB – “flat plate”Upright KUB – looking for intraperitoneal air and/or air/fluid levelsUpright PA chest – also looking for free airAnd is ordered for suspected acute or emergency conditions like bowel obstruction, perforations, intra-abdominal masses, situs inversus
15 Upper GIShows hiatal hernias (stomach above diaphragm), gastric ulcers (crater fills with barium)Requires patient to drink barium
16 Barium Enema/Lower GI Barium is inserted through the rectum Can shows ulcerative colitis, Crohn’s disease, colon cancer, diverticula, polyps, etc.Fewer Barium Enemas are being doneGetting colonoscopies, virtual (CT) colonoscopies
17 Small BowelPatient drinks barium – should show from duodenum all the way to terminal ileumShows Crohns disease wellMay take up to 6 hours for the barium to progress from mouth to cecum
18 IVP/IVUIodinated contrast is injected intravenously and picked up by the kidneysPatients who have compromised renal function may suffer deleterious effects from the contrastIf looking for renal calculi only, most places can perform a CT –Renal Stone protocol without using contrastCan show hydronephrosis, renal calculi, etc.VERY few of these are being done in this area
19 Bony PathologiesOsteoporosis – often an incidental finding on other examsBone metastasisMRSAFracturesColles – distal radius fx, caused by falling on an outstretched armComminuted - splintered
20 Bony Pathologies Cervical spine Lumbar spine Lateral shows alignment Should see all 7 vertebrae in lateral C-spine filmLumbar spineOsteoporosis – bone is less denseSpondylolithesis – one vertebrae slips forward on anotherBone metsMultiple myeloma
22 Sonography Pros Cons Ionizing radiation not used Relatively inexpensiveConsVisualization may be difficult withLots of bowel gasObesity/Overweight patients
23 Nuclear Medicine Pros Cons Bone scans (osteomyelitis/bony mets/occult fractures)VQ scans for PE if CT can’t be usedConsUses radioactivityInjections/oral dosing may be inconvenient
24 MammographyLess helpful with dense breast tissue (usually seen in younger women)More helpful for solid masses while breast sonography is better for cystic masses
25 CTPros – fast, shows many body parts well, not as influenced by body size as other modalitiesCons – radiation dose, obese patients may not fit through the gantry or may exceed weight limits (depends on facility – average around 400 pounds)
26 MRI Pros – great for soft tissue and detail Cons – certain patients can’t be scanned (those with certain metals, pacemakers, etc.)Claustrophobic patients may be scanned under anesthesiaLONG!Not good for areas with high motion (orbits, abdomen)
27 CT vs. MRI Most bone issues – order a CT For most joint issues (ligaments, tendons) – order MRIAbdomen and Pelvis – order a CTMS – MRIChest – CTSpines – MRI (CT okay post myelogram)Head exams – order CT unless…Tumor followup, very fine detail (pituitary) then MRI
28 Contrast Rules of thumb Very few head CTs need contrast Tumor followup, MS (although MRI is better), infections, and known mets will probably use contrastCT Soft tissue necks always use contrastChest CT – use contrast if cancer/staging (otherwise unnecessary for screening, nodules, etc)
29 Contrast Most Abd/Pelv will use oral contrast and IV contrast Renal stone protocols use NO contrastCT Spines – don’t use contrastIV contrast is the ONLY way to see vessels in CT (MRAs don’t require contrast)MRI spines – use contrast if they’ve had surgery on spine beforeIf you’re looking for an infection, use contrast
30 ContrastOral contrast takes approx 2-3 hours for complete transition if done as a work in patient before we can scan them. They drink approx 900ml of contrast. Oral contrast is used in CTEnterography is ordered to look at the small bowel and the patient has to prep at the hospital the morning of.If patients are allergic to contrast they need to be premedicated for possible reaction, recommendation of protocol to use is in the radiology department and can be asked for.If the patient has had a break through reaction (reaction after being premed) they will not receive IV contrast again.
31 Contrast infoPrep instructions are given to office at time of scheduling, rule of thumb IV contrast is NPO four hours prior minimum whether CT or MR. If oral contrast is needed some offices stock this or the patient has to go to the respective imaging department to pick this up the day before the appointment.When looking for a structure that lies within the abdominal cavity if any of that structure( such as colon) lies below the umbilicus then a Pelvis order is also needed.Can scan pelvis for bony detail only if for traumaBiggest thing is to make sure to include the diagnosis or what you’re looking for on the order so we can make sure the correct protocol is used.If venous access is issue or allergy a VQ scan(nuc med study) can be done instead of a PE study