pneumothorax, interstitial lung disease, heart failure, bone fracture and hiatal hernia. typically an erect postero-anterior (pa) projection is the preferred projection. chest radiographs are also used to screen for job-related lung disease in industries such as mining where workers are exposed to dust. for some conditions of the chest, radiography is good for screening but poor for diagnosis. when a condition is suspected based on chest radiography, additional imaging of the chest can be obtained to definitively diagnose the condition or to provide evidence in favor of the diagnosis suggested by initial chest radiography. unless a fractured rib is suspected of being displaced, and therefore likely to cause damage to the lungs and other tissue structures, x-ray of the chest is not necessary as it will not alter patient management. abdomen main article: abdominal x-ray abdominal radiograph. in children, abdominal radiography is indicated in the acute setting in suspected bowel obstruction, gastrointestinal perforation, foreign body in the alimentary tract, suspected abdominal mass and intussusception (latter as part of the differential diagnosis). yet, ct scan is the best alternative for diagnosing intra-abdominal injury in children. for acute abdominal pain in adults, an abdominal x-ray has a low sensitivity and accuracy in general. computed tomography provides an overall better surgical strategy planning, and possibly less unnecessary laparotomies. abdominal x-ray is therefore not recommended for adults presenting in the emergency department with acute abdominal pain. the standard abdominal x-ray protocol is usually a single anteroposterior projection in supine position. a kidneys, ureters, and bladder projection (kub) is an anteroposterior abdominal projection that covers the levels of the urinary system, but does not necessarily include the diaphragm. head cerebral angiography allows visualization of blood vessels in and around the brain. a contrast agent is injected prior to the radiographs of the head, orbital radiography, imaging both left and right eye sockets, generally including the frontal and maxillary sinuses. dental radiography uses a small radiation dose with high penetration to view teeth, which are relatively dense. a dentist may examine a painful tooth and gum using x-ray equipment. the machines used are typically single-phase pulsating dc, the oldest and simplest sort. dental technicians or the dentist may run these machines; radiographers are not required by law to be present. a derivative technique from projectional radiography used in dental radiography is orthopantomography. this is a panoramic imaging technique of the upper and lower jaw using focal plane tomography, where the x-ray generator and x-ray detector are simultaneously moved so as to keep a consistent exposure of only the plane of interest during image acquisition. sinus - the standard protocol in the uk is om with open mouth. facial bones - the standard protocol in the uk is om and om 30°. in case of trauma, the standard uk protocol is to have a ct scan of the skull instead of projectional radiography. a skeletal survey including the skull can be indicated in for example multiple myeloma. other axial skeleton whole-body radiograph of a major trauma case (where, however, full-body ct scan is usually preferable), showing bilateral femur fractures. the spine (that is, the vertebral column. a projectional radiograph of the spine confers an effective dose of approximately 1.5 msv, comparable to a background radiation equivalent time of 6 months. cervical spine: the standard projections in the uk ap and lateral. peg projection with trauma only. obliques and flexion and extension on special request. in the us, five or six projections are common; a lateral, two 45 degree obliques, an ap axial (cephalad), an ap "open mouth" for c1-c2, and cervicothoracic lateral (swimmer's) to better visualize c7-t1 if necessary. special projections include a lateral with flexion and extension of the cervical spine, an axial for c1-c2 (fuchs or judd method), and an ap axial (caudad) for articular pillars. thoracic spine - ap and lateral in the uk. in the us, an ap and lateral are basic projections. obliques 20 degrees from lateral may be ordered to better visualize the zygapophysial joint. lumbar spine - ap and lateral +/- l5/s1 view in the uk, with obliques and flexion and extension requests being rare. in the us, basic projections include an ap, two obliques, a lateral, and a lateral l5-s1 spot to better visualize the l5-s1 interspace. special projections are ap right and left bending, and laterals with flexion and extension. pelvis - ap only in the uk, with sij projections (prone) on special request. sacrum and coccyx: in the us, if both bones are to be examined separate cephalad and caudad ap axial projections are obtained for the sacrum and coccyx respectively as well as a single lateral of both bones. ribs: in the us, common rib projections are based on the location of the area of interest. these are obtained with shorter wavelengths/higher frequencies/higher levels of radiation than a standard cxr. anterior area of interest - a pa chest x-ray, a pa projection of the ribs, and a 45 degree anterior oblique with the non-interest side closest to the image receptor. posterior area of interest - a pa chest x-ray, an ap projection of the ribs, and a 45 degree posterior oblique with the side of interest closest to the image receptor. sternum. the standard projections in the uk are pa chest and lateral sternum. in the us, the two basic projections are a 15 to 20 degree right anterior oblique and a lateral. sternoclavicular joints - are usually ordered as a single pa and a right and left 15 degree right anterior obliques in the us. shoulders ap glenoid (grashey view). these include: ap-projection 40° posterior oblique after grashey the body has to be rotated about 30 to 45 degrees towards the shoulder to be imaged, and the standing or sitting patient lets the arm hang. this method reveals the joint gap and the vertical alignment towards the socket. transaxillary projection the arm should be abducted 80 to 100 degrees. this method reveals: the horizontal alignment of the humerus head in respect to the socket, and the lateral clavicle in respect to the acromion. lesions of the anterior and posterior socket border or of the tuberculum minus. the eventual non-closure of the acromial apophysis. the coraco-humeral interval y-projection the lateral contour of the shoulder should be positioned in front of the film in a way that the longitudinal axis of the scapula continues parallel to the path of the rays. this method reveals: the horizontal centralization of the humerus head and socket. the osseous margins of the coraco-acromial arch and hence the supraspinatus outlet canal. the shape of the acromion this projection has a low tolerance for errors and accordingly needs proper execution. the y-projection can be traced back to wijnblath's 1933 published cavitas-en-face projection. in the uk, the standard projections of the shoulder are ap and lateral scapula or axillary projection. transaxillary y-projection extremities a projectional radiograph of an extremity confers an effective dose of approximately 0.001 msv, comparable to a background radiation equivalent time of 3 hours. the standard projection protocols in the uk are: clavicle - ap and ap cranial humerus - ap and lateral elbow - ap and lateral. radial head projections available on request lateral projection anteroposterior projection left elbow by 30 degrees internal oblique projection left elbow by 30 degrees external oblique projection radius and ulna - ap and lateral wrist - dp and lateral left wrist by dorsoplantar projection lateral projection scaphoid - dp with ulna deviation, lateral, oblique and dp with 30° angulation hip joint: ap and lateral. the lauenstein projection a form of examination of the hip joint emphasizing the relationship of the femur to the acetabulum. the knee of the affected leg is flexed, and the thigh is drawn up to nearly a right angle. this is also called the frog-leg position. ap view of normal hip lauenstein projection of normal hips applications include x-ray of hip dysplasia. hand - dp and oblique left hand by dorsoplantar projection lateral projection oblique projection fingers - dp and lateral thumb - ap and lateral femur - ap and lateral knee - ap and lateral. intra condular projections on request patella - skyline projection right knee, anteroposterior right knee, lateral patella, (slightly skew) skyline tibia and fibula - ap and lateral ankle - ap/mortice and lateral ankle - frontal 15 degrees internal rotation lateral (this one a bit suboptimal by not seeing straight through the ankle joint) lateral oblique (to visualize the posterior border of the tibia) calcaneum - axial and lateral foot / toes - dorsoplantar, oblique and lateral. normal right foot by dorsoplantar projection oblique projection lateral projection certain suspected conditions require specific projections. for example, skeletal signs of rickets are seen predominantly at sites of rapid growth, including the proximal humerus, distal radius, distal femur and both the proximal and the distal tibia. therefore, a skeletal survey for rickets can be accomplished with anteroposterior radiographs of the knees, wrists, and ankles. general disease mimics radiological disease mimics are visual artifacts, normal anatomic structures or harmless variants that may simulate diseases or abnormalities. in projectional radiography, general disease mimics include jewelry, clothes and skin folds. in general medicine a disease mimic shows symptoms and/or signs like those of another. a hip fracture (black arrow) next to a skin fold (white arrow). bed sheets looking like lung opacities on a chest radiograph