new-skull頭顱影像學(xué)(已修改)
2025-01-24 08:35 本頁面
【正文】 1 COURSE RAD331 Layout and design by A Musa, Department of Radiological Sciences, Faculty of Applied Medical Sciences, King Saud University, Riyadh, Copyright ? 2022 A Musa 1 2 TECHNICAL ASPECTS Sitting erect positions are preferred to exclude any airfluid levels within the cranial cavities or sinuses. Patient fort and skull immobilization are necessary. Exposure factors range between 75 kVp and 85 kVp. A small focus is to be used with short times and high mA. A high lattice grid (40 lines/inch) must be used. Good collimation (Narrow cone for small parts) and nonrepeats helps in minimizing the radiation exposure to the patient. A contact shield should be used over the neck and chest to reduce the exposure to the thyroid and female breast in the AP projection. PA Skull (0? Occipitalfrontal) projection ?B 3 For frontal bone, s and neoplastic processes of the cranium, Paget’s disease, orbits (obscured by petrous temporals), , frontal and ethmoidal sinuses, dorsum sellae. Patient nose and forehead against the couch center, neck flexed so that OML is 90? to the couch, MSP 90? to couch center, head not rotated, EAMS equidistant from the couch top. Film: HD 24x30 cm CP: Exits the glabella CR: 0? (that is 90?) to film center NB/ AP is not remended as it produces 200 times eyes absorbed dose produced in the PA position. PA (or PA Axial) Skull (for mandible ) ?B 4 ?Best for the body of mandible for s, inflammatory and neoplastic processes. PA axial well shows rami and elongated view of condyloid process. ?Patient positioned as or PA (0?), chin tucked so that OML is 90? to film, MSP 90? to the couch top, head not rotated. ?Film: HD 24x30 cm ?CR: PA: 90? to film center (CP to junction of the lips). PA axial: 20? 25? cephalic (CP to the acanthion) PA Axial Skull (15? Caldwell) projection for facial bones ?B 5 For s, neoplastic processes of frontal, parietal and facial bones, and for cranium and an unobstructed view of the orbits, , frontal and ethmoidal sinuses, clinoids, dorsum sellae, zygomatic bones. Same position as for PA Film: HD 24x30 cm CP: Exits the naison. CR: 15? caudal (for showing the petrous ridges). 25? 30? gives better view of orbital rim and floors and superior orbita
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