1、1 COURSE RAD331The SkullLayout and design by A Musa, Department of Radiological Sciences, Faculty of Applied Medical Sciences, King Saud University, Riyadh, Copyright 2003 A Musa12 TECHNICAL ASPECTS Sitting erect positions are preferred to exclude any air-fluid levels within the cranial cavities or

2、sinuses. Patient comfort 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 non-repeats helps in minim

3、izing 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 Occipital-frontal) projection B3For frontal bone, #s and neoplastic processes of the cranium, Pagets disease,

4、orbits (obscured by petrous temporals), I.A.M, 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 cmCP: Exits the gla

5、bellaCR: 0 (that is 90) to film centerNB/ AP is not recommended as it produces 200 times eyes absorbed dose produced in the PA position.PA (or PA Axial) Skull (for mandible ) B4Best for the body of mandible for #s, inflammatory and neoplastic processes. PA axial well shows rami and elongated view of

6、 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 cmCR: 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 fac

7、ial bones B5For #s, neoplastic processes of frontal, parietal and facial bones, and for cranium and an unobstructed view of the orbits, I.A.M, frontal and ethmoidal sinuses, clinoids, dorsum sellae, zygomatic bones.Same position as for PAFilm: HD 24x30 cmCP: Exits the naison.CR: 15 caudal (for showi

8、ng the petrous ridges). 25 - 30 gives better view of orbital rim and floors and superior orbital fissure. PA Axial Skull (Haas projection ) B7An alternate projection for the Townes view if the patient cannot flex his neck sufficiently for the reverse (counter) Towne projection. It shows occipital bo

9、ne, petrous pyramids, the foramen magnum, and the posterior clinoids of the sella turcica, and results in reduced doses to facial structures and to the thyroid. It is not recommended, however, for the occipital bone because of the magnification it produces. Same position as for PAFilm: HD 24x30 cmCP

10、: Exits the glabella.CR: 25 cephalic.AP Axial (Townes projection) B8For occipital bone, cranial #s, neoplasms, and Pagets disease. Also for AP dorsum sellae, and advanced pathology of the temporal bone (advanced acoustic neuroma), anterior clinoids, foramen magnum, mastoids, foramen magnum.Patient s

11、upine, or in erect AP sitting, chin is depressed (OML 90 to film), no rotation of the headFilm: HD 24x30 cmCP: 6 cm above the glabella (2 cm superior to level of EAMs).CR: 30 caudal (30 caudal for the posterior clinoids).AP Axial (Townes projection for mandible) B10For #s, neoplastic or inflammatory

12、 processes of the condyloid processes of the mandible. Same position as for Towne AP (OML 90 to couch top. Film: HD 18x24 cmCP: Glabella (midway between EAMs and angles of the mandible). A CP at one inch anterior to level of TMJs will show TMJs.CR: 35- 40 caudal to RBL . Lateral Skull (general) B11S

13、ame indication as for PA (0). A horizontal beam is used for trauma cases to show air-fluid levels in the sphenoid sinus (a sign of # in the base of skull with internal bleeding) with CR 25-30 caudad Clark! Patient in a semiprone (Sims position), recumbent or erect sitting, head in a true lateral (re

14、quired side close to the film), MSP parallel to couch, IPL 90 to couch top. Film: HD 18x24 cmCP: 5 cm superior to EAM .CR: 90 to film center .Lateral Skull (for lateral Sella Turcica) BTo show evidence of pituitary adenomas. Same position as for the lateral skull (as in Sims position), IOML 90 to co

15、uch top. Film: HD 18x24 cmCP: 2 cm anterior and 2 cm superior to EAM.CR: 90 to film centerNB/ (1) Both laterals may be done with stress on macroradiography. (2) A long narrow (slender) cone should be used.12Lateral Skull (for nasal bones) BFor nasal bone fractures. Head in true lateral (same positio

16、n as for lateral skull as in Sims position) or erect, chin adjusted so that both IPL and IOML are 90 to couch top. Film: HD 18x24 cmCP: 1.25 cm inferior to naisonCR: 90 to film centerNB/ A long narrow cone should be used.14Lateral Skull (for sinuses) BFor inflammatory conditions: Secondary osteomyel

17、itis, sinusitis, and sinus polyps (good for sphenoid, frontal, ethmoid, and maxillary sinuses).Patient erect sitting, head in true lateral (IPL 90 to film) Film: HD 18x24 cmCP: Midway between outer canthus and EAMCR: 90 horizontal to film center15Lateral 15 (Modified Law for TMJs) SFor advanced bony

18、 pathology of the mastoid process.Patient prone or erect, head in lateral, IPL 90 to film, face ( and MSP) then rotated 15 toward the film. Film: HD 18x24 cmCP: 4 cm superior to upside EAMCR: 15 caudal to pass through the downside TMJ.17Axiolateral (Schller for mastoids) SFor advanced bony pathology

19、 of the mastoid air cells. Patient prone or erect, head in the true lateral, IPL 90 to film, MSP parallel to the film.Film: HD 18x24 cmCP: downside mastoid tip (4 cm superior, 4 cm posterior to upside EAM).CR: 25 - 30 caudal.18Axioanterior Oblique (Stenvers for mastoids) BFor advanced pathology of t

20、emporal bone, e.g., acoustic neuroma. Both sides are to be examined. Patient prone or erect, IOML 90 to film, chin adjusted so that head is rotated 45 oblique with the couch, side of interest down, downside mastoid region centered to film. Film: HD 18x24 cmCP: 7 10 cm posterior, and 1.25 cm inferior

21、 to upside EAM to exit through downside mastoid process.CR: 12 cephalic.19Axiolateral Oblique (Modified Law for mastoids) BFor advanced pathology of mastoids. Patient prone or erect, each auricle taped forward, head in lateral, then rotated 15 oblique toward the film, IPL 90 to couch, side of intere

22、st down. Film: HD 18x24 cmCP: Exit downside mastoid tip (1 inch posterior, 2.5 cm posterior, 2.5 cm superior to upside EAM).CR: 15 caudal20Tangential Superoinferior (Axial) (nasal bones) SFor fractures of the nasal bones.Patient prone or in the erect sitting, chin extended and rested on cassette, an

23、gle support under film, glabelloalvolar line (GAL) 90 to cassette, long narrow cone used Film: HD 18x24 cm (or occlusal film).CP: Naison (parallel to GAL).CR: Angle as needed to ensure CR is parallel to GAL.21Submentovertex (SMV) S22For base of the skull (Basilar view), occipital bone, mandible, for

24、amen ovale and foramen magnum, TMJs, orbits, zygomatic arches, sphenoidal, maxillary sinuses and mastoid processes.Patient supine or erect sitting, chin raised, neck hyperextended till IOML is parallel to film, MSP 90 to couch top. A pillow under patients back allows for sufficient extension.Film: H

25、D 24x30 cm.CP: Midway between angles of mandible (2 cm anterior to level of EAMs).CR: 90 to IOML.ORTHOPANTOMOGRAPHY (tomography of the mandible) S24For #s of the mandible and TM joint. Tube and film attached at starting position, chin rest raised to same level as patients chin, chin rested on a ster

26、ile bite block, patient as close as possible to the tube stand, chin adjusted until IOML is parallel with the floor, occlusal plane declines 10 from posterior to anterior, patients lips placed together, tongue on roof of the mouth.Film: HD 23x30 cm, or curved non-grid cassetteCP: Fixed CR and FFD. F

27、or TMJ, another film must be done with open mouth.Submentovertex (SMV) (for zygomatic arches) B25For #s, neoplastic, or inflammatory processes of the zygomatic arch (usually taken as a soft-tissue technique). Patient supine or erect sitting, chin raised, neck hyperextended till IOML is parallel to f

28、ilm, MSP 90 to couch top. A pillow under patients back allows for sufficient extension.Film: HD 18x24 cmCP: Midway between zygomatic arches (4 cm inferior to mandibular symphysis).CR: 90 to film.Parieto-orbital (Rhese View) for optic foramina S27For bony abnormalities of the optic foramen. Both sides must be done for comparison. Patient prone or erect, chin, cheek, and nose against couch, head adjusted so that the MSP makes 53 with the couch top, the acanthiomeata