520

TECHNICAL NOTES

done by altering the speed of the rotating film holder independently of the x-ray-tube travel: the faster the rotation, the wider the arch of the focal layer. This modification made it convenient to observe other structures. For example, the lateral mass of the cervical spine is pictured easily in the same position as for intervertebral foramina by speeding up the rotation of the film holder (Fig. 4) due to its more lateral location. Work-up of patients with trauma to the lateral mass may be possible with further refinement of the unit (5); and this can be also applied to imaging of the hypoglossal canal (Fig. 5). The estimated radiation exposure dose to various portions in orthopantomography is low enough for practical use. The eyes received less than 10 mR from a single exposure in our experimental study using a thermoluminescent dosimeter. To decrease the exposure dose further, the central unwanted portion of the exposure could be interrupted (2); however, this could obscure the anatomical details of the vertebral body. In conclusion, we would say on the basis of our clinical experience that orthopantomography is best applied to outlining the lateral vertebral

August 1977

mass or intervertebral foramina in patients with cervical spondylosis. REFERENCES 1. Christensen EE, Curry TS III, Nunnally JE: An Introduction to the Physics of Diagnostic Radiology. Philadelphia, Lea and Febiger, 1972, pp 196-212 2. Greig JH, MusaphFW: A method of radiological demonstration of the temporomandibular joints using the orthopantomograph. Radiology 106:307-310, Feb 1973 3. Jaffe C, Webster EW: Radiographic contrast improvement by means of slit radiography. Radiology 116:631-635, Sep 1975 4. Paatero YV: A new tomographical method for radiographing curved outer surfaces. Acta Radiol 32: 177-184, 1949 5. Smith RG, Abel MS: Visualizationof the posterolateralelements of the upper cervical vertebrae in the anteroposterior projection. Radiology 115:219-220, Apr 1975

1 From the Department of Radiology, Jichi Medical School, Minamikawachi-Machi, Tochigi Pref., Japan 329-04. Accepted for publication in June 1976. sjh

Cervical Spine Lateral Horizontal Beam Technique 1 Richard F. Tenney, M.D., and Ernest S. Kerekes, M.D. Two techniques are suggested for satisfactory horizontal beam laterals in the operating room for fusion level localization: (a) the prone cervical myelographic lateral in which a modification is suggested for the "swimmer's" position; and (b) patient supine with a 15 X 3Q-cmrolled sheet placed under the occiput and/or midline upper dorsal spine, which enables the shoulders to drop to the table, clearing the low cervical spine. INDEX TERMS: (Cervical spine, other special projections, 3[1].1259). Myelography, technique. Spine, radiography Radiology 124:520, August 1977

Fig. 1.

Prone cervical myelographic lateral.

Previously, horizontal beam-laterals in the operating room for fusion-level localization were usually unsatisfactory in the low cervical area, as the shoulders interfere. PRONE CERVICAL MYELOGRAPHIC LATERAL This is a substitute for "swimmer's" position. When controls are set for the horizontal beam lateral, the patient is instructed to place hands palms down under each shoulder, then roll the shoulder blades together in back like a soldier at attention (Fig. 1). SUPINE CERVICAL SPINE Roll a sheet into a firm 15 X 30-cm tube, tape to prevent unravelling and place it under the occiput and/or midline upper cervical and dorsal spine. The shoulders drop to the table, clearing the low cervical area. Caudad arm traction may give further improvement. In either the emergency room or x-ray department, after sandbag head immobilization, the "roll" can be tried under the stretcher; usually, there is enough "sag" to clear both stretcher side arms, and shoulders. If not, angle the primary beam slightly

Fig. 2.

Supine cervical spine.

caudad, skipping the top of the "near" shoulder (Fig. 2).

1 From the Departments of Neurosurgery and Radiology, St. John's Hospital, 1923 South Utica Avenue, Tulsa, Okla. 74104. Accepted for shan publication in May 1976.

Cervical spine lateral horizontal beam technique.

520 TECHNICAL NOTES done by altering the speed of the rotating film holder independently of the x-ray-tube travel: the faster the rotation, the wide...
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