Pakbaznejad Esmaeili Elmira, Hurmerinta Kirsti, Rice David, Suomalainen Anni
1 Department of Radiology, University of Helsinki and HUS Radiology (Medical Imaging Center), Helsinki, Finland.
2 Oral Radiology, Department of Oral and Maxillofacial Diseases, University of Helsinki, Helsinki, Finland.
Dentomaxillofac Radiol. 2016;45(3):20150341. doi: 10.1259/dmfr.20150341. Epub 2016 Feb 3.
Lateral cephalometric radiography is a common radiographic examination technique in children. The exclusion of the thyroid gland from the primary X-ray beam is important especially with children. However, patient treatment might require displaying the four most cranial cervical vertebrae (C1-C4) for the assessment of cervical vertebral maturation. Our aim was to present a safe way to display C1-C4 and exclude the thyroid gland from the X-ray beam during lateral cephalometric radiography.
The thyroid glands of 25, 7- to 12-year-old patients were localized by ultrasound examination and shielded prior to lateral cephalometric radiography. A roentgen-positive mark was taped on the patient's skin at the level of most cranial level of the thyroid gland in the midsagittal plane. After exposure, each lateral cephalometric radiograph (LCR) was analyzed for the visibility of the cervical vertebrae. The distance between the ear post and the highest edge of the thyroid shield (TS) at the lateral part of the neck was measured and compared with the distance between the centre of the radiological external auditory meatus, and a roentgen-positive mark was made on the LCR.
68% of the LCRs displayed C1-C4, and the rest of them displayed C1-C3. In all of the patients, the highest edge of the TS in the lateral parts of the neck was located in a higher position than the actual most cranial level of the thyroid gland.
Despite localizing the thyroid gland prior to lateral cephalometric radiography, simultaneous visualization of C1-C4 and exclusion of the thyroid gland from the primary X-ray beam during lateral cephalometric radiography might not be completely possible in children because of the design and poor fitness of the TS.
头颅侧位X线摄影是儿童常见的X线检查技术。在初次X线投照时排除甲状腺尤其对于儿童很重要。然而，患者治疗可能需要显示最靠头端的四个颈椎（C1 - C4）以评估颈椎成熟度。我们的目的是提出一种在头颅侧位X线摄影期间安全显示C1 - C4并将甲状腺排除在X线射束之外的方法。
对25名7至12岁患者的甲状腺进行超声检查定位，并在头颅侧位X线摄影前进行遮挡。在患者皮肤矢状面中甲状腺最靠头端水平处粘贴一个X线阳性标记。曝光后，分析每张头颅侧位X线片（LCR）上颈椎的可见性。测量颈部外侧耳柱与甲状腺防护装置（TS）最高边缘之间的距离，并与放射学外耳道中心之间的距离进行比较，并在LCR上做出X线阳性标记。
68%的LCR显示了C1 - C4，其余显示C1 - C3。在所有患者中，颈部外侧TS的最高边缘位于高于甲状腺实际最靠头端水平的位置。
尽管在头颅侧位X线摄影前对甲状腺进行了定位，但由于TS的设计和贴合性差，在儿童头颅侧位X线摄影期间可能无法完全同时实现C1 - C4的可视化以及将甲状腺排除在初次X线射束之外。
