Tsiklakis Kostas, Donta Catherine, Gavala Sophia, Karayianni Kety, Kamenopoulou Vasiliki, Hourdakis Costas J
Department of Oral Diagnosis and Oral Radiology, School of Dentistry, University of Athens, Greece.
Eur J Radiol. 2005 Dec;56(3):413-7. doi: 10.1016/j.ejrad.2005.05.011. Epub 2005 Jun 22.
(a) To measure the absorbed dose at certain anatomical sites of a RANDO phantom and to estimate the effective dose in radiographic imaging of the jaws using low dose Cone Beam computed tomography (CBCT) and (b) to compare the absorbed and the effective doses between thyroid and cervical spine shielding and non-shielding techniques.
Thermoluminescent dosimeters (TLD-100) were placed at 14 sites in a RANDO phantom, using a Cone Beam CT device (Newtom, Model QR-DVT 9000, Verona, Italy). Dosimetry was carried out applying two techniques: in the first, there was no shielding device used while in the second one, a shielding device (EUREKA!, TRIX) was applied for protection of the thyroid gland and the cervical spine. Effective dose was estimated according to ICRP(60) report (E(ICRP)). An additional estimation of the effective dose was accomplished including the doses of the salivary glands (E(SAL)). A Wilcoxon Signed Ranks Test was used for statistical analysis.
In the non-shielding technique the absorbed doses ranged from 0.16 to 1.67 mGy, while 0.32 and 1.28 mGy were the doses to the thyroid and the cervical spine, respectively. The effective dose, E(ICRP), was 0.035 mSv and the E(SAL) was 0.064 mSv. In the shielding technique, the absorbed doses ranged from 0.09 to 1.64 mGy, while 0.18 and 0.95 mGy were the respective values for the thyroid and the cervical spine. The effective dose, E(ICRP), was 0.023 mSv and E(SAL) was 0.052 mSv.
The use of CBCT for maxillofacial imaging results in a reduced absorbed and effective dose. The use of lead shielding leads to a further reduction of the absorbed doses of thyroid and cervical spine, as well as the effective dose.
(a)测量RANDO体模特定解剖部位的吸收剂量，并使用低剂量锥形束计算机断层扫描（CBCT）估计颌骨放射成像中的有效剂量；(b)比较甲状腺和颈椎屏蔽与非屏蔽技术之间的吸收剂量和有效剂量。
使用锥形束CT设备（Newtom，型号QR-DVT 9000，意大利维罗纳），将热释光剂量计（TLD-100）放置在RANDO体模的14个部位。剂量测定采用两种技术：第一种不使用屏蔽装置，第二种使用屏蔽装置（EUREKA!，TRIX）保护甲状腺和颈椎。根据国际辐射防护委员会（ICRP）第60号报告（E(ICRP)）估计有效剂量。包括唾液腺剂量（E(SAL)）在内，对有效剂量进行了额外估计。采用Wilcoxon符号秩检验进行统计分析。
在非屏蔽技术中，吸收剂量范围为0.16至1.67 mGy，而甲状腺和颈椎的剂量分别为0.32和1.28 mGy。有效剂量E(ICRP)为0.035 mSv，E(SAL)为0.064 mSv。在屏蔽技术中，吸收剂量范围为0.09至1.64 mGy，而甲状腺和颈椎的相应值分别为0.18和0.95 mGy。有效剂量E(ICRP)为0.023 mSv，E(SAL)为0.052 mSv。
使用CBCT进行颌面成像可降低吸收剂量和有效剂量。使用铅屏蔽可进一步降低甲状腺和颈椎的吸收剂量以及有效剂量。
