Schulze Ralf Kurt Willy, Cremers Catrin, Karle Heiko, de Las Heras Gala Hugo
Department of Oral Surgery (and Oral Radiology), University Medical Center of the Johannes Gutenberg-University, Augustusplatz 2, 55131, Mainz, Germany.
Department of Radiation Oncology and Radiation Therapy, University Medical Center of the Johannes Gutenberg-University, Mainz, Germany.
Clin Oral Investig. 2017 May;21(4):1327-1333. doi: 10.1007/s00784-016-1886-0. Epub 2016 Jun 21.
The aim of this study was to compare the dose at skin level at five significant anatomical regions for panoramic radiography devices with and without lead apron by means of a highly sensitive dosimeter.
A female RANDO-phantom was exposed in five different digital panoramic radiography systems, and the dose at skin level was assessed tenfold for each measurement region by means of a highly sensitive solid-state-dosimeter. The five measurement regions selected were the thyroid, both female breasts, the gonads, and a central region in the back of the phantom. For each panoramic machine, the measurements were performed in two modes: with and without a commercial lead apron specifically designed for panoramic radiography. Reproducibility of the measurements was expressed by absolute differences and the coefficient of variation. Values between shielded and unshielded doses were pooled for each region and compared by means of the paired Wilcoxon tests (p ≤ 0.05).
Reproducibility as represented by the mean CV was 22 ± 52 % (median 2.3 %) with larger variations for small dose values. Doses at skin level ranged between 0.00 μGy at the gonads and 85.39 μGy at the unshielded thyroid (mean ± SD 15 ± 24 μGy). Except for the gonads, the dose in all the other regions was significantly lower (p < 0.001) when a lead apron was applied. Unshielded doses were between 1.02-fold (thyroid) and 112-fold (at the right breast) higher than those with lead apron shielding (mean: 14-fold ± 18-fold).
Although the doses were entirely very low, we observed a significant increase in dose in the radiation-sensitive female breast region when no lead apron was used. Future discussions on shielding requirements for panoramic radiography should focus on these differences in the light of the linear non-threshold (LNT) theory which is generally adopted in medical imaging.
本研究旨在通过高灵敏度剂量计，比较有铅防护衣和无铅防护衣的全景X线摄影设备在五个重要解剖区域皮肤表面的剂量。
在五个不同的数字全景X线摄影系统中对女性RANDO人体模型进行照射，并通过高灵敏度固态剂量计对每个测量区域的皮肤表面剂量进行十次评估。所选的五个测量区域为甲状腺、双侧女性乳房、性腺以及人体模型背部的中央区域。对于每台全景X线机，测量在两种模式下进行：使用专门为全景X线摄影设计的商用铅防护衣和不使用铅防护衣。测量的重复性通过绝对差值和变异系数表示。将每个区域屏蔽和未屏蔽剂量的值汇总，并通过配对Wilcoxon检验进行比较（p≤0.05）。
以平均变异系数表示的重复性为22±52%（中位数2.3%），小剂量值的变异较大。皮肤表面剂量范围在性腺处为0.00μGy至未屏蔽甲状腺处的85.39μGy之间（平均值±标准差15±24μGy）。除性腺外，使用铅防护衣时所有其他区域的剂量均显著降低（p<0.001）。未屏蔽剂量比铅防护衣屏蔽时高1.02倍（甲状腺）至112倍（右乳房）（平均值：14倍±18倍）。
尽管剂量总体非常低，但我们观察到不使用铅防护衣时，辐射敏感的女性乳房区域剂量显著增加。鉴于医学成像中普遍采用的线性无阈（LNT）理论，未来关于全景X线摄影屏蔽要求的讨论应关注这些差异。
