Kuhnen Saskia C, Müller Martin, Schmeling Andreas, Zech Wolf-Dieter, Klaus Jeremias B, Lombardo Paolo, Ith Michael, Egli Rainer J, Ruder Thomas D
Institute of Diagnostic, Interventional and Pediatric Radiology InselspitaI, Bern University Hospital, University of Bern, Rosenbühlgasse 27, Bern, Bern, CH-3010, Switzerland.
Department of Emergency Medicine, Bern University Hospital, InselspitaI, University of Bern, Bern, Switzerland.
Int J Legal Med. 2025 May 29. doi: 10.1007/s00414-025-03521-2.
To compare the effect of arm positioning on radiation dose, scan length, and image noise in computed tomography (CT) scans of the medial clavicular epiphysis for forensic age estimation performed with the arms alongside the body (arms-down) versus elevated above the head (arms-up).
Twenty consecutive CT scans were analysed, ten performed with arms-down and ten with arms-up. The scans were conducted at 120 kVp and 37 mAs reference tube current. Scan length extended from 10 mm above to 10 mm below the medial clavicular epiphysis. Dose-relevant parameters (effective CT tube current, volume CT dose index (CTDIvol), CT dose length product (DLP), and effective dose) as well as scan length and image noise were compared between arms-up and arms-down CT scans.
Population characteristics: 19 males, 1 female; mean weight 65.8 ± 9.2 kg; height 174.6 ± 7.8 cm; and body mass index (BMI) 21.6 ± 2.5 kg/m². Dose-relevant parameters were significantly lower with arms-up compared to arms-down (effective tube current: 80.9 ± 21.7 mAs vs. 146.0 ± 47.5 mAs, p = 0.001; CTDIvol: 5.5 ± 1.5 mGy vs. 9.9 ± 3.2 mGy, p = 0.001; DLP: 40.2 ± 13.7 mGycm vs. 63.8 ± 21.9 mGycm, p = 0.010; effective dose: 0.6 ± 0.2 mSv vs. 0.9 ± 0.3 mSv, p = 0.010). No significant differences were found in scan length, image noise, or population characteristics.
Removing the arms from the CT beam path reduced radiation dose by 33% without affecting scan length or image noise. Given the importance of dose optimisation in non-medical examinations of potentially minor individuals, CT scans of the medial clavicular epiphysis should be performed with arms elevated above the head.
比较在法医年龄估计的锁骨内侧骨骺计算机断层扫描（CT）中，手臂置于身体两侧（手臂下垂）与举过头顶（手臂上举）时，手臂位置对辐射剂量、扫描长度和图像噪声的影响。
分析连续20例CT扫描，其中10例手臂下垂，10例手臂上举。扫描在120 kVp和37 mAs参考管电流下进行。扫描长度从锁骨内侧骨骺上方10 mm延伸至下方10 mm。比较手臂上举和手臂下垂CT扫描之间的剂量相关参数（有效CT管电流、容积CT剂量指数（CTDIvol）、CT剂量长度乘积（DLP）和有效剂量）以及扫描长度和图像噪声。
人群特征：19名男性，1名女性；平均体重65.8±9.2 kg；身高174.6±7.8 cm；体重指数（BMI）21.6±2.5 kg/m²。与手臂下垂相比，手臂上举时剂量相关参数显著更低（有效管电流：80.9±21.7 mAs对146.0±47.5 mAs，p = 0.001；CTDIvol：5.5±1.5 mGy对9.9±3.2 mGy，p = 0.001；DLP：40.2±13.7 mGycm对63.8±21.9 mGycm，p = 0.010；有效剂量：0.6±0.2 mSv对0.9±0.3 mSv，p = 0.010）。扫描长度、图像噪声或人群特征方面未发现显著差异。
将手臂移出CT光束路径可使辐射剂量降低33%，且不影响扫描长度或图像噪声。鉴于在对潜在未成年人进行非医学检查时剂量优化的重要性，锁骨内侧骨骺的CT扫描应在手臂举过头顶的情况下进行。
