Rybicki Frank, Nawfel Richard D, Judy Philip F, Ledbetter Stephen, Dyson Rebecca L, Halt Peter S, Shu Kirstin M, Nuñez Diego B
Department of Radiology, Brigham and Women's Hospital, 75 Francis St., Boston, MA 02115, USA.
AJR Am J Roentgenol. 2002 Oct;179(4):933-7. doi: 10.2214/ajr.179.4.1790933.
The first objective of this study was to test the hypothesis that estimates of radiation dose from an ionization chamber correspond to thermoluminescent dosimeter measurements in patients with suspected cervical spine injury. The second objective was to compare the radiation dose of a protocol using helical CT of the entire cervical spine with that of a protocol using radiography alone.
Thermoluminescent dosimeter measurements of radiation dose to the skin over the thyroid were made in two patient groups: six patients evaluated with CT of the cervical spine and six patients evaluated with radiography. The skin dose for both groups was estimated with an ionization chamber, and the thermoluminescent dosimeter measurements and ionization chamber estimates of skin dose were compared for both groups. Using the ionization chamber, we estimated the radiation dose to the thyroid for all 12 patients. With these estimates, we computed the ratios of skin dose and thyroid dose (CT / radiography).
Thermoluminescent dosimeter measurements correlated with ionization chamber estimates of skin dose in both patient groups. Using the ionization chamber estimates, we found that CT delivered 26.0 mGy to the thyroid. In the patients evaluated with radiography, the mean thyroid dose was 1.80 mGy (95% confidence interval, 1.05-2.55 mGy). Ionization chamber dose ratios (CT / radiography) for the skin and thyroid were 9.69 and 14.4 mGy, respectively.
The correlation between the ionization chamber estimates and the thermoluminescent dosimeter measurements supports the use of ionization chamber estimates in future research. Although helical CT of the entire cervical spine is cost-effective in patients at high risk for fracture, the greater than 14-fold increase in the radiation dose to the thyroid emphasizes the importance of clinical stratification to identify patients at high risk for fracture and the judicious use of CT in patients with suspected cervical spine injury.
本研究的首要目的是检验以下假设：对于疑似颈椎损伤的患者，电离室测得的辐射剂量估计值与热释光剂量计测量值相符。第二个目的是比较使用全颈椎螺旋CT方案与仅使用X线摄影方案的辐射剂量。
对两组患者进行甲状腺上方皮肤辐射剂量的热释光剂量计测量：6例接受颈椎CT检查的患者和6例接受X线摄影检查的患者。两组的皮肤剂量均用电离室进行估计，并比较两组热释光剂量计测量值与电离室估计的皮肤剂量。我们用电离室估计了所有12例患者的甲状腺辐射剂量。根据这些估计值，我们计算了皮肤剂量与甲状腺剂量的比值（CT/ X线摄影）。
两组患者热释光剂量计测量值均与电离室估计的皮肤剂量相关。根据电离室估计值，我们发现CT对甲状腺的辐射剂量为26.0 mGy。在接受X线摄影检查的患者中，甲状腺平均剂量为1.80 mGy（95%置信区间，1.05 - 2.55 mGy）。皮肤和甲状腺的电离室剂量比值（CT/ X线摄影）分别为9.69和14.4 mGy。
电离室估计值与热释光剂量计测量值之间的相关性支持在未来研究中使用电离室估计值。尽管全颈椎螺旋CT对骨折高危患者具有成本效益，但甲状腺辐射剂量增加超过14倍强调了临床分层以识别骨折高危患者的重要性，以及在疑似颈椎损伤患者中明智使用CT的重要性。
