Akyalcin S, English J, Abramovitch K, Rong J
University of Texas Health Sciences Center at Houston, School of Dentistry, Houston, TX.
MD Anderson Cancer Center, Houston, TX.
Med Phys. 2012 Jun;39(6Part4):3626. doi: 10.1118/1.4734720.
To directly measure skin dose using point-dosimeters from dental cone-beam CT (CBCT) scans. To compare the results among three different dental CBCT scanners and compare the CBCT results with those from a conventional panoramic and cephalomic dental imaging system.
A head anthropomorphic phantom was used with nanoDOT dosimeters attached to specified anatomic landmarks of selected radiosensitive tissues of interest. To ensure reliable measurement results, three dosimeters were used for each location. The phantom was scanned under various modes of operation and scan protocols for typical dental exams on three dental CBCT systems plus a conventional dental imaging system. The Landauer OSL nanoDOT dosimeters were calibrated under the same imaging condition as the head phantom scan protocols, and specifically for each of the imaging systems. Using nanoDOT dosimeters, skin doses at several positions on the surface of an adult head anthropomorphic phantom were measured for clinical dental imaging.
The measured skin doses ranged from 0.04 to 4.62mGy depending on dosimeter positions and imaging systems. The highest dose location was at the parotid surface for all three CBCT scanners. The surface doses to the locations of the eyes were ∼4.0mGy, well below the 500mGy threshold for possibly causing cataract development. The results depend on x-ray tube output (kVp and mAs) and also are sensitive to SFOV. Comparing to the conventional dental imaging system operated in panoramic and cephalometric modes, doses from all three CBCT systems were at least an order of magnitude higher. No image artifact was caused by presence of nanoDOT dosimeters in the head phantom images.
Direct measurements of skin dose using nanoDOT dosimeters provided accurate skin dose values without any image artifacts. The results of skin dose measurements serve as dose references in guiding future dose optimization efforts in dental CBCT imaging.
使用牙科锥形束CT（CBCT）扫描的点剂量计直接测量皮肤剂量。比较三种不同牙科CBCT扫描仪的结果，并将CBCT结果与传统全景和头颅牙科成像系统的结果进行比较。
使用头部仿真人体模型，将纳米DOT剂量计附着在选定的感兴趣的放射敏感组织的特定解剖标志上。为确保测量结果可靠，每个位置使用三个剂量计。在三种牙科CBCT系统以及传统牙科成像系统上，对该人体模型进行各种操作模式和扫描协议下的典型牙科检查扫描。Landauer OSL纳米DOT剂量计在与头部人体模型扫描协议相同的成像条件下进行校准，并且针对每个成像系统进行专门校准。使用纳米DOT剂量计测量成人头部仿真人体模型表面多个位置的皮肤剂量，用于临床牙科成像。
根据剂量计位置和成像系统的不同，测得的皮肤剂量范围为0.04至4.62mGy。所有三台CBCT扫描仪的最高剂量位置均在腮腺表面。眼睛位置的表面剂量约为4.0mGy，远低于可能导致白内障形成的500mGy阈值。结果取决于X射线管输出（kVp和mAs），并且对扫描野（SFOV）也很敏感。与在全景和头颅测量模式下运行的传统牙科成像系统相比，所有三台CBCT系统的剂量至少高出一个数量级。头部人体模型图像中纳米DOT剂量计的存在未引起图像伪影。
使用纳米DOT剂量计直接测量皮肤剂量可提供准确的皮肤剂量值，且无任何图像伪影。皮肤剂量测量结果可作为剂量参考，指导未来牙科CBCT成像中的剂量优化工作。
