Zarghami Niloufar, Jensen Michael D, Talluri Srikanth, Foster Paula J, Chambers Ann F, Dick Frederick A, Wong Eugene
Department of Medical Biophysics, The University of Western Ontario, 1151 Richmond Street, London, Ontario N6A 3K7, Canada.
Department of Biochemistry, The University of Western Ontario, 1151 Richmond Street, London, Ontario N6A 3K7, Canada and London Regional Cancer Program, London Health Sciences Centre, 800 Commissioners Road East, London, Ontario N6A 5W9, Canada.
Med Phys. 2015 Nov;42(11):6507-13. doi: 10.1118/1.4933200.
Small animal immobilization devices facilitate positioning of animals for reproducible imaging and accurate focal radiation therapy. In this study, the authors demonstrate the use of three-dimensional (3D) printing technology to fabricate a custom-designed mouse head restraint. The authors evaluate the accuracy of this device for the purpose of mouse brain irradiation.
A mouse head holder was designed for a microCT couch using cad software and printed in an acrylic based material. Ten mice received half-brain radiation while positioned in the 3D-printed head holder. Animal placement was achieved using on-board image guidance and computerized asymmetric collimators. To evaluate the precision of beam localization for half-brain irradiation, mice were sacrificed approximately 30 min after treatment and brain sections were stained for γ-H2AX, a marker for DNA breaks. The distance and angle of the γ-H2AX radiation beam border to longitudinal fissure were measured on histological samples. Animals were monitored for any possible trauma from the device.
Visualization of the radiation beam on ex vivo brain sections with γ-H2AX immunohistochemical staining showed a sharp radiation field within the tissue. Measurements showed a mean irradiation targeting error of 0.14±0.09 mm (standard deviation). Rotation between the beam axis and mouse head was 1.2°±1.0° (standard deviation). The immobilization device was easily adjusted to accommodate different sizes of mice. No signs of trauma to the mice were observed from the use of tooth block and ear bars.
The authors designed and built a novel 3D-printed mouse head holder with many desired features for accurate and reproducible radiation targeting. The 3D printing technology was found to be practical and economical for producing a small animal imaging and radiation restraint device and allows for customization for study specific needs.
小动物固定装置有助于将动物放置在可重复成像和精确聚焦放射治疗的位置。在本研究中，作者展示了使用三维（3D）打印技术制造定制设计的小鼠头部固定器。作者评估了该装置用于小鼠脑部照射的准确性。
使用计算机辅助设计软件为微型计算机断层扫描（microCT）床设计了一个小鼠头部固定器，并使用丙烯酸基材料进行打印。十只小鼠在3D打印的头部固定器中接受半脑放射治疗。使用机载图像引导和计算机化非对称准直器实现动物放置。为了评估半脑照射时束定位的精度，在治疗后约30分钟处死小鼠，并对脑切片进行γ-H2AX染色，γ-H2AX是DNA断裂的标志物。在组织学样本上测量γ-H2AX放射束边界与大脑纵裂的距离和角度。监测动物是否受到该装置可能造成的任何创伤。
用γ-H2AX免疫组织化学染色对离体脑切片上的放射束进行可视化显示，组织内有清晰的放射野。测量显示平均照射靶向误差为0.14±0.09毫米（标准差）。束轴与小鼠头部之间的旋转角度为1.2°±1.0°（标准差）。固定装置易于调节以适应不同大小的小鼠。未观察到使用牙垫和耳棒对小鼠造成创伤的迹象。
作者设计并制造了一种新型的3D打印小鼠头部固定器，具有许多理想的特性，可实现准确且可重复的放射靶向。发现3D打印技术对于生产小动物成像和放射固定装置既实用又经济，并且可以根据研究的特定需求进行定制。
