Mupparapu Mel, Bass Tetiana, Axline David, Felice Marc, Magill Dennise
Quintessence Int. 2020;51(6):502-509. doi: 10.3290/j.qi.a44495.
Commercial intraoral rectangular collimators are available for collimating to size 2 image receptor. The benefits of reducing the x-ray beam to match the area of the image detector in adult intraoral radiography are endorsed internationally. However, in pediatric dentistry the image receptor can be further decreased to size 1 and 0.
For this study size 1 and 0 rectangular collimators were fabricated using 1.65-mm lead sheets (Rotometals). The custom-fabricated collimators were fixed to the plastic body of a Rinn (Dentsply) Universal Collimator attachment. Aperture sizes were extrapolated based on the active imaging area of size 1 and 0 digital image receptors. A dose area product (DAP) measuring device was used to determine the change in radiation absorbed dose as a function of the imaging field of view.
DAP measurements were evaluated in the 31.7 cm2 conventional round collimation, Rinn 12.0 cm2 Universal rectangular collimator, and in the manufactured size 1 (8.25 cm2) and size 0 (5.72 cm2) rectangular collimators. The size 1 collimator had a 32% DAP reduction from the size 2, and a 53% reduction for the size 0.
Size 1 and size 0 rectangular collimators can be independently manufactured and utilized in pediatric dentistry. This study suggests that a considerable radiation dose reduction is possible in pediatric intraoral imaging when using the size 1 and 0 matched collimation. Since the pediatric population is vulnerable to radiation exposure, any measurable reduction has a potential for long-term health benefits and is therefore clinically significant.
市面上有用于口腔内成像的矩形准直器，可将X射线束准直到尺寸2的影像接收器大小。在成人口腔内放射摄影中，将X射线束缩小以匹配影像探测器面积的益处已得到国际认可。然而，在儿童牙科中，影像接收器尺寸可进一步减小至尺寸1和尺寸0。
在本研究中，使用1.65毫米铅板（Rotometals）制作尺寸1和尺寸0的矩形准直器。定制的准直器固定在Rinn（登士柏）通用准直器附件的塑料主体上。根据尺寸1和尺寸0数字影像接收器的有效成像面积推断孔径大小。使用剂量面积乘积（DAP）测量装置来确定辐射吸收剂量随视场的变化。
在31.7平方厘米的传统圆形准直、Rinn 12.0平方厘米通用矩形准直器以及制作的尺寸1（8.25平方厘米）和尺寸0（5.72平方厘米）矩形准直器中对DAP测量值进行了评估。尺寸1的准直器相比尺寸2的DAP降低了32%，尺寸0的降低了53%。
尺寸1和尺寸0的矩形准直器可以独立制作并用于儿童牙科。本研究表明，在儿童口腔内成像中使用尺寸1和尺寸0匹配的准直器可显著降低辐射剂量。由于儿童群体对辐射暴露较为敏感，任何可测量的剂量降低都可能带来长期健康益处，因此具有临床意义。
