Altschuler M D, Findlay P A, Epperson R D
Phys Med Biol. 1983 Nov;28(11):1305-18. doi: 10.1088/0031-9155/28/11/010.
The three-dimensional (3D) locations of the radioactive seeds in an interstitial implant can be obtained from stereo-shift or orthogonal radiographs. When an implant contains a large number of seeds, however, there are often ambiguities in identifying corresponding seed images on two radiographs. Our method achieves accurate spatial locations by using three radiographs whose x-ray source positions are (i) in a plane which does not intersect the implant and (ii) widely separated to achieve adequate parallax. All triangulation is done in an anatomical coordinate reference frame attached to the patient so that patient motion does not introduce errors. We achieve independent error-insensitive calibration of each radiograph, rapid and accurate data entry in the local coordinates of each radiograph, 3D seed location in the patient (anatomical) reference frame, and automatic verification of each calculation.
间质植入物中放射性籽源的三维（3D）位置可从立体移位或正交射线照片中获取。然而，当植入物包含大量籽源时，在两张射线照片上识别相应的籽源图像常常存在模糊性。我们的方法通过使用三张射线照片来实现精确的空间定位，其中X射线源位置（i）位于不与植入物相交的平面内，且（ii）相距较远以获得足够的视差。所有三角测量均在附着于患者的解剖坐标参考系中进行，这样患者的运动就不会引入误差。我们实现了每张射线照片的独立误差不敏感校准、在每张射线照片的局部坐标中快速准确的数据输入、患者（解剖）参考系中的3D籽源定位以及对每次计算的自动验证。
