![k 3d measure button k 3d measure button](https://img.alicdn.com/imgextra/i2/3816698184/O1CN01hEBe9k2AKK1ARE2tO_!!3816698184.jpg)
The tumor motion was modeled as a sinusoidal movement with varying asymmetry. The time-averaged tumor position was closer to the exhale position, because the tumor spent more time in the exhalation than in the inhalation phase. For the lateral and anterior-posterior directions, tumor motion was small both for upper- and lower-lobe tumors (2 +/- 1 mm). The average amplitude of the tumor motion was greatest (12 +/- 2 mm ) in the cranial-caudal direction for tumors situated in the lower lobes and not attached to rigid structures such as the chest wall or vertebrae. The recorded tumor motion was analyzed in terms of the amplitude and curvature of the tumor motion in three directions, the differences in breathing level during treatment, hysteresis (the difference between the inhalation and exhalation trajectory of the tumor), and the amplitude of tumor motion induced by cardiac motion. The system provided the coordinates of the gold marker during beam-on and beam-off time in all directions simultaneously, at a sample rate of 30 images per second.
![k 3d measure button k 3d measure button](https://live.staticflickr.com/5286/5353991186_3095c79980.jpg)
The linear accelerator was triggered to irradiate the tumor only when the gold marker was located within a certain volume. The 3D position of the implanted gold marker was determined by using real-time pattern recognition and a calibrated projection geometry. A real-time tumor tracking system using two fluoroscopy image processor units was installed in the treatment room. Before treatment, a 2-mm gold marker was implanted in or near the tumor. Twenty patients were included in this study. Understanding the behavior of tumor motion in lung tissue to model tumor movement is necessary for accurate (gated or breath-hold) radiotherapy or CT scanning. In this work, three-dimensional (3D) motion of lung tumors during radiotherapy in real time was investigated.