Correction of Patient Positioning Errors based on In-Line Cone Beam CTs: Clinical Implementation and First Experiences

Evaluation of the Geometric Accuracy of Anatomic Landmarks as Surrogates for Intrapulmonary Tumors in Image-guided Radiotherapy

“…It is commonly accepted that automated registration should be followed by manual verification of the visible tumors to determine if the target position is consistent with the planning target volume (PTV). In cases where the target is outside the PTV, manual adjustments are made to avoid a mismatch (Thilmann et al, 2006;Bissonnette et al, 2009;Higgins et al, 2009;Chen et al, 2011), however, some confusion still exists in the practice of employing manual registration of the planning CT and online volumetric images of lung tumors. First, if the tumor is round or oval and large, the tumors in adjacent slices will also be similar, making manual slice-to-slice matching very difficult.…”

Investigation and Application of High Megavoltage X-Ray Imaging Mode in Radiotherapy

“…From above theories and formulas, Figure 2 illustrates region distribution of relative predominate with the three main forms of photon interaction with matter corresponding to the function of photon energy and atomic number [11]. The relationship between the mass attenuation coefficient and the photon energy are shown in Figure 3 [12].…”

Patient Alignment Estimation in Six Degrees of Freedom Using a CT-scan and a Single X-ray Image

“…Tracking external markers or patient fixation does not suffice the setup precision requirements. It is common practice in image guided radiotherapy to align patients manually in the device by visual evaluation of X-ray images and digital reconstructed radiographs (DRRs) to estimate misalignments [2]. The CT data recorded during the treatment planning serves as reference position of the relevant body part.…”