Simulator verification of the accuracy of patient repositioning after virtual simulation: Is physical simulation still needed?

• Published in: Strahlentherapie und Onkologie Vol. 178; no. 12; pp. 715 - 721
• Main Authors: SCHÜLLER, Patrick, BRUNS, Frank, HESSELMANN, Stefan, HORN, Kirsten, PANKE, Joan E, SCHUCK, Andreas, SCHÄFER, Ulrich, MICKE, Oliver, WILLICH, Normann
• Format: Journal Article
• Language: English
• Published: München Springer 01-12-2002; Springer Nature B.V
• Subjects: Adult; Aged; Biological and medical sciences; Breast cancer; Calibration; Computer Simulation; Female; Fluoroscopy; Humans; Imaging, Three-Dimensional; Male; Medical sciences; Middle Aged; Neoplasms - radiotherapy; Prone Position; Radiation therapy and radiosensitizing agent; Radiotherapy Planning, Computer-Assisted; Reproducibility of Results; Software; Supine Position; Tomography, X-Ray Computed; Treatment with physical agents; Treatment. General aspects; Tumors; User-Computer Interface; Human; Radiodiagnosis; Virtual simulation; Radioscopy; Malignant tumor; Radiotherapy; Patient positioning; Accuracy; Treatment; Simulation; Medical imagery; Computerized axial tomography; Patient position
• ISSN: 0179-7158; 1439-099X
• DOI: 10.1007/s00066-002-1037-1

To evaluate the frequency and amount of displacements after repositioning a patient on the physical simulator following virtual simulation.
After laser marking at the CT scanner and virtual simulation, patients were repositioned on the simulator. The isocenter obtained from the calculated table movements was checked by fluoroscopically measuring the distances to standardized anatomic landmarks and comparing them to the treatment plan.
In 86% of patients, displacements were < or = 0.5 cm. There was no significant difference between the supine and prone position, diagnosis categories or CT reconstruction indices. The use of immobilization devices and cranial versus body stem localization did make a significant difference. Rates of exact repositioning were high in brain and head and neck patients and comparatively low in abdominal tumors and breast cancer.
Immobilization devices play an important role for the precision of radiotherapy. Whenever precise positioning is possible (e. g. with a head mask), virtual simulation alone might be sufficient. Patients with abdominal and breast tumors, were repositioning precision is often suboptimal, might profit from an additional physical simulation.