Quantification and Assessment of Interfraction Setup Errors Based on Cone Beam CT and Determination of Safety Margins for RadiotherapyReport as inadecuate




Quantification and Assessment of Interfraction Setup Errors Based on Cone Beam CT and Determination of Safety Margins for Radiotherapy - Download this document for free, or read online. Document in PDF available to download.

Introduction

To quantify interfraction patient setup-errors for radiotherapy based on cone-beam computed tomography and suggest safety margins accordingly.

Material and Methods

Positioning vectors of pre-treatment cone-beam computed tomography for different treatment sites were collected n = 9504. For each patient group the total average and standard deviation were calculated and the overall mean, systematic and random errors as well as safety margins were determined.

Results

The systematic and random errors in the superior-inferior, left-right and anterior-posterior directions were: for prostate, 2.53.0, 2.63.9 and 2.93.9mm; for prostate bed, 1.72.0, 2.23.6 and 2.63.1mm; for cervix, 2.83.4, 2.34.6 and 3.23.9mm; for rectum, 1.63.1, 2.12.9 and 2.53.8mm; for anal, 1.73.7, 2.15.1 and 2.54.8mm; for head and neck, 1.92.3, 1.42.0 and 1.72.2mm; for brain, 1.01.5, 1.11.4 and 1.01.1mm; and for mediastinum, 3.34.6, 2.63.7 and 3.54.0mm. The CTV-to-PTV margins had the smallest value for brain 3.6, 3.7 and 3.3mm and the largest for mediastinum 11.5, 9.1 and 11.6mm. For pelvic treatments the means and standard deviations were 7.3 1.6, 8.5 0.8 and 9.6 0.8mm.

Conclusions

Systematic and random setup-errors were smaller than 5mm. The largest errors were found for organs with higher motion probability. The suggested safety margins were comparable to published values in previous but often smaller studies.



Author: Macarena Cubillos Mesías, Judit Boda-Heggemann, Johannes Thoelking, Frank Lohr, Frederik Wenz, Hansjoerg Wertz

Source: http://plos.srce.hr/



DOWNLOAD PDF




Related documents