ABSTRACT
The purpose of this study was to clinically evaluate the automatic outline extraction properties using general-purpose deformable image registration (DIR) software for the head and neck region. To this end, we evaluated the following: (1) the difference between manual outline extraction carried out by a radiation therapy specialist and automatic outline extraction using the DIR software, and (2) the precision of the automatic outline extraction for the diachronic figure change and change in the organ shape. The manually-extracted outline and that extracted using the DIR software closely resembled each other at 0.70. Further, in the same case, the automatic outline extraction precision of the DIR software was greater at about 0.80. Our findings suggest DIR software to be useful for lessening the work involved in outline extraction.
Subject(s)
Head and Neck Neoplasms/diagnostic imaging , Head and Neck Neoplasms/radiotherapy , Radiographic Image Interpretation, Computer-Assisted/methods , Radiotherapy, Intensity-Modulated/methods , Software , Tomography, X-Ray Computed/methods , Aged , Humans , Middle AgedABSTRACT
In multileaf collimator (MLC)-based intensity modulated radiation therapy (IMRT), the dose is influenced by the uncertainty of MLC driving control. In this study, we examined the influence of MLC driving control accuracy on dose evaluation (gamma analysis) by evaluating 60-day MLC driving control accuracy (stationary positioning accuracy and positioning reproducibility) once a week as well as measuring IMRT dose distribution. The MLC positioning accuracy accompanied variation over time and tended to expand by 0.1 to 0.15 mm in one week and about 1 mm in 60 days. In terms of reproducibility, errors were within 0.2 mm for more than 95%. For prostate IMRT, when MLC stationary positioning accuracy was around 1 mm, no significant difference was observed in the pass rate in gamma analysis. Therefore, the results suggest that regular maintenance by setting a permissible value determined by the MLC positioning accuracy test can be an effective indicator in the future for maintaining the safety of IMRT.
Subject(s)
Radiotherapy, Intensity-Modulated/methods , Calibration , Humans , Male , Patient Positioning , Radiotherapy Dosage , Radiotherapy, Intensity-Modulated/standards , Reproducibility of ResultsABSTRACT
PURPOSE: Radiographic film is generally used for inspection of dose distribution in intensity modulated radiation therapy (IMRT) at many institutions. However, the distribution of filmless systems can be expected to be used increasingly in the future. Therefore, we confirmed the utility of radiochromic film by comparing it with radiographic film that does not need an automatic processor. RESULT: Difference in does measured by radiographic film and radiochromic film tended to increase in the low does area, but it was limited in a range of 1.5%. CONCLUSION: When the dose distribution was verified in a highly accurate radiation therapy such as IMRT, the results suggested that radiochromic film can be useful in addition to radiographic film.
