Publications by authors named "Shiro Nishiyama"
We have proposed a method for patient-specific dose-volume histogram (DVH) verification using a 40-ms high-sampling-rate log file (HLF) available in an Elekta linac. Ten prostate volumetric-modulated arc therapy plans were randomly selected, and systematic leaf position errors of ±0.2, ±0.
View Article and Find Full Text PDFIn this study, we implemented a practical dosimetry procedure of air kerma for kilovoltage X-ray beams using a 0.6-cc cylindrical ionization chamber, and validated the procedure with the accuracy of the measurements using the 0.6-cc chamber compared to the measurements using a 6-cc chamber and a semiconductor device.
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- A multi-institutional study was conducted to confirm the feasibility of using 3-5% action levels for independent monitor unit (MU) verification across 12 institutions, analyzing a total of 5936 fields.
- The results showed that the mean verification difference was 1.0 ± 3.6%, but larger discrepancies were noted specifically in breast and lung treatments, highlighting the need for careful analysis.
- It concluded that while the 5% action level is usable, clinicians must pay attention to the significant variations found in breast and lung treatment plans, especially related to field shape and reference point placements.
Article Synopsis
- * Researchers conducted a multi-institutional investigation into the precision of independent dose verifications using a wedge off-axis calculation and found improved agreement with treatment planning systems.
- * Results indicated that using the wedge off-axis calculation led to better confidence limits (around 2% for both physical and non-physical wedges) compared to over 5% without it, suggesting a tolerance level of 5% for these plans similar to conventional techniques.
An add-on micro multi-leaf collimator (mMLC) is used for stereotactic radiosurgery (SRS) and brain stereotactic radiotherapy (SRT), in which rotational radiotherapy may make more complex and time-consuming. We performed a retrospective study of an independent dose calculation verification for brain SRS and SRT in two institutions to show the accuracy of the verification system and propose a tolerance value for the verification. Several comparisons of static plans and patients' plans were conducted using a phantom measurement, and patients' plans using the patients' own computed tomography image.
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