Lung dose reduction in patients with stage III non-small-cell lung cancer using software that estimates patient-specific dose reduction feasibility

Abstract

Purpose: In radiotherapy, the dose to organs-at-risk must be kept as low as possible to preserve their function. We aimed to determine the acceptable f-value upper bound of the Feasibility DVH in the PlanIQ software to achieve dose reduction to the normal lung in patients with stage III non-small cell lung cancer.

Methods: By using the Feasibility DVH, the f-values corresponding to the pulmonary dosimetric parameters of each treatment plan for 11 patients were calculated. The acceptable f-value upper bound was defined as the value that added one standard deviation of the f-value to the mean. Additionally, the treatment plan for additional fourteen patients was designed to evaluate the effectiveness of the acceptable f-value upper bound for the normal lung dose reduction. The value beyond the acceptable f-value upper bound was judged as inadequate dose reduction.

Results: The acceptable f-value upper bound was different for dosimetric parameters (range, 0.22-0.26). These values were < 0.5, which is typically used as the acceptable f-value upper bound. Evaluation by the treatment plan of fourteen patients detected that the f-value of the normal lung of five patients exceeded the acceptable f-value upper bound, and the replanning was able to reduce the dose of the normal lung.

Conclusions: We could efficiently reduce the normal-lung dose using the acceptable f-value upper bound calculated in this study and provide an effective acceptable f-value upper bound of the normal lung dose in the lung cancer radiotherapy.

Keywords: Feasibility dose volume histogram; Lung dose; Non-small-cell lung cancer; PlanIQ; Radiotherapy.