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"Dose of the day" based on cone beam computed tomography and deformable image registration for lung cancer radiotherapy.

ABSTRACT: PURPOSE:Adaptive radiotherapy (ART) has potential to reduce toxicity and facilitate safe dose escalation. Dose calculations with the planning CT deformed to cone beam CT (CBCT) have shown promise for estimating the "dose of the day". The purpose of this study is to investigate the "dose of the day" calculation accuracy based on CBCT and deformable image registration (DIR) for lung cancer radiotherapy. METHODS:A total of 12 lung cancer patients were identified, for which daily CBCT imaging was performed for treatment positioning. A re-planning CT (rCT) was acquired after 20 Gy for all patients. A virtual CT (vCT) was created by deforming initial planning CT (pCT) to the simulated CBCT that was generated from deforming CBCT to rCT acquired on the same day. Treatment beams from the initial plan were copied to the vCT and rCT for dose calculation. Dosimetric agreement between vCT-based and rCT-based accumulated doses was evaluated using the Bland-Altman analysis. RESULTS:Mean differences in dose-volume metrics between vCT and rCT were smaller than 1.5%, and most discrepancies fell within the range of ± 5% for the target volume, lung, esophagus, and heart. For spinal cord Dmax , a large mean difference of -5.55% was observed, which was largely attributed to very limited CBCT image quality (e.g., truncation artifacts). CONCLUSION:This study demonstrated a reasonable agreement in dose-volume metrics between dose accumulation based on vCT and rCT, with the exception for cases with poor CBCT image quality. These findings suggest potential utility of vCT for providing a reasonable estimate of the "dose of the day", and thus facilitating the process of ART for lung cancer.

SUBMITTER: Yuan Z

PROVIDER: S-EPMC6964750 | biostudies-literature | 2020 Jan

REPOSITORIES: biostudies-literature

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"Dose of the day" based on cone beam computed tomography and deformable image registration for lung cancer radiotherapy.

Yuan Zilong Z Rong Yi Y Benedict Stanley H SH Daly Megan E ME Qiu Jianfeng J Yamamoto Tokihiro T

Journal of applied clinical medical physics 20191209 1

<h4>Purpose</h4>Adaptive radiotherapy (ART) has potential to reduce toxicity and facilitate safe dose escalation. Dose calculations with the planning CT deformed to cone beam CT (CBCT) have shown promise for estimating the "dose of the day". The purpose of this study is to investigate the "dose of the day" calculation accuracy based on CBCT and deformable image registration (DIR) for lung cancer radiotherapy.<h4>Methods</h4>A total of 12 lung cancer patients were identified, for which daily CBCT ...[more]

PMID: 31816170

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Project description:BackgroundThis study aimed to quantify the dosimetric differences between the planned and delivered dose to tumor and normal organs in locally advanced non-small cell lung cancer (LANSCLC) treated with hypofractionated radiotherapy (HRT), and to explore the necessity and identify optimal candidates for adaptive radiotherapy (ART).MethodsTwenty-seven patients with stage III NSCLC were enrolled. Planned radiation dose was 51Gy in 17 fractions with cone-beam CT (CBCT) acquired at each fraction. Virtual CT was generated by deformable image registration (DIR) of the planning CT to CBCT for dose calculation and accumulation. Dosimetric parameters were compared between original and accumulated plans using Wilcoxon signed rank test. Correlations between dosimetric differences and clinical variables were analyzed using Mann-Whitney U test or Chi-square test.ResultsPatients had varied gross tumor volume (GTV) reduction by HRT (median reduction rate 11.1%, range?-?2.9-44.0%). The V51 of planning target volume for GTV (PTV-GTV) was similar between original and accumulated plans (mean, 88.2% vs. 87.6%, p?=?0.452). Only 11.1% of patients had above 5% relative decrease in V51 of PTV-GTV in accumulated plans. Compared to the original plan, limited increase (median relative increase <?5%) was observed in doses of total lung (mean dose, V20 and V30), esophagus (mean dose, maximum dose) and heart (mean dose, V30 and V40) in accumulated plans. Less than 30% of patients had above 5% relative increase of lung or heart doses. Patients with quick tumor regression or baseline obstructive pneumonitis showed more notable increase in doses to normal structures. Patients with baseline obstructive atelectasis showed notable decrease (10.3%) in dose coverage of PTV-GTV.ConclusionsLANSCLC patients treated with HRT had sufficient tumor dose coverage and acceptable normal tissue dose deviation. ART should be applied in patients with quick tumor regression and baseline obstructive pneumonitis/atelectasis to spare more normal structures.

Dataset Information

"Dose of the day" based on cone beam computed tomography and deformable image registration for lung cancer radiotherapy.

Publications

"Dose of the day" based on cone beam computed tomography and deformable image registration for lung cancer radiotherapy.

Similar Datasets

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