Accuracy of dose calculation based on artefact corrected Cone Beam CT images of lung cancer patients

Thing, Rune Slot; Bernchou, U.; Hansen, Olfred; Brink, Carsten

doi:10.1016/j.phro.2016.11.001

Cited by 39 publications

(43 citation statements)

References 23 publications

(31 reference statements)

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“…However, direct use of CBCT in dose calculation is limited by inferior image quality and thus inaccurate Hounsfield units (HU) . Methods to mitigate or resolve this issue include image correction and image deformation . The former has shown promises, yet dose calculation inaccuracy still varies by up to 5% in phantom and patient studies of various sites .…”

Section: Introductionmentioning

confidence: 99%

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

Yuan

Rong

Benedict

et al. 2019

J Applied Clin Med Phys

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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 D max , 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. K E Y W O R D S adaptive radiotherapy, CBCT, dose of the day, virtual CT

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Section: Introductionmentioning

confidence: 99%

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

Yuan

Rong

Benedict

et al. 2019

J Applied Clin Med Phys

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“…Patient‐specific HU tables have been proposed for dose calculation on 3D CBCT with acceptable accuracy for lung cancer patient . The HU/density table is generated by manually selecting the homogeneous areas of different tissues on both the CT and the CBCT, which is time consuming and error prone.…”

Section: Discussionmentioning

confidence: 99%

“…Numerous studies have demonstrated the feasibility of using CBCT to construct treatment dose for photon and recently for proton radiotherapy on various treatment sites. However, few such systems actually are running in real clinical routine due to various practical reasons.…”

Section: Introductionmentioning

confidence: 99%

A clinical 3D/4D CBCT‐based treatment dose monitoring system

Qin

Gersten

Liang

et al. 2018

J Applied Clin Med Phys

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To monitor delivered dose and trigger plan adaptation when deviation becomes unacceptable, a clinical treatment dose (Tx‐Dose) reconstruction system based on three‐dimensional (3D)/four‐dimensional (4D)‐cone beam computed tomograpy (CBCT) images was developed and evaluated on various treatment sites, particularly for lung cancer patient treated by stereotactic body radiation therapy (SBRT). This system integrates with our treatment planning system (TPS), Linacs recording and verification system (R&V), and CBCT imaging system, consisting of three modules: Treatment Schedule Monitoring module (TSM), pseudo‐CT Generating module (PCG), and Treatment Dose Reconstruction/evaluation module (TDR). TSM watches the treatment progress in the R&V system and triggers the PCG module when new CBCT is available. PCG retrieves the CBCTs and performs planning CT to CBCT deformable registration (DIR) to generate pseudo‐CT. The 4D‐CBCT images are taken for target localization and correction in lung cancer patient before treatment. To take full advantage of the valuable information carried by 4D‐CBCT, a novel phase‐matching DIR scheme was developed to generate 4D pseudo‐CT images for 4D dose reconstruction. Finally, TDR module creates TPS scripts to automate Tx‐Dose calculation on the pseudo‐CT images. Both initial quantitative commissioning and patient‐specific qualitative quality assurance of the DIR tool were utilized to ensure the DIR quality. The treatment doses of ten patients (six SBRT‐lung, two head and neck (HN), one breast and one prostate cancer patients) were retrospectively constructed and evaluated. The target registration error (mean ± STD: 1.05 ± 1.13 mm) of the DIR tool is comparable to the interobserver uncertainty (0.88 ± 1.31 mm) evaluated by a publically available lung‐landmarks dataset. For lung SBRT patients, the D99 of the final cumulative Tx‐Dose of GTV is 93.8 ± 5.5% (83.7–100.1%) of the originally planned D99. CTV D99 decreases by 3% and mean ipsilateral parotid dose increases by 11.5% for one of the two HN patients. In conclusion, we have demonstrated the feasibility and effectiveness of a treatment dose verification system in our clinical setting.

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“…It should be noted that the Elekta XVI CBCT system used in many of the cited studies [10][11][12][13][14][15] differs in several key aspects from the Varian Clinac OBI system used in this study and Refs. [9,13,18]; the most notable being scatter correction strategy, HU calibration and field of view [13].…”

Section: Percentage Of Ct Dosementioning

confidence: 90%

Cone beam CT based dose calculation in the thorax region

Kaplan

Elstrøm

Møller

et al. 2018

Physics and Imaging in Radiation Oncology

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A B S T R A C TBackground and purpose: The limited image quality in Cone Beam CT (CBCT) stemming primarily from scattered radiation hinders accurate CBCT based dose calculation in radiotherapy. We investigated the use of a stoichiometric calibration for dose calculation on CBCT images of lung cancer patients. Materials and methods: CBCT calibrations were performed with thorax scan protocols, using a phantom with approximately the diameter of an average human thorax and a central cavity simulating the thoracic cavity. Thus scatter conditions resembling those in clinical thorax CBCT scans were simulated. A published stoichiometric parametrization was used. A treatment plan was simulated on CBCT and CT scans of an anthropomorphic phantom, the dose distributions were calculated, and clinically relevant DVH parameters were compared. Twelve lung cancer patients had surveillance CT scans (s-CT) taken twice during their treatment course in addition to daily setup CBCTs. Dose calculations were performed on the s-CTs and the corresponding CBCTs taken on the same day, and DVH parameters were compared. Results: Eighty percent of CBCT DVH parameters found for the phantom were within ± 1% of CT doses, and 98% were within ± 3%. For patients, the median CT/ CBCT dose difference was within ± 2%, and 98% of DVH parameters were within ± 4%. Minimum dose to the tumor was underestimated (median 1.9%) on CBCT, while maximum doses to most organs at risk were slightly overestimated. Conclusion: Direct dose calculations on CBCTs of lung cancer patients were feasible within ∼4% accuracy using a simple calibration method, which is easily implemented in a clinical setting.

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Accuracy of dose calculation based on artefact corrected Cone Beam CT images of lung cancer patients

Cited by 39 publications

References 23 publications

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

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

A clinical 3D/4D CBCT‐based treatment dose monitoring system

Cone beam CT based dose calculation in the thorax region

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