Nobutaka Mukumoto1, Mitsuhiro Nakamura2, Masahiro Yamada1, Kunio Takahashi3, Hiroaki Tanabe4, Shinsuke Yano5, Yuki Miyabe1, Nami Ueki1, Shuji Kaneko1, Yukinori Matsuo1, Takashi Mizowaki1, Akira Sawada6, Masaki Kokubo7, Masahiro Hiraoka1. 1. Department of Radiation Oncology and Image-applied Therapy, Kyoto University Graduate School of Medicine, Japan. 2. Department of Radiation Oncology and Image-applied Therapy, Kyoto University Graduate School of Medicine, Japan. Electronic address: m_nkmr@kuhp.kyoto-u.ac.jp. 3. Advanced Mechanical Systems Department, Mitsubishi Heavy Industries Ltd, Hiroshima, Japan. 4. Division of Radiation Oncology, Institute of Biomedical Research and Innovation, Kobe, Japan. 5. Division of Clinical Radiology Service, Kyoto University Hospital, Japan. 6. Department of Radiation Oncology and Image-applied Therapy, Kyoto University Graduate School of Medicine, Japan; Department of Radiological Technology, Faculty of Medical Science, Kyoto College of Medical Science, Nantan, Japan. 7. Division of Radiation Oncology, Institute of Biomedical Research and Innovation, Kobe, Japan; Department of Radiation Oncology, Kobe City Medical Center General Hospital, Japan.
Abstract
PURPOSE: To verify the intrafractional tracking accuracy in infrared (IR) marker-based hybrid dynamic tumour tracking irradiation ("IR Tracking") with the Vero4DRT. MATERIALS AND METHODS: The gimballed X-ray head tracks a moving target by predicting its future position from displacements of IR markers in real-time. Ten lung cancer patients who underwent IR Tracking were enrolled. The 95th percentiles of intrafractional mechanical (iEM(95)), prediction (iEP(95)), and overall targeting errors (iET(95)) were calculated from orthogonal fluoroscopy images acquired during tracking irradiation and from the synchronously acquired log files. RESULTS: Averaged intrafractional errors were (left-right, cranio-caudal [CC], anterior-posterior [AP])=(0.1mm, 0.4mm, 0.1mm) for iEM(95), (1.2mm, 2.7mm, 2.1mm) for iEP(95), and (1.3mm, 2.4mm, 1.4mm) for iET(95). By correcting systematic prediction errors in the previous field, the iEP(95) was reduced significantly, by an average of 0.4mm in the CC (p<0.05) and by 0.3mm in the AP (p<0.01) directions. CONCLUSIONS: Prediction errors were the primary cause of overall targeting errors, whereas mechanical errors were negligible. Furthermore, improvement of the prediction accuracy could be achieved by correcting systematic prediction errors in the previous field.
PURPOSE: To verify the intrafractional tracking accuracy in infrared (IR) marker-based hybrid dynamic tumour tracking irradiation ("IR Tracking") with the Vero4DRT. MATERIALS AND METHODS: The gimballed X-ray head tracks a moving target by predicting its future position from displacements of IR markers in real-time. Ten lung cancerpatients who underwent IR Tracking were enrolled. The 95th percentiles of intrafractional mechanical (iEM(95)), prediction (iEP(95)), and overall targeting errors (iET(95)) were calculated from orthogonal fluoroscopy images acquired during tracking irradiation and from the synchronously acquired log files. RESULTS: Averaged intrafractional errors were (left-right, cranio-caudal [CC], anterior-posterior [AP])=(0.1mm, 0.4mm, 0.1mm) for iEM(95), (1.2mm, 2.7mm, 2.1mm) for iEP(95), and (1.3mm, 2.4mm, 1.4mm) for iET(95). By correcting systematic prediction errors in the previous field, the iEP(95) was reduced significantly, by an average of 0.4mm in the CC (p<0.05) and by 0.3mm in the AP (p<0.01) directions. CONCLUSIONS: Prediction errors were the primary cause of overall targeting errors, whereas mechanical errors were negligible. Furthermore, improvement of the prediction accuracy could be achieved by correcting systematic prediction errors in the previous field.
Authors: Vincent Caillet; Ricky O'Brien; Douglas Moore; Per Poulsen; Tobias Pommer; Emma Colvill; Amit Sawant; Jeremy Booth; Paul Keall Journal: Med Phys Date: 2019-03-04 Impact factor: 4.071