Comparison of dynamic tumor tracking error measurement methods for robotic radiosurgery.

Background: Dynamic tumor motion tracking is used in robotic radiosurgery for targets subject to respiratory motion, such as lung and liver cancers. Different methods of measuring tracking error have been reported, but the differences among these methods have not been studied, and the optimal method is unknown.

Purpose: The purpose of this study was to assess and compare tracking errors encountered with individual patients using different evaluation methods for method optimization.

Development of a tracking error prediction system for the CyberKnife Synchrony Respiratory Tracking System with use of support vector regression.

Purpose: The accuracy of the CyberKnife Synchrony Respiratory Tracking System is dependent on the breathing pattern of a patient. Therefore, the tracking error in each patient must be determined. Support vector regression (SVR) can be used to easily identify the tracking error in each patient.

CyberKnife Stereotactic Radiosurgery and Hypofractionated Stereotactic Radiotherapy As First-line Treatments for Imaging-diagnosed Intracranial Meningiomas.

Definitive radiotherapy is an important alternative treatment for meningioma patients who are inoperable or refuse surgery. We evaluated the efficacy and toxicity of CyberKnife-based stereotactic radiosurgery (SRS) and hypofractionated stereotactic radiotherapy (hSRT) as first-line treatments for intracranial meningiomas that were diagnosed using magnetic resonance imaging (MRI) and/or computed tomography (CT). Between February 2005 and September 2015, 41 patients with intracranial meningiomas were treated with CyberKnife-based SRS or hSRT.

A phase I/II study on stereotactic body radiotherapy with real-time tumor tracking using CyberKnife based on the Monte Carlo algorithm for lung tumors.

Background: In this phase I/II study, we assessed the safety and initial efficacy of stereotactic body radiotherapy (SBRT) for lung tumors with real-time tumor tracking using CyberKnife based on the Monte Carlo algorithm.

Methods: Study subjects had histologically confirmed primary non-small-cell lung cancer staged as T1a-T2aN0M0 and pulmonary oligometastasis. The primary endpoint was the incidence of Grade ≥3 radiation pneumonitis (RP) within 180 days of the start of SBRT.

Comparison of multileaf collimator and conventional circular collimator systems in Cyberknife stereotactic radiotherapy.

Multileaf collimator (MLC) technology has been newly introduced with the Cyberknife system. This study investigated the advantages of this system compared with the conventional circular collimator (CC) system. Dosimetric comparisons of MLC and CC plans were carried out.

Long-term results of hypofractionated stereotactic radiotherapy with CyberKnife for growth hormone-secreting pituitary adenoma: evaluation by the Cortina consensus.

The aim of the present study was to evaluate the safety and feasibility of hypofractionated stereotactic radiotherapy (SRT) with CyberKnife for growth hormone-secreting pituitary adenoma (GH-PA). Fifty-two patients with GH-PA were treated with hypofractionated SRT between September 2001 and October 2012. Eight patients had clinically silent GH-PA and 44 were symptomatic.

Percutaneous fiducial marker placement prior to stereotactic body radiotherapy for malignant liver tumors: an initial experience.

The aim of this study was to describe our initial experience with a gold flexible linear fiducial marker and to evaluate the safety and technical and clinical efficacy of stereotactic body radiotherapy using this marker for malignant liver tumors. Between July 2012 and February 2015, 18 patients underwent percutaneous fiducial marker placement before stereotactic body radiotherapy for malignant liver tumors. We evaluated the technical and clinical success rates of the procedure and the associated complications.

Re-irradiation of recurrent anaplastic ependymoma using radiosurgery or fractionated stereotactic radiotherapy.

Purpose: Recurrent ependymomas were retreated with stereotactic radiosurgery (SRS) or fractionated stereotactic radiotherapy (FSRT). The efficacy, toxicities, and differences between SRS and FSRT were analyzed.

Methods: Eight patients with recurrent ependymomas fulfilling the criteria described below were evaluated.

Pituitary metastases: current practice in Japan.

Object: With advancement of cancer treatment and development of neuroimaging techniques, contemporary clinical pictures of pituitary metastases (PMs) must have changed from past reports. The goal of this paper was to elucidate the clinical features of PMs and current clinical practice related to those lesions. In this retrospective study, questionnaires were sent to 87 physicians who had treated PMs in Japan.

Development of system using beam's eye view images to measure respiratory motion tracking errors in image-guided robotic radiosurgery system.

The accuracy of the CyberKnife Synchrony Respiratory Tracking System (SRTS) is considered to be patient-dependent because the SRTS relies on an individual correlation between the internal tumor position (ITP) and the external marker position (EMP), as well as a prediction method to compensate for the delay incurred to adjust the position of the linear accelerator (linac). We aimed to develop a system for obtaining pretreatment statistical measurements of the SRTS tracking error by using beam's eye view (BEV) images, to enable the prediction of the patient-specific accuracy. The respiratory motion data for the ITP and the EMP were derived from cine MR images obtained from 23 patients.

Dose-volume histogram comparison between static 5-field IMRT with 18-MV X-rays and helical tomotherapy with 6-MV X-rays.

We treated prostate cancer patients with static 5-field intensity-modulated radiation therapy (IMRT) using linac 18-MV X-rays or tomotherapy with 6-MV X-rays. As X-ray energies differ, we hypothesized that 18-MV photon IMRT may be better for large patients and tomotherapy may be more suitable for small patients. Thus, we compared dose-volume parameters for the planning target volume (PTV) and organs at risk (OARs) in 59 patients with T1-3 N0M0 prostate cancer who had been treated using 5-field IMRT.

Evaluation of Dose Uncertainty to the Target Associated With Real-Time Tracking Intensity-Modulated Radiation Therapy Using the CyberKnife Synchrony System.

We investigated the dose uncertainty caused by errors in real-time tracking intensity-modulated radiation therapy (IMRT) using the CyberKnife Synchrony Respiratory Tracking System (SRTS). Twenty lung tumors that had been treated with non-IMRT real-time tracking using CyberKnife SRTS were used for this study. After validating the tracking error in each case, we did 40 IMRT planning using 8 different collimator sizes for the 20 patients.

Intensity modulated stereotactic body radiation therapy for single or multiple vertebral metastases with spinal cord compression.

Purpose: The purpose of this study was to evaluate the efficacy and toxicity of intensity modulated radiation therapy with simultaneous integrated boost (SIB-IMRT) for single or multiple vertebral metastases (VM) with spinal cord compression using tomotherapy.

Methods And Materials: Thirty patients with 40 VM were treated with SIB-IMRT as initial radiation therapy. Either 40 Gy in 8 fractions or 48 Gy in 16 fractions was prescribed depending on the Katagiri prognostic index.

Effect of residual patient motion on dose distribution during image-guided robotic radiosurgery for skull tracking based on log file analysis.

Purpose: The present study aimed to assess the effect of residual patient motion on dose distribution during intracranial image-guided robotic radiosurgery by analyzing the system log files.

Materials And Methods: The dosimetric effect was analyzed according to the difference between the original and estimated dose distributions, including targeting error, caused by residual patient motion between two successive image acquisitions. One hundred twenty-eight treatments were analyzed.

Fractionated stereotactic radiotherapy using CyberKnife for the treatment of large brain metastases: a dose escalation study.

Aims: To evaluate the toxicity and efficacy of fractionated stereotactic radiotherapy (FSRT) with doses of 18-30 Gy in three fractions and 21-35 Gy in five fractions against large brain metastases.

Materials And Methods: Between 2005 and 2012, 61 large brain metastases (≥ 2.5 cm in maximum diameter) of a total of 102 in 54 patients were treated with FSRT as a first-line therapy.