Estimation of imaging intervals and intrafraction displacement in CyberKnife image-guided radiotherapy for intracranial lesions.

Purpose: A recent report by the American Association of Physicists in Medicine Task Group 75 and 180 provided imaging dose estimates for image-guided CyberKnife radiotherapy. However, to our knowledge, there have been no concrete demonstrations of imaging intervals that are directly linked to exposure dose. We hypothesized that setting a rational standard may be clearer through a balance of treatment accuracy and reducing imaging doses if the margin of the planned treatment volume is controlled through the imaging interval.

Relationship between pressure levels on the occipital region and intrafraction motion using an individualized head support for intracranial treatment.

The purpose of this study was to evaluate the relationship between pressure on the occipital region and intrafraction motion using an individualized vacuum pillow and a thermoplastic mask for intracranial treatment. We calculated head displacement during treatment from 8811 image verifications in 59 patients and divided them into two groups according to the magnitude of the mean and standard deviation (SD) of the displacement in the 59 patients. Pressure was compared between the small (n = 29) and large (n = 30) displacement groups using Welch's t-test for the mean and SD of displacement.

Development of a real-time monitoring system for intra-fractional motion in intracranial treatment using pressure sensors.

This study developed a dedicated real-time monitoring system to detect intra-fractional head motion in intracranial radiotherapy using pressure sensors. The dedicated real-time monitoring system consists of pressure sensors with a thickness of 0.6 mm and a radius of 9.

Observation of intrafraction prostate displacement through the course of conventionally fractionated radiotherapy for prostate cancer.

Purpose: Intrafraction prostate displacement (IFPD) through the course of conventionally fractionated radiotherapy was observed by real-time tracking.

Materials And Methods: IFPD was observed by using a CyberKnife real-time tracking system over 39 serial fractions in two patients. Stereoscopic X-ray images tracking the implanted fiducial markers were obtained with mean intervals of 58 s.

Development of a phantom to evaluate the positioning accuracy of patient immobilization systems using thermoplastic mask and polyurethane cradle.

Purpose: The purpose of this study was to develop a new phantom to evaluate the positioning accuracy of patient immobilization systems.

Methods: The phantom was made of papers formed into a human shape, paper clay, and filling rigid polyester. Acrylonitrile butadiene styrene (ABS) pipes were inserted at anterior-posterior (A-P) and right-left (R-L) directions in the phantom to give static load by pulling ropes through the pipes.