[Effect of source positional discrepancy on dose and dose distributions in cobalt-60 stereotactic radiosurgery units].

We assessed the impact of source positional discrepancy on dose and dose distributions in Gamma Knife (GK) Perfexion (PFX) stereotactic radiosurgery. A spherical phantom dedicated in GK machine was used and irradiated by 2 Gy in each position moved at an interval of 0.1 mm from its original position using three types of collimators (4, 8, 16 mm) to evaluate the changes of dose.

[Validation and analysis of dose distributions in a new and entirely redesigned cobalt-60 stereotactic radiosurgery units].

The objective of this study was to evaluate the reproducibility of dose distributions in stereotactic treatment planning throughout Gamma Knife (GK) stereotactic radiosurgery (SRS) procedures in both GK model C and Perfexion (PFX). An originally-developed phantom and a radiochromic film were used for obtaining actual dose distributions. The phantom, with inserted films, was placed on a Leksell skull frame.

Geometric accuracy of 3D coordinates of the Leksell stereotactic skull frame in 1.5 Tesla- and 3.0 Tesla-magnetic resonance imaging: a comparison of three different fixation screw materials.

We assessed the geometric distortion of 1.5-Tesla (T) and 3.0-T magnetic resonance (MR) images with the Leksell skull frame system using three types of cranial quick fixation screws (QFSs) of different materials-aluminum, aluminum with tungsten tip, and titanium-for skull frame fixation.

Assessment of spatial uncertainty in computed tomography-based Gamma Knife stereotactic radiosurgery process with automated positioning system.

Background: In this study, we assessed the geometric accuracy of an automated positioning system in Gamma Knife (GK) surgery. Specifically, we looked at the total spatial uncertainty over the entire treatment range of GK stereotactic radiosurgery (SRS) procedures in both the GK model C and the Perfexion (PFX).

Methods: An originally-developed phantom and a radiochromic film were used for obtaining actual dose distributions.

[Assessment of overall spatial accuracy in image guided stereotactic body radiotherapy using a spine registration method].

Stereotactic body radiotherapy (SBRT) for lung and liver tumors is always performed under image guidance, a technique used to confirm the accuracy of setup positioning by fusing planning digitally reconstructed radiographs with X-ray, fluoroscopic, or computed tomography (CT) images, using bony structures, tumor shadows, or metallic markers as landmarks. The Japanese SBRT guidelines state that bony spinal structures should be used as the main landmarks for patient setup. In this study, we used the Novalis system as a linear accelerator for SBRT of lung and liver tumors.

[Image distortion and artifacts caused by the use of a titanium aneurism clip in 1.5 tesla- and 3 tesla-magnetic resonance imaging: effect on 60cobalt stereotactic radiosurgery treatment planning].

In gamma knife stereotactic radiosurgery (GKSRS) treatment planning, 1.5 tesla (T)-magnetic resonance imaging (MRI) is normally used to identify the target lesion. Image artifacts and distortion arise in MRI if a titanium clip is surgically implanted in the brain to treat cerebral aneurysm.

[Effect on treatment planning based on properties of cobalt-60 stereotactic radiosurgery units].

The brand-new version of gamma knife, Perfexion, is equipped with an automatic collimator arrangement system that does not require manual collimator exchange and a couch-traveling system that is approximately ten times faster than Model C, so treatment time with multiple shots is assumed to remain within a clinically acceptable range. In this study, the treatment plans for Model C and Perfexion were compared from the viewpoint of number of shots, coverage, selectivity, conformity, and gradient in planning target volume (PTV) coverage. We enrolled 187 and 89 patients with vestibular schwannomas treated by Model C and Perfexion in the study.

Simulational study of a dosimetric comparison between a Gamma Knife treatment plan and an intensity-modulated radiotherapy plan for skull base tumors.

Fractionated stereotactic radiotherapy (SRT) is performed with a linear accelerator-based system such as Novalis. Recently, Gamma Knife Perfexion (PFX) featured the Extend system with relocatable fixation devices available for SRT. In this study, the dosimetric results of these two modalities were compared from the viewpoint of conformity, heterogeneity and gradient in target covering.

[Setup accuracy of stereotactic body radiation therapy (SBRT) using virtual isocenter in image-guided radiation therapy (IGRT)].

We use Novalis Body system for stereotactic body radiation therapy (SBRT) in lung and liver tumors. Novalis system is dedicated to SBRT with image-guided patient setup system ExacTrac. The spinal bone is the main landmark in patient setup during SBRT using ExacTrac kV X-ray system.

Assessment of spatial uncertainties in the radiotherapy process with the Novalis system.

Purpose: The purpose of this study was to evaluate the accuracy of a new version of the ExacTrac X-ray (ETX) system with statistical analysis retrospectively in order to determine the tolerance of systematic components of spatial uncertainties with the Novalis system.

Methods And Materials: Three factors of geometrical accuracy related to the ETX system were evaluated by phantom studies. First, location dependency of the detection ability of the infrared system was evaluated.

Stereotactic imaging for radiosurgery: localization accuracy of magnetic resonance imaging and positron emission tomography compared with computed tomography.

Computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography (PET) provide complementary information for treatment planning in stereotactic radiosurgery. We evaluated the localization accuracy of MRI and PET compared with CT. Two kinds of phantoms applicable to the Leksell G stereotactic skull frame (Elekta, Tokyo) were developed.

[Survey of patients' impressions of radiotherapy and their need for additional medical information: Japanese domestic survey of 1,529 patients in 2002].

Purpose: We clarified the images, impressions, and information about radiotherapy in standard Japanese patients and, at the same time, investigated their need for information about radiotherapy, in order to identify what we, as radiation oncologists, should do to decrease patient anxiety and create good physician-patient relationships.

Materials And Methods: We handed out 10 questionnaires to 1529 patients from April 2002 through July 2002 in 22 Japanese institutions that were equipped with radiotherapy machines. Questionnaires contained 10 items asking about patients' background, their impression of radiotherapy, frequency of exposure to information about radiotherapy, need to obtain information about radiotherapy, and ideal additional medical informational resources or their content.

Long-term results of gamma knife surgery for growth hormone-producing pituitary adenoma: is the disease difficult to cure?

Object: The authors conducted a study to determine the long-term results of gamma knife surgery for residual or recurrent growth hormine (GH)-producing pituitary adenomas and to compare the results with those after treatment of other pituitary adenomas.

Methods: The series consisted of 67 patients. The mean tumor diameter was 19.

[Three-dimensional conformal radiotherapy with multi-leaf collimator].

In radiation therapy, it is very important to concentrate the high dose to the clinical target volume. For this purpose, S. Takahashi developed the dynamic conformal radiotherapy in 1960.