Pacemaker Malfunction During Passive Proton Beam Therapy for Localized Prostate Cancer: Case Reports and a Literature Review.

We report two cases of pacemaker malfunction occurring during proton beam therapy (PBT) for localized prostate cancer treatment. The first case involved mode changes in the pacemaker, while the second exhibited prolongation of the RR interval. Remarkably, both cases did not manifest significant clinical changes.

Wedged field using the half-field method with a flattening filter-free photon beam.

In this study, we propose a novel wedged field using a half-field flattening filter-free beam without a metallic filter or a moving jaw, and investigate the characteristics of the proposed technique. Dose distributions of the proposed method were first determined in virtual-water or anthropomorphic phantom using a radiotherapy planning system. We evaluated the wedge angle as a function of the field size, collimator rotation, and depth.

Contrast Enhancement in Breast Cancer and Background Mammary-Gland Tissue During the Super-Early Phase of Dynamic Breast Magnetic Resonance Imaging.

Rationale And Objectives: We aimed to compare the contrast enhancement between tumor and mammary-gland tissue to distinguish lesions in the super-early phase, during which minimal contrast media uptake is observed in mammary-gland tissue.

Materials And Methods: Dynamic magnetic resonance imaging, including the super-early phase with bolus tracking (BT) method (to determine the optimal imaging start time), was performed by using identical parameters to obtain transverse fat-suppressed T1-weighted images of both breasts. The percent enhancement (PE) and the contrast ratio (CR) indicators for tumor and mammary-gland tissue were assessed in each dynamic phase.

[Wiener spectrum and relative electron density resolution in heavy ion CT based on measurement of residual range distribution].

The relative electron density resolution was discussed by the Wiener spectrum in the heavy ion CT image. The two-dimensional (2D) Wiener spectrum in the CT image was obtained from the one-dimensional (1D) Wiener spectrum of the measured residual range distribution of the water phantom for a single projection angle, and the relative electron density resolution in the CT image was calculated from the 2D Wiener spectrum. To examine the usefulness of this method, the relative electron density resolution was also estimated by other two methods; the calculation using the Wiener spectrum of the reconstructed image of the water phantom, and the estimation by the reconstructed image of the electron density resolution phantom.

Heavy ion CT system based on measurement of residual range distribution.

The heavy ion CT system is proposed which is based on measurement of the residual range distribution by a fluoroscopy detector consisting of an intensifying screen and a CCD video camera. To investigate the fundamental performance of the proposed system, the spatial and density resolutions of the CT image were evaluated. The heavy ion beam 12C accelerated up to 400 MeV/u by HIMAC was used in this study.