Development of Continuous Line Scanning System Prototype for Proton Beam Therapy.

Purpose: Taking advantage of the continuous, high-intensity beam of the cyclotron at the National Cancer Center Hospital East, we developed a continuous line scanning system (CLSS) prototype for prostate cancer in collaboration with Sumitomo Heavy Industries, Ltd (Tokyo, Japan).

Materials And Methods: The CLSS modulates dose distribution at each beam energy level by varying scanning speed while keeping the beam intensity constant through a beam-intensity control system and a rapid on/off beam-switching system. In addition, we developed a beam alignment system to improve the precision of the beam position.

Microdosimetric measurements and estimation of human cell survival for heavy-ion beams.

The microdosimetric spectra for high-energy beams of photons and proton, helium, carbon, neon, silicon and iron ions (LET = 0.5-880 keV/microm) were measured with a spherical-walled tissue-equivalent proportional counter at various depths in a plastic phantom. Survival curves for human tumor cells were also obtained under the same conditions.