  In this paper, we describe the development of monolithic pixel detectors by
using a Silicon-on-Insulator (SOI) technology for X-ray and charged particle
applications. The detectors are based on a 0.2 {\mu}m CMOS fully depleted SOI
process (Lapis Semiconductor Co., Ltd). The SOI wafer consists of a thick
high-resistivity substrate for sensing and a thin low resistivity Si layer for
CMOS circuits.
  We developed the integration-type SOI pixel detector, INTPIX4 mainly for
X-ray imaging; it is made of a Float Zone (FZ) or Czochralski (Cz) silicon
wafer. Since 2005, Cz SOI detectors were used initially. After 2011, FZ SOI
detectors were successfully fabricated. In this paper, we state recent
progresses and test results of the SOI monolithic pixel detector using a FZ
silicon and compare them with the results obtained using the Cz detector.
