The clinical trials of tumor therapy using heavy ions beam 12C are now in progress at Institute of Modern Physics in Lanzhou. In order to achieve the precise radiotherapy with the high energy 12C beam in active pencil beam scanning mode, we have developed an ionization chamber(IC) as an online monitor for beam intensity and also a dosimeter after calibration. Through the choosing of working gas and voltage, optimizing of the electrics and the read-out system, calibrating the linearity, the detector system provide us one of the simple and highly reliable way to monitoring the beam during the active pencil beam scanning treatments. The measurement results of this detector system show that it could work well under the condition of high energy 12C beam in active pencil beam scanning mode.
A prototype of time-of-flight positron emission computed tomography （TOF-PET） has been developed for acquiring the coincident detection of 511 keV γ-rays produced from positron annihilation. It consists of two 80.5 minx80.5 mm LYSO scintillator arrays （composed of 35 ×35 pixel finger crystals） with the position sensitive photomultiplier tubes R2487 as the readout. Each array is composed of 2 mm ×2m×15 mm finger crystals and the average pixel pitch is 2.30 mm. The measured results indicate that the TOF information has the potential to significantly enhance the image quality by improving the noise variance in the image recon- struction. The best spatial resolution （FWHM） of the prototype for the pairs of 511 keV T-rays is 1.98 mm and 2.16 mm in the x and y directions, respectively, which are smaller than the average pixel pitch of 2.30 mm.
