Eiko Nakata, Presenter: Nothing to Disclose

Shogo Yamada MD, Abstract Co-Author: Nothing to Disclose

Yoshiyuki Hosokai RT, PhD, Abstract Co-Author: Nothing to Disclose

Tatsuo Shikama PhD, Abstract Co-Author: Nothing to Disclose

Shinji Nagata PhD, Abstract Co-Author: Nothing to Disclose

Hisao Kanzaki BA, Abstract Co-Author: Nothing to Disclose

Yoshihiro Ogawa MD, Abstract Co-Author: Nothing to Disclose

Issei Mori PhD, Abstract Co-Author: Nothing to Disclose

Hidetoshi Matsuki PhD, Abstract Co-Author: Nothing to Disclose

Keizo Ishii PhD, Abstract Co-Author: Nothing to Disclose

et al, Abstract Co-Author: Nothing to Disclose

In radiation therapy, sometimes medical accidents occur by over and under dose of the irradiation. To reduce these accidents and to increase accuracy of radiation therapy, we are developing an implantable real time mycrodosimetly system using a scintillator as asensor. A scintillator implanted into the patient body/or tumor generates a permeable fluorescence during the irradiation. The doses of radiation are monitored by measuring the intensity of the fluorescence using high sencitive CCD camera. We found that the fluorescence of 694 nm permeated a meet of 2 cm thickness, and was proportionally generated from the scintillator while the LINAC was working at the dose rate of 4Gy/min. Also we successfully got these data with wireless way at a distance of 170 cm between scintillator and detection device (CCD camera).

1. ScintillatorArtificial ruby and demarquest (Al2O3 :Cr) were used as a scintillator. These are very attractive materials for radiation sensor especially for this system cause these scintillations have the high permeability through the body.2. RadiationTo irradiate a scintillator, LINAC (Clinac 2300; VARIAN, 4Gy/min X-ray) was used in this experiment.3. Detection instrumentsTo measure a wave length of a fluorescence from a scintillator, measurement instrument (SP2300i+PIXIS100B; Princeton Instruments), CCD camera (Dual Mode Cool CCD Camera C4880; HAMAMATSU) and Photomultiplier system (PMT series HAMATSU) were used.

The spectrum of the Desmarquest and Ruby were successfully gotten through a meet of 2 cm thickness by a CCD camera while the LINAC is operated. The peak was 694nm. As for the relationship between the intensity of the scintillation and thickness of the meet, it was found that the intensity was at an inverse proportion to the thickness. There was no difference between Ruby and Desmarquest in this relationship. As for the relationship between the intensity of the scintillation and the X-ray dose, we found that the intensity was increased proportionally to the X-ray exposure. As for the timing between X-ray exposure and the detection of scintillate, no time difference was found in this system.

Our data showed that the intensity of a fluorescence from an irradiated scintillator increases proportionally to X-ray exposure. And the spectrum of the fluorescence of 694nm was the high permeability. The intensity of the fluorescence was the enough for getting the data to CCD camera when using a pig meet thickness of 2cm. In addition to those data, our system has the advantage with an unnecessary electric power from the outside. So it will be very useful in the radiation therapy. We are now trying to implant this scintillator into a mouse body.

Nakata, E, Yamada, S, Hosokai, Y, Shikama, T, Nagata, S, Kanzaki, H, Ogawa, Y, Mori, I, Matsuki, H, Ishii, K, et al, , Novel Implantable Wireless Real Time Micro Dosimeter System Using Radiation Scintillator.  Radiological Society of North America 2008 Scientific Assembly and Annual Meeting, February 18 - February 20, 2008 ,Chicago IL. http://archive.rsna.org/2008/7001364.html