Author:
Nagata J.,Yamamoto S.,Nakanishi K.,Noguchi Y.,Okudaira K.,Kataoka J.
Abstract
Abstract
In high-dose-rate (HDR) brachytherapy, verification of an
Ir-192 source's position during treatment is required. One of the
methods for this used a high-energy pinhole gamma camera to image
the position of the source, but the absolute position of the source
cannot be measured. To confirm the absolute position, it will be
useful to acquire the transmission image of a subject in addition to
the gamma photon image at the same time without using an additional
X-ray system. To measure the transmission images, we tried to use
the high-energy gamma photons emitted from the Ir-192 source used
for the therapy. We developed a high-energy gamma photon imaging
system composed of 1-mm-thick Pr doped Gd2O2S (GOS), a
surface mirror, and a cooled charge-coupled device (CCD) camera. The
developed imaging system achieved transmission imaging of
high-energy gamma photons by transporting the Ir-192 source in front
of the imaging system. The spatial resolution of the imaging system
was better than 2.4 mm FWHM with and without a 10-cm-thick acrylic
block set between the imaging system and the source. Moderate
spatial resolution and contrast images of phantoms were obtained
with the system. For the dynamic imaging mode, continuous images of
the phantoms were measured with 1-sec intervals. There was no
observable difference in the transmission images by the movement of
the Ir-192 source. Transmission imaging of subjects using an Ir-192
source for HDR brachytherapy could be achieved using our developed
imaging system. The system offers a new method to measure the
real-time transmission images of the subject during HDR
brachytherapy.
Subject
Mathematical Physics,Instrumentation