A new gamma-ray detector solves a host of problems for medical professionals. It only weighs 580 g and fits in the palm of a hand, making it the world's most compact Compton camera.
A research group invented a medical gamma-ray detector (Compton camera) and succeeded in high-resolution, multicolor 3D molecular imaging of a live mouse which was administered with three different radioactive tracers. They discovered that the tracers iodine, strontium and zinc accumulated in the thyroid, bones and liver respectively, confirming that these new tracers concentrated in each target organ.
"The measurement time took 10 minutes per angle, so we were able to obtain an image taken from 12 angles in just two hours. The time could be reduced even more by using multiple Compton cameras,” said Jun Kataoka, professor of applied physics at Waseda University in Japan. "For example, if there are 12 Compton cameras surrounding an object, the same image as this study could be obtained in just 10 minutes, suggesting a new way to understand biodynamics by looking at how a drug is taken into the body in 10-minute increments."
Professor Kataoka's research group developed the camera with high detection efficiency and practical spatial resolution, enabling flexible measurements. The camera was then rotated around the mouse from 12 angles, which was administered with three different radioactive tracers: iodine (131I, 364 keV), strontium (85Sr, 514 keV) and zinc (65Zn, 1116 keV). The measurement time totaled two hours, and the group successfully demonstrated the effectiveness of simultaneous in vivo imaging of multiple tracers and imaged the gamma rays nearly real-time with a resolution of 3mm, equivalent to PET.
Based on this study, Professor Kataoka is now working towards developing a gamma-ray camera which works like the human eye. "The human eye can instantly distinguish the colors and brightness of light from all directions, as well as determine the object's shape in 3D from the displacement between the left and right eye. Therefore, stereoscopic imaging becomes theoretically feasible by using multiple ultra-compact Compton cameras."
This technology could also help track behaviors of cancer cells and minerals in the body by combining the conventional PET drugs with newly found tracers, calculate the survival rate of a transplanted organ, develop cheaper and more convenient drugs for medical imaging, and monitor online the effectiveness of particle therapy by measuring various prompt gamma rays emitted during treatment.
"As radiation technology is still emerging, we look forward to expanding the possibilities of next-generation radiation imaging with this 'on demand' Compton camera," Professor Kataoka said.