| Abstract: |
An intraoperative beta probe was designed, built, and tested for detection of radio-labeled malignant tissues that has the advantage of being selectively sensitive to beta while insensitive to gamma radiation. Since beta radiation (electrons or positrons) has a short range in tissue, this probe is ideal for detecting tracers in tumors at the surface of the surgical field. This probe contains a plastic scintillation detector sensitive to beta rays and to a lesser degree some background gamma rays. A second detector counts spurious gamma rays and allows for their subtraction from the activity measured by the first detector. Sensitivity of the dual probe for 1–131 and F-18 was measured to be 108 counts/s/kBq (4000 counts/s/μCi). The dual-detector probe faithfully measured the 10:1 “tumor” to background ratio of radioactivity concentrations in a simulated environment of a tumor in the presence of intense background 511 keV photons. In another phantom experiment, simulating abdominal tumor deposits with various realistic 1–131 radioactive concentrations, the probe was able to accurately identify tumors of approximately 50 mg with a tumor/normal radioactivity concentration of 3/1 in 10 s. © 1994, American Association of Physicists in Medicine. All rights reserved. |
