TY - JOUR
T1 - Rapid two-dimensional dose measurement in brachytherapy using plastic scintillator sheet
T2 - linearity, signal-to-noise ratio, and energy response characteristics
AU - Perera, Harold
AU - Williamson, Jeffrey F.
AU - Monthofer, Suzanne P.
AU - Binns, Walter R.
AU - Klarmann, Joseph
AU - Fuller, Gary L.
AU - Wong, John W.
N1 - Funding Information:
Reprint requests to: Jeffrey F. Williamson, Ph.D. Acknowledgement-This work was supported by NIH grant RO 1 CA 46640 and by a research contract awarded by Computerized Medical Systems Inc., St. Louis, MO.
PY - 1992
Y1 - 1992
N2 - Because of the large dose gradients encountered near brachytherapy sources, an efficient, accurate, low-atomic number areal detector, which can record dose at many points simultaneously, is highly desirable. We have developed a prototype of such a system using thin plates of plastic scintillator as detectors. A micro-channel plate (MCP) image intensifier was used to amplify the optical scintillation images produced by radioactive 125I and 137Cs sources in water placed 0.5-5.7 cm distance from the detector. A charge-coupled device (CCD) digital camera was used to acquire 2-D light-intensity distributions from the image intensifier output window. For both isotopes, a small area (2 × 3 mm2) PVT detector yields a CCD net count rate that is linear with respect to absorbed dose rate within ± 3% out to 5.7 cm distance. Acquisition times range from 1.5-400 sec with a reproducibility of 0.5-5.5%. If a large-area (6 × 20 em2) PVT detector is used, a four-fold increase in count rate and large deviations from linearity are observed, indicating that neighboring pixels contribute light to the signal through diffusion and scattering in PVT and water. A detailed noise analysis demonstrates that the image intensifier reduces acquisition time 10000-fold, reduces noise relative to signal 200-fold, and reduces amplifier gain noise as well.
AB - Because of the large dose gradients encountered near brachytherapy sources, an efficient, accurate, low-atomic number areal detector, which can record dose at many points simultaneously, is highly desirable. We have developed a prototype of such a system using thin plates of plastic scintillator as detectors. A micro-channel plate (MCP) image intensifier was used to amplify the optical scintillation images produced by radioactive 125I and 137Cs sources in water placed 0.5-5.7 cm distance from the detector. A charge-coupled device (CCD) digital camera was used to acquire 2-D light-intensity distributions from the image intensifier output window. For both isotopes, a small area (2 × 3 mm2) PVT detector yields a CCD net count rate that is linear with respect to absorbed dose rate within ± 3% out to 5.7 cm distance. Acquisition times range from 1.5-400 sec with a reproducibility of 0.5-5.5%. If a large-area (6 × 20 em2) PVT detector is used, a four-fold increase in count rate and large deviations from linearity are observed, indicating that neighboring pixels contribute light to the signal through diffusion and scattering in PVT and water. A detailed noise analysis demonstrates that the image intensifier reduces acquisition time 10000-fold, reduces noise relative to signal 200-fold, and reduces amplifier gain noise as well.
KW - Brachytherapy
KW - Dosimetry
KW - Monte Carlo simulation
KW - Plastic scintillator detectors
UR - http://www.scopus.com/inward/record.url?scp=0026771378&partnerID=8YFLogxK
U2 - 10.1016/0360-3016(92)90914-4
DO - 10.1016/0360-3016(92)90914-4
M3 - Article
C2 - 1639641
AN - SCOPUS:0026771378
SN - 0360-3016
VL - 23
SP - 1059
EP - 1069
JO - International journal of radiation oncology, biology, physics
JF - International journal of radiation oncology, biology, physics
IS - 5
ER -