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Showing 2 results for Sato
F. Babapour Mofrad, R. Aghaeizadeh Zoroofi, A. Abbaspour Tehrani Fard, Sh. Akhlaghpoor, Y.w. Chen, Y. Sato,
Volume 7, Issue 4 (3-2010)
Abstract
Background: In nuclear medicine application
often it is required to use computational methods for
evaluation of organ absorbed dose. Monte Carlo
simulation and phantoms have been used in many
works before. The shape, size and volume in organs
are varied, and this variation will produce error in
dose calculation if no correction is applied. Materials
and Methods: A computational framework for
constructing individual phantom for dosimetry was
performed on five liver CT scan data sets of Japanese
normal individuals. The Zubal phantom was used as
an original phantom to be adjusted by each individual
data set. This registration was done by Spherical
Harmonics (SH) and Thin-Plate Spline methods.
Hausdorff distance was calculated for each case.
Results: Result of Hausdorff distance for five individual
phantoms showed that before registration ranged
from 140.9 to 192.1, and after registration it
changed to 52.5 to 76.7. This was caused by index
similarity ranged from %56.4 to %70.3. Conclusion: A
new and automatic three-dimensional (3D) phantom
construction approach was suggested for individual
internal dosimetry simulation via Spherical Harmonics
(SH) and Thin-Plate Spline methods. The results
showed that the individual comparable phantom can
be calculated with acceptable accuracy using
geometric registration. This method could be used for
race-specific statistical phantom modeling with major
application in nuclear medicine for absorbed dose
calculation. Iran. J. Radiat. Res., 2010 7 (4): 201-206
K. Ichise, Ph.d., K. Hirose, M. Sato, F. Komai, M. Tanaka, I. Fujioka, H. Kawaguchi, Y. Hatayama, Y. Takai, M. Aoki,
Volume 20, Issue 2 (4-2022)
Abstract
Background: Tumor cells with high aldehyde dehydrogenase activity (ALDHhigh cells) are induced by an intratumoral hypoxic condition and lead to radioresistance, tumor recurrence, and metastasis. Therefore, to enhance the anti-tumor effect of radiotherapy, it is reasonable to efficiently control ALDHhigh cells by targeting them. In this study, we evaluated the effect of tirapazamine, a hypoxic toxin, combined with irradiation on ALDHhigh cells. Materials and Methods: Human tongue squamous cell carcinoma SAS cells were used in this study. Spheroids were irradiated with 6 Gy following treatment with 40 μM tirapazamine. After 24, 48, and 72 hours, the populations of ALDHhigh cells were analyzed. The frozen sections of spheroids were prepared, and hypoxia-inducible factor-1α-positive areas and ALDH1-positive areas were detected. Results: Compared with the cells grown in monolayer culture, the SAS cells grown in spheroids exhibited radioresistance. Furthermore, the proportion of ALDHhigh cells was significantly higher in spheroids than in monolayer culture. The ALDHhigh cells were sustained in a hypoxic fraction localized at the center of the spheroids after irradiation. Tirapazamine effectively reduced these ALDHhigh cells. The combination of tirapazamine with irradiation showed an additive cytotoxic effect in spheroids, but not in parental cells, which was consistent with a preferential killing effect of tirapazamine on ALDHhigh cells. Conclusion: Combined tirapazamine and radiotherapy administration appeared to be a reasonable approach to control ALDHhigh cells in hypoxic regions that may be involved in recurrence and metastasis.
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