1990 Fiscal Year Final Research Report Summary
A Study for Optimization in Brachytherapy-Volume-Dose Relationship and Relating Biologic Factors-
| Project/Area Number |
01570584
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Radiation science
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| Research Institution | Nippon Medical School (1990)
Tokyo Medical and Dental University (1989) |
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Principal Investigator |
HORIUCHI Junichi School of Medicine, Nippon Medical School, professor, 医学部 (90013870)
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| Co-Investigator(Kenkyū-buntansha) |
SHIBUYA Hitoshi School of Medicine, Tokyo Medical and Dental University associate professor, 医学部, 助教授 (10014292)
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| Project Period (FY) |
1989 – 1990
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| Keywords | brachytherapy / volume-dose factor / optimization, / dose distribution |
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| Research Abstract |
Introduction of recent afterloading source of Ir-192 (Ir) was successfully decreased undue exposure for medical staff. Treatment results of Ir was obtained equivalent to Radium (Ra) for similar stage of patients, but, late damage was more frequent in Ir group. In order to clarify the optimization of brachytherapy, discriminant analysis based on a volume-dose relationship was examined for tongue cancer patients with Ir. From discriminant analysis of volume-dose histogram (VDH), there was apparent difference between Ir and Ra. Main difference was shape of VDH, concentrating along the peak of modedose with sharp slope in lr group compared to blunt one in Ra. These results demonstrated that stability in source arrangement seemed to be superior in Ir source as the source could be introduced through non-radioactive guide-gutter, and this was compatible to dose distribution of Ir source. As the effective dose distance from the implanted plane in Ir was thin compared to Ra, clinical application of Ir single implant was suitable for rather superficial lesion. Frequent late damage in Ir group seemed to be based on high cumulative volume rate (CVR) which received doses higher than 70Gy. In the case of Ir implant alone, mandibular damage could be markedly decreased with specially made dental guard.
While, in the case of combined external beam irradiation with brachytherapy, higher complication was observed ; as the contribution of external beam was arranged to small as possible, the analysis of VDH was rather difficult, but, some threshold dose must be considered among the stage of the primary lesion.
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