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Michinori Yamamoto - One of the best experts on this subject based on the ideXlab platform.

  • The results of radiation therapy for glottic carcinoma: prognostic significance of tumor size in laryngoscopic findings.
    Oncology reports, 2000
    Co-Authors: Michinori Yamamoto, Yoshihiro Hada, Makoto Shirane, Masakaze Nakata
    Abstract:

    Seventy-five patients with carcinoma of the true vocal cord were treated with curative intent by radiotherapy at Kure National Hospital between 1977 and 1997. All tumors were classified according to stage (T1, T2 and T3), degree of differentiation (well-differentiated, moderately differentiated, poorly differentiated and unknown), and size (very small, small and large). All patients were treated using a Cobalt-60 Unit to a total dose that ranged from 56 Gy to 64 Gy (mean, 60 Gy). The mean treatment time was 44 days (range, 38-50 days). The local control and ultimate local control rates at 5 years were 75.8% and 91.4% for all patients, respectively. Univariate analysis showed that tumor size (p=0.0350) and stage T (p=0.0416) affected local control. In multivariate analysis, tumor size was the only significant factor that affected local control (p=0.0012). The most significant factor that affected local control was tumor size in laryngoscopic findings. Tumor size was inversely related to local control.

  • The results of radiotherapy for T1 glottic cancers; influence of radiation beam energy.
    Acta medica Okayama, 1999
    Co-Authors: Michinori Yamamoto, Ikuo Joja, Mitsuhiro Takemoto, Masahiro Kuroda, Yoshio Hiraki
    Abstract:

    We analyzed the influence of various parameters on the results of radiotherapy for T1 glottic cancer by assessing the outcomes of 60 patients with this cancer who received definitive radiotherapy between 1985 and 1994. Seven patients were treated with a Cobalt-60 Unit, and the other 53 with a linear accelerator (26 patients at 3-MV, 10 at 6-MV, and 17 at 10-MV). Of the 17 patients treated at 10-MV, 4 also received part of their treatment with a Cobalt-60 Unit. The total radiation dose ranged from 56 Gy to 70 Gy (mean, 61 Gy). The total radiation dose of 51 patients (85%) was 60 Gy. The factors found to influence local control were the strength of the radiation beam energy and whether or not there was gross tumor invasion of the anterior commissure. The local control rate was 71% in the patients treated with a 10-MV linear accelerator, 56% in those treated with a 6-MV linear accelerator and, 97% in those treated with a Cobalt-60 Unit or a 3-MV linear accelerator (P = 0.0173). The local control rate was 43% in the patients with gross anterior commissure invasion and 88% in those without (P = 0.0075). We conclude that low energy photon beams are more suitable for the treatment of early glottic cancers, especially if the lesion grossly invades the anterior commissure.

  • 2113 The results of radiotherapy for T1 glottic cancers; influence of radiation beam energy
    International Journal of Radiation Oncology*Biology*Physics, 1996
    Co-Authors: Michinori Yamamoto, Masahiro Kuroda, Tomio Nakagawa, Katsuyoshi Sakae, Yoshio Hiraki
    Abstract:

    We analyzed the influence of various parameters on the results of radiotherapy for T1 glottic cancer by assessing the outcomes of 60 patients with this cancer who received definitive radiotherapy between 1985 and 1994. Seven patients were treated with a Cobalt-60 Unit, and the other 53 with a linear accelerator (26 patients at 3-MV, 10 at 6-MV, and 17 at 10-MV). Of the 17 patients treated at 10-MV, 4 also received part of their treatment with a Cobalt-60 Unit. The total radiation dose ranged from 56 Gy to 70 Gy (mean, 61 Gy). The total radiation dose of 51 patients (85%) was 60 Gy. The factors found to influence local control were the strength of the radiation beam energy and whether or not there was gross tumor invasion of the anterior commissure. The local control rate was 71% in the patients treated with a 10-MV linear accelerator, 56% in those treated with a 6-MV linear accelerator and, 97% in those treated with a Cobalt-60 Unit or a 3-MV linear accelerator (P = 0.0173). The local control rate was 43% in the patients with gross anterior commissure invasion and 88% in those without (P = 0.0075). We conclude that low energy photon beams are more suitable for the treatment of early glottic cancers, especially if the lesion grossly invades the anterior commissure.

M. W. Johnson - One of the best experts on this subject based on the ideXlab platform.

  • Recommendations for measurement of tray and wedge factors for high energy photons.
    Medical physics, 1994
    Co-Authors: S. C. Sharma, M. W. Johnson
    Abstract:

    Transmission factors for beam modifers such as wedges and blocking trays in dosimetry calculations are very common, but various methods have been used in measuring these factors. A systematic study to measure these factors as a function of field size and point of measurement was carried out. The beam modifiers were a blocking tray and the standard wedges supplied with a Cobalt-60 Unit and a medical electron accelerator (6- and 18-MV x rays). Several points of measurement were selected, using several depths: dmax, TG-21 calibration depth, 10 cm (wedge angle defining depth, ICRU), 15 cm and in-air (miniphantom), and various field sizes. The results show a small field size dependence in these transmission factors with more dependence found in the point of measurement.

A Ciresianu - One of the best experts on this subject based on the ideXlab platform.

  • SU‐F‐T‐530: Characterization of a 60‐Leaf Motorized MLC Designed for Cobalt‐60 Units
    Medical Physics, 2016
    Co-Authors: L Smith, A Ciresianu
    Abstract:

    Purpose: In a continuing effort to improve conformal radiation therapy with Cobalt-60 Units, a 60-leaf MLC was designed, manufactured, and released to market. This work describes the physics measurements taken to characterize the clinical performance of this MLC. Methods: A 60 leaf MLC was custom designed with tungsten leaves of 4.5 cm height, single focused, achieving field size of 30×30 cm^2 when mounted on a 100cm SAD Cobalt-60 Unit. Leakage and output factor measurements were performed using a single ion chamber in a solid water phantom. Penumbra and surface dose were measured using scanning chambers and diodes in a water phantom. Radiation-light coincidence measurements were performed using radiographic films. Results: With MLC mounted, measured penumbras at all depths are smaller than with jaws only. Surface doses were not significantly affected by the presence of MLC, and remained below values recommended by regulatory bodies. Light-radiation coincidences were found to be better than 3 mm for all field sizes. Leakage through the MLC was found to be strongly dependent on field size, increasing from 1.0 % for a 10×10 cm field to 2.0% for a 30×30 cm field. Such results meet the requirements of IEC 60601-2-11. The MLC was found to have significant influence on the output factor, when field size defined by MLC is significantly smaller than field size defined by jaws. Such effect is also observed on linear accelerators, but it is more pronounced on Cobalt-60 Units. A 10×10 “diamond” MLC shape inside a 14×14 cm jaw showed output factor that is 5.7% higher than 10×10 cm field defined by matching MLC and jaws. Conclusion: The MLC offers clinically acceptable performance in penumbra, surface dose, and light-radiation coincidence. Several Units of this MLC have recently been installed and used clinically. Validation of Cobalt-60 based IMRT with this MLC is ongoing. The authors are employees of Best Theratrnics Ltd.

Yoshio Hiraki - One of the best experts on this subject based on the ideXlab platform.

  • The results of radiotherapy for T1 glottic cancers; influence of radiation beam energy.
    Acta medica Okayama, 1999
    Co-Authors: Michinori Yamamoto, Ikuo Joja, Mitsuhiro Takemoto, Masahiro Kuroda, Yoshio Hiraki
    Abstract:

    We analyzed the influence of various parameters on the results of radiotherapy for T1 glottic cancer by assessing the outcomes of 60 patients with this cancer who received definitive radiotherapy between 1985 and 1994. Seven patients were treated with a Cobalt-60 Unit, and the other 53 with a linear accelerator (26 patients at 3-MV, 10 at 6-MV, and 17 at 10-MV). Of the 17 patients treated at 10-MV, 4 also received part of their treatment with a Cobalt-60 Unit. The total radiation dose ranged from 56 Gy to 70 Gy (mean, 61 Gy). The total radiation dose of 51 patients (85%) was 60 Gy. The factors found to influence local control were the strength of the radiation beam energy and whether or not there was gross tumor invasion of the anterior commissure. The local control rate was 71% in the patients treated with a 10-MV linear accelerator, 56% in those treated with a 6-MV linear accelerator and, 97% in those treated with a Cobalt-60 Unit or a 3-MV linear accelerator (P = 0.0173). The local control rate was 43% in the patients with gross anterior commissure invasion and 88% in those without (P = 0.0075). We conclude that low energy photon beams are more suitable for the treatment of early glottic cancers, especially if the lesion grossly invades the anterior commissure.

  • 2113 The results of radiotherapy for T1 glottic cancers; influence of radiation beam energy
    International Journal of Radiation Oncology*Biology*Physics, 1996
    Co-Authors: Michinori Yamamoto, Masahiro Kuroda, Tomio Nakagawa, Katsuyoshi Sakae, Yoshio Hiraki
    Abstract:

    We analyzed the influence of various parameters on the results of radiotherapy for T1 glottic cancer by assessing the outcomes of 60 patients with this cancer who received definitive radiotherapy between 1985 and 1994. Seven patients were treated with a Cobalt-60 Unit, and the other 53 with a linear accelerator (26 patients at 3-MV, 10 at 6-MV, and 17 at 10-MV). Of the 17 patients treated at 10-MV, 4 also received part of their treatment with a Cobalt-60 Unit. The total radiation dose ranged from 56 Gy to 70 Gy (mean, 61 Gy). The total radiation dose of 51 patients (85%) was 60 Gy. The factors found to influence local control were the strength of the radiation beam energy and whether or not there was gross tumor invasion of the anterior commissure. The local control rate was 71% in the patients treated with a 10-MV linear accelerator, 56% in those treated with a 6-MV linear accelerator and, 97% in those treated with a Cobalt-60 Unit or a 3-MV linear accelerator (P = 0.0173). The local control rate was 43% in the patients with gross anterior commissure invasion and 88% in those without (P = 0.0075). We conclude that low energy photon beams are more suitable for the treatment of early glottic cancers, especially if the lesion grossly invades the anterior commissure.

Jose A. Bencomo - One of the best experts on this subject based on the ideXlab platform.