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論文(リポジトリ)

論文(リポジトリ)
斎藤, 眞理 ; 清野, 康夫 ; 植松, 孝悦 ; 栗田, 雄三 ; 横山, 晶
出版情報: 新潟医学会雑誌 — 新潟医学会雑誌.  109  pp.332-337,  1995-07.  新潟医学会
本文リンク: http://hdl.handle.net/10191/42515
概要: In comparison with operation, we observed more recurrence after external beam radiotherapy for roentogenographically occ ult lung cancer. Then, since July 1991, we have treated that lung cancer, with external beam radiotherapy and intraluminal afterloading irradiation using ^<192>Iridium thin wire. The indication of this method is roentogenographically occult lung cancer, diagnosed inoperable for their respiratory function, age, and complications, and for refusal of operation. Up to Sept. 1994, 36 patients (44 lesions) were treated by this method. The follow-up period ranged from 0 to 41 months. Recurrence occured in 2 cases on whom an operation was done:one is well and the other is alive with disease. Radiation pneumonitis required treatment was observed in another 2 cases. Other recurrence or severe complications from irradiation have not been observed. We think this treatment is effective for roentogenographically occult lung cancer. 続きを見る
2.

論文(リポジトリ)

論文(リポジトリ)
笹本, 龍太
出版情報: 新潟大学保健学雑誌 — 新潟大学保健学雑誌.  15  pp.57-65,  2018-03.  新潟大学医学部保健学科
本文リンク: http://hdl.handle.net/10191/49819
概要: 放射線治療計画における計画標的体積(PTV)は,照射位置のばらつきによる等線量曲線の偏位を補償するための余白(PTVマージン)を,腫瘍細胞の存在範囲に加えることで作成する.今回,必要なPTVマージンの値に照射野の形状が及ぼす影響を検討するこ とを目的に,van Herkの理論値(正確法,近似法)の妥当性を検討した.部分的に凸形~凹形を有する7種類の照射野を作成し,照射方向は対向2門,4 MV X線と10 MV X線でそれぞれ線量分布を計算した.線量分布にばらつきを加える数値シミュレーションを行い,等線量曲線(処方線量の95%)の偏位を理論値と比較した.正確法は照射野辺縁が平坦な場合はシミュレーションと一致したが,照射野の凹凸が大きくなると不一致が見られた.近似法は多くの場合不一致が見られたが,不一致の範囲は正確法より小さかった.PTVマージンの算出に際しては,照射野形状の考慮が必要である.<br />The planning target volume (PTV) on the radiotherapy plan is created by adding a margin (PTV margin) to the volume in which tumor cells spread, for compensating the deviation of the isodose curve due to geometrical uncertainties. In this study, the validity of van Herk's theoretical value (precise method, approximation method) was evaluated for the purpose of examining the impact of the irradiation field shape on necessary PTV margin value. Seven types of irradiation fields with partially convex to concave shapes were prepared, and the dose distributions were calculated with the parallel opposed fields, using 4 MV X-ray and 10 MV X-ray data. Numerical simulation was carried out to add geometrical uncertainties to the dose distribution, and the deviation of the isodose line (95% of the prescribed dose) was compared with the theoretical value. The precise method was consistent with the simulation when the edge of the irradiated field was flat, but inconsistency was observed when the irregularities of the irradiation field was increased. Although the approximation method was found to be inconsistent in many cases, the range of inconsistency was smaller than that of the precise method. When calculating the PTV margin, the influence of the irradiation field shape should be taken into account. 続きを見る
3.

論文(リポジトリ)

論文(リポジトリ)
笹本, 龍太 ; 宇都宮, 悟 ; 早川, 岳英
出版情報: 新潟大学保健学雑誌 — 新潟大学保健学雑誌.  14  pp.9-15,  2017-03.  新潟大学医学部保健学科
本文リンク: http://hdl.handle.net/10191/47192
概要: 放射線治療の呼吸同期照射において,同期信号の発生からビームオン・オフまでには遅延時間(time\ndelay)がある.今回,time delayの計測に適した動体ファントムの運動パターンと,新潟大学医歯学総合病院の呼吸同期照射システムにおけ るtime delayを明らかにすることを目的として検討を行った.動体ファントムの運動波形はサイン波形と等速波形とし,運動幅は30 mmとした.ラジオクロミックフィルムを動体ファントムに乗せ,直径4 mm coneで連続照射を行ったところ,フィルム上の照射陰影はサイン波形で31.7±0.2mm,等速波形で30.4±0.1 mmであり,等速波形の方が実際の運動幅に近く,測定精度が高かった.次に等速波形を用いた10-40%位相の同期照射を行い,照射陰影の長さを理論値と比較したところ,time delayはビームオンで0.11±0.01秒,ビームオフで0.07±0.00秒であった.<br />In respiratory gated radiotherapy, there are time delays between the target entering the gated region and treatment beam on, and between the target exiting the gated region and treatment beam off. The aim of this study was to clarify the appropriate motion profile of motion phantom for measuring the time delays, and to measure the beam on and beam off time delays in respiratory gated radiotherapy system at Niigata University Medical and Dental Hospital. We irradiated radiochromic films on the motion phantom using 4 mm diameter cone without gating. As a motion profile for the motion phantom (motion width: 30.0 mm), a sinusoidal profile and a constant velocity profile ware used. Measured length of the exposure streaks on the films were more accurate with the constant velocity profile than those with the sinusoidal profile (30.4±0.1 mm vs. 31.7±0.2 mm). Then we used the constant velocity profile for gating irradiation with a gating phase range of 10-40%, and compared the exposure streak length with a theoretical value. The calculated beam on time delay was 0.11±0.01 sec, and the beam off time delay was 0.07±0.00 sec. 続きを見る