PubMed日本語 - 子宮頸癌の腔内高線量率近接照射療法の生物効果線量。―QLifePro医療翻訳医療翻訳 QLifePro



Biological effective doses in the intracavitary high dose rate brachytherapy of cervical cancer.

Published date 2011 Dec 30

Biological effective doses in the intracavitary high dose rate brachytherapy of cervical cancer.


Published date



B Arunkumar Sharma, Th Tomcha Singh, L Jaichand Singh, Y Indibor Singh, Y Sobita Devi


Department of Radiotherapy, Regional Cancer Centre, Regional Institute of Medical Sciences, Imphal, India.


PURPOSE: The aim of this study is to evaluate the decrease of biological equivalent dose and its correlation with local/loco-regional control of tumour in the treatment of cervical cancer when the strength of the Ir-192 high dose rate (HDR) brachytherapy (BT) source is reduced to single, double and triple half life in relation to original strength of 10 Ci (∼ 4.081 cGy x m(2) x h(-1)).


MATERIAL AND METHODS: A retrospective study was carried out on 52 cervical cancer patients with stage II and III treated with fractionated HDR-BT following external beam radiation therapy (EBRT). International Commission on Radiation Units and Measurement (ICRU) points were defined according to ICRU Report 38, using two orthogonal radiograph images taken by Simulator (Simulix HQ). Biologically effective dose (BED) was calculated at point A for different Ir-192 source strength and its possible correlation with local/loco-regional tumour control was discussed.


RESULT: The increase of treatment time per fraction of dose due to the fall of dose rate especially in HDR-BT of cervical cancer results in reduction in BED of 2.59%, 7.02% and 13.68% with single, double and triple half life reduction of source strength, respectively. The probabilities of disease recurrence (local/loco-regional) within 26 months are expected as 0.12, 0.12, 0.16, 0.39 and 0.80 for source strength of 4.081, 2.041, 1.020, 0.510 and 0.347 cGy x m(2) x h(-1), respectively. The percentages of dose increase required to maintain the same BED with respect to initial BED were estimated as 1.71, 5.00, 11.00 and 15.86 for the dose rate of 24.7, 12.4, 6.2 and 4.2 Gy/hr at point A, respectively.


CONCLUSIONS: This retrospective study of cervical cancer patients treated with HDR-BT at different Ir-192 source strength shows reduction in disease free survival according to the increase in treatment time duration per fraction. The probable result could be associated with the decrease of biological equivalent dose to point A. Clinical end point of this study is more significant from double half life reduction of original source strength.


目的:本研究の目的は、Ir-192高線量率(HDR)近接照射療法(BT)ソースの強さが10Ci(∼4.081cGyのx m(2)×h(-1))の最初の強さに関して単一、倍のおよび3倍の半減期になるとき、子宮頸癌の治療で腫瘍の局所/局所限局制御で生物学的等価線量とその相関の減少を評価することである。
ICRU報告38によると、放射装置と測定(ICRU)点の上の国際的委員会は、シミュレータ(Simulix HQ)で撮られる2つの直角ラジオグラフ画像を使用して定義された。
26ヵ月以内の疾患再発(局所の/局所限局)の確率は、それぞれ4.081、2.041、1.020、0.510および0.347 cGy x m(2) x h(-1)のソース強さ0.12、0.12、0.16、0.39および0.80として予想される。
最初のBEDに関して同じBEDを維持することを要求される用量増加のパーセンテージは、それぞれ点A 24.7、12.4、6.2および4.2 Gy/hrの線量率のための1.71、5.00、11.00および15.86として推定された。
結果が本研究のA. Clinicalエンドポイントを示すために生物学的等価線量の減少に関連していることがありえた候補は、最初のソース強さの倍の半減期減少から、より有意である。

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