Using Two Fractions per Day in Clinical Radiotherapy of Nasopharyngeal and Non-Small Cell Lung Cancer: A Tentative Isoeffect Dose Calculation Based on the LQ Model and Radiobiological and Clinical Inf

本文以鼻咽癌及非小型細胞肺癌為例，嘗試利用放射生物及文獻中相關之臨床經驗，提出一建議之放射線劑量，以用於臨床上每日照射兩次、每次120及150匣葛雷時之治療方式。作者利用LQ模式及其相關公式，計算理論之等效值並作成二表。表中列出理論上當使用每日照射兩次、每次120或150匣葛雷之治療方式時，所需對應於5000、6000、7000、8000匣葛雷傳統照射方式（每日一次200匣葛雷）之等效劑量。表中分列不同α/β值下（2,3,4,10葛雷）之等效劑量。如兩次照射間隔為六小時，修復半時設定為二小時，則可得到相對之不完全修復因子為0.125；此值並用於修正等效劑量。對鼻咽癌病人之正常組織，每日兩次、每次120匣葛雷之照射，其等效於傳統照射7000匣葛雷之等效劑量為8000匣葛雷。若將文獻中相關之經驗納入考慮，7800匣葛雷似為一合理劑量。有淋巴結轉移之頸部建議用7000-7500匣葛雷，沒有的建議用5500-6000匣葛雷。若使用每日兩次、每次150壓葛雷的照射方式，並考慮文獻中使用每日兩次、每次160匣葛雷之經驗，則對原病灶的合理劑量應為7200匣葛雷。同時由於7200匣葛雷以上述方式照射，所需之治療天數比一日200匣葛雷、總劑量7000匣葛雷之照射方式縮短15天，相當於於900匣葛雷之獲益。至於脊柱之劑量，由於已有臨床及實驗結果顯示，其耐受劑量並未因減低每次照射劑量而昇高，因此建議兩種照射方式下均不宜高於4800壓葛雷。對於非小型細胞肺癌，40-45日內照射6000-6500匣葛雷之傳統照射方式，其對應於每日兩次、每次120匣葛雷之總劑量建議為7000匣葛雷。每日兩次、每次150匣葛雷之照射方式則未在文獻中出現，但6500屢葛雷似為一合理建議，因理論上此劑量至少有相等之腫瘤控制率以及較低之晚期併發症，同時整個療程比傳統方式縮短10-15日。除此兩種方式外，改變每日一次照射之方法甚多，並不僅此例，如先使用120匣葛雷每日兩次於前一半療程、再用150匣葛雷每日兩次於後一半療程。

關鍵字

劑量學；放射腫瘤學；放射治療學

並列摘要

Tentative doses obtained using radiobiological and clinical data are proposed when 120 & 150 cGy bid is used for nasopharyngeal cancer (NPC) & non-small-cell lung cancer (NSCLC). Theoretical isoeffective doses are made into 2 tables using the LQ model and its related formalisms. The tables show the total dose needed using 120 or 150 cGy bid for an equivalent effect of a total dose of 5000, 6000, 7000, & 8000 cGy when given conventionally (200 Gy qd). α/β ratios of 2, 3, 4, and 10 Gy are used for the calculation. A repair half time of 2 hours is adopted and an incomplete repair factor of 0.125 is obtained for correction when a 6-h interfraction interval is used. For the primary tumour of NPC, 8000 cGy given 120 cGy bid is equivalent to 7000 cGy given conventionally for the normal tissue tolerance. When the clinical experience from the literature is considered, a dose of 7800 cGy is suggested. For the neck with and without metastatic nodes, doses of 7000-7500 and 5500-6000 cGy are considered reasonable. When 150 cGy bid is used, a dose of 7200 cGy is recommended for the primary tumour when clinical experience using 160 cGy bid is taken into account. As 7200 cGy given 150 cGy bid is completed 15 days shorter than 7000 cGy given 200 cGy qd, a further therapeutic gain equivalent to a dose of 900 cGy would be available. The dose to the spinal cord is recommended to be no more than 4800 cGy as clinical and experimental data have both shown a lack of increased tolerance of the cord when a small fraction size is given bid or tid. For a conventional dose of 6000-6500 cGy over 40-45 days given to NSCLC, a dose of 7000 cGy using 120 cGy bid is proposed considering the theoretical isoeffective dose and the experience reported. Less clinical literature is available regarding 150 cGy bid for NSCLC patients. A dose of 6500 cGy may be reasonable as it should theoretically give the same tumour control rate, less late complications, as well as a 10-15 days shorter treatment period. Many other ways of altering the dose-fractionation is also possible, e.g., 120 cGy bid followed by 150 bid in the same regimen.

並列關鍵字

Dosimetry ； radiation oncology ； therapeutic radiololy

國際替代計量

Using Two Fractions per Day in Clinical Radiotherapy of Nasopharyngeal and Non-Small Cell Lung Cancer: A Tentative Isoeffect Dose Calculation Based on the LQ Model and Radiobiological and Clinical Inf

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