• 1 四川大學華西醫(yī)院放射物理技術中心（成都，610041）; 2 成都市第一人民醫(yī)院腫瘤科;3 四川大學華西醫(yī)院腹部腫瘤科;

【摘要】　目的　 調(diào)強放射治療（IMRT）能較好的保護危及器官并給予腫瘤足夠的致死劑量，基于多葉準直器（MLC）分步照射的IMRT技術對復雜病例需要更多子野。研究對直腸癌術后放射治療使用不同子野數(shù)目的IMRT計劃進行比對，選擇合理的子野數(shù)。　方法　 選取2010年4-8月入院的直腸癌術后患者10例，保持射野入射角度及優(yōu)化目標參數(shù)相同，僅改變MLC子野數(shù)目，設計不同IMRT對每一患者治療計劃的靶區(qū)適形指數(shù)（CI）、均勻性指數(shù)、最大劑量、最小劑量、平均劑量，危及器官關注體積的受照劑量，機器跳數(shù)及治療時間進行分析。　結果　 所有治療計劃中靶區(qū)及危及器官的劑量學評估指標無統(tǒng)計學意義（P gt;0.05），只有亞臨床計劃靶區(qū)（PTV）CI在15個子野的方案中（0.74±0.06）明顯差于25個子野方案（0.82±0.03）、40個子野方案（0.81±0.06）及60個子野方案（0.84±0.03），有統(tǒng)計學意義（P lt;0.05）；治療機器跳數(shù)（MU）隨子野數(shù)目增多明顯增大，15、20、40及60個子野方案所需MU分別為（458±56）、（559±62）、（614±74）、（622±82），有統(tǒng)計學意義（P lt;0.05），但40個子野方案與60個子野方案間無統(tǒng)計學意義。治療時間明顯隨子野數(shù)增加而增大。　結論　 直腸癌術后IMRT計劃使用25個子野能滿足臨床劑量要求，同時能有效降低治療時間，可作為臨床應用參考值。
【Abstract】　Objective　 The intensity modulated radiotherapy (IMRT) can deliver tumor enough doses and protect risk organs as much as possible at the same time. The MLC-based step and shoot IMRT(sIMRT) plan needs much more segment member to meet clinical aims. In this study, several sIMRT plans using different segment number for postoperative rectal cancer were compared to find out the most reasonable segment number setting.　Methods　 Ten patients with rectal carcinoma underwent postoperative adjuvant radiotherapy for rectal cancer from April to August 2010 were selected. For each patient, the angle of field, the prescription expected and the physical parameters optimized were kept the same, while only the number of segments was changed in sIMRT plans. The dose volume histogram-based parameters [conformity index (CI) and homogeneous index (HI)]　 and other parameters concerned were compared and analyzed.　Results　 The indexes of dosimetry associated with the targets and risk organs showed no significant statistical difference among the 4 sIMRT plans with different segment numbers. The index CI of PTV in the sIMRT plan with 15 segments (CI 0.74±0.06) was less than that in the sIMRT plan with 25 segments (CI 0.82±0.03), the sIMRT plan with 40 segments plan (CI 0.81±0.06), and the sIMRT plan with 60 segments (CI 0.84±0.03) (P lt;0.05). There were significant differences in MU among the sIMRT plans with 15 segments (average MU: 458±56) , with 25 segments (average MU: 559±62 ), and with 40 segments (average MU: 614±74)or with the 60 segments (average MU: 622±82 (P lt;0.05). The more segments meant more MU and more irradiation time.　Conclusion　 The sIMRT plan for patients of rectal cancer to receive postoperative adjuvant radiotherapy may require at least 25 segments to balance the accepted dose results and efficient delivering.

引用本文： 蔣曉芹,王武,沈亞麗,許峰,柏森. 子野數(shù)目對直腸癌術后調(diào)強放射治療計劃的影響. 華西醫(yī)學, 2010, 25(12): 2138-2142. doi: 復制

1. 　Greard JP, Chapet O, Nemoz C, et al. Improved sphincter preservation in low rectal cancer with high-dose preoperative radiotherapy: the lyon R96-02 randomized trial[J]. J Clin Oncol, 2004, 22(12): 2404-2409.
2. 　Glimelins B, Cronberg H, Jarhule J, et al. A systematic overview of radiation therapy effects in rectal cancer[J]. Aeta Oncol, 2003, 42(5-6): 477-492.
3. 　姚波, 鄭明民, 王平, 等. 直腸癌五野調(diào)強放療與傳統(tǒng)適形放療劑量學研究[J]. 臨床腫瘤學雜志, 2005, 14(6): 483-486.
4. 　錢立庭, 金大偉, 劉新, 等. 直腸癌術后輔助性放療不同照射技術的劑量學研究[J]. 中華放射腫瘤學雜志, 2006, 15(1): 411-415.
5. 　姚波, 鄭明民, 張艷, 等. 低位直腸術前調(diào)強同步加量并同步口服卡培他濱化療的初步研究[J]. 癌癥進展雜志, 2009, 7(4): 442-447.
6. 　胡逸民. 調(diào)強適形放射治療. 腫瘤放射物理學[M]. 北京: 原子能出版社，1999: 538-572.
7. 　Samuel Hellman. Treatment planning consideration in IMRT. A practical guide to intensity-modulated radiation therapy[M]. WI: Medical Physics publishing Madison, 2003: 103-122.
8. 　Luan S, Saia J, Young M. Approximation algorithm for minimizaing segments in radiation therapy[J]. Inf Proc Lett, 2007, 101(6): 239-244.
9. 　Engel K. A new algorithm for multileaf collimator field segmentation[J]. Discrete Applied Mathematics, 2005, 152(1-3): 35-51.
10. 　伍志紅, 張九堂, 曾彪, 等. 鼻咽癌三種子野方案對調(diào)強放療劑量分布的影響[J]. 醫(yī)學臨床研究, 2009, 26(2): 241-244.
11. 　陳真云, 馬悅冰, 盛修貴, 等. 32例婦科惡性腫瘤術后調(diào)強適形放射治療分析[J]. 中華腫瘤雜志, 2007, 29(4): 3058-308.
12. 　房輝, 李曄雄, 余子豪, 等. 前列腺癌三維適形和調(diào)強放療的初步結果[J]. 中華放射腫瘤學雜志, 2006, 15(3): 197-200.
13. 　袁智勇, 高黎, 徐國鎮(zhèn), 等. 初治鼻咽癌調(diào)強放療的初步結果[J]. 中華放射腫瘤學雜志, 2006, 15(4): 237-243.
14. 　蔡勇, 何玉香, 韓樹奎, 等. 直腸癌盆腔常規(guī)放療與三維適形放療的劑量學研究[J]. 中華放射腫瘤學雜志, 2007, 16(3): 201-205.
15. 　Urbano MTG, Henrys AJ, Adams EJ, et al. Intensity-Modulated radiotherapy in patients with locally advanced rectal cancer reduces volume of bowel treated to high dose levels[J]. Int J Radiat Oncol Biol Phys, 2006, 65(3): 907-916.
16. 　耿輝, 戴建榮, 李曄雄, 等. 一種簡單調(diào)強放療技術應用的初步研究[J]. 中華放射腫瘤學雜志, 2006, 15(1): 411-415.
  1. 1. 　Greard JP, Chapet O, Nemoz C, et al. Improved sphincter preservation in low rectal cancer with high-dose preoperative radiotherapy: the lyon R96-02 randomized trial[J]. J Clin Oncol, 2004, 22(12): 2404-2409.
  2. 2. 　Glimelins B, Cronberg H, Jarhule J, et al. A systematic overview of radiation therapy effects in rectal cancer[J]. Aeta Oncol, 2003, 42(5-6): 477-492.
  3. 3. 　姚波, 鄭明民, 王平, 等. 直腸癌五野調(diào)強放療與傳統(tǒng)適形放療劑量學研究[J]. 臨床腫瘤學雜志, 2005, 14(6): 483-486.
  4. 4. 　錢立庭, 金大偉, 劉新, 等. 直腸癌術后輔助性放療不同照射技術的劑量學研究[J]. 中華放射腫瘤學雜志, 2006, 15(1): 411-415.
  5. 5. 　姚波, 鄭明民, 張艷, 等. 低位直腸術前調(diào)強同步加量并同步口服卡培他濱化療的初步研究[J]. 癌癥進展雜志, 2009, 7(4): 442-447.
  6. 6. 　胡逸民. 調(diào)強適形放射治療. 腫瘤放射物理學[M]. 北京: 原子能出版社，1999: 538-572.
  7. 7. 　Samuel Hellman. Treatment planning consideration in IMRT. A practical guide to intensity-modulated radiation therapy[M]. WI: Medical Physics publishing Madison, 2003: 103-122.
  8. 8. 　Luan S, Saia J, Young M. Approximation algorithm for minimizaing segments in radiation therapy[J]. Inf Proc Lett, 2007, 101(6): 239-244.
  9. 9. 　Engel K. A new algorithm for multileaf collimator field segmentation[J]. Discrete Applied Mathematics, 2005, 152(1-3): 35-51.
  10. 10. 　伍志紅, 張九堂, 曾彪, 等. 鼻咽癌三種子野方案對調(diào)強放療劑量分布的影響[J]. 醫(yī)學臨床研究, 2009, 26(2): 241-244.
  11. 11. 　陳真云, 馬悅冰, 盛修貴, 等. 32例婦科惡性腫瘤術后調(diào)強適形放射治療分析[J]. 中華腫瘤雜志, 2007, 29(4): 3058-308.
  12. 12. 　房輝, 李曄雄, 余子豪, 等. 前列腺癌三維適形和調(diào)強放療的初步結果[J]. 中華放射腫瘤學雜志, 2006, 15(3): 197-200.
  13. 13. 　袁智勇, 高黎, 徐國鎮(zhèn), 等. 初治鼻咽癌調(diào)強放療的初步結果[J]. 中華放射腫瘤學雜志, 2006, 15(4): 237-243.
  14. 14. 　蔡勇, 何玉香, 韓樹奎, 等. 直腸癌盆腔常規(guī)放療與三維適形放療的劑量學研究[J]. 中華放射腫瘤學雜志, 2007, 16(3): 201-205.
  15. 15. 　Urbano MTG, Henrys AJ, Adams EJ, et al. Intensity-Modulated radiotherapy in patients with locally advanced rectal cancer reduces volume of bowel treated to high dose levels[J]. Int J Radiat Oncol Biol Phys, 2006, 65(3): 907-916.
  16. 16. 　耿輝, 戴建榮, 李曄雄, 等. 一種簡單調(diào)強放療技術應用的初步研究[J]. 中華放射腫瘤學雜志, 2006, 15(1): 411-415.