發(fā)布時間：2018-04-27 05:36

  本文選題：高能光子 + 劑量驗證��； 參考：《蘇州大學》2013年碩士論文

【摘要】：精確放療是現(xiàn)代腫瘤放射治療的發(fā)展趨勢，是提高腫瘤放療治愈率與減少放療副作用或并發(fā)癥的關鍵技術。而照射劑量的精確驗證是制定精確放療計劃、提高放療增益比及實施精確放療的重要環(huán)節(jié)。目前基于透射劑量分布的驗證方法尚不成熟，且無法實現(xiàn)三維實時劑量驗證。隨著新一代醫(yī)用跑道式電子回旋加速器MM50的出現(xiàn)，以及PET在重離子加速器治療過程的應用，使得利用PET成像技術開展劑量實時驗證成為可能。項目利用MM50電子回旋加速器和PET裝置開展了高能光子放射治療的三維劑量驗證實驗，并模擬計算了高能掃描光子束的性能和劑量分布，系統(tǒng)地研究了高能光子在模體材料中產(chǎn)生正電子核素的光核反應產(chǎn)額、正電子核素活度分布與劑量分布，分析討論了利用正電子核素斷層成像開展劑量驗證驗證的臨床可行性。 論文根據(jù)新一代跑道式電子回旋加速器MM50的機頭構造和射束特點，利用Monte Carlo程序模塊建立MM50加速器機頭結構模型，通過模擬計算和水箱測量，，分析了不同類型射野的射束特征和劑量分布。結果表明MM50高能掃描射線均整性和對稱性良好，均在5%以內(nèi)，半影為8mm，模擬和測量結果相符。 根據(jù)高能光子產(chǎn)生~(11)C和~(15)O正電子核素的光核反應相關理論及光中子反應的反應截面數(shù)據(jù)，制作了水凝膠、聚乙烯和不均勻模體等三種實驗模體。利用TPS及模擬軟件計算了MM50加速器的高能X射線束在不同模體中的劑量分布。 在25MV和50MV兩種X線能量條件下開展劑量的PET三維劑量驗證實驗，利用MM50所產(chǎn)生的X射線分別照射三種模體并即時進行PET掃描，通過對比模體中正電子活度分布及劑量分布研究PET劑量驗證的可行性。實驗結果表明，對于高能光子放療，50MV X線照射2Gy產(chǎn)生的正電子活度可達MBq數(shù)量級，可實現(xiàn)PET清晰成像；50MV X線產(chǎn)生的~(11)C和~(15)O正電子數(shù)量分別為25MV的3.86和3.88倍；三種模體中正電子三維分布和劑量分布相似。另外對小動物和病例開展了實驗，并與模體進行了對比分析，結果表明高能光子放療的PET劑量驗證是準確可行的。
[Abstract]:Accurate radiotherapy is the development trend of modern tumor radiotherapy. It is the key technology to improve the cure rate and reduce the side effects or complications of radiotherapy. The accurate verification of radiation dose is an important step in making accurate radiotherapy plan, improving the gain ratio of radiotherapy and carrying out accurate radiotherapy. At present, the verification method based on transmission dose distribution is not mature, and can not realize 3D real-time dose verification. With the emergence of a new generation of medical racetrack electron cyclotron (MM50) and the application of PET in the treatment process of heavy ion accelerator, it is possible to use PET imaging technology to carry out real-time dose verification. The three dimensional dose verification experiment of high energy photon radiation therapy was carried out by using MM50 electron cyclotron and PET device, and the performance and dose distribution of high energy scanning photon beam were simulated and calculated. The photoreaction yield, activity distribution and dose distribution of positron nuclides produced by high-energy photons in motifs are systematically studied. The feasibility of dose verification using positron radionuclide tomography is analyzed and discussed. According to the configuration and beam characteristics of the new generation racetrack electron cyclotron (MM50), the model of the MM50 accelerator's head structure is established by using the Monte Carlo program module. The model is simulated and measured by water tank. The beam characteristics and dose distribution of different types of field are analyzed. The results show that the uniformity and symmetry of MM50 high energy scanning rays are all within 5% and the penumbra is 8 mm. The simulation results are in good agreement with the measured results. According to the theory of photonuclear reaction and the cross section data of photoneutron reaction, three experimental motifs, hydrogel, polyethylene and inhomogeneous motifs, have been prepared according to the theory of photo-nuclear reaction of high-energy photonic radionuclides (11 ~ (11) C) and ~ (15) O ~ (15) O positron nuclides. The dose distribution of high energy X-ray beam of MM50 accelerator in different motifs was calculated by TPS and simulation software. Three dimensional dose verification experiments of PET were carried out under the condition of 25MV and 50MV X-ray energy. The three kinds of motifs were irradiated by X ray produced by MM50 and PET scanning was carried out immediately. The feasibility of PET dose verification was studied by comparing positron activity distribution and dose distribution in motifs. The experimental results show that the positron activity of 2Gy irradiated by 50MV X-ray of high energy photon radiation can reach the order of MBq, and the positron number produced by 50 MV X-ray of PET imaging can be 3.86 times and 3.88 times of that of 25MV, respectively. The three-dimensional distribution and dose distribution of positron in the three kinds of motifs are similar. In addition, experiments were carried out on small animals and cases, and the results were compared with those of motifs. The results show that the PET dose verification of high energy photon radiation is accurate and feasible.
【學位授予單位】：蘇州大學
【學位級別】：碩士
【學位授予年份】：2013
【分類號】：R730.55

【參考文獻】

相關期刊論文 前2條

1 張圈世,楊亮,張木,R.Joyner,D.Thenberg;MM50加速器一維掃描調(diào)強的研究[J];中國醫(yī)學物理學雜志;2005年02期

2 周鸞杰;宋傳軍;周寶林;;跑道式醫(yī)用電子回旋加速器的原理[J];醫(yī)療衛(wèi)生裝備;2007年11期

本文編號：1809438