本文選題：擺位誤差　切入點：體重指數(shù)　出處：《蘇州大學》2010年碩士論文

【摘要】： 目的:應用機載千伏級CBCT監(jiān)測鼻咽癌調(diào)強放療患者療程中擺位誤差的變化和影響因素,分析擺位誤差對物理劑量的影響,以達到減少和/或消除擺位誤差對放療的影響。 方法:本實驗選取病理學確診的鼻咽癌早期患者15例,行調(diào)強放療�；颊呙恐馨粗委熡媱潣酥军c擺位,利用機載KV-CBCT掃描獲取擺位誤差,將擺位誤差代入治療計劃,模擬出未使用IGRT時,實際擺位位置中劑量分布情況。計算在相同治療階段所有患者三維線性方向和水平面旋轉(zhuǎn)方向擺位誤差平均值、標準差及95%可信區(qū)間(CI);分析隨療程進行擺位誤差的變化情況;探討體重指數(shù)和體重變化對擺位誤差的影響;研究不同方向的擺位誤差對危及器官劑量影響;分析三維移動矢量和旋轉(zhuǎn)誤差對靶區(qū)劑量影響,并探討本科室鼻咽癌患者靶區(qū)外放邊界范圍。 結(jié)果:患者在腹背、頭腳、左右三個坐標軸和水平面旋轉(zhuǎn)方向的擺位誤差均值分別為-0.1833cm、-0.0322cm、0.0967cm和-0.8333°,95%的可信區(qū)間分別為[-0.2117cm,-0.1549cm],[-0.0768cm,0.0124cm],[0.0563cm,0.1371cm]和[-1.0987°,-0.5687°]。隨療程進行,擺位中心點向腹側(cè)偏移。BMI≥25患者在左右方向及水平面旋轉(zhuǎn)方向首次擺位誤差絕對值較BMI25患者明顯增大;BMI≥25患者在左右方向及水平面旋轉(zhuǎn)方向的系統(tǒng)誤差較BMI25患者明顯;患者體重下降會引起擺位中心點往腹側(cè)偏移和水平面逆時針旋轉(zhuǎn)。擺位中心點向背側(cè)偏移0.2cm,腦干D1和脊髓D1cc增高率均值分別為6.58%和4.70%,擺位中心點向頭側(cè)偏移0.2cm,視交叉D1增高率均值為8.94%,擺位中心點向左側(cè)偏移0.2cm,同側(cè)腮腺D50增高率均值為4.95%。CTV2 D95、GTVnd D98與三維移動矢量和旋轉(zhuǎn)誤差有相關性(P0.05,|r|0.4);CTV1 D95和GTVnx D98與旋轉(zhuǎn)誤差無明顯相關性(P0.05);而GTVnx D98與三維移動矢量無明顯相關性(P=0.077,|r|=0.187)。BMI≥25患者各個方向的MPTV值較BMI25患者明顯增大。 結(jié)論:在鼻咽癌調(diào)強放療中:1、BMI≥25患者有必要進行自適應放療;2放療療程中體重減少超過7.10%時,需要及時調(diào)整放療計劃;3、擺位中心點偏移應盡量控制在0.2cm以內(nèi);4、GTVnd和CTV2劑量較GTVnx、CTV1劑量對線性誤差和旋轉(zhuǎn)誤差敏感;5、BMI≥25患者可通過機載千伏級CBCT在線或離線糾正擺位誤差,縮小CTV至PTV外放邊界而獲益。
[Abstract]:Objective: to monitor the changes and influencing factors of positioning error in the course of intensity modulated radiotherapy for nasopharyngeal carcinoma (NPC) by airborne kilovolt CBCT, and to analyze the effect of pendulum error on physical dose in order to reduce and / or eliminate the effect of pendulum error on radiotherapy. Methods: fifteen patients with early stage nasopharyngeal carcinoma diagnosed by pathology were selected and received intensity modulated radiotherapy. The patients were placed weekly according to the treatment plan. The positioning error was obtained by airborne KV-CBCT scan, and the positioning error was substituted into the treatment plan. The dose distribution in the actual pendulum position was simulated when IGRT was not used. The mean value of three dimensional linear direction and horizontal rotation direction pendulum error were calculated for all patients in the same treatment stage. The standard deviation and 95% confidence interval (CI) were analyzed, the effects of body mass index (BMI) and body mass change on the pendulum error were discussed, and the effects of different directions on organ dose were studied. The effects of 3D moving vector and rotation error on target dose were analyzed, and the boundary range of target area extravasation in nasopharyngeal carcinoma patients was discussed. Results: the mean values of pendulum error in the rotation direction of the three axes and horizontal plane were -0.1833 cm ~ (-1) -0.0322 cm ~ (-1) and -0.8333 擄~ 95% confidence interval [-0.2117 cm ~ (-1) -0.1549 cm], [-0.0768 cm ~ 0.0124 cm], [0.056 3 cm ~ 0.1371 cm] and [-1.0987 擄-0.5687 擄], respectively. The absolute value of the first pendulum error in the left and right direction and horizontal rotation direction in the patients with center point deviation to the ventral side. BMI 鈮，

本文編號：1663129