臺灣博碩士論文加值系統

在現有的治療計畫演算系統中，對高密度物質的劑量演算能力均有所限制，此限制降低了含有假牙補綴物的頭頸部病患其劑量的準確度。而近幾年，在頭頸部體外放射治療中，RapidArc治療的使用愈來愈普及，因此本平台建立的目的即是試圖利用蒙地卡羅方法對不均質物質計算的準確性來評估假牙補綴物對於使用RapidArc治療的頭頸部病患劑量的影響。
　　本平台的建立是以現有的MC-Arc系統為基礎，驗證確認其模擬結果準確可信後，再增加原系統功能，對CT影像中的假牙CT number做修正，使假牙可以正確轉換為蒙地卡羅計算所使用的模擬假體，以得到準確的劑量模擬結果。並在假體轉換前刪除影像中的電腦斷層模擬床，以避免其在PA角度造成射束衰減影響模擬結果。最後再將劑量模擬結果與治療計畫系統的劑量演算結果進行比較，建立出新的MC-ArcII系統，以評估假牙補綴物對劑量的影響。
　　本平台在MC-Arc系統的均質假體驗證模擬中，包括一組頭頸部假體及三組軀幹假體，其二維等劑量曲線與TPS相較的Gamma test分別為99.99%及99.98%，99.48%，94.64%，顯示其劑量模擬結果準確可信。另外，未刪除電腦斷層模擬床的均質假體模擬結果亦顯示電腦斷層模擬床在PA角度對劑量模擬有超過6%的影響。而MC-ArcII系統建立時所選的臨床病患治療計畫，經過刪除電腦斷層模擬床，並使用修正假牙CT number的轉換假體進行劑量模擬，所得的模擬結果表現出金屬假牙附近有明顯的劑量差異，但在GTV的劑量則無明顯不同。此與Chin等人的研究結論相似，即超過等效水厚度3~5 mm的距離之後金屬假牙將不會造成劑量影響。
　　透過本平台所選臨床病患治療計畫的模擬結果顯示，MC-ArcII系統確實可用於評估假牙補綴物對劑量的影響。且其模擬結果明顯證明在金屬假牙附近的組織劑量確實會受到影響。但此個案的評估結果並無法代表所有假牙病患的情況，需要收集更多研究數據才能針對假牙補綴物對病患劑量的影響提出富統計意義的建議。

Until now, all the treatment planning systems (TPS) have limitation on dose calculation accuracy for head and neck patients with dental restoration and prostheses. As the use of RapidArc treatment increases, dose impact of dental restoration and prostheses on head and neck patients becomes an issue. The purpose of the current study is to build a Monte Carlo based dose simulation system to take advantage of its ability in evaluating dose impact from highly heterogeneous tissue composition such as dental restoration and prostheses. This dose evaluation system is established through extending functions of an existing MC-Arc system and renamed as the MC-ArcII system.
Before these extended functions can be added, accuracy of the original MC-Arc system was re-verified in homogeneous phantoms. One RapidArc plan was created in a head and neck phantom. In addition, three clinical patient plans were implemented on a torso phantom and isodose distributions re-calculated to be compared to those from the Eclipse treatment planning system. For the new MC-ArcII system, extended functions include processing of patient CT images to eliminate CT tables and adding a virtual treatment couch to better coincide with the real treatment condition. The system also modifies its CT number to material conversion function to include those high density materials for dental restoration and prostheses. One clinical head and neck case was simulated and the result compared to that from the Eclipse TPS to evaluate the dose impact.
Verification results of the MC-Arc system in homogeneous phantoms showed high passing rates of 2D Gamma test with 99.99%, 99.98%, 99.48%, and 94.64% for the four test cases, respectively. Furthermore, simulation result showed maximum 6% dose difference with/without the CT table when comparing isocenter doses for open PA fields. For evaluation of the head and neck case with dental restoration and prostheses, the result showed ignorable dose impact on dose distribution near the GTV. It, however, demonstrated strong influence for doses surrounding the high density filling. The result is compatible with that reported by Chin et al which suggests minimum dose impact for region outside 3-5 mm water equivalent thickness.
In conclusion, the MC-ArcII system successfully demonstrates its ability in evaluating dose impact of dental restoration and prostheses for the test case. However, more patient cases must be studied in the future to draw any statistically significant result.

指導教授推薦書…………………………………………………………
論文口試委員審定書……………………………………………………
國家圖書館授權書………………………………………………………iii
長庚大學授權書…………………………………………………………iv
誌謝………………………………………………………………………v
中文摘要……………………………………………………………… vi
英文摘要…………………………………………………………… viii
目錄………………………………………………………………………x
圖目錄……………………………………………………………… xiii
表目錄…………………………………………………………………xvi
第1章 緒論…………………………………………………………… 1
1.1 前言…………………………………………………………… 1
1.2 文獻回顧……………………………………………………… 3
1.3 研究目的……………………………………………………… 9
第2章 材料與方法…………………………………………………… 10
2.1 研究架構……………………………………………………… 10
2.2 MC-Arc system驗證………………………………………… 11
2.2.1 蒙地卡羅/絕對劑量轉換因子……………………… 12
2.2.2 開放照野劑量驗證………………………………… 14
2.2.3 弧形治療計畫均質假體劑量驗證………………… 15
2.3 MC-ArcII system建立………………………………………16
2.3.1 治療床射束衰減修正……………………………… 17
2.3.1.1 刪除電腦斷層模擬床………………………… 18
2.3.1.2 置入TPS虛擬治療床………………………… 19
2.3.2 高密度假牙及補綴物不均質處理…………………21
2.3.2.1 假牙及補綴物的圈選及修正………………… 21
2.3.2.2 修正假體轉換的CT-density ramp………… 22
2.3.2.3 模擬含有假牙補綴物假體的劑量分布……… 24
2.3.3 劑量評估軟體(evaluation.m)的功能增強………24
第3章 結果………………………………………………………… 26
3.1 蒙地卡羅/絕對劑量轉換因子………………………………26
3.2 開放照野劑量……………………………………………… 27
3.3 弧形治療計畫均質假體劑量……………………………… 28
3.4 刪除電腦斷層模擬床……………………………………… 33
3.5 置入TPS虛擬治療床 ………………………………………34
3.6 假牙及補綴物的CT number修正………………………… 35
3.7 含有假牙補綴物的CT影像轉換假體………………………36
3.8 修正假牙及補綴物後的模擬結果………………………… 36
第4章 討論與結論………………………………………………… 41
參考文獻………………………………………………………………43
附錄一：DelCouchII.m………………………………………………47
附錄二：AddVirtualCouch.m…………………………………………55
附錄三：mouseROI.m……………………………………………………67
附錄四：assignROI.m…………………………………………………72
附錄五：exportROI.m…………………………………………………79
附錄六：evaluationII.m………………………………………………80
附錄七：readdoseMedia.m……………………………………………86
附錄八：contourringII.m……………………………………………87
附錄九：isocompII.m…………………………………………………94
附錄十：gammaII.m……………………………………………………100
附錄十一：dvhcompII.m………………………………………………102
圖1-1a: 使用四種物質與五種物質的CT-density ramp其模擬結果的深度劑量比較 [10]………………………………………………………7
圖1-1b: 使用四種物質與五種物質的CT-density ramp其模擬結果的DVH比較 [10]…………………………………………………………8
圖2-1: 研究架構………………………………………………………10
圖2-2: 參考設定示意圖………………………………………………13
圖2-3: 電腦斷層模擬床及TPS虛擬治療床對劑量影響的模擬條件示意圖 ……………………………………………………………………18
圖2-4: TPS虛擬治療床幾何配置及CT number……………………20
圖2-5: 使用者透過滑鼠點選方式定義出假牙範圍…………………22
圖2-6: XYZ座標方向示意圖…………………………………………25
圖3-1: 模擬結果的3ddose檔案原始劑量紀錄………………………26
圖3-2: CF換算後的模擬結果與TPS百分深度劑量曲線比較………27
圖3-3: 開放照野劑量--模擬結果與TPS的等劑量曲線比較………27
圖3-4a: 頭頸部假體劑量--模擬結果與TPS的等劑量曲線比較…28
圖3-4b: 頭頸部假體劑量--模擬結果與TPS的Gamma test評估結果.28
圖3-5a: 頭頸部假體劑量--模擬結果與TPS的X-profile比較……29
圖3-5b: 頭頸部假體劑量--模擬結果與TPS的Y-profile比較……30
圖3-5c: 頭頸部假體劑量--模擬結果與TPS的Z-profile比較……30
圖3-6: 頭頸部假體劑量--模擬結果與TPS的DVH比較…………30
圖3-7a: 軀幹假體劑量1--模擬結果與TPS的等劑量曲線比較……31
圖3-7b: 軀幹假體劑量1--模擬結果與TPS的X-profile比較……32
圖3-7c: 軀幹假體劑量1--模擬結果與TPS的Y-profile比較……32
圖3-7d: 軀幹假體劑量1--模擬結果與TPS的Z-profile比較……32
圖3-8: 軀幹假體劑量1-3--模擬結果與TPS的Gamma test評估結果.33
圖3-9: 密度確認刪除電腦斷層模擬床結果…………………………34
圖3-10: 密度確認加入TPS虛擬治療床結果………………………35
圖3-11: 假牙的CT number修正結果………………………………35
圖3-12: 物質編碼確認含假牙的假體 (物質編碼6=假牙)………36
圖3-13: 病患假體劑量--模擬結果與TPS的等劑量曲線比較……37
圖3-14a: 病患假體劑量--模擬結果與TPS的X-profile比較 (GTV)……………………………………………………………………38
圖3-14b: 病患假體劑量--模擬結果與TPS的Y-profile比較 (GTV)……………………………………………………………………38
圖3-14c: 病患假體劑量--模擬結果與TPS的Z-profile比較 (GTV)……………………………………………………………………38
圖3-15a: 病患假體劑量--模擬結果與TPS的X-profile比較 (假牙)………………………………………………………………………39
圖3-15b: 病患假體劑量--模擬結果與TPS的Y-profile比較 (假牙)………………………………………………………………………39
圖3-15c: 病患假體劑量--模擬結果與TPS的Z-profile比較 (假牙)………………………………………………………………………39
圖3-16: 病患假體劑量--模擬結果與TPS的DVH比較……………40
表1-1: MC-Arc 系統使用的CT-density ramp及阻擋本領 [10]…… 6
表2-1: 均質假體的治療計畫參數……………………………………15
表2-2: 金屬假牙樣品物質組成及比例(Degubound®4) [15] ……… 23
表2-3: MC-ArcII使用的六種物質CT-density ramp……………… 23
表3-1: 治療中心點劑量評估電腦斷層模擬床及治療系統附屬治療床的影響的影響………………………………………………………… 34

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