| Summary: | 碩士 === 長庚大學 === 醫學影像暨放射科學系 === 107 === The two-field technique is currently used to treat left sided breast cancer in the proton center of the Chang Gung Memorial Hospital. But studies have shown that using the En face single-field technique with field direction parallel to the patient’s respiratory motion can effectively reduce uncertainty caused by breathing. Therefore, the purpose of this study is to investigate 3D & 4D dose difference between the single-field and the two-field technique to evaluate feasibility of replacing current two-field patient treatment plans by the single-field plans. 12 patients with left sided breast cancers in the proton center of the Chang Gung Memorial Hospital were included in this study. For individual patient, a new En face single-field treatment plan was designed in addition to the existing two-field treatment plan, 3D and 4D dose distribution were obtained for the single and the two-field plans respectively. This study used the 4D dose evaluation system developed previously (involving the CERR and DIRART two research software) to calculate patient’s 4D dose which represents more realistic dose distribution and to assess treatment uncertainty due to respiratory motion. This study also used the Wilcoxon Signed-Rank Test, a non-parametric statistics test, to quantitatively analyze statistical significance of difference between the single and the two-field techniques as well as that between the 3D and the 4D doses. Results of this study showed that comparing to the current two-field technique in the CGMH proton center, the En face single-field technique can achieve the same or better dose distribution whether in 3D or 4D doses. In addition, statistically significant dose differences were also found between the 3D and the 4D doses. Therefore, this study concludes that it is feasible to treat left sided breast cancer using the En face single-field treatment technique.
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