| Summary: | 博士 === 國立陽明大學 === 生物醫學影像暨放射科學系暨研究所 === 99 === Purpose: To compare the RapidArc for primary hepatocellular carcinoma (HCC) with 3-D conformal radiotherapy (3DCRT) and intensity-modulated radiotherapy (IMRT) plans by using dosimetric analysis.
Methods and Materials: Nine patients with unresectable HCC were enrolled in this study. Dosimetric values for RapidArc, IMRT, and 3DCRT were calculated for 45~50.4 Gy of total dose using 1.8 Gy/day. The parameters included the conformal index (CI), homogeneity index (HI), and hot spot (V107%) for the planned target volume (PTV); the Dmean for the organs at risk. The V40Gy, V30Gy, V20Gy, and V10Gy of the normal liver and the normal tissue complication probability (NTCP) were evaluated.
Results: All three methods achieved comparable homogeneity to the PTV. RapidArc achieved significantly better CI and V107% values than IMRT or 3DCRT (p < 0.05). The MUs were significantly lower for RA (323.8 + 60.7) and 3DCRT (322.3 + 28.6) than for IMRT (1165.4 + 170.7) (p < 0.001). IMRT achieved a significantly lower Dmean of the normal liver than did 3DCRT or RapidArc (p = 0.001). Although the V10Gy to the normal liver was higher with RapidArc than with 3DCRT or IMRT (p < 0.01), the NTCP did not differ significantly between RapidArc (4.38 + 2.69) and IMRT (3.98 + 3.00) and both were better than 3DCRT (7.57 + 4.36) (p = 0.02).
Conclusions: RapidArc could obtain favorable tumor coverage compared with IMRT or 3DCRT, but RapidArc is not superior to IMRT for liver protection. Further investigation of treatment outcomes is warranted.
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