Volumetric intensity-modulated Arc (RapidArc) therapy for primary hepatocellular carcinoma: comparison with intensity-modulated radiotherapy and 3-D conformal radiotherapy

摘要

Background To compare the RapidArc plan for primary hepatocellular carcinoma (HCC) with 3-D conformal radiotherapy (3DCRT) and intensity-modulated radiotherapy (IMRT) plans using dosimetric analysis. Methods Nine patients with unresectable HCC were enrolled in this study. Dosimetric values for RapidArc, IMRT, and 3DCRT were calculated for total doses of 45~50.4 Gy using 1.8 Gy/day. The parameters included the conformal index (CI), homogeneity index (HI), and hot spot (V_107%) for the planned target volume (PTV) as well as the monitor units (MUs) for plan efficiency, the mean dose (D_mean) for the organs at risk (OAR) and the maximal dose at 1% volume (D_1%) for the spinal cord. The percentage of the normal liver volume receiving ≥ 40, > 30, > 20, and > 10 Gy (V_{40 Gy}, V_{30 Gy}, V_{20 Gy}, and V_{10 Gy}) and the normal tissue complication probability (NTCP) were also evaluated to determine liver toxicity. Results All three methods achieved comparable homogeneity for the PTV. RapidArc achieved significantly better CI and V_107% values than IMRT or 3DCRT (p p mean of the normal liver than did 3DCRT or RapidArc (p = 0.001). 3DCRT had higher V_{40 Gy} and V_{30 Gy} values for the normal liver than did RapidArc or IMRT. Although the V_{10 Gy} to the normal liver was higher with RapidArc (75.8 ± 13.1%) than with 3DCRT or IMRT (60.5 ± 10.2% and 57.2 ± 10.0%, respectively; p p = 0.02). Conclusions RapidArc provided favorable tumor coverage compared with IMRT or 3DCRT, but RapidArc is not superior to IMRT in terms of liver protection. Further studies are needed to establish treatment outcome differences between the three approaches.