| BackgroundHepatocellular carcinoma cancer is a common malignant tumor. Most patients lose the surgery opportunity when diagnosed HCC. Now radiationtherapy has become a trend of the treatment for HCC, but a high dose may induce radiation-induced liver disease (RILD). In China, about 60% of HCC cancer was caused by hepatitis B virus (HBV) infection. Relevant study showed that HBV infection was associated with RILD. Also, V20, V30 and Dmean were associated with RILD. Three-dimensional conformal (3DCRT), intensity modulated radiotherapy (IMRT) and RapidArc (RA) have been used in HCC. To compare the predicting parameters among 3DCRT, IMRT and RA and evaluate which can maintain more normal liver volume are essencial for HCC.PurposeThe analysis was designed to compare dosimetric parameters among three-dimensional conformal radiotherapy (3DCRT), intensity-modulated radiotherapy (IMRT) and RapidArc (RA) to identify which can achieve the lowest risk of radiation-induced liver disease (RILD) for hepatocellular carcinoma (HCC).MethodsTwenty patients with HCC were selected for our study. Three kinds of treatment planning were made for each patient, including 3DCRT, IMRT and RA. Dosimetric values for 3DCRT, IMRT, and RA were calculated for total dose of 50Gy/25f. There plans were designed by Varian Eclipse version 8.6.23.The dose distribution and protection of organs at risk were evaluated by dose volume histogram (DVH). The evaluation indicators include HI, CI, V95%, V100%, and V110% Dmean and D1%. For normal liver, V5, V10 V20, V30 and V40 were evaluated.Results1. Dose distribution of target volume:(1) RA and IMRT achieved significantly better CI and lower V110% values than 3DCRT (P<0.05).3DCRT had better HI than RA (P=0.041). For V95% and V100%, no significant difference was observed..2. Protection of organs at risk:The mean dose of the normal liver for each plan was 20.57±7.12 Gy for 3DCRT,22.34±7.33 Gy for IMRT, and 20.51±7.12 Gy for RA, IMRT>3DCRT (P=0.045). For low-dose region of V5, RA>IMRT>3DCRT (P<0.05) was observed. For V10, IMRT>RA (P=0.031) was observed. For V20,3DCRT>RA (P=0.012) was observed. For high-dose region V30 and V40,3DCRT>IMRT or RA was observed. For Dmean of stomach, bilateral kidneys and the maximum dose spinal cord received (D1%), there were no significant differences.3. Protection of liver at different diameter:For smaller tumors (D<8cm), no difference was observed among three techniques for Dmean, V20, and V30. For V5 and V10, RA >3DCRT (P= 0.019 and P=0.017) or IMRT (P=0.084 and P=0.08). For larger tumors (D> 8cm), the Dmean of 3DCRT was lower than IMRT (P=0.014) or RA (P=0.026). For V5, V10, V20, and V30, no difference was observed among three techniques.4. Treatment time and monitor units:Compared with 3DCRT and IMRT, RA took significantly less treatment time and monitor units.Conclusion1. Compared with 3DCRT, IMRT and RA can significantly improve target of coverage and uniformity for HCC.2. For right lobe tumors, RapidArc may have the lowest risk of RILD with the lowest V20 and V30 compared with 3DCRT or IMRT.3. For diameters of tumors>8cm in our study, the value of Dmean for 3DCRT was lower than IMRT or RapidArc. This may indicate that 3DCRT is more suitable for larger tumors. |
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