Superiority Of Helical Tomotherapy On Liver Sparing And Dose Escalation In Hepatocellular Carcinoma

PurposeTo compare the difference of liver sparing and dose escalation among three-dimensional conformal radiotherapy(3DCRT),intensity-modulated radiotherapy(IMRT)and helical tomotherapy(HT)in hepatocellular carcinoma(HCC)radiotherapy.Exploring the characteristic of dose distribution and advantages of HT in the treatment of HCC to provide evidence for selecting optimal clinical solution.MethodsSixteen CT scan images of unresectable HCC patients in our hospital were selected and transferred to Eclipse Version 8.6.23 and TomoH? Version 2.0.1 planning system.The target volume and organs at risk(OARs)were re-outlined manually and 3DCRT,IMRT and HT plans were also redesigned for each patient.The dose distribution in target volume and OARs was evaluated based on prescription dose at 50 Gy/25 fractions.Then prescription dose was escalated using HT or IMRT independently by a gradient of 2 Gy until either the prescription dose reached to 70 Gy or any normal tissue reached the dose limit according to quantitative analysis of normal tissue effects in the clinic criteria(QUANTEC).Results1.The conformity index(CI)of 3DCRT was lower than that of IMRT(P < 0.001)or HT(P < 0.001),and the CI was similar between the IMRT and HT.The mean value of homogeneity index(HI)of 3DCRT was higher by 4.50% and 1.85% than that of IMRT and HT(P < 0.05).There was no statistically significant difference between the IMRT and the HT groups(P = 0.28).2.HT had lower Dmean(mean dose)and V20(Vn: the percentage of organ volume receiving ? n Gy)of liver compared with 3DCRT(P = 0.005,P = 0.005)or IMRT(P = 0.508,P = 0.007).For Dmean of NTNL(non-target normal liver)and V30 of liver,the value of 3DCRT was higher than that of IMRT(P = 0.005,P = 0.005)or HT(P = 0.005,P = 0.005).3.For V50%(fraction of normal liver treated to at least 50% of the isocenter dose)of the normal liver,there was a significant difference: 3DCRT > IMRT > HT(P < 0.001).There were seven patients in IMRT(43.75%)and nine patients in HT(56.25%)that isodose could reach to 70 Gy with meeting the dose limit of the OARs.ConclusionThe CI and HI of IMRT and HT were superior than that of 3DCRT in the radiotherapy of HCC.Compared with IMRT,HT may provide significantly better liver sparing and made more patients achieve higher prescription dose in HCC radiotherapy with meeting the target CI and HI.