Comparison of Internal Target Volumes for Hepatocellular Carcinoma Defined Using 3DCT with Active Breathing Coordinator and 4DCT

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Abstract

The aim of this paper is to study the feasibility for determining the individual internal target volume (ITV) for hepatocellular carcinoma (HCC) using 3DCT associated with active breathing coordinator (ABC), comparing the ITVs defined by 3DCT associated with ABC and 4DCT. Thirteen patients with HCC after transarterial chemoembolization (TACE) treatment underwent 4DCT simulation and 3DCT simulation associated with ABC in free breathing (FB), end inspiration hold (EIH) and end expiration hold (EEH). The 4DCT images were sorted into 10 phases according to the respiratory cycle and labeled as CT0, CT10…CT90; and CTMIP (the maximum intensity projection image) was reconstructed. GTV0, GTV10…GTV90, GTVMIP on 4DCT, and the GTVFB, GTVEIH, GTVEEH on 3DCT were contoured. GTV0,10…90, GTV0 and GTV50, GTVEIH and GTVEEH were merged into ITV1, ITV2 and ITV3. The individual margins from GTVFB to ITV1–3 were obtained and applied to ITVFB (labeled as ITVFB-1 ITVFB-2 ITVFB-3), respectively. All the target volumes were normalized by ITV1. The volume of GTVs, ITVs and the margins were compared. There was no significant difference of diaphragm mobility between 4DCT and 3DCT (P > 0.05), nor significant difference among the volume of the GTVs. The three ITVs were larger than the GTVMIP (P < 0.05), but there was no significant difference among three ITVs. It's similar to the differences both in the margins of three dimensions from GTVFB to ITV1–3 and in the volumes among ITVFB-1 ITVFB-2 and ITVFB-3 (P > 0.05). This study shows that it's safe and feasible to determine the individual ITV for HCC using 3DCT associated with ABC in comparison with 4DCT.

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