Hepatic arterial phase and portal venous phase computed tomography for dose calculation of stereotactic body radiation therapy plans in liver cancer: a dosimetric comparison study

Jianghong Xiao,Nianyong Chen,Fraser Henderson Jr,Guangjun Li,Yongsheng Wang,Xiaoqin Jiang,Lan Sun,Yan Li,Qingfeng Jiang

doi:10.1186/1748-717x-8-264

Jianghong Xiao, Nianyong Chen + Show 7 more

Open Access

https://doi.org/10.1186/1748-717x-8-264

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Journal: Radiation Oncology	Publication Date: Nov 9, 2013
Citations: 22	License type: cc-by

Affiliation: Sichuan University, University of Virginia

Abstract

PurposeTo investigate the effect of computed tomography (CT) using hepatic arterial phase (HAP) and portal venous phase (PVP) contrast on dose calculation of stereotactic body radiation therapy (SBRT) for liver cancer.MethodsTwenty-one patients with liver cancer were studied. HAP, PVP and non-enhanced CTs were performed on subjects scanned in identical positions under active breathing control (ABC). SBRT plans were generated using seven-field three-dimensional conformal radiotherapy (7 F-3D-CRT), seven-field intensity-modulated radiotherapy (7 F-IMRT) and single-arc volumetric modulated arc therapy (VMAT) based on the PVP CT. Plans were copied to the HAP and non-enhanced CTs. Radiation doses calculated from the three phases of CTs were compared with respect to the planning target volume (PTV) and the organs at risk (OAR) using the Friedman test and the Wilcoxon signed ranks test.ResultsSBRT plans calculated from either PVP or HAP CT, including 3D-CRT, IMRT and VMAT plans, demonstrated significantly lower (p <0.05) minimum absorbed doses covering 98%, 95%, 50% and 2% of PTV (D98%, D95%, D50% and D2%) than those calculated from non-enhanced CT. The mean differences between PVP or HAP CT and non-enhanced CT were less than 2% and 1% respectively. All mean dose differences between the three phases of CTs for OARs were less than 2%.ConclusionsOur data indicate that though the differences in dose calculation between contrast phases are not clinically relevant, dose underestimation (IE, delivery of higher-than-intended doses) resulting from CT using PVP contrast is larger than that resulting from CT using HAP contrast when compared against doses based upon non-contrast CT in SBRT treatment of liver cancer using VMAT, IMRT or 3D-CRT.

Highlights

Hepatocellular carcinoma (HCC) is the fifth most common cancer worldwide [1]
It was reported that in treatment of upper abdominal tumors contrast agent is responsible for greater than 2% increase in monitor units (MUs) of three-dimensional conformal radiotherapy (3D-CRT) [16], but that the effect of contrast agent on dose calculation decreased with an increasing number of incident beams [12]
Patients were trained to adapt to active breathing control (ABC) beforehand at moderate deep inspiration breath-hold with 75% of maximum inspiratory volume

Summary

Introduction

Hepatocellular carcinoma (HCC) is the fifth most common cancer worldwide [1]. liver is a common site for metastases from a variety of primary malignancies [2]. One is based on phantoms, or mathematical algorithms, designed to take into account parameters that include photon beam energies, molarities and contrast agent expansion [11,12]. Human studies are another mode, and they have revealed a negligible effect on dose calculation in regions with low contrast agent penetration [13,14,15]. It was reported that in treatment of upper abdominal tumors contrast agent is responsible for greater than 2% increase in monitor units (MUs) of three-dimensional conformal radiotherapy (3D-CRT) [16], but that the effect of contrast agent on dose calculation decreased with an increasing number of incident beams [12]. Since VMAT plans are designed using a larger number of segments (typically, there are 91 segments in a single-arc VMAT plan), the effect of contrast agent on VMAT plans is unknown

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