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

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Abstract

Purpose

To 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.

Methods

Twenty-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.

Results

SBRT 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%.

Conclusions

Our 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.

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Most cited references 15

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Comparison of dose calculation algorithms for treatment planning in external photon beam therapy for clinical situations.

Tommy Knöös, Elinore Wieslander, Luca Cozzi … (2006)

A study of the performance of five commercial radiotherapy treatment planning systems (TPSs) for common treatment sites regarding their ability to model heterogeneities and scattered photons has been performed. The comparison was based on CT information for prostate, head and neck, breast and lung cancer cases. The TPSs were installed locally at different institutions and commissioned for clinical use based on local procedures. For the evaluation, beam qualities as identical as possible were used: low energy (6 MV) and high energy (15 or 18 MV) x-rays. All relevant anatomical structures were outlined and simple treatment plans were set up. Images, structures and plans were exported, anonymized and distributed to the participating institutions using the DICOM protocol. The plans were then re-calculated locally and exported back for evaluation. The TPSs cover dose calculation techniques from correction-based equivalent path length algorithms to model-based algorithms. These were divided into two groups based on how changes in electron transport are accounted for ((a) not considered and (b) considered). Increasing the complexity from the relatively homogeneous pelvic region to the very inhomogeneous lung region resulted in less accurate dose distributions. Improvements in the calculated dose have been shown when models consider volume scatter and changes in electron transport, especially when the extension of the irradiated volume was limited and when low densities were present in or adjacent to the fields. A Monte Carlo calculated algorithm input data set and a benchmark set for a virtual linear accelerator have been produced which have facilitated the analysis and interpretation of the results. The more sophisticated models in the type b group exhibit changes in both absorbed dose and its distribution which are congruent with the simulations performed by Monte Carlo-based virtual accelerator.

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Phase I feasibility trial of stereotactic body radiation therapy for primary hepatocellular carcinoma.

Mary Maluccio, Kathy Tudor, Ashleigh R. Price … (2010)

Hepatocellular carcinoma (HCC) is increasing in incidence and the majority of patients are not candidates for radical therapies. Therefore, interest in minimally invasive therapies in growing. A Phase I dose escalation trial was conducted at Indiana University to determine the feasibility and toxicity of stereotactic body radiation therapy (SBRT) for primary HCC. Eligible patients had Child-Turcotte-Pugh's Class (CTP) A or B, were not candidates for resection, had 1-3 lesions and cumulative tumour diameter less than or equal to 6 cm. Dose escalation started at 36 Gy in 3 fractions (12 Gy/fraction) with a subsequent planned escalation of 2 Gy/ fraction/level. Dose-limiting toxicity (DLT) was defined as Common Terminology Criteria for Adverse Events v3.0 grade 3 or greater toxicity. Seventeen patients with 25 lesions were enrolled. Dose was escalated to 48 Gy (16 Gy/fraction) in CTP-A patients without DLT. Two patients with CPC-B disease developed grade 3 hepatic toxicity at the 42-Gy (14 Gy/fraction) level. The protocol was amended for subsequent CTP-B patients to receive a regimen of 5 fractions starting at 40 Gy (8 Gy/fraction) with one patient experiencing progressive liver failure. Four additional patients were enrolled (one died of unrelated causes after an incomplete SBRT course) without DLT. The only factor related to more than one grade 3 or greater liver toxicity or death within 6 months was the CTP score (p=0.03). Six patients underwent a liver transplant. Ten patients are alive without progression with a median FU of 24 months (10-42 months), with local control/stabilisation of the disease of 100%. One and two-year Kaplan-Meier estimates for overall survival are 75% and 60%, respectively. SBRT is a non-invasive feasible and well tolerated therapy in adequately selected patients with HCC. The preliminary local control and survival are encouraging. A confirmatory Phase II trial is currently open to accrual.

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Conformal radiotherapy for lung cancer: different delineation of the gross tumor volume (GTV) by radiologists and radiation oncologists.

Jean-Marc Cosset, Claude Alzieu, Jean-Claude Rosenwald … (2001)

Delineation of the gross tumor volume (GTV) and organs at risk constitutes one of the most important phases of conformal radiotherapy (CRT) procedures. In the absence of a clear redefinition of the GTV, for a given pathology, complemented by detailed contouring procedures, the GTV are likely to be estimated rather arbitrarily with the risk of tumor underdosage or detriment to the surrounding healthy tissues. The objective of this study was to compare the delineation of the GTV of intrathoracic tumors by radiologists and radiation oncologists with experience in the field in various centers. The computed tomography images of ten patients with nonoperated non-small cell lung cancer (NSCLC) eligible for CRT were reviewed. Nine radiologists and eight radiation oncologists working in five different centers, classified as either 'junior' or 'senior' according to their professional experience, had to delineate the GTV (primary tumor and involved lymph nodes) with predefined visualization parameters. A dedicated software was used to compare the delineated volumes in terms of intersection and union volumes and to calculate the 'concordance index' for each patient and each subgroup of physicians. Significant differences between physicians and between centers were observed. Compared to radiation oncologists, radiologists tended to delineate smaller volumes and encountered fewer difficulties to delineate 'difficult' cases. Junior physicians, regardless of their specialty, also tended to delineate smaller and more homogeneous volumes than senior physicians, especially for 'difficult' cases. Major discordances were observed between the radiation oncologists' and the radiologists' delineations, indicating that this step needs to be improved. A better training of radiation oncologists in thoracic imaging and collaboration between radiation oncologists and radiologists should decrease this variability. New imaging techniques (image fusion, positron emission tomography, magnetic resonance imaging spectroscopy, etc.) may also provide a useful contribution to this difficult delineation.

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Author and article information

Contributors

Jianghong Xiao

Yan Li

Qingfeng Jiang

Lan Sun

Fraser Henderson Jr

Yongsheng Wang

Xiaoqin Jiang

Guangjun Li

Nianyong Chen

Journal

Journal ID (nlm-ta): Radiat Oncol

Journal ID (iso-abbrev): Radiat Oncol

Title: Radiation Oncology (London, England)

Publisher: BioMed Central

ISSN (Electronic): 1748-717X

Publication date Collection: 2013

Publication date (Electronic): 9 November 2013

Volume: 8

Page: 264

Affiliations

[1 ]Department of Radiation Oncology, Cancer Center, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, PR China

[2 ]Center for Radiation Physics and Technology, Cancer Center, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, PR China

[3 ]University of Virginia School of Medicine, Charlottesville, Va 22908, USA

Article

Publisher ID: 1748-717X-8-264

DOI: 10.1186/1748-717X-8-264

PMC ID: 4225861

PubMed ID: 24209300

SO-VID: ecf0a1dc-1c36-4740-9a17-b248103e1fb4

License:

This is an open access article distributed under the terms of the Creative Commons Attribution License ( http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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

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Karger: Oncology

Most cited references 15

Comparison of dose calculation algorithms for treatment planning in external photon beam therapy for clinical situations.

Phase I feasibility trial of stereotactic body radiation therapy for primary hepatocellular carcinoma.

Conformal radiotherapy for lung cancer: different delineation of the gross tumor volume (GTV) by radiologists and radiation oncologists.

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