Whole Brain Radiotherapy With Hippocampal Avoidance and Simultaneous Integrated Boost for 1–3 Brain Metastases: A Feasibility Study Using Volumetric Modulated Arc Therapy

Hsu, Fred; Carolan, Hannah; Nichol, Alan; Cao, Fred; Nuraney, N; Lee, Richard; Gete, E.; Wong, Frances; Schmuland, M.; Heran, Manraj K.S.; Otto, Karl F.

doi:10.1016/j.ijrobp.2009.03.032

Cited by 110 publications

(80 citation statements)

References 20 publications

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“…Using volumetric‐modulated arc therapy (VMAT) planning, simultaneous integrated boost (SIB) dose delivery has been studied by several researchers 10 , 22 , 23 , 24 , 25 , 26 using varieties of prescription doses in the treatment of up to eight brain tumors. Specifically, Gutierrez and colleagues (10) evaluated the feasibility of using helical tomotherapy for WBRT with hippocampal sparing and SIB to the brain metastases.…”

Section: Discussionmentioning

confidence: 99%

Potential for reduced radiation‐induced toxicity using intensity‐modulated arc therapy for whole‐brain radiotherapy with hippocampal sparing

Pokhrel

Sood

Lominska

et al. 2015

J Applied Clin Med Phys

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The purpose of this study was to retrospectively investigate the accuracy, plan quality, and efficiency of using intensity‐modulated arc therapy (IMAT) for whole brain radiotherapy (WBRT) patients with sparing not only the hippocampus (following RTOG 0933 compliance criteria) but also other organs at risk (OARs). A total of 10 patients previously treated with nonconformal opposed laterals whole‐brain radiotherapy (NC‐WBRT) were retrospectively replanned for hippocampal sparing using IMAT treatment planning. The hippocampus was volumetrically contoured on fused diagnostic T1‐weighted MRI with planning CT images and hippocampus avoidance zone (HAZ) was generated using a 5 mm uniform margin around the hippocampus. Both hippocampi were defined as one paired organ. Whole brain tissue minus HAZ was defined as the whole‐brain planning target volume (WB‐PTV). Highly conformal IMAT plans were generated in the Eclipse treatment planning system for Novalis TX linear accelerator consisting of high‐definition multileaf collimators (HD‐MLCs: 2.5 mm leaf width at isocenter) and 6 MV beam for a prescription dose of 30 Gy in 10 fractions following RTOG 0933 dosimetric criteria. Two full coplanar arcs with orbits avoidance sectors were used. In addition to RTOG criteria, doses to other organs at risk (OARs), such as parotid glands, cochlea, external/middle ear canals, skin, scalp, optic pathways, brainstem, and eyes/lens, were also evaluated. Subsequently, dose delivery efficiency and accuracy of each IMAT plan was assessed by delivering quality assurance (QA) plans with a MapCHECK device, recording actual beam‐on time and measuring planed vs. measured dose agreement using a gamma index. On IMAT plans, following RTOG 0933 dosimetric criteria, the maximum dose to WB‐PTV, mean WB‐PTV D2%, and mean WB‐PTV D98% were 34.9±0.3 Gy,33.2±0.4 Gy, and 26.0±0.4 Gy, respectively. Accordingly, WB‐PTV received the prescription dose of 30 Gy and mean V30 was 90.5%±0.5%. The D100%, and mean and maximum doses to hippocampus were 8.4±0.3 Gy,11.2±0.3 Gy, and 15.6±0.4 Gy, on average, respectively. The mean values of homogeneity index (HI) and conformity index (CI) were 0.23×0.02 and 0.96×0.02, respectively. The maximum point dose to WB‐PTV was 35.3 Gy, well below the optic pathway tolerance of 37.5 Gy. In addition, compared to NC‐WBRT, dose reduction of mean and maximum of parotid glands from IMAT were 65% and 50%, respectively. Ear canals mean and maximum doses were reduced by 26% and 12%, and mean and maximum scalp doses were reduced by 9 Gy (32%) and 2 Gy (6%), on average, respectively. The mean dose to skin was 9.7 Gy with IMAT plans compared to 16 Gy with conventional NC‐WBRT, demonstrating that absolute reduction of skin dose by a factor of 2. The mean values of the total number of monitor units (MUs) and actual beam on time were 719×44 and 2.34×0.14 min, respectively. The accuracy of IMAT QA plan delivery was (98.1±0.8) %, on average, with a 3%/3 mm gamma index passing rate criteria. All of these plans were considered clinically acceptable per ...

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Section: Discussionmentioning

confidence: 99%

Potential for reduced radiation‐induced toxicity using intensity‐modulated arc therapy for whole‐brain radiotherapy with hippocampal sparing

Pokhrel

Sood

Lominska

et al. 2015

J Applied Clin Med Phys

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“…We use clinical VMAT plans of the whole brain with metastases in the brain, similar to the simultaneous integrated boost described by Hsu et al, (20) but the metastases were irradiated to the dose of 50 Gy and 40 Gy to the GTV and the PTV, respectively (in 5 fractions), while the remaining part of the brain received the total dose of 20 Gy. The avoidance structures included the spinal cord and the optics (> 25 Gy), with the anterior chamber constrained to 10 Gy.…”

Section: Methodsmentioning

confidence: 99%

On using the dosimetric leaf gap to model the rounded leaf ends in VMAT/RapidArc plans

Szpala

Cao

Kohli

2014

J Applied Clin Med Phys

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Partial transmission through rounded leaf ends of Varian multileaf collimators (MLC) is accounted for with a parameter called the dosimetric leaf gap (DLG). Verification of the value of the DLG is needed when the dose delivery is accompanied by gantry rotation in VMAT plans. We compared the doses measured with GAFCHROMIC film and an ionization chamber to treatment planning system (TPS) calculations to identify the optimum values of the DLG in clinical plans of the whole brain with metastases transferred to a phantom. We noticed the absence of a single value of the DLG that properly models all VMAT plans in our cohort (the optimum DLG varied between 0.93±0.15 mm and 2.2±0.2 mm). The former value is considerably different from the optimum DLG in sliding window plans (about 2.0 mm) that approximate IMRT plans. We further found that a single‐value DLG model cannot accurately reproduce the measured dose profile even of a uniform static slit at a fixed gantry, which is the simplest MLC‐delimited field. The calculation overestimates the measurement in the proximal penumbra, while it underestimates in the distal penumbra. This prompted us to expand the DLG parameter from a plan‐specific number to a mathematical concept of the DLG being a function of the distance in the beam's eye view (BEV) between the dose point and the leaf ends. Such function compensates for the difference between the penumbras in a beam delimited with a rounded leaf MLC and delimited with solid jaws. Utilization of this concept allowed us generating a pair of step‐and‐shoot MLC plans for which we could qualitatively predict the value of the DLG providing best match to ionization chamber measurements. The plan for which the leafs stayed predominantly at positions requiring low values of the DLG (as seen in the profiles of 1D slits) yielded the combined DLG of 1.1±0.2 mm, while the plan with leafs staying at positions requiring larger values of the DLG yielded the DLG 2.4±0.2 mm. Considering the DLG to be a function of the distance (in BEV) between the dose point and the leaf ends allowed us to provide an explanation as to why conventional single‐number DLG is plan‐specific in VMAT plans.PACS numbers: 87.56.jf, 87.56.nk

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“…Single isocentre techniques would be preferable as treatment time is shorter and there is less potential for set-up error. Another feasibility study by Hsu et al [138] found that VMAT was able to deliver WBRT with SIB for 1-3 brain metastases with the addition of hippocampal avoidance, which could potentially reduce the risk of neurocognitive dysfunction.…”

Section: Metastatic Lesionsmentioning

confidence: 99%

Volumetric modulated arc therapy: a review of current literature and clinical use in practice

Teoh

Clark²,

Wood³

et al. 2011

BJR

578

440

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ABSTRACT. Volumetric modulated arc therapy (VMAT) is a novel radiation technique, which can achieve highly conformal dose distributions with improved target volume coverage and sparing of normal tissues compared with conventional radiotherapy techniques. VMAT also has the potential to offer additional advantages, such as reduced treatment delivery time compared with conventional static field intensity modulated radiotherapy (IMRT). The clinical worldwide use of VMAT is increasing significantly. Currently the majority of published data on VMAT are limited to planning and feasibility studies, although there is emerging clinical outcome data in several tumour sites. This article aims to discuss the current use of VMAT techniques in practice and review the available data from planning and clinical outcome studies in various tumour sites including prostate, pelvis (lower gastrointestinal, gynaecological), head and neck, thoracic, central nervous system, breast and other tumour sites.

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Whole Brain Radiotherapy With Hippocampal Avoidance and Simultaneous Integrated Boost for 1–3 Brain Metastases: A Feasibility Study Using Volumetric Modulated Arc Therapy

Cited by 110 publications

References 20 publications

Potential for reduced radiation‐induced toxicity using intensity‐modulated arc therapy for whole‐brain radiotherapy with hippocampal sparing

Potential for reduced radiation‐induced toxicity using intensity‐modulated arc therapy for whole‐brain radiotherapy with hippocampal sparing

On using the dosimetric leaf gap to model the rounded leaf ends in VMAT/RapidArc plans

Volumetric modulated arc therapy: a review of current literature and clinical use in practice

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