Evaluation of Radiation Dose and Image Quality for the Varian Cone Beam Computed Tomography System

Cheng, Ho Ming; Wu, Weiju; Liu, Eva S.F.; Kwong, Dora L.W.

doi:10.1016/j.ijrobp.2010.06.014

Cited by 55 publications

(43 citation statements)

References 37 publications

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“…Despite the efforts to reduce the dose to the patient, the H T and ED values determined by others in 2011 (OBI version 1.4.13)6 and 20127 are of the same order as presented in this study. Hälg et al 7.…”

Section: Discussionsupporting

confidence: 48%

“…In the last years, many studies have been conducted about CBCT dose for different protocols 2, 3, 4, 5, 6, 7, 8, 9. Some of them evaluated only the CTDI values 3, 9.…”

Section: Introductionmentioning

confidence: 99%

“…Some of them evaluated only the CTDI values 3, 9. Kan et al.,10 Cheng et al.,6 and Hälg et al 7. determined the effective dose (ED) for pelvis protocols using the OBI of a Varian linear accelerator.…”

Section: Introductionmentioning

confidence: 99%

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Technical note: No increase in effective dose from half compared to full rotation pelvis cone beam CT

Hauri

Hälg

Schneider

2017

J Applied Clin Med Phys

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PurposeTo image the abdomen of a patient with a gantry mounted imaging system of a linear accelerator, different cone beam computed tomography (CBCT) protocols are available. The whole‐body dose of a full rotation abdomen CBCT and a half rotation CBCT was compared. In our clinic, both CBCT protocols are used in daily routine work.MethodsWith an adult anthropomorphic Alderson phantom, the whole‐body dose per CBCT scan was measured with thermoluminescence dosimeters. The half rotation CBCT was applied such that the gantry mounted X‐ray source rotated around the right side of the phantom. The 183 measurement locations covered all ICRP recommended critical organs (except the gonads). The effective dose was calculated with the mean organ dose and the corresponding tissue weighting factors. A point‐by‐point dose comparison of both protocols was conducted.ResultsThe effective dose was 5.4 mSv ±5% and 5.0 mSv ±5% (estimated type B 1σ) for the full and the half rotation CBCT respectively. There was no significant difference (α = 0.05) in the effective dose within the precision of the measurement (1σ = 5%). The half rotation CBCT displayed an inhomogeneous dose distribution in a transversal phantom slice in contrast with the full rotation CBCT. In the imaging region, the mean dose was (20.5 ± 3.4) mGy and (19.2 ± 7.4) mGy (measured type A 1σ) for the full and the half rotation CBCT respectively.ConclusionThe half compared to the full rotation CBCT displays a smaller field‐of‐view in a transversal slice and no significant difference in the effective dose. Hence, the full rotation CBCT is favorable compared to the half rotation CBCT. However, by using the half rotation protocol, critical volumes in the patient can be spared compared to the full rotation protocol.

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Section: Discussionsupporting

confidence: 48%

“…In the last years, many studies have been conducted about CBCT dose for different protocols 2, 3, 4, 5, 6, 7, 8, 9. Some of them evaluated only the CTDI values 3, 9.…”

Section: Introductionmentioning

confidence: 99%

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Technical note: No increase in effective dose from half compared to full rotation pelvis cone beam CT

Hauri

Hälg

Schneider

2017

J Applied Clin Med Phys

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“…If cone‐beam CT (CBCT) were required, it could be performed with minimal fetal dose on a modern TrueBeam system. Scaling organ doses previously published for a prior generation of Varian CBCT system by the CTDI ratios between the older On‐Board Imager (OBI) CBCT system and the TrueBeam CBCT system, one could estimate up to 0.0006 cGy fetal dose per “head” CBCT and up to 0.005 cGy fetal dose per “thorax” CBCT (using kidneys as a conservative surrogate for the fetus) 19, 20, 21. TomoTherapy image guidance would be performed with the “coarse” MVCT protocol with 3 mm slice thickness to minimize the MU required for MVCT imaging.…”

Section: Methodsmentioning

confidence: 99%

Radiation treatment planning and delivery strategies for a pregnant brain tumor patient

Labby

Barraclough

Bayliss

et al. 2018

J Applied Clin Med Phys

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The management of a pregnant patient in radiation oncology is an infrequent event requiring careful consideration by both the physician and physicist. The aim of this manuscript was to highlight treatment planning techniques and detail measurements of fetal dose for a pregnant patient recently requiring treatment for a brain cancer. A 27‐year‐old woman was treated during gestational weeks 19–25 for a resected grade 3 astrocytoma to 50.4 Gy in 28 fractions, followed by an additional 9 Gy boost in five fractions. Four potential plans were developed for the patient: a 6 MV 3D‐conformal treatment plan with enhanced dynamic wedges, a 6 MV step‐and‐shoot (SnS) intensity‐modulated radiation therapy (IMRT) plan, an unflattened 6 MV SnS IMRT plan, and an Accuray TomoTherapy HDA helical IMRT treatment plan. All treatment plans used strategies to reduce peripheral dose. Fetal dose was estimated for each treatment plan using available literature references, and measurements were made using thermoluminescent dosimeters (TLDs) and an ionization chamber with an anthropomorphic phantom. TLD measurements from a full‐course radiation delivery ranged from 1.0 to 1.6 cGy for the 3D‐conformal treatment plan, from 1.0 to 1.5 cGy for the 6 MV SnS IMRT plan, from 0.6 to 1.0 cGy for the unflattened 6 MV SnS IMRT plan, and from 1.9 to 2.6 cGy for the TomoTherapy treatment plan. The unflattened 6 MV SnS IMRT treatment plan was selected for treatment for this particular patient, though the fetal doses from all treatment plans were deemed acceptable. The cumulative dose to the patient's unshielded fetus is estimated to be 1.0 cGy at most. The planning technique and distance between the treatment target and fetus both contributed to this relatively low fetal dose. Relevant treatment planning strategies and treatment delivery considerations are discussed to aid radiation oncologists and medical physicists in the management of pregnant patients.

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“…In the past few years, studies have been published regarding CBCT performance comparisons. [6][7][8] Vero4DRT (MHI-TM2000) system was recently developed by Mitsubishi Heavy Industries, Ltd., Japan (MHI) in collaboration with the Kyoto University and the Institute of Biomedical Research and Innovation (IBRI). The American Association of Physicists in Medicine (AAPM) Task Group (TG) 142 recommends daily, monthly and annual imaging quality assurance (QA) of IGRT.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of cone-beam computed tomography image quality assurance for Vero4DRT system

Miura¹,

Ozawa

Hayata³

et al. 2017

Reports of Practical Oncology & Radiotherapy

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a b s t r a c tWe report the characteristics of quality assurance (QA) image for Vero4DRT system with a kilo-voltage (kV) cone-beam computed tomography (CBCT) capability to perform imageguided radiation therapy (IGRT). To acquire a set of CBCT, the kV source is rotated either 215• clockwise (CW) (tube 1 from 5• to 220 • rotation, which leads to a loss in uniformity for image acquisition.Separations were observed for high-contrast resolution, with eight line pairs per centimeter corresponding to a gap size of 0.063 cm. For low-contrast resolution, the seventh largest hole was visible. This hole has a 4-mm diameter with 1.0% contrast level. We should check the contrast linearity compared with known value, even though it is out of range from the manufacturer manual.

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Evaluation of Radiation Dose and Image Quality for the Varian Cone Beam Computed Tomography System

Abstract: The new Varian CBCT provided volumetric information for image guidance with acceptable image quality and lower radiation dose. This imaging tool gave a better standard for patient daily setup verification.

Cited by 55 publications

References 37 publications

Technical note: No increase in effective dose from half compared to full rotation pelvis cone beam CT

Technical note: No increase in effective dose from half compared to full rotation pelvis cone beam CT

Radiation treatment planning and delivery strategies for a pregnant brain tumor patient

Evaluation of cone-beam computed tomography image quality assurance for Vero4DRT system

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