The impacts of dental filling materials on RapidArc treatment planning and dose delivery: Challenges and solution

Mail, Noor; Albarakati, Y.; Khan, Mubashra; Saeedi, F.; Safadi, N.; Al-Ghamdi, Suliman; Saoudi, A.

doi:10.1118/1.4816307

Cited by 37 publications

(34 citation statements)

References 23 publications

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“…For dose calculations with the Cerrobend implant and the dental case, silver kernels were used because this is a high-Z material that falls within the range of various dental amalgams in terms of atomic number and physical density and therefore was selected to be a reasonable representative for such high-Z metals. [27][28][29] These metal energy deposition kernels were simulated using the EGSsnrc Monte Carlo system, characterized in previous work, 20 and implemented in the M3D algorithm using a density threshold. For voxels with an assigned density greater than the threshold value (e.g., 4.0 g/cm 3 ), metal kernels were used to describe the energy deposition for energy released from those voxels.…”

Section: D M3d Dose Calculationsmentioning

confidence: 99%

Approaches to reducing photon dose calculation errors near metal implants

et al. 2016

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Though successful at improving dose calculation accuracy upstream of metal implants, metal kernels were not found to substantially improve accuracy for clinical cases. Of the commercial artifact reduction methods investigated, o-mar was found to be the most consistent candidate for all-purpose CT simulation imaging. The mars algorithm for gsi should be used with caution for titanium implants, larger implants, and implants located near heterogeneities as it can distort the size and shape of implants and increase calculation errors.

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Section: D M3d Dose Calculationsmentioning

confidence: 99%

Approaches to reducing photon dose calculation errors near metal implants

et al. 2016

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“…This allows more accurate modeling of the beam attenuation properties of the material. Other more advanced techniques, such as the application of a virtual filter around the teeth, have also been explored (27) . In contrast, standard MRI sequences are neither able to image dental implants nor normal teeth, prohibiting the ability of MRI‐based treatment plans to model the high X‐ray attenuation of the implant material.…”

Section: Introductionmentioning

confidence: 99%

Feasibility and limitations of bulk density assignment in MRI for head and neck IMRT treatment planning

Chin

Lin

Anamalayil

et al. 2014

J Applied Clin Med Phys

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Head and neck cancers centered at the base of skull are better visualized on MRI than on CT. The purpose of this investigation was to investigate the accuracy of bulk density assignment in head and neck intensity‐modulated radiation therapy (IMRT) treatment plan optimization. Our study investigates dose calculation differences between density‐assigned MRI and CT, and identifies potential limitations related to dental implants and MRI geometrical distortion in the framework of MRI‐only‐based treatment planning. Bulk density assignment was performed and applied onto MRI to generate three MRI image sets with increasing levels of heterogeneity for seven patients: 1) MRInormalW: all water‐equivalent; 2) MRIW + B: included bone with density of 1.53 normalg/cm3; and 3) MRIW + B + A: included bone and air. Using identical planning and optimization parameters, MRI‐based IMRT plans were generated and compared to corresponding, forward‐calculated, CT‐based plans on the basis of target coverage, isodose distributions, and dose‐volume histograms (DVHs). Phantom studies were performed to assess the magnitude and spatial dependence of MRI geometrical distortion. MRInormalW‐based dose calculations overestimated target coverage by 16.1%. Segmentation of bone reduced differences to within 2% of the coverage area on the CT‐based plan. Further segmentation of air improved conformity near air–tissue interfaces. Dental artifacts caused substantial target coverage overestimation even on MRIW + B + A. Geometrical distortion was less than 1 mm in an imaging volume 20 × 20 × 20 cm3 around scanner isocenter, but up to 4 mm at 17 cm lateral to isocenter. Bulk density assignment in the framework of MRI‐only IMRT head and neck treatment planning is a feasible method with certain limitations. Bone and teeth account for the majority of density heterogeneity effects. While soft tissue is well visualized on MRI compared to CT, dental implants may not be visible on MRI and must be identified by other means and assigned appropriate density for accurate dose calculation. Far off‐center geometrical distortion of the body contour near the shoulder region is a potential source of dose calculation inaccuracy.PACS numbers: 87.61.‐c, 87.55.‐D

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“…This issue could be settled by overriding the contour of the lok‐bars using the appropriate values determined using CT. However, producing a radiotherapy plan to adjust each contour would take a long time and complicate operations …”

Section: Discussionmentioning

confidence: 99%

Development of a novel low‐radiation‐absorbent lok‐bar to reduce X‐ray scattering and absorption in RapidArc^® treatment planning and dose delivery

Monzen

Kubo

Tamura

et al. 2017

J Applied Clin Med Phys

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We developed a novel low‐radiation‐absorbent lok‐bar (HM‐bar) that is used to secure the immobilizers to the couch. The aim of this study was to investigate the X‐ray scattering and absorption properties of the HM‐bar in computed tomography (CT) simulation and radiotherapy dose delivery using the Varian Exact™ lok‐bar (VL‐bar) as a benchmark. CT images were obtained with or without lok‐bar, and then each image was visually evaluated for artifacts. The attenuation rates for each lok‐bar were measured using a farmer‐type ionization chamber (PTW30013) and the I'mRT phantom (IBA Dosimetry GmbH). Measurement points were between gantry angles of 110 and 180°. The treatment apparatus was a NovalisTx (Brainlab AG); X‐ray energies were set at 6 MV and 10 MV. In the presence of each lok‐bar, the radiation dose was measured in accordance with 10 volumetric modulated arc therapy–stereotactic body radiation therapy (VMAT‐SBRT) plans for lung cancer. Artifacts were seldom observed in the CT scans of the HM‐bar. The attenuation rate of each lok‐bar was higher when the X‐ray energy was set at 6 MV than at 10 MV. The highest attenuation rate in the VL‐bar was observed at a gantry angle of 112°; the rates were 22.4% at 6 MV and 19.3% at 10 MV. Similarly, the highest attenuation rate for the HM‐bar was also observed at a gantry angle of 112°; the rates were 12.2% and 10.1% at 6 MV and 10 MV, respectively. When the VL‐bar was evaluated, the isocenter dose of the VMAT‐SBRT plans was attenuated by 2.6% as a maximum case. In the case of the HM‐bar, the maximum attenuation was 1.4%. In the measurements of each VMAT‐SBRT plan, the difference of the dose attenuation rate between the VL‐bar and HM‐bar was approximately 1%. The HM‐bar could be used to minimize the occurrence of artifacts and provide good images in CT scans regarding radiotherapy planning and dose calculation. It can be used for patient therapy at hospitals to provide accurate dose delivery because of its low X‐ray scattering and absorption characteristics.

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The impacts of dental filling materials on RapidArc treatment planning and dose delivery: Challenges and solution

Cited by 37 publications

References 23 publications

Approaches to reducing photon dose calculation errors near metal implants

Approaches to reducing photon dose calculation errors near metal implants

Feasibility and limitations of bulk density assignment in MRI for head and neck IMRT treatment planning

Development of a novel low‐radiation‐absorbent lok‐bar to reduce X‐ray scattering and absorption in RapidArc^® treatment planning and dose delivery

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The impacts of dental filling materials on RapidArc treatment planning and dose delivery: Challenges and solution

Cited by 37 publications

References 23 publications

Approaches to reducing photon dose calculation errors near metal implants

Approaches to reducing photon dose calculation errors near metal implants

Feasibility and limitations of bulk density assignment in MRI for head and neck IMRT treatment planning

Development of a novel low‐radiation‐absorbent lok‐bar to reduce X‐ray scattering and absorption in RapidArc® treatment planning and dose delivery

Contact Info

Product

Resources

About

Development of a novel low‐radiation‐absorbent lok‐bar to reduce X‐ray scattering and absorption in RapidArc^® treatment planning and dose delivery