The impact of dental metal artifacts on head and neck IMRT dose distributions

Kim, Yusung; Tomé, Wolfgang A.; Bal, M.; McNutt, Todd; Spies, Lothar

doi:10.1016/j.radonc.2006.03.022

Cited by 56 publications

(45 citation statements)

References 17 publications

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“…For the purpose of this study, we Table 1 of Ref. [15]. Patients were immobilized using custom head molds, half facial thermoplastic masks, and treated using a bite tray coupled with an optical probe that attaches to the upper maximally dentition.…”

Section: Imrt Treatment Planningmentioning

confidence: 99%

“…[1,24,34,36] and references there in), the effects on the accuracy of H&N IMRT dose distribution due to dental-metal-artifacts in the treatment planning computerized tomography (CT) images has not been extensively studied. In our previous work [15] we have quantified the cold and the hot spots introduced by metal artifacts present in H&N treatment planning CT images in terms of physical dose. However, the dose response curves for a tumor and normal tissues are not linearbut sigmoid ('S') shaped [12,19,23].…”

Section: Introductionmentioning

confidence: 99%

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On the radiobiological impact of metal artifacts in head-and-neck IMRT in terms of tumor control probability (TCP) and normal tissue complication probability (NTCP)

Kim

2007

Med Bio Eng Comput

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To investigate the effects of distorted head-and-neck (H&N) intensity-modulated radiation therapy (IMRT) dose distributions (hot and cold spots) on normal tissue complication probability (NTCP) and tumor control probability (TCP) due to dental-metal artifacts. Five patients' IMRT treatment plans have been analyzed, employing five different planning image data-sets: (a) uncorrected (UC); (b) homogeneous uncorrected (HUC); (c) sinogram completion corrected (SCC); (d) minimum-value-corrected (MVC); and (e) streak-artifact-reduction including minimum-value-correction (SAR-MVC), which has been taken as the reference data-set. The effects on NTCP and TCP were evaluated using the Lyman-NTCP model and the Logistic-TCP model, respectively. When compared to the predicted NTCP obtained using the reference data-set, the treatment plan based on the original CT data-set (UC) yielded an increase in NTCP of 3.2 and 2.0% for the spared parotid gland and the spinal cord, respectively. While for the treatment plans based on the MVC CT data-set the NTCP increased by a 1.1% and a 0.1% for the spared parotid glands and the spinal cord, respectively. In addition, the MVC correction method showed a reduction in TCP for target volumes (MVC: delta TCP = -0.6% vs. UC: delta TCP = -1.9%) with respect to that of the reference CT data-set. Our results indicate that the presence of dental-metal-artifacts in H&N planning CT data-sets has an impact on the estimates of TCP and NTCP. In particular dental-metal-artifacts lead to an increase in NTCP for the spared parotid glands and a slight decrease in TCP for target volumes.

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Section: Imrt Treatment Planningmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

On the radiobiological impact of metal artifacts in head-and-neck IMRT in terms of tumor control probability (TCP) and normal tissue complication probability (NTCP)

Kim

2007

Med Bio Eng Comput

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“…So, because the CT number can be calculated by the attenuation coefficient, this means that the photon energy also affects the CT number [1]. In addition, if a metal is inserted into a CT image, the metal artifact is generated and may cause changes in the CT number and photon density, so it can also influence the CT number [2][3][4]. The generation of high-density artifacts in CT images is primarily caused by missing projection data.…”

Section: Introductionmentioning

confidence: 99%

Differential Absorption Analysis of Nonmagnetic Material in the Phantom using Dual CT

Kim¹,

Lee²,

Cho³

2016

Journal of Magnetics

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This study evaluates the change of computer tomography (CT) number in the case of the metal artifact reduction (MAR) algorithm, using the phantom. The images were obtained from dual CT using a gammex 467 tissue characterization phantom, which is similar to human tissues. The test method was performed by dividing pre and post MAR algorithm and measured CT values of nonmagnetic materials within the phantom. In addition, the changes of CT values for each material were compared and analyzed after measuring CT values up to 140 keV, using the spectral HU curve followed by CT scan. As a result, in the cases of N rod (trabecular bone) and E rod (trabecular bone), the CT numbers decreased as keV increasing but were constant above 90 keV. In the cases of I rod (dense bone) and K rod (dense bone), the CT numbers also decreased as keV increased but were uniform above 90 keV. The CT numbers from 40 keV to 140 keV were consistent in the cases of J rod (liver), D rod (liver), L rod (muscle), and F rod (muscle). For A rod (adipose), G rod (adipose), B rod (breast) and O rod (breast), the CT numbers increased as keV increased but were constant after 90 keV. The CT numbers from 40 keV to 140 keV were consistent in the cases of C rod (lung (exhale)), P rod (lung (exhale)), M rod (lung (inhale)) and H rod (lung (exhale)). Conclusively, because dual CT exhibits no changes in image quality and is able to analyze nonmagnetic materials by measuring the CT values of various materials, it will be used in the future as a useful tool for the diagnosis of lesions.

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“…Hatton et al [14] used a cone beam CT on a Varian 2100iX linear accelerator (Varian, Palo Alto, CA) and showed that differences in CT number can influence the dose by up to 20 % in extreme cases. Kim et al [15] did not specify the manufacturer CT imager; nevertheless they showed that imaging artefacts can result in differences in treatment plan dose distributions.…”

Section: Introductionmentioning

confidence: 99%

“…For all phantom geometries, objects within the eFOV were geometrically overestimated with elongation of phantom shapes into the eFOV. The percentage increase in size ranged from 0.22 to 15.94 % over all phantoms considered. The difference between eFOV and sFOV CT numbers was dependent upon insert density.…”

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confidence: 99%

An assessment of image distortion and CT number accuracy within a wide-bore CT extended field of view

Beeksma

Truant

Holloway

et al. 2015

Australas Phys Eng Sci Med

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Although wide bore computed tomography (CT) scanners provide increased space for patients, the scan field of view (sFOV) remains considerably smaller than the bore size. Consequently, patient anatomy which spans beyond the sFOV is truncated and the information is lost. As a solution, some manufacturers provide the capacity to reconstruct CT images from a partial dataset at an extended field of view (eFOV). To assess spatial distortion within this eFOV three phantoms were considered a 30 x 30 x 20 cm 3 slab of solid water, the Gammex electron density CT phantom and a female anthropomorphic phantom. For each phantom, scans were taken centrally within the sFOV as a reference image and with the phantom edge extended at 1 cm intervals from 0 to 5 cm beyond the sFOV into the eFOV. To assess CT number accuracy various tissue equivalent materials were scanned in the eFOV and resulting CT numbers were compared to inserts scanned within the sFOV. For all phantom geometries, objects within the eFOV were geometrically overestimated with elongation of phantom shapes into the eFOV. The percentage increase in size ranged from 0.22 to 15.94 % over all phantoms considered. The difference between eFOV and sFOV CT numbers was dependent upon insert density. The eFOV underestimated CT numbers in the range of −127 to −230 HU for soft tissue densities and −278 to −640 for bone densities. This trend reversed for low tissue densities with the CT numbers in the eFOV being overestimated by 100-130 HU for lung equivalent inserts. Initial correlation between eFOV and sFOV CT numbers was seen and a correction function was successfully applied to better estimate the CT number representative of that seen within the sFOV. Abstract Although wide bore computed tomography (CT) scanners provide increased space for patients, the scan field of view (sFOV) remains considerably smaller than the bore size. Consequently, patient anatomy which spans beyond the sFOV is truncated and the information is lost. As a solution, some manufacturers provide the capacity to reconstruct CT images from a partial dataset at an extended field of view (eFOV). To assess spatial distortion within this eFOV three phantoms were considered a 30 9 30 9 20 cm 3 slab of solid water, the Gammex electron density CT phantom and a female anthropomorphic phantom. For each phantom, scans were taken centrally within the sFOV as a reference image and with the phantom edge extended at 1 cm intervals from 0 to 5 cm beyond the sFOV into the eFOV. To assess CT number accuracy various tissue equivalent materials were scanned in the eFOV and resulting CT numbers were compared to inserts scanned within the sFOV. For all phantom geometries, objects within the eFOV were geometrically overestimated with elongation of phantom shapes into the eFOV. The percentage increase in size ranged from 0.22 to 15.94 % over all phantoms considered. The difference between eFOV and sFOV CT numbers was dependent upon insert density. The eFOV underestimated CT numbers in the range of -127 to -230 HU for so...

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The impact of dental metal artifacts on head and neck IMRT dose distributions

Cited by 56 publications

References 17 publications

On the radiobiological impact of metal artifacts in head-and-neck IMRT in terms of tumor control probability (TCP) and normal tissue complication probability (NTCP)

On the radiobiological impact of metal artifacts in head-and-neck IMRT in terms of tumor control probability (TCP) and normal tissue complication probability (NTCP)

Differential Absorption Analysis of Nonmagnetic Material in the Phantom using Dual CT

An assessment of image distortion and CT number accuracy within a wide-bore CT extended field of view

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