An adaptive approach to metal artifact reduction in helical computed tomography for radiation therapy treatment planning: Experimental and clinical studies

Yazdia, Mehran; Gingras, L.; Beaulieu, Luc

doi:10.1016/j.ijrobp.2005.02.052

Cited by 130 publications

(84 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Metallic hardware causes severe beam hardening and dramatically attenuates the X-ray beam, degrading image quality to the extent that the resultant image is either incomplete or is a faulty projection of the data with consequent reconstruction artifacts [2][3][4]. The generation of artifacts at CT from metal hardware is related to the X-ray kilovolt peak, tube current (in mA) pitch, hardware composition, geometry (shape), location, and the image reconstruction parameters [5].…”

Section: Ctmentioning

confidence: 99%

Metal-related artifacts in instrumented spine. Techniques for reducing artifacts in CT and MRI: state of the art

et al. 2009

View full text Add to dashboard Cite

The projectional nature of radiogram limits its amount of information about the instrumented spine. MRI and CT imaging can be more helpful, using cross-sectional view. However, the presence of metal-related artifacts at both conventional CT and MRI imaging can obscure relevant anatomy and disease. We reviewed the literature about overcoming artifacts from metallic orthopaedic implants at high-field strength MRI imaging and multi-detector CT. The evolution of multichannel CT has made available new techniques that can help minimizing the severe beam-hardening artifacts. The presence of artifacts at CT from metal hardware is related to image reconstruction algorithm (filter), tube current (in mA), X-ray kilovolt peak, pitch, hardware composition, geometry (shape), and location. MRI imaging has been used safely in patients with orthopaedic metallic implants because most of these implants do not have ferromagnetic properties and have been fixed into position. However, on MRI imaging metallic implants may produce geometric distortion, the so-called susceptibility artifact. In conclusion, although 140 kV and high milliamperage second exposures are recommended for imaging patients with hardware, caution should always be exercised, particularly in children, young adults, and patients undergoing multiple examinations. MRI artifacts can be minimized by positioning optimally and correctly the examined anatomy part with metallic implants in the magnet and by choosing fast spin-echo sequences, and in some cases also STIR sequences, with an anterior to posterior frequencyencoding direction and the smallest voxel size.

show abstract

Section: Ctmentioning

confidence: 99%

Metal-related artifacts in instrumented spine. Techniques for reducing artifacts in CT and MRI: state of the art

et al. 2009

View full text Add to dashboard Cite

show abstract

“…Treatment planning in the presence of metals can be handled by contouring the high‐density material and scatter artifacts, and manually assigning a CT number to those regions corresponding to the desired relative electron density (RED) (1) . Metal artifact reduction (MAR) algorithms have been studied with respect to image improvement and treatment planning accuracy 2 , 3 , 4 , 5 , 6 , 7 . Regardless of how scatter artifacts are handled, the CT number of the metal itself must accurately correspond to a RED in the treatment planning system (TPS) for proper handling of dose calculation.…”

Section: Introductionmentioning

confidence: 99%

Treatment planning for metals using an extended CT number scale

Mullins

Grams

Herman

et al. 2016

J Applied Clin Med Phys

View full text Add to dashboard Cite

Metal implants which saturate the CT number scale may require dosimetrist and physicist involvement to manually contour and assign an appropriate value to the metal for accurate dose calculation. This study investigated dose calculation based directly on extended CT scale images for different metals and geometries. The aim was to evaluate extended CT accuracy as a suitable alternative to standard CT methods in the presence of high‐Z materials and artifacts, despite the reduced HU resolution of extended CT. Gafchromic film measurements were made for comparison to calculated doses. The method of direct dose calculation on extended CT scale was compared to our institution's standard method of manually contouring and assigning metal values on saturated CT images for each of the metal samples. Clinical patient plans with metal implants were investigated and DVHs were compared between standard CT and extended CT dose calculations. Dose calculations showed agreement within 2% between the two methods of metal characterization and the film measurement in the case of the strongest metal attenuator, cobalt‐chromium. In the clinical treatment plans, the greatest dose discrepancy between the two methods was 1.2%. This study suggests that direct dose calculation on an extended scale CT image in the presence of metal implants can produce accurate clinically viable treatment plans, thereby improving efficiency of clinical workflow and eliminating a potential source of human error by manual CT number assignment.PACS number(s): 87.55.dk

show abstract

“…Metal artifact reduction (MAR) methods have been employed to improve CT image quality when gold marker‐introduced image artifacts are present 17 , 18 A study by Kassim et. al (17) .…”

Section: Discussionmentioning

confidence: 99%

Determination of optimal fiducial marker across image‐guided radiation therapy (IGRT) modalities: visibility and artifact analysis of gold, carbon, and polymer fiducial markers

Handsfield¹,

Yue²,

Zhou³

et al. 2012

J Applied Clin Med Phys

View full text Add to dashboard Cite

The purpose of this study was to evaluate the visibility and artifact created by gold, carbon, and polymer fiducial markers in a simple phantom across computed tomography (CT), kilovoltage (kV), and megavoltage (MV) linear accelerator imaging and MV tomotherapy imaging. Three types of fiducial markers (gold, carbon, and polymer) were investigated for their visibility and artifacts in images acquired with various modalities and with different imaging parameters (kV, mAs, slice thickness). The imaging modalities include kV CT, 2D linac‐based kilovoltage and megavoltage X‐ray imaging systems, kV cone‐beam CT, and normal and fine tomotherapy imaging. The images were acquired on a phantom constructed using Superflab bolus in which markers of each type were inserted into the center layer. The visibility and artifacts produced by each marker were assessed qualitatively and quantitatively. All tested markers could be identified clearly on the acquired CT and linac‐based kV images; gold markers demonstrated the highest contrast. On the CT images, gold markers produced a significant artifact, while no artifacts were observed with polymer markers. Only gold markers were visible when using linac‐based MV and tomotherapy imaging. For linac‐based kV images, the contrast increased with kV and mAs values for all the markers, with the gold being the most pronounced. On CT images, the contrast increased with kV for the gold markers, while decreasing for the polymer and carbon marker. With the bolus phantom used, we found that when kV imaging‐based treatment verification equipment is available, polymer and carbon markers may be the preferred choice for target localization and patient treatment positioning verification due to less image artifacts. If MV imaging will be the sole modality for positioning verification, it may be necessary to use gold markers despite the artifacts they create on the simulation CT images.PACS number: 87

show abstract

An adaptive approach to metal artifact reduction in helical computed tomography for radiation therapy treatment planning: Experimental and clinical studies

Cited by 130 publications

References 13 publications

Metal-related artifacts in instrumented spine. Techniques for reducing artifacts in CT and MRI: state of the art

Metal-related artifacts in instrumented spine. Techniques for reducing artifacts in CT and MRI: state of the art

Treatment planning for metals using an extended CT number scale

Determination of optimal fiducial marker across image‐guided radiation therapy (IGRT) modalities: visibility and artifact analysis of gold, carbon, and polymer fiducial markers

Contact Info

Product

Resources

About