The effects of the orthopedic metal artifact reduction (O-MAR) algorithm on contouring and dosimetry of head and neck radiotherapy patients Journal Article


Authors: Sillanpaa, J.; Lovelock, M.; Mueller, B.
Article Title: The effects of the orthopedic metal artifact reduction (O-MAR) algorithm on contouring and dosimetry of head and neck radiotherapy patients
Abstract: Metallic objects, such as dental fillings, cause artifacts in computed tomography (CT) scans. We quantify the contouring and dosimetric effects of Orthopedic Metal Artifact Reduction (O-MAR), in head and neck radiotherapy. The ease of organ contouring was assessed by having a radiation oncologist identify the CT data set with or without O-MAR for each of 28 patients that was easier to contour. The effect on contouring was quantified further by having the physician recontour parotid glands, previously drawn by him on the O-MAR scans, on uncorrected scans, and calculating the Dice coefficent (a measure of overlap) for the contours. Radiotherapy plans originally generated on scans reconstructed with O-MAR were recalculated on scans without metal artifact correction. The study was done using the Analytical Anisotropic Algorithm (AAA) dose calculation algorithm. The 15 patients with a planning target volume (PTV) extending to the same slice as the artifacts were used for this part of the study. The normal tissue doses were not significantly affected. The PTV mean dose and V95 were not affected, but the cold spots became less severe in the O-MAR corrected plans, with the minimum point dose on average being 4.1% higher. In 79% of the cases, the radiation oncologist identified the O-MAR scan as easier to contour; in 11% he chose the uncorrected scan and in 11% the scans were judged to have equal quality. A total of nine parotid glands (on both scans—18 contours in total) in 5 patients were recontoured. The average Dice coefficient for parotids drawn with and without O-MAR was found to be 0.775 +/− 0.045. The O-MAR algorithm does not produce a significant dosimetric effect in head and neck plans when using the AAA dose calculation algorithm. It can therefore be used for improved contouring accuracy without updating the critical structure tolerance doses and target coverage expectations. © 2019 American Association of Medical Dosimetrists
Keywords: clinical article; controlled study; intensity modulated radiation therapy; treatment planning; cancer patient; cancer radiotherapy; computer assisted tomography; retrospective study; head and neck cancer; imrt; dosimetry; nasopharynx cancer; tongue cancer; larynx cancer; parotid gland; mouth cancer; volumetric modulated arc therapy; tonsil cancer; parotid gland cancer; planning target volume; human; priority journal; article; radiation oncologist; constants and coefficients; dice coefficient; image artifact; imaging algorithm; metal artifact correction; anisotropic analytical algorithm; orthopedic metal artifact reduction algorithm
Journal Title: Medical Dosimetry
Volume: 45
Issue: 1
ISSN: 0958-3947
Publisher: Elsevier Science, Inc.  
Date Published: 2020-01-01
Start Page: 92
End Page: 96
Language: English
DOI: 10.1016/j.meddos.2019.07.003
PUBMED: 31375297
PROVIDER: scopus
PMCID: PMC6989373
DOI/URL:
Notes: The publisher's record lists the publication date as Spring -- Article -- Source: Scopus
Altmetric
Citation Impact
MSK Authors
  1. Boris A Mueller
    91 Mueller
  2. Dale M Lovelock
    181 Lovelock