The Effects of the Orthopedic Metal Artifact Reduction (O-MAR) Algorithm on Contouring and Dosimetry of Head and Neck Radiotherapy Patients

Overview

Journal Med Dosim

Specialty Radiology

Date 2019 Aug 4

PMID 31375297

Citations 3

Authors

Jussi Sillanpaa

Michael Lovelock

Boris Mueller

Affiliations

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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.

Citing Articles

The Relationship between the Contouring Time of the Metal Artifacts Area and Metal Artifacts in Head and Neck Radiotherapy.

Katsura K, Tanabe S, Nakano H, Sakai M, Ohta A, Kaidu M Tomography. 2023; 9(1):98-104.

PMID: 36648996 PMC: 9844309. DOI: 10.3390/tomography9010009.

Geometric and dosimetric impact of 3D generative adversarial network-based metal artifact reduction algorithm on VMAT and IMPT for the head and neck region.

Nakamura M, Nakao M, Imanishi K, Hirashima H, Tsuruta Y Radiat Oncol. 2021; 16(1):96.

PMID: 34092240 PMC: 8182914. DOI: 10.1186/s13014-021-01827-0.

The application of metal artifact reduction methods on computed tomography scans for radiotherapy applications: A literature review.

Puvanasunthararajah S, Fontanarosa D, Wille M, Camps S J Appl Clin Med Phys. 2021; 22(6):198-223.

PMID: 33938608 PMC: 8200502. DOI: 10.1002/acm2.13255.

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