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Title: SU-F-T-410: Investigation of Treatment Planning Accuracy with the Presence of Magnetic Injection Port (breast Tissue Expander)

Abstract

Purpose: Mastectomy patients with breast reconstruction usually have a magnetic injection port inside the breast during radiation treatments. The magnet has a very high CT number and produces severe streaking artifact across the entire breast in CT images. Our routine strategy is to replace the artifact volumes with uniform water, and it is necessary to validate that the planned dose, with such an artifact correction, is sufficiently accurate. Methods: A phantom was made with a gelatine-filled container sitting on a Matrixx detector, and the magnetic port was inserted into gelatine with specific depths and orientations. The phantom was scanned on a CT simulator and imported into Eclipse for treatment planning. The dose distribution at the Matrixx detector plane was calculated for raw CT images and artifact-corrected images. The treatment beams were then delivered to the phantom and the dose distributions were acquired by the Matrixx detector. Gamma index was calculated to compare the planned dose and the measurement. Results: Three field sizes (10×10, 15×15 and 20×20) and two depths (50mm and 20mm) were investigated. With the 2%/2mm or 3%/3mm criteria, several points (6–10) failed in the plan for raw CT images, and the number of failure was reduced close tomore » zero for the corrected CT images. An assignment of 10,000 HU to the magnet further reduced the dose error directly under the magnet. Conclusion: It is validated that our routine strategy of artifact correction can effectively reduce the number of failures in the detector plane. It is also recommended to set the magnet with a CT number of 10,000HU, which could potentially improve the dose calculation at the points right behind the magnet.« less

Authors:
; ; ;  [1]
  1. Brigham and Women’s Hospital, Boston, MA and Harvard Medical School, Boston, MA (United States)
Publication Date:
OSTI Identifier:
22649006
Resource Type:
Journal Article
Resource Relation:
Journal Name: Medical Physics; Journal Volume: 43; Journal Issue: 6; Other Information: (c) 2016 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
60 APPLIED LIFE SCIENCES; 61 RADIATION PROTECTION AND DOSIMETRY; COMPUTERIZED TOMOGRAPHY; CORRECTIONS; IMAGES; MAMMARY GLANDS; PHANTOMS; PLANNING; RADIATION DOSE DISTRIBUTIONS; RADIATION DOSES; RADIOTHERAPY

Citation Formats

Cai, W, Wagar, M, Lyatskaya, Y, and Czerminska, M. SU-F-T-410: Investigation of Treatment Planning Accuracy with the Presence of Magnetic Injection Port (breast Tissue Expander). United States: N. p., 2016. Web. doi:10.1118/1.4956595.
Cai, W, Wagar, M, Lyatskaya, Y, & Czerminska, M. SU-F-T-410: Investigation of Treatment Planning Accuracy with the Presence of Magnetic Injection Port (breast Tissue Expander). United States. doi:10.1118/1.4956595.
Cai, W, Wagar, M, Lyatskaya, Y, and Czerminska, M. Wed . "SU-F-T-410: Investigation of Treatment Planning Accuracy with the Presence of Magnetic Injection Port (breast Tissue Expander)". United States. doi:10.1118/1.4956595.
@article{osti_22649006,
title = {SU-F-T-410: Investigation of Treatment Planning Accuracy with the Presence of Magnetic Injection Port (breast Tissue Expander)},
author = {Cai, W and Wagar, M and Lyatskaya, Y and Czerminska, M},
abstractNote = {Purpose: Mastectomy patients with breast reconstruction usually have a magnetic injection port inside the breast during radiation treatments. The magnet has a very high CT number and produces severe streaking artifact across the entire breast in CT images. Our routine strategy is to replace the artifact volumes with uniform water, and it is necessary to validate that the planned dose, with such an artifact correction, is sufficiently accurate. Methods: A phantom was made with a gelatine-filled container sitting on a Matrixx detector, and the magnetic port was inserted into gelatine with specific depths and orientations. The phantom was scanned on a CT simulator and imported into Eclipse for treatment planning. The dose distribution at the Matrixx detector plane was calculated for raw CT images and artifact-corrected images. The treatment beams were then delivered to the phantom and the dose distributions were acquired by the Matrixx detector. Gamma index was calculated to compare the planned dose and the measurement. Results: Three field sizes (10×10, 15×15 and 20×20) and two depths (50mm and 20mm) were investigated. With the 2%/2mm or 3%/3mm criteria, several points (6–10) failed in the plan for raw CT images, and the number of failure was reduced close to zero for the corrected CT images. An assignment of 10,000 HU to the magnet further reduced the dose error directly under the magnet. Conclusion: It is validated that our routine strategy of artifact correction can effectively reduce the number of failures in the detector plane. It is also recommended to set the magnet with a CT number of 10,000HU, which could potentially improve the dose calculation at the points right behind the magnet.},
doi = {10.1118/1.4956595},
journal = {Medical Physics},
number = 6,
volume = 43,
place = {United States},
year = {Wed Jun 15 00:00:00 EDT 2016},
month = {Wed Jun 15 00:00:00 EDT 2016}
}