Medical College of Wisconsin
CTSICores SearchResearch InformaticsREDCap

Management of independent motion between multiple targets in lung cancer radiation therapy. Pract Radiat Oncol 2017 Jan - Feb;7(1):26-34

Date

10/16/2016

Pubmed ID

27742559

DOI

10.1016/j.prro.2016.08.013

Scopus ID

2-s2.0-85002279742

Abstract

PURPOSE: To quantify interfractional independent motions between multiple primary targets in radiation therapy (RT) of lung cancer and to study the dosimetric benefits of an online adaptive replanning method to account for these variations.

METHODS AND MATERIALS: Ninety-five on-treatment diagnostic-quality computed tomography (CT) scans acquired for 9 lung cancer patients treated with image-guided RT (IGRT) using a CT-on-rails (CTVision, Siemens) were analyzed. On each on-treatment CT set, contours of the targets (gross tumor volume, clinical target volume, or involved nodes), and organs at risk were generated by populating the planning contours using an autosegmentation tool (ABAS, Elekta) with manual editing. For each patient, an intensity modulated RT plan was generated based on the planning CT with a prescription dose of 60 Gy in 2 Gy per fraction. Three plans were generated and compared for each on-treatment CT set: an IGRT (repositioning) plan by copying the original plan with the required shifts, an online adaptive plan by rapidly modifying the aperture shapes, and segment weights of the original plan to conform to the on-treatment anatomy and a new fully reoptimized plan based on the on-treatment CT.

RESULTS: The interfractional deviations of the distance between centers of masses of the targets from the planning CTs varied from -1.0 to 0.8 cm with an average -0.09 ± 0.41 cm (1 standard deviation). The average combined CTV receiving at least 100% of the prescribed dose (V100) were 99.0 ± 0.7%, 97.8 ± 2.8%, 99.0 ± 0.6%, and 99.1 ± 0.6%, and the lung V20Gy 928 ± 332 cm3, 944 ± 315 cm3, 917 ± 300 cm3, and 891 ± 295 cm3 for the original, repositioning, adaptive, and reoptimized plans, respectively. Wilcoxon signed-rank tests showed that the adaptive plans were statistically significantly better than the repositioning plans and comparable with the reoptimized plans.

CONCLUSION: Interfractional, relative volume changes and independent motions between multiple primary targets during lung cancer RT, which cannot be accounted for by the current IGRT repositioning exist, but can be corrected by the online adaptive replanning method.

Author List

Liu F, Tai A, Ahunbay E, Gore E, Johnstone C, Li XA

Authors

Ergun Ahunbay PhD Associate Professor in the Radiation Oncology department at Medical College of Wisconsin
Elizabeth M. Gore MD Professor in the Radiation Oncology department at Medical College of Wisconsin
Candice A. Johnstone MD, MPH Associate Professor in the Radiation Oncology department at Medical College of Wisconsin
X Allen Li PhD Professor in the Radiation Oncology department at Medical College of Wisconsin
An Tai PhD Associate Professor in the Radiation Oncology department at Medical College of Wisconsin




MESH terms used to index this publication - Major topics in bold

Humans
Lung Neoplasms
Organs at Risk
Radiosurgery
Radiotherapy Planning, Computer-Assisted
Radiotherapy, Image-Guided
Radiotherapy, Intensity-Modulated
Tomography, X-Ray Computed
jenkins-FCD Prod-480 9a4deaf152b0b06dd18151814fff2e18f6c05280