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Using 4DCT-Ventilation to Evaluate Lung Response for Pediatric Patients Getting Thoracic Radiotherapy

Y Vinogradskiy

Y Vinogradskiy1*, A Faught1 , E Castillo2 , R Castillo3 , A Liu1 , M Miften1 , (1) University of Colorado Denver, Aurora, CO, (2) Beaumont Health System, Royal Oak, Michigan, (3) Univ Texas Medical Branch at Galveston, Galveston, TX


MO-RPM-GePD-J(B)-5 (Monday, July 31, 2017) 3:45 PM - 4:15 PM Room: Joint Imaging-Therapy ePoster Lounge - B

Purpose: A new form of lung functional imaging has been developed that uses 4DCT data to calculate ventilation (4DCT-ventilation). Because 4DCTs are acquired as standard of care to manage breathing motion during radiotherapy, 4DCT-ventilation provides functional information at no extra dosimetric or monetary cost. 4DCT-ventilation has yet to be described in children. 4DCT-ventilation can be used as a tool to help assess post treatment lung function and predict for future clinical thoracic toxicities for pediatric patients receiving radiotherapy to the chest. The purpose of this work was to evaluate 4DCT-ventilation-based lung function changes for pediatric patients receiving radiotherapy to the lungs.

Methods: The study used three patients with pre and post-radiotherapy 4DCTs. The 4DCTs, deformable image registration, and a density-change-based algorithm were used to compute a pre and post-treatment 4DCT-ventilation image. The post-treatment 4DCT-ventilation was compared to the pre-treatment 4DCT-ventilation image for a global lung response and for an intrapatient dose response. The intrapatient dose response was assessed using ventilation changes in 4 dose bins between 0 and 20 Gy.

Results: For 2 of the 3 patients, a global ventilation decline of 37% was observed, while for the third patient no global change in lung function was present. The dose response analysis did not reveal an intrapatient dose response from 0 to 20 Gy; in other words, the lung function did not worsen differentially in regions within the deposited dose.

Conclusion: Compared to adults, pediatric patients have unique lung function, dosimetric, and toxicity profiles. We evaluated spatial lung function changes in pediatric patients using 4DCT-ventilation and showed lung function changes for 2 of the 3 patients. The early changes demonstrated with lung function imaging warrant further longitudinal work to determine whether the imaging-based early changes can predict for long term clinical toxicity.

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