Fluoroscopic Demonstration of Thoracic Tumor Immobilization with High Frequency Percussive Ventilation

Abstract

Purpose: The purpose of this first-in-man study is to directly measure thoracic tumor immobilization by high frequency percussive ventilation (HFPV). Methods: In an IRB approved protocol (IRB # 2017-046) we screened patients with conspicuous lung tumors that exhibited motion >10 mm to undergo kV fluoroscopy with HFPV. Two sets of consecutive AP (anterior posterior) fluoroscopy frames were acquired during multiple breathing cycles for freeand HFPVbreathing. All images were acquired using our kV source/panel of the therapeutic linear accelerator. Percussions were delivered via the intrapulmonary percussive ventilation device (IPV-2C) and phasitron (Percussionaire Corp., Sagle, Idaho). The baseline settings for the IPV-2C (pressure, frequency, CPAP and inspiration time) were set during an initial training session, but minor adjustments were made prior to imaging at the direction and comfort of the patient. Results: Patient recruited was a 69 y.o. female with stage IB (cT2a, cN0, cM0) adenocarcinoma of the LLL with lepidic and acinar growth pattern. She experienced slight discomfort lying flat on the treatment table, however successfully completed HFPV. Peak-to-peak tumor motion during 4DCT sim was 11.0 mm, however patient had already received 4x 10Gy fractions of SBRT when enrolled in the study, and therefore peak-to-peak motion during free-breathing measured with fluoroscopy, at the time of the study, was 6.2 mm. Subsequently, peak-to-peak motion measured with fluoroscopy during HFPV was at 2.7 mm. This resulted in a 57 % tumor motion reduction. Conclusion: In this first-in-man study, we have shown that HFPV is a novel respiratory motion technique that can significantly reduce tumor motion.