The DIBH (Deep Inspiration Breath-Hold) Monitoring Development Using Ultrasonic and IR Sensors with a Microcontroller

Abstract

<h3>Purpose/Objective(s)</h3> We devised and developed a motion tracking system by using an ultrasonic (HC-SRO4) and an IR (Infrared- VL6180X Time of Flight) distance sensor and detector interfacing with a microcontroller and the 3D printed devices such as a detector assembly and supporting holders. The purpose of this study was to demonstrate the functionality and performance of our system. <h3>Materials/Methods</h3> The first step of this project was to check the functionality of a detector of DIBH motion interfacing a microcontroller. This was tested on an RPM (Real-Time Positioning Management) phantom to check a breathing motion. Ultrasonic and IR sensors were utilized on the Arduino microcontroller. Based upon the phantom tests with customized programming in Arduino, we tried to devise this on CT scan in terms of real patient scan's situation using a body phantom to mimic DIBH pattern. From a several trials, we recognized to need a detector holder which was mounted perpendicularly on between the xiphoid and umbilicus with 6-degree variables in longitudinal, lateral, vertical, rotational, pitching and rolling motion. The versatility allowed for compensation of various patient body habitus and adaptation in the clinical setup. The plastic devices for this project were created on 3D printer and programming. The sensors were mounted on approximately 100mm to receive the directed echo signals and prevent any unwanted signals from scattering or recoiling from other parts such as detection edges and supporting holders. <h3>Results</h3> The acquired results (n=20) demonstrated the entire process of the DIBH visualization project with a real-time breathing tracking and recording the breathing pattern. The patient's breathing between inhale and exhale was detected on amplitude change with time. In case of s, we observed that big fluctuations before the stable plateau of holding breathing on the DIBH were due to the mismatched echo signals in terms of irregular breathing patterns from patients and scattered signals outside of detector. There were also noisy patterns due to the sensor resolution of 3mm. We noticed the signal detection was angular dependent between the fixed sensor and moving surface from patient breathing. We used a focusing cup to reduce the angular dependency, but there was not much of improvement. In order to resolve the difficulties of ultrasonic sensor, we have utilized an IR sensor with the same setup of the ultrasonic and evaluated that it has compensated the signal detection with ±20 degrees of angular variation during the DIBH and the maximum clinical range of 450mm. The ratio of amplitude on DIBH to free breathing has increased to 1.7 times. <h3>Conclusion</h3> Comparing with the ultrasonic sensor, the IR sensor DIBH system demonstrated of breathing rhythm without big fluctuations and reduced a battle with noise. For various irregular breathings, it showed comparable RPM breathing motion, adequate breathing amplitude, clinically acceptable DIBH pattern to check chest and abdominal motion.