https://openworks.mdanderson.org/sumexp23/1033/thumbnail.jp

Kohler, Benjamin M

Marinello, Poliana

Reis, Marco Tulio

Sawakuchi, Gabriel

English

OpenWorks @ MD Anderson

ResultsFigure 1. Components of the α-particle irradiator before the addition of a shutter. Photo A depicts the α source, B shows the cell dish with mylar to adhere to, and C is the complete assembly.Enhancing the Design and Consistency of anα-particle Irradiator for In Vitro ExperimentsIntroductionRadiation therapy employs various radiation forms with different capacities to impact DNA within cells. This depends on their linear energy transfer (LET), which measures the energy deposited by ionizing radiation per unit length of tissue. High-LET α-particles (70-200 keV/µm), are effective in inducing clustered DNA lesions, resulting in higher cell kill and immunostimulatory effects [1]. However, delivering α-particles to the entire solid tumor volume through conventional brachytherapy is challenging due to limited range (<90 µm in water). Diffusing α-Emitters Radiation Therapy (DaRT) addresses this by using interstitial cylindrical seeds coated with radium-224, which extends α-particles' range by utilizing a unique decay chain, including radon-220. This allows α-particles to deposit doses over 2-3 mm from the seed [2]. In 2D cultures, achieving consistent dosimetry with DaRT is challenging due to the geometry of the seeds, causing a rapid dose rate decline. To overcome this, a specialized α-particle irradiator was designed, utilizing an Americium-241 (Am-241) source to provide controlled and predictable exposure. Improving on this, a shutter system was incorporated to block and expose α-particles at desired time-points, creating an efficient system for consistent and accurate α-particle exposure during in vitro experiments.MethodsSolenoid Actuation: To test the controlled shutter movement, a high-performance solenoid (DSRS-0640-26-45D) was employed. The solenoid was activated using an Arduino Uno micro-controller, which was programmed to generate a small signal pulse to the BTS7960 power motor, functioning as an H-bridge driver circuit. This configuration allowed the full voltage to pass through, powering the solenoid to induce the desired shutter movement.Arduino IDE Code:  The code defines pins to interface with the BTS7960 motor driver and the motor. It uses a library to simplify interaction with the motor driver, providing predefined functions for motor rotation and speed control. Initialization is done in setup(), and in loop(), various motor control operations are performed, including rotation in both clockwise and counterclockwise directions with different speeds and delays.3D CAD Enclosure: The physical integrity and protection of the sensitive components were achieved through a custom-designed enclosure manufactured using 3D CAD software (Autodesk Fusion 360). The utilization of advanced design software enabled precise measurements, intricate detailing, and the creation of a robust casing to house the solenoid, Arduino Uno, BTS7960 motor driver, and associated circuitry.DiscussionOne of the primary objectives of this study was to improve the accuracy of dosimetry delivery by implementing a reliable shutter system. The utilization of a high-performance solenoid, driven by the Arduino Uno microcontroller, demonstrated the feasibility of achieving controlled and precise shutter movements. The combination of the BTS7960 power motor allowed for seamless interfacing with the Arduino Uno, facilitating full voltage delivery to the solenoid. As a result, the shutter system demonstrated robust and consistent performance, eliminating potential errors associated with manual interventions and leading to improved dosimetric accuracy during radiation exposureFurther WorkSome critical aspects need attention before declaring the irradiator complete, such as addressing power consumption and heating issues by using a higher-quality solenoid with reduced voltage requirements. Additionally, incorporating a collimator could enhance dosimetry precision, leading to more sophisticated in vitro experiments. Despite the current limitations, this work lays a solid foundation for ongoing improvements to α irradiators, showcasing dedication and ingenuity in the pursuit of enhanced radiation delivery systems for in vitro experimentation.Figure 2. Solenoid shutter system controlled with an Arduino Uno and BTS7960) References1. Bonaventura P, Shekarian T, Alcazer V, Valladeau-Guilemond J, Valsesia-Wittmann S, Amigorena S, Caux C, Depil S. Cold Tumors: A Therapeutic Challenge for Immunotherapy [published online ahead of print 2019/02/26]. Front Immunol. 2019;10:168.2. Popovtzer A, Rosenfeld E, Mizrachi A, Bellia SR, Ben-Hur R, Feliciani G, Sarnelli A, Arazi L, Deutsch L, Kelson I, Keisari Y. Initial Safety and Tumor Control Results From a “First-in-Human” Multicenter Prospective Trial Evaluating a Novel Alpha-Emitting Radionuclide for the Treatment of Locally Advanced Recurrent Squamous Cell Carcinomas of the Skin and Head and Neck. International Journal of Radiation Oncology*Biology*Physics. 2020;106(3):571-578.Figure 3. Circuit diagram for the system including the solenoid, arduino, BTS7960, and power source (24V)Figure 4. Arduino IDE code written to control the solenoid for a specified time periodBenjamin Kohler, Marco Tulio Reis, Poliana Marinello, Gabriel SawakuchiThe University of Texas MD Anderson Cancer Center, Houston, Texas Michigan State University, East Lansing, MichiganAcknowledgmentsThis Research was partially funded by Alpha Tau Medical, Radiation Oncology Strategic Initiatives from MD Anderson Cancer Center, and NCI (RO1CA279119-01).

Enhancing the Design and Consistency of an α-particle Irradiator for In Vitro Experiments

https://openworks.mdanderson.org/cgi/viewcontent.cgi?article=1033&context=sumexp23

Enhancing the Design and Consistency of an α-particle Irradiator for In Vitro Experiments

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