Design and Fabrication of a Four-Dimentional Respiratory Phantom for Studying Tumor Movement in Radiotherapy with Magnetic Resonance Imaging

Abstract

Background: In radiation therapy, determining the location of the tumor accurately is one of the most important requirements. But, lung tumors due to respiratory motion during radiotherapy are not fixed in a single location and move. Due to limitations in assessing such movements, using a lung phantom can be useful and operational in fast, easy and inexpensive assessment of such movements. The aim of this study was to design and build a four-dimensional respiratory phantom for studying tumor movement in radiation therapy. Methods: By molding the normal human lung, artificial lung was made of silicon. The chest was made of plexiglas and a double-walled container. The wall was filled with water to increase the signal strength of Magnetic Resonance Imaging (MRI). A 1.5-liter thin bag of silicon was made as the synthetic diaphragm and was placed into the chest. A piston pump was used to simulate the breathing and an engine and gearbox were used to create the reciprocating motion. Finally, the silicon lung model, capable of simulating the natural movement of the human lung was built with 7 tumors in it. Findings: The four-dimensional phantom lung was designed and constructed for examining the tumor motion during radiotherapy while breathing, according to the images obtained from the lung for examining the motion and the types of movements of the lung. Conclusion: It can be declared that this artificial lung (phantom), unlike the previously designed ones, is largely similar to human lungs and can be a useful tool for quality control of the imagine devices and the new protocols of radiotherapy.

Keywords

• Moving phantom
• Magnetic resonance imaging
• Radiotherapy
• Lung