Microfluidic Chip Calorimeter for Small-Field Radiation Dosimetry

Recent advances in medical radiation technologies have enabled small field radiotherapy with a beam size as small as a few millimeters for precise dose delivery to patients. However, conventional radiation dosimeters for small field radiotherapy suffer from inaccurate dose measurements due to their large absorber size. Herein, we present a nanofabricated chip calorimeter as a new platform for a miniaturized dosimeter for measurements of the absorbed dose. The calorimeter consists of a microscale absorber body built with a SU-8 photoresist and a microfluidic water container. The measurement system was constructed such that the calorimeter operates in the heat compensation mode, where the temperature change of the absorber was proportional to the absorbed energy. The operability of the heat compensation calorimeter was examined with electric heating and a visible light source. The feasibility of application of the microfluidic chip calorimeter for medical radiation sensor was successfully demonstrated by measuring the absorbed dose from the small radiation field of the Gamma Knife.