Together with the American Association of Physicists in Medicine (AAPM), American College of Cardiology (ACC), American College of Radiology (ACR), American Society of Nuclear Cardiology (ASNC), and Society of Nuclear Medicine and Molecular Imaging (SNMMI), ASTRO sent a letter to Commerce Secretary Howard Lutnick expressing concern about negative effects of potential tariffs on the import of radipharmaceuticals, medical isotopes, and related materials for patient care and urges the Administration to exempt these materials from tariffs. The letter highlights the U.S.' heavy reliance on foreign sources for isotopes such as Mo-99 and Tc-99m, and warns that trade restrctions could lead to higher health care costs, reduced patient access, and critical diagnostic delays.