Even during busy work hours, he always keeps his patients' well-being in his thoughts.

thoughts 是名词 thought 的复数形式，thought 的意思是"想法、思考"。这里指"心里惦记着、时刻想着"。 keep...in one's thoughts 这个短语表示"把...放在心上、时刻惦记着"，强调持续性的关心和关注。