Can " treatment program" be substituted with "regime" here?

Yes.

Thank you Contrex.
But it should have been "regimen". A typo.

I have seen 'regime' used thus. In numerous dictionaries and thesauruses regime and regimen are said to be synonymous when used to mean a plan or a regulated course such as a diet, exercise or treatment, designed to give a good result. Some sources state that regimen must be used for that, and that regime only means an authoritarian government. However, in both US and British English, for at least 100 years, regime and regimen have been considered to be interchangeable when used as you quoted. Low-salt regime, high protein regime,

Excellent!
Thank you.