Is imprisonment a necessary system for dealing with all criminal acts?

Is imprisonment a necessary system for dealing with all criminal acts?
I have to answer "yes" to this question,  because we don't have an alternative way to deal with them now.

But how about this question:
Is imprisonment a appropriate system for dealing with all criminal acts?

I cannot answer "yes" to this question, because I think this system doesn't accomplish its role.

The role of imprisonment system is to let prisoner to be born again, and eventually decrease the number of crime.
As everyone knows, many criminals repeat committing crimes after released from prisons, and the number of crime isn't decrease after all.
So we have to change its system.

In U.S., some experiments are already performed.
In one experiment, prisoners are made to breed stray dogs. Through this experience, they can learn patience and satisfaction of accomplishing tasks, and the percentage of repeating commit crimes is greatly decreasing.

I think we have to come up with such new ways and adopt actively in Japan, too.
Imprisonment is necessary, so we must change its system in order to make society better.