Logic Masters Deutschland e.V.

I was Inspired by @pwinn 's puzzle. I was wondering if can quads and windoku are good combination to this puzzle. I had the eureka moment while setting this puzzle. So here's the puzzle. This is also my 1st puzzle to be published on LMD.

Normal Sudoku Rules Apply. Each row, column, and 3x3 box contains the digits 1-9 exactly once each.

Digits in a Quadruple circle must be placed at least once in the four cells touching that circle.

There are four additional regions marked in green. Each also contains the digits 1 through 9.

Solve in Sudokupad