TestLink

Am a new user of Testlink and jus exploring its features. Can nebody explain how a test case reviewing process b incorporated-
- A tester completes writing test cases in a test suite and assign it to Test lead.
- Test lead reviews those test cases.
1. Assign back to tester for improvements/alteration
2. Or completes review and assign those as ready for testing.

I tried making custom field of 'Review status' but it can be assign on Test case level or test suite level. Both of these are available to test lead and tester and tester can modify Review status which I donot want to. It should be only modified by Test lead.

Can anyone give me any idea how to implement this??

custom fields has no role concept => can be edit by everyone

We are aware about missing support for review. There is request http://www.testlink.org/mantis/view.php?id=1810. I hope that it will be available in the next major version.
Meantime there is not better workaround than custom fields.