Diagnostic centers give a pre-fixed percentage to doctors against each test/investigation if the doctor suggest/send patient to the center for testing. And if the center doesn't provide the percentage it doesn't take less form patient. Is it halal to give such percentage? If it's haram, is it halal to do job in such institute?
The doctor is paid for their service. The commission that is paid is against nothing. This payment will fall under the definition of bribery. To give and take bribery is forbidden in Islam. Hence, one should avoid it.
To work in a diagnostic centre will be permissible as the centre involves in doing tests etc, if the role specifically deals in paying such commissions as mentioned above then it will not be permissible.