There are 4 tables which are mentioned as below :
a) {Test , Testlog} : Test being on "many" side of the testlog relationship can be merged hence..
b) {Patient , Checks} : Similar reason as above
c) {Performed_By}
d) {Doctors} : Any of test , doctors and performed_by cannot be merged with each other as performed_by is many to many relationship between test and doctors entities..
Hence we have 4 tables in total for the given ER diagram..