The MT positive status is expected in a child infected with tuberculosis
and hence the repetition of this test post completion of Anti-TB medication
is not required.
If the X-ray shows healing ,Complete blood count
is normal and the child is healthy with no complains then it should be considered that the child is cured of the infection and needs to be monitored for weight and height for few more months.
Lung scan is just a diagnostic tool and if clinically child is fine then there is no requirement for further investigations.
Hope to have answered your query.