It depends mostly on sputum test. Three consecutive sputum test is to see if there's any detectable culture in the sputum. If the sputum tested positive, your father would have been put on treatment plan immediately. So, his sputum test must have came back negative. But, they will grow culture from his sputum for two months and see if they can detect TB. If that came back positive, then he'd be placed on treatment plan as well.
If both the sputum and culture tests came back negative, they will likely want to get another X-ray done in about three months to make sure that there's no changes in his X-ray. Sometimes, people can have scars on their lungs and can be misdiagnosed as TB. Having a consistent X-ray even after the treatment will confirm that it is not TB, but a scar.
In your case, your dad is going through the first culture test. Once you get the result back, you will know what your next steps are. Generally speaking, your father will go through sputum test and get his first X-ray. He will then have another X-ray in three to six months to compare it to the first one. Once those steps are clear (i.e no positive result from sputum and culture tests plus no changes in his X-ray), he will have his medical pass status.
Here are a few useful links pertaining TB:
http://www.cic.gc.ca/english/department/partner/pp/pdf/IMEI_Tuberculosis.pdf
http://www.cic.gc.ca/english/resources/tools/medic/surveillance/surveillance.asp
http://www.cic.gc.ca/english/resources/tools/medic/admiss/health.asp