Hi kabir,
Thank you!
Just to give you an idea, if sputum test will turn out as negative, i think final xray will only be a formality that everything is ok and it is part of the procedure to follow.
In my mom's case, when she had her final xray on Aug. 24, 2015 after sputum test, they saw a haze on her lungs, maybe because she had coughs during that time. She was given 7-day antibiotics by the panel physician and was told to wait for CIC's instruction within 3 months. they said CIC may ask for another xray. That's why i got surprised when i received the PPR on Sept. 30th, after 5 weeks from final xray. Which means, my mom's xray though there was a haze was cleared of any lung disease that needs immediate attention. Now, i can say that CIC is not that they want us to have a burden but they are also considerate if they think nothing is a big deal on the results of the medical.
So if your mom's sputum is negative, I think she will be done by first quarter of 2016