Thanks for your question on Health Care Magic. 
I can understand your concern. 
Yes, old, healed TB scar can be the reason for your visa rejection. 
To avoid this rejection, we need to prove that these  lesions on chest 
x ray are not active infectious lesions. 
And for this, you need to 
consult pulmonologist and get done CT thorax with Contrast and 
bronchoscopy with BAL (
bronchoalveolar lavage) analysis. 
If both these are negative for 
tuberculosis than you can argue with visa authority about not having active, infectious disease and lesions on x ray are old, healed, inactive lesions. 
So consult pulmonologist and discuss all these. 
Hope I have solved your query. 
Wish you good health. Thanks.