alexanders, my understanding is that the Japanese authorities...

alexanders, my understanding is that the Japanese authorities do not do much TST testing as all there are BCG vaccinated thus the TST gives pretty hopeless results.

As you say Xray is the main technique presently used and this of course only picks up active pulmonory TB.

However QFT-Gold and intube not only pick up latent TB but also pick up pulmonory and non-pulmonory active TB. Thus there has to be a strong case for using QFT as the primary test and if positive then have a medico assess for active TB with Xray and sputum culture if active TB is suspected.

Are you sure the authorities there are not going to treat latent TB? With an estimated 5% of latent TB cases sure to progress to active surely non-treatment of latent TB just would not make sense if they are serious about getting on top of their TB epidemic?
What I have read from time to time has indicated the intention there to test all citizens 65yo or older each year in which case of course QFT would be ideal. Then any positives would be assessed and even if confirmed as latent isonaid would be prescribed.

QFT apparently already has the majority of the contact tracing market in Japan and it would be very surprising if cases of latent TB would not be treated.

regards