What is the central ray entrance point for a PA projection of the contrast filled stomach when performing a double-contrast UGI study on a sthenic patient?
1) Midsagittal plane at the level of the iliac crests
2) Midsagittal plane at the level of T11
3) Midsagittal plane at the level of the interspace between L1 and L2
4) Midsagittal plane at the level of L3