Drinking barium to protect the fetus during CT pulmonary angiography

This phantom study suggests that ingestion of barium will shield the fetus of a woman undergoing CT pulmonary angiography.
It's cheap, harmless and seems logical, so why not?

Yousefzadeh DK, Ward MB, Reft C.
Internal barium shielding to minimize fetal irradiation in spiral chest CT: a phantom simulation experiment.
Radiology. 2006 Jun;239(3):751-8.