But critics, say some of MammoSite's popularity is a result of the relatively high reimbursements paid by insurers.
Meanwhile, a public interest group, Democracy 21, has asked Mr. DeLay to disclose the donors to his charitable foundation, as well as any reimbursements paid to House members to cover their participation in his Florida golfing event.
But because Mr. Margoles has never tried to transform the clinic into a federally qualified health center, it is not eligible for the higher reimbursements paid to those centers.
Tenet Healthcare, reeling from concerns about special Medicare reimbursements paid to its hospitals and a raid by federal agents of one of its facilities in California, outlined steps yesterday that it said it was taking to try to reassure investors.
Lawmakers who use campaign funds to pay relatives should be required to disclose that the payment is going to a family member, Ms. Sloan said, and there should be more detailed accounting of reimbursements paid to lawmakers or their family members for campaign expenses.
Over the last three weeks, Tenet's stock has plummeted amid a series of surprises, including an F.B.I. raid at a California hospital, the Redding Medical Center, where two heart doctors are accused of performing unnecessary surgeries, and a Medicare audit into special reimbursements paid to Tenet to handle costly cases.
Representative Ciro D. Rodriguez, a Texas Democrat who requested the study of his state, said, "A major reason for the substandard conditions in many Texas nursing homes is the shortage of staff, and that in turn results from the low level of reimbursements paid by the state under the Medicaid program".
Reimbursements paid to hospitals are based on a flat rate per admission which is set according to diagnosis-related groups.
Furthermore, these costs comprise the majority of reimbursements paid to the hospital (by any party involved) in financing the care for a specific patient either directly or indirectly.
Some saw the move as a potential sign of a more hardline approach from Washington, although the amount held back represents a drop in a bucket for Pakistan, which has received more than $14 billion since 2002 in Coalition Support Fund reimbursements, paid to foreign governments for the cost of military operations against terror groups.
