This excerpt taken from the RDNT DEF 14A filed Oct 20, 2006.
Fair Value of Financial Instruments
Statement of Financial Accounting Standards No. 107, Disclosure About Fair Value of Financial Instruments, requires disclosure about the fair value of certain financial instruments. The carrying amounts of cash and cash equivalents, accounts receivable, accounts payable and accrued expenses approximate fair value due to the short maturity of these instruments. The estimates of fair value are based upon the quoted market prices for the same or similar issues of long term-debt with the same maturities, when available, or discounted cash flows.