CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
CASH FLOWS FROM OPERATING ACTIVITIES
Net income (loss)	$ 64,287	$ 7,342	$ (12,685)
Adjustments to reconcile net income ( loss ) to net cash provided by operating activities:
Depreciation and amortization	57,740	57,481	53,997
Provision for bad debt	25,904	22,339	21,995
Equity in earnings of joint ventures	(6,476)	(5,224)	(4,952)
Distributions from joint ventures	6,477	4,993	7,639
Deferred rent amortization	3,608	2,282	1,848
Amortization of deferred financing cost	2,474	2,940	2,797
Amortization of bond and term loan discounts	1,163	244	164
Loss (gain) on sale and disposal of equipment	456	(2,240)	1,136
Gain on bargain purchase	(810)
Loss on extinguishment of debt			9,871
Gain on de-consolidation of joint venture	(2,777)
Amortization of cash flow hedge	918	1,225	917
Stock-based compensation	2,736	3,110	3,718
Changes in operating assets and liabilities, net of assets acquired and liabilities assumed in purchase transactions:
Accounts receivable	(17,350)	(45,014)	(24,822)
Other current assets	3,565	(3,935)	(3,226)
Other assets	(60,975)	43	24
Deferred revenue	197	(492)	207
Accounts payable, accrued expenses	(5,868)	12,542	8,256
Net cash provided by operating activities	75,269	57,636	66,884
CASH FLOWS FROM INVESTING ACTIVITIES
Purchase of imaging facilities	(45,493)	(42,990)	(61,774)
Purchase of property and equipment	(44,448)	(42,720)	(40,293)
Proceeds from sale of equipment	1,549	325	685
Proceeds from insurance claims on damaged equipment		2,740
Proceeds from sale of imaging facilities	2,300
Proceeds from sale of joint venture interests	1,800
Purchase of equity interest in joint ventures	(2,756)	(5,094)
Net cash used in investing activities	(87,048)	(87,739)	(101,382)
CASH FLOWS FROM FINANCING ACTIVITIES
Principal payments on notes and leases payable	(22,223)	(18,756)	(21,463)
Proceeds from borrowings upon refinancing	344,485		478,313
Repayment of debt	(277,875)		(412,000)
Deferred financing costs	(3,753)	(944)	(13,566)
Proceeds from, net of payments on, line of credit	(25,000)	58,000
Payments to counterparties of interest rate swaps, net of amounts received	(5,823)	(6,455)	(6,382)
Distributions to noncontrolling interests	(71)	(154)	(131)
Purchase of non-controlling interests	(117)
Proceeds from issuance of common stock upon exercise of options/warrants		242	271
Net cash provided by financing activities	9,623	31,933	25,042
EFFECT OF EXCHANGE RATE CHANGES ON CASH	63	(2)	(11)
NET (DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS	(2,093)	1,828	(9,467)
CASH AND CASH EQUIVALENTS, beginning of period	2,455	627	10,094
CASH AND CASH EQUIVALENTS, end of period	362	2,455	627
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION
Cash paid during the period for interest	47,806	47,310	40,352
Cash paid during the period for income taxes	$ 918	$ 514	$ 659