SEGMENT REPORTING (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended		24 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2021
Segment Reporting Information [Line Items]
Revenue	$ 341,767	$ 315,319
Cost of Operations	315,039	282,280
Depreciation and amortization	27,118	22,656
Loss (gain) on sale and disposal of equipment and other	1,128	(1,307)
Severance	201	285
(Loss) Income from Operations	(1,719)	11,405
COVID-19 Pandemic
Segment Reporting Information [Line Items]
Proceeds from provider relief funding	0	6,200	$ 9,100	$ 26,300	$ 35,400
Imaging Centers
Segment Reporting Information [Line Items]
Revenue	341,168	315,319
Cost of Operations	310,110	281,013
Depreciation and amortization	25,805	22,569
Loss (gain) on sale and disposal of equipment and other	1,154	(1,307)
Severance	201	285
(Loss) Income from Operations	3,898	12,759
AI
Segment Reporting Information [Line Items]
Revenue	599	0
Cost of Operations	4,929	1,267
Depreciation and amortization	1,313	87
Loss (gain) on sale and disposal of equipment and other	(26)	0
Severance	0	0
(Loss) Income from Operations	$ (5,617)	$ (1,354)