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FDA > CDRH > Radiological Health Program > Radiation Safety > Nationwide Evaluation of X-Ray Trends (Next) > Data Summaries

Data Summaries

Each year the NEXT survey program selects a particular radiological examination for study and collects radiation exposure data from a nationally representative sample of U.S. clinical facilities. Surveys are repeated periodically to track trends as technology and clinical practices change. Since 1973, NEXT has been conducting surveys on examinations related to the adult chest, abdomen, lumbosacral (LS) spine, upper gastrointestinal fluoroscopy, mammography, computed tomography, dental radiography, and pediatric chest radiography. The following is a breakdown by year of the NEXT surveys that have been performed and the corresponding number of facilities surveyed:

NEXT Surveys Performed

Survey Year	Survey Type	Number of Facilities Surveyed
1984	Adult Chest	429
1985	Mammography	232
1986	Adult Chest (Private Practice)	137
1987	Abdomen and Lumbosacral (LS) Spine (Hospitals)	496
1988	Mammography	231
1989	Abdomen and LS Spine (Private Practice)	374
1990	Computed Tomography	264
1991	Upper GI Fluoroscopy	373
1992	Mammography	356
1993	Dental Radiography	322
1994	Adult Chest	314
1995	Abdomen and LS Spine	240 Abdomen / 320 LS Spine
1996	Upper GI Fluoroscopy	344
1998	Pediatric Chest	397
1999	Dental Radiography	342
2000	Computed Tomography	265
2001	Adult Chest	220
2002	Abdomen and LS Spine	*200
2003	Upper GI Fluoroscopy	*

*As of 8/03

The NEXT surveys today capture comprehensive data on radiation exposure and image quality associated with the practice of medical diagnostic radiology. Among the data obtained are the evaluations of film processing quality, the integrity of the film processing darkroom environment, x-ray film-image quality, and information about the facility's general practice.

The following are data summary tables for the NEXT exams that have been performed:

Adult Chest Exam

	2001	1994	1986	1984
Number of Facilities	220	314	137	429
Entrance Air Kerma (mGy)	0.13	0.14	0.14	0.14
Clinical kVp	109	101	87	104
Exposure Time (ms)	29	31	64	22
Percent Using Grids	93	79	32	71
Phantom Film Optical Density	1.64	1.67	1.42	1.43

Abdomen Exams

	2002	1995	1989	1987
Number of Facilities	*200	240	374	496
Entrance Air Kerma (mGy)	2.73	2.82	3.39	3.23
Clinical kVp	75	76	78	75
Exposure Time (ms)	306	145	371	247
Phantom Film OD	1.83	1.74	1.73	1.80
Half-Value Layer (mm Al)	3.1	3.0	3.1	3.2

*Preliminary

Lumbosacral Spine Exams

	2002	1995	1989	1987
Number of Facilities	*200	320	374	496
Entrance Air Kerma (mGy)	3.21	3.22	3.85	3.71
Clinical kVp	78	78	80	77
Exposure Time (ms)	351	145	371	247
Phantom Film Optical Density	1.41	1.32	1.26	1.15
Half Value Layer (mm Al)	3.2	3.0	3.1	3.2

*As of 8/03

Fluoroscopy- Upper GI Exam and Special Topics

	1996	1996	1996	1991
Number of Facilities	321	25	52	320
Type	Upper GI	Cardiac Catch Labs	Mobile C-Arm Units	Upper GI
Entrance Air Kerma Rate (mGy/min)	45	38	22	43
Clinical kVp	99	82	78	102
Tube Current (mA)	2.3	5.1	3.0	2.1
*Air Kerma Rate with contrast (mGy/min)**	67	71	41	65
Maximum Air Kerma Rate (mGy/min)	70	74	44	67

*Copper is used to simulate the presence of barium contrast

Pediatric Chest Exam

	1998
Number of Facilities	397
Entrance Air Kerma (mGy)	.051
Clinical kVp	71
Exposure Time (ms)	12
Percent Using Grids	9.0
Phantom Film Optical Density	1.73
Patient Restraint Method Most Frequent Used	Adult
Percent AP / Percent PA	40/60

Dental (Intraoral) Exam

	1999	1993
Number of Facilities	342	320
Entrance Air Kerma (mGy)	1.60	1.90
Clinical kVp	71	72
Percent Manual Film Processing	10.0	29.0
Phantom Film Optical Density	1.49	1.48
Percent using D-speed Film	65	90

Computed Tomography

Head Exam (axial scanning)

	2000	1990
MSAD (mGy)	50.3	45.9
mAs	347	459
kVp	127	122
Effective Dose (mSv)	1.2	--

Body Exams (helical scanning) - Effective Dose (mSv)

	2000	1990
Chest	9.3	--
Abdomen+Pelvis	13.7	--
Abdomen	9.1	--
Pelvis	6.2	--

Darkroom Fog and Film Processing

Darkroom fog is a measure of optical density on clinical radiographs that results from ambient light conditions in the darkroom. Darkroom fog can result from light leaks, improper safelight conditions from the use of inappropriate bulbs or damaged filters, and from inadvertent exposure during film storage or handling.

The quality of film processing is evaluated by a procedure known as the "Sensitometric Technique for the Evaluation of Processing" or STEP. This test utilizes a selected control batch of radiographic film with a pre-determined sensitometric curve when processed according to film manufacturer recommendations. The control film is flashed by a sensitometer and then processed the same way as film is processed normally at the facility. A comparison is made of the optical densities obtained at the facility with what should be obtained were the control film processed as required by the film manufacturer. Any deviation of the control film optical density produced at the facility from what should be obtained were the facility processing according to the "gold standard" determines the extent of under- or over-processing of the film by the facility. The resulting processing speed value is then determined, with a speed range of 80 to 120 considered acceptable for standard cycle processing. Under processing, which corresponds to a processor speed value of below 80, is an inefficiency that maybe inappropriately compensated with increased radiation exposure to patients.

The following is an overall survey comparison of Film Processing and Darkroom Fog:

Year	Survey Type	N	Mean Processing Speed	Percent (%) of Under-processing**	Darkroom Fog (OD)
1984	Chest (Hospitals)	408	96	18.9	N/A
1985	Mammography	139	91	20.9	N/A
1986	Chest (Private Practice)	99	86	40.4	N/A
1987	Abdomen/LS Spine (Hospitals)	261	88	37.2	N/A
1988	Mammography	176	102	10.2	N/A
1989	Abdomen/LS Spine (Private Practice)	301	89	41.9	N/A
1991	Fluoroscopy	349	96	18.6	N/A
1992	Mammography	238	98	7.1	0.12
1993	Dental	103	83	49.5	0.08
1994	Chest (Hospitals)	134	115	4.5	0.09
1994	Chest (Private Practice)	148	107	15.5	0.11
1995	Abdomen/LS spine (Hospitals)	141	98	7.2	0.09
1995	Abdomen/LS Spine (Private Practice)	178	92	27	0.12
1995	Abdomen/LS Spine (Chiropractic)	62	87	37.1	0.09
1995	Mammography*	7100	98	5.0	0.04
1996	Fluoroscopy	316	107	10.3	0.06
1997	Mammography*	5737	107	1.0	0.03
1998	Pediatric Chest	380	100	5.6	0.13
1999	Dental	122	99	31.0	0.07
2000	Mammography*	9300	101	1.6	0.02
2001	Chest	220	101	5.7	0.10
2002	Abdomen/LS Spine (Hospitals)	41	107	4.2	0.09
2002	Abdomen/LS Spine (Private Practice)	90	104	6.7	0.14
2002	Abdomen/LS Spine (Chiropractic)	15	102	5.3	0.07

*Results are from MQSA inspections

**The range of acceptable processing speed is 80 to 120 (standard cycle), and 100-130 (extended cycle)

Updated May 11, 2007

horizonal rule

Center for Devices and Radiological Health / CDRH