Radiation-Emitting Products

NEXT 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)

Page Last Updated: 08/12/2014
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