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)