Mythreyi Bhargavan

Radiologic and Nuclear Medicine Studies in the United States and Worldwide: Frequency, Radiation Dose, and Comparison with Other Radiation Sources—1950–2007

The U.S. National Council on Radiation Protection and Measurements and United Nations Scientific Committee on Effects of Atomic Radiation each conducted respective assessments of all radiation sources in the United States and worldwide. The goal of this article is to summarize and combine the results of these two publicly available surveys and to compare the results with historical information. In the United States in 2006, about 377 million diagnostic and interventional radiologic examinations and 18 million nuclear medicine examinations were performed. The United States accounts for about 12% of radiologic procedures and about one-half of nuclear medicine procedures performed worldwide. In the United States, the frequency of diagnostic radiologic examinations has increased almost 10-fold (1950-2006). The U.S. per-capita annual effective dose from medical procedures has increased about sixfold (0.5 mSv [1980] to 3.0 mSv [2006]). Worldwide estimates for 2000-2007 indicate that 3.6 billion medical procedures with ionizing radiation (3.1 billion diagnostic radiologic, 0.5 billion dental, and 37 million nuclear medicine examinations) are performed annually. Worldwide, the average annual per-capita effective dose from medicine (about 0.6 mSv of the total 3.0 mSv received from all sources) has approximately doubled in the past 10-15 years.

MEDICAL RADIATION EXPOSURE IN THE U.S. IN 2006 : PRELIMINARY RESULTS

Medical radiation exposure of the U.S. population has not been systematically evaluated for almost 25 y. In 1982, the per capita dose was estimated to be 0.54 mSv and the collective dose 124,000 person-Sv. The preliminary estimates of the NCRP Scientific Committee 6-2 medical subgroup are that, in 2006, the per capita dose from medical exposure (not including dental or radiotherapy) had increased almost 600% to about 3.0 mSv and the collective dose had increased over 700% to about 900,000 person-Sv. The largest contributions and increases have come primarily from CT scanning and nuclear medicine. The 62 million CT procedures accounted for 15% of the total number procedures (excluding dental) and over half of the collective dose. Nuclear medicine accounted for about 4% of all procedures but 26% of the total collective dose. Medical radiation exposure is now approximately equal to natural background radiation.

Diagnostic reference levels from the ACR CT Accreditation Program.

PURPOSE The aim of this study was to assess the distribution of CT dose index (CTDI) values reported by sites undergoing ACR CT accreditation between 2002 and 2004. METHODS Weighted CTDI (CTDI(w)) values were measured and reported by sites applying for ACR CT accreditation, and the percentage of scanners with values above the 2002 ACR diagnostic reference levels (DRLs) was determined. Acquisition parameters for a sites adult head, adult abdominal, and pediatric abdominal examinations were used to calculate volume CTDI (CTDI(vol)), and the average and standard deviation were calculated by year. Histogram analysis was performed to determine 75th and 90th percentiles of CTDI(vol). RESULTS Between September 2002 and December 2004, 829 scanners underwent the accreditation process. Volume CTDI values (average ± SD) for 2002, 2003, 2004, and 2002 to 2004, respectively, were 66.7 ± 23.5, 58.5 ± 17.5, 55.8 ± 15.7, and 59.1 ± 18.6 mGy for adult head examinations; 18.7 ± 8.0, 19.2 ± 8.6, 17.0 ± 7.6, and 18.4 ± 8.3 for adult abdominal examinations; and 17.2 ± 9.7, 15.9 ± 8.6, 14.0 ± 7.0, and 15.5 ± 8.4 for pediatric abdominal examinations. For 2004 data, 23.8%, 2.3%, and 6.9% of sites reported doses above the 2002 CTDI(w) reference levels, compared with 49.6%, 4.7%, and 15% for 2002 data for adult head, adult abdominal, and pediatric abdominal examinations, respectively. Seventy-fifth percentiles of CTDI(vol) were 76.8 mGy (adult head, 2002 only), 22.2 mGy (adult abdominal), and 20.0 mGy (pediatric abdominal). CONCLUSIONS From 2002 to 2004, average CTDI(vol) values decreased by 10.9, 1.7, and 3.2 mGy for adult head, adult abdominal, and pediatric abdominal examinations. Effective January 1, 2008, the ACR program implemented United States-specific diagnostic reference levels of 75, 25, and 20 mGy, respectively, for the CTDI(vol) of routine adult head, adult abdominal, and pediatric abdominal CT scans.

Trends in the utilization of medical procedures that use ionizing radiation.

Medical procedures that use ionizing radiation have grown rapidly in volume over the last two decades and constitute a substantial portion of the collective radiation doses to the U.S. population. The purpose of this study is to describe the components of this growth. Summarized claims data from Medicare are used to describe trends for the period 1986–2005; supplemental data from other payers and surveys are used for verification and to describe age distributions of those who have these procedures. A notable trend is the rapid growth of CT and nuclear medicine, with CT volume per fee-for-service Medicare enrollee growing, on average, at 8% per y and nuclear medicine at 7% per y during the period 1986–2005. Cardiac procedures—nuclear medicine and interventional radiology—grew at over 15% per y per fee-for-service enrollee during the same period. The share of nuclear medicine procedures performed in physician offices increased from 10% in 1986 to 55% in 2005; the share of CT in the emergency room increased from 3% in 1992 to 17% in 2005. With this expansion in imaging volumes across practice settings, there is an increased need for radiation safety education of ordering physicians, imaging physicians, and patients, so that adequate consideration is given to radiation risk when determining the appropriateness of a prescribed procedure.

Nuclear Medicine Exposure in the United States, 2005-2007: Preliminary Results

Medical radiation exposure of the U.S. population has not been systematically evaluated for almost 25 years. In 1982, the per-capita dose was estimated to be 0.54 mSv and the collective dose 124,000 person-Sv. The preliminary estimates of the National Council on Radiation Protection and Measurements Scientific Committee 6-2 medical subgroup are that, in 2006, the per-capita dose from all medical exposure (not including radiotherapy) had increased almost 600% to 3.0 mSv and the collective dose had increased more than 700% to approximately 900,000 person-Sv. >Nuclear medicine accounted for only about 2% of all procedures but 26% of the total collective dose from diagnostic studies in medicine. In 1982, the estimated number of nuclear medicine procedures was about 7.5 million. The per-capita effective dose from nuclear medicine was 0.14 mSv and the collective dose was 32,000 person Sv. By 2005, the estimated number of procedures had increased to about 19.6 million. The per-caput effective dose increased to about 0.75 mSv and the collective dose to about 220,000 person Sv. There also has been a marked shift in the type of procedures being performed with cardiac scanning accounting for about 70% of procedures.

The State of Teleradiology in 2003 and Changes Since 1999

OBJECTIVE The purpose of our study is to describe in detail the use of teleradiology in 2003 and to report on changes since 1999 in this rapidly evolving field. MATERIALS AND METHODS We analyze non-individually identified data from the American College of Radiologys 2003 Survey of Radiologists, a stratified random sample mail survey that achieved a response rate of 63%, and data from the American College of Radiologys 1999 Survey of Practices. Responses were weighted to represent the distribution of individual radiologists and radiology practices nationwide. We present descriptive statistics and multivariable regression analysis results on the prevalence and uses of teleradiology in 2003 and comparisons with 1999. RESULTS Overall, 67% of all radiology practices in the United States, which included 78% of all U.S. radiologists, reported using teleradiology. A significant increase (p < 0.05) was seen in the prevalence of teleradiology or PACS, from 58% of practices in 1999 to 73% in 2003. Regression results indicate that, other practice characteristics being equal, in 2003, primarily academic practices were less likely to use teleradiology than private radiology practices, and medium-sized practices (5-14 radiologists) were more likely to have teleradiology than larger ones. In practices using teleradiology, home was the most frequent receiving site in both 1999 (81%) and 2003 (75%), the percentages being not significantly different. CONCLUSION Already a fixture of radiology practice in 1999, teleradiology increased in prevalence substantially by 2003. The primary use of teleradiology, transmission of images to home, did not change, suggesting that easing the burden of call remains the main use of teleradiology.

Imaging Self-Referral Associated with Higher Costs and Limited Impact on Duration of Illness

Self-referral for imaging services occurs when a physician sends patients to receive an imaging procedure from a device that the physician owns or leases. Advocates argue that this shortens the duration of illness and lowers costs. For twenty common combinations of medical conditions and types of imaging, we evaluated the association between self-referral, duration of illness episode, and three measures of cost. Self-referral was associated with significantly and substantially higher episode costs for most of the combinations of medical conditions and imaging that we studied. There was no decrease in the length of illness, except when doctors self-referred patients to receive x-rays for a few common conditions. These findings indicate that except for x-rays, constraining the self-referral of imaging may be appropriate.

A Portrait of Breast Imaging Specialists and of the Interpretation of Mammography in the United States

OBJECTIVE Because of the importance of breast imaging as a radiology subspecialty and concerns about malpractice, the purpose of our study is to provide a detailed portrait of breast imaging specialists, their professional activities and practices, and information on all radiologists who interpret mammograms. MATERIALS AND METHODS We analyzed data from the American College of Radiologys 2003 Survey of Radiologists, a large, stratified random sample survey that achieved a 63% response. Responses were weighted to make them representative of all radiologists in the United States. RESULTS Approximately 10% of all radiologists, or 2,700-2,800 radiologists, are breast imaging specialists, but 61% of radiologists interpret mammograms, and only approximately 30% of mammograms are interpreted by breast imaging specialists. Of radiologists who reported that breast imaging was their primary specialty, only 21% took a fellowship in the field (much lower than for other subspecialties), 59% spent > or = 50% of their clinical work time in the specialty, 82% interpret > or = 2,000 mammograms annually, and only 11% (also well below other subspecialties) report that the main subspecialty society (the Society of Breast Imaging) is one of the two most important professional organizations for them. On average, breast imaging specialists, like other radiologists, report that their workload is about as heavy as desired. Their level of enjoyment of radiology does not differ significantly from average. CONCLUSION Breast imaging appears not to be as strongly organized to raise awareness of and support for its problems as are other subspecialties. Although others find evidence of likely future problems, breast imaging specialists are not currently overworked or less satisfied in their profession than other radiologists, despite relatively low revenue generation and a particularly high risk of a malpractice lawsuit.

Radiology practices' use of external off-hours teleradiology services in 2007 and changes since 2003.

OBJECTIVE Our objective is to report patterns of utilization of external off-hours teleradiology services (EOTSs) in 2007 and changes since 2003. MATERIALS AND METHODS We analyzed non-individually identified data from the American College of Radiologys 2007 Survey of Member Radiologists and its 2003 Survey of Radiologists. Responses were weighted to be nationally representative of individual radiologists and radiology practices. We present descriptive statistics and multivariable regression analysis results on the use of EOTSs in 2007 and comparisons with 2003. RESULTS Overall, 44% of all radiology practices in the United States reported using EOTSs in 2007. These practices included 45% of all U.S. radiologists. Out-of-practice teleradiology had been used by 15% of practices in 2003. Regression analysis indicates that, other practice characteristics being equal, in 2007, primarily academic practices had lower odds of using EOTSs than private radiology practices. Also, large practices (>or= 30 radiologists) had lower odds of using EOTSs than practices with 15-29 radiologists. Small practices (1-10 radiologists) had high odds, but nonmetropolitan practices did not. There were no significant differences by geographic region of the United States. CONCLUSION Use of EOTSs was widespread by 2007, and it had been increasing rapidly in the preceding few years. Patterns of use were generally as might be expected except that nonmetropolitan practices did not have high odds of using EOTSs.

The Practice Of Imaging Self-Referral Doesn’t Produce Much One-Stop Service

Imaging as a result of self-referral-when a physician refers patients for imaging tests at a facility owned or leased by the same physician-is widespread. The practice has come under much scrutiny because it is associated with higher volumes of imaging services. Proponents of such self-referral argue that the practice offers patients convenient same-day, one-stop service and allows treatment to start sooner. Our analysis of 2006 and 2007 Medicare data showed that self-referral provided same-day imaging for 74 percent of straightforward x-rays, but for only 15 percent of more-advanced procedures such as computed tomography and magnetic resonance imaging. Policy makers attempting to make the use of imaging more responsible should consider narrowing Medicares special provision allowing referrals to a physicians own practice so that the provision covers x-rays only.