[show abstract][hide abstract] ABSTRACT: In the past 30 y, the numbers and types of fluoroscopically-guided (FG) procedures have increased dramatically. The objective of the present study is to provide estimated radiation doses to physician specialists, other than cardiologists, who perform FG procedures. The authors searched Medline to identify English-language journal articles reporting radiation exposures to these physicians. They then identified several primarily therapeutic FG procedures that met specific criteria: well-defined procedures for which there were at least five published reports of estimated radiation doses to the operator, procedures performed frequently in current medical practice, and inclusion of physicians from multiple medical specialties. These procedures were percutaneous nephrolithotomy (PCNL), vertebroplasty, orthopedic extremity nailing for treatment of fractures, biliary tract procedures, transjugular intrahepatic portosystemic shunt creation (TIPS), head/neck endovascular therapeutic procedures, and endoscopic retrograde cholangiopancreatography (ERCP). Radiation doses and other associated data were abstracted, and effective dose to operators was estimated. Operators received estimated doses per patient procedure equivalent to doses received by interventional cardiologists. The estimated effective dose per case ranged from 1.7-56 μSv for PCNL, 0.1-101 μSv for vertebroplasty, 2.5-88 μSv for orthopedic extremity nailing, 2.0-46 μSv for biliary tract procedures, 2.5-74 μSv for TIPS, 1.8-53 μSv for head/neck endovascular therapeutic procedures, and 0.2-49 μSv for ERCP. Overall, mean operator radiation dose per case measured over personal protective devices at different anatomic sites on the head and body ranged from 19-800 (median = 113) μSv at eye level, 6-1,180 (median = 75) μSv at the neck, and 2-1,600 (median = 302) μSv at the trunk. Operators' hands often received greater doses than the eyes, neck, or trunk. Large variations in operator doses suggest that optimizing procedure protocols and proper use of protective devices and shields might reduce occupational radiation dose substantially.
Health physics 07/2012; 103(1):80-99. · 0.92 Impact Factor
[show abstract][hide abstract] ABSTRACT: Although CT scans are very useful clinically, potential cancer risks exist from associated ionising radiation, in particular for children who are more radiosensitive than adults. We aimed to assess the excess risk of leukaemia and brain tumours after CT scans in a cohort of children and young adults.
In our retrospective cohort study, we included patients without previous cancer diagnoses who were first examined with CT in National Health Service (NHS) centres in England, Wales, or Scotland (Great Britain) between 1985 and 2002, when they were younger than 22 years of age. We obtained data for cancer incidence, mortality, and loss to follow-up from the NHS Central Registry from Jan 1, 1985, to Dec 31, 2008. We estimated absorbed brain and red bone marrow doses per CT scan in mGy and assessed excess incidence of leukaemia and brain tumours cancer with Poisson relative risk models. To avoid inclusion of CT scans related to cancer diagnosis, follow-up for leukaemia began 2 years after the first CT and for brain tumours 5 years after the first CT.
During follow-up, 74 of 178,604 patients were diagnosed with leukaemia and 135 of 176,587 patients were diagnosed with brain tumours. We noted a positive association between radiation dose from CT scans and leukaemia (excess relative risk [ERR] per mGy 0·036, 95% CI 0·005-0·120; p=0·0097) and brain tumours (0·023, 0·010-0·049; p<0·0001). Compared with patients who received a dose of less than 5 mGy, the relative risk of leukaemia for patients who received a cumulative dose of at least 30 mGy (mean dose 51·13 mGy) was 3·18 (95% CI 1·46-6·94) and the relative risk of brain cancer for patients who received a cumulative dose of 50-74 mGy (mean dose 60·42 mGy) was 2·82 (1·33-6·03).
Use of CT scans in children to deliver cumulative doses of about 50 mGy might almost triple the risk of leukaemia and doses of about 60 mGy might triple the risk of brain cancer. Because these cancers are relatively rare, the cumulative absolute risks are small: in the 10 years after the first scan for patients younger than 10 years, one excess case of leukaemia and one excess case of brain tumour per 10,000 head CT scans is estimated to occur. Nevertheless, although clinical benefits should outweigh the small absolute risks, radiation doses from CT scans ought to be kept as low as possible and alternative procedures, which do not involve ionising radiation, should be considered if appropriate.
US National Cancer Institute and UK Department of Health.
The Lancet 06/2012; 380(9840):499-505. · 39.06 Impact Factor
[show abstract][hide abstract] ABSTRACT: Computed tomography (CT) has become the predominant test for diagnosing acute appendicitis in adults. In children and young adults, exposure to CT radiation is of particular concern. We evaluated the rate of negative (unnecessary) appendectomy after low-dose versus standard-dose abdominal CT in young adults with suspected appendicitis.
In this single-institution, single-blind, noninferiority trial, we randomly assigned 891 patients with suspected appendicitis to either low-dose CT (444 patients) or standard-dose CT (447 patients). The median radiation dose in terms of dose-length product was 116 mGy·cm in the low-dose group and 521 mGy·cm in the standard-dose group. The primary end point was the percentage of negative appendectomies among all nonincidental appendectomies, with a noninferiority margin of 5.5 percentage points. Secondary end points included the appendiceal perforation rate and the proportion of patients with suspected appendicitis who required additional imaging.
The negative appendectomy rate was 3.5% (6 of 172 patients) in the low-dose CT group and 3.2% (6 of 186 patients) in the standard-dose CT group (difference, 0.3 percentage points; 95% confidence interval, -3.8 to 4.6). The two groups did not differ significantly in terms of the appendiceal perforation rate (26.5% with low-dose CT and 23.3% with standard-dose CT, P=0.46) or the proportion of patients who needed additional imaging tests (3.2% and 1.6%, respectively; P=0.09).
Low-dose CT was noninferior to standard-dose CT with respect to negative appendectomy rates in young adults with suspected appendicitis. (Funded by GE Healthcare Medical Diagnostics and others; ClinicalTrials.gov number, NCT00913380.).
New England Journal of Medicine 04/2012; 366(17):1596-605. · 51.66 Impact Factor
[show abstract][hide abstract] ABSTRACT: To establish an organ dose database for pediatric and adolescent reference individuals undergoing computed tomography (CT) examinations by using Monte Carlo simulation. The data will permit rapid estimates of organ and effective doses for patients of different age, gender, examination type, and CT scanner model.
The Monte Carlo simulation model of a Siemens Sensation 16 CT scanner previously published was employed as a base CT scanner model. A set of absorbed doses for 33 organs∕tissues normalized to the product of 100 mAs and CTDI(vol) (mGy∕100 mAs mGy) was established by coupling the CT scanner model with age-dependent reference pediatric hybrid phantoms. A series of single axial scans from the top of head to the feet of the phantoms was performed at a slice thickness of 10 mm, and at tube potentials of 80, 100, and 120 kVp. Using the established CTDI(vol)- and 100 mAs-normalized dose matrix, organ doses for different pediatric phantoms undergoing head, chest, abdomen-pelvis, and chest-abdomen-pelvis (CAP) scans with the Siemens Sensation 16 scanner were estimated and analyzed. The results were then compared with the values obtained from three independent published methods: CT-Expo software, organ dose for abdominal CT scan derived empirically from patient abdominal circumference, and effective dose per dose-length product (DLP).
Organ and effective doses were calculated and normalized to 100 mAs and CTDI(vol) for different CT examinations. At the same technical setting, dose to the organs, which were entirely included in the CT beam coverage, were higher by from 40 to 80% for newborn phantoms compared to those of 15-year phantoms. An increase of tube potential from 80 to 120 kVp resulted in 2.5-2.9-fold greater brain dose for head scans. The results from this study were compared with three different published studies and∕or techniques. First, organ doses were compared to those given by CT-Expo which revealed dose differences up to several-fold when organs were partially included in the scan coverage. Second, selected organ doses from our calculations agreed to within 20% of values derived from empirical formulae based upon measured patient abdominal circumference. Third, the existing DLP-to-effective dose conversion coefficients tended to be smaller than values given in the present study for all examinations except head scans.
A comprehensive organ∕effective dose database was established to readily calculate doses for given patients undergoing different CT examinations. The comparisons of our results with the existing studies highlight that use of hybrid phantoms with realistic anatomy is important to improve the accuracy of CT organ dosimetry. The comprehensive pediatric dose data developed here are the first organ-specific pediatric CT scan database based on the realistic pediatric hybrid phantoms which are compliant with the reference data from the International Commission on Radiological Protection (ICRP). The organ dose database is being coupled with an adult organ dose database recently published as part of the development of a user-friendly computer program enabling rapid estimates of organ and effective dose doses for patients of any age, gender, examination types, and CT scanner model.
Medical Physics 04/2012; 39(4):2129-46. · 2.91 Impact Factor
[show abstract][hide abstract] ABSTRACT: Socio-economic status is known to influence health throughout life. In childhood, studies have shown increased injury rates in more deprived settings. Socio-economic status may therefore be related to rates of certain medical procedures, such as computed tomography (CT) scans. This study aimed to assess socio-economic variation among young people having CT scans in Northern England between 1990 and 2002 inclusive.
Electronic data were obtained from Radiology Information Systems of all nine National Health Service hospital Trusts in the region. CT scan data, including sex, date of scan, age at scan, number and type of scans were assessed in relation to quintiles of Townsend deprivation scores, obtained from linkage of postcodes with census data, using χ2 tests and Spearman rank correlations.
During the study period, 39,676 scans were recorded on 21,089 patients, with 38,007 scans and 19,485 patients (11344 male and 8132 female) linkable to Townsend scores. The overall distributions of both scans and patients by quintile of Townsend deprivation scores were significantly different to the distributions of Townsend scores from the census wards included in the study (p < 0.0001). There was a significant association between type of scan and deprivation quintile (p < 0.0001), primarily due to the higher proportions of head scans in the three most deprived quintiles, and slightly higher proportions of chest scans and abdomen and pelvis scans in the least deprived groups. There was also a significant association (p < 0.0001) between the patient's age at the time of the CT scan and Townsend deprivation quintiles, with slightly increasing proportions of younger children with increasing deprivation. A similar association with age (p < 0.0001) was seen when restricting the data to include only the first scan of each patient. The number of scans per patient was also associated with Townsend deprivation quintiles (p = 0.014).
Social inequalities exist in the numbers of young people undergoing CT scans with those from deprived areas more likely to do so. This may reflect the rates of injuries in these individuals and implies that certain groups within the population may receive higher radiation doses than others due to medical procedures.
BMC Health Services Research 01/2012; 12:24. · 1.77 Impact Factor
[show abstract][hide abstract] ABSTRACT: Background. Although using computed tomography (CT) can be greatly beneficial, the associated relatively high radiation doses have led to growing concerns in relation to potential associations with risk of future cancer. Very little has been published regarding the trends of CT use in young people. Therefore, our objective was to assess temporal and other patterns in CT usage among patients aged under 22 years in Great Britain from 1993 to 2002. Methods. Electronic data were obtained from the Radiology Information Systems of 81 hospital trusts within Great Britain. All included patients were aged under 22 years and examined using CT between 1993 and 2002, with accessible radiology records. Results. The number of CT examinations doubled over the study period. While increases in numbers of recorded examinations were seen across all age groups, the greatest increases were in the older patients, most notably those aged 15-19 years of age. Sixty percent of CT examinations were of the head, with the percentages varying with calendar year and patient age. Conclusions. In contrast to previous data from the North of England, the doubling of CT use was not accompanied by an increase in numbers of multiple examinations to the same individual.
Radiology research and practice. 01/2012; 2012:594278.
[show abstract][hide abstract] ABSTRACT: Computed tomography (CT) dosimetry computer codes have been most commonly used due to their user friendliness, but with little consideration for potential uncertainty in estimated organ dose and their underlying limitations. Generally, radiation doses calculated with different CT dosimetry computer codes were comparable, although relatively large differences were observed for some specific organs or tissues. The largest difference in radiation doses calculated using different computer codes was observed for Siemens Sensation CT scanners. Radiation doses varied with patient age and sex. Younger patients and adult females receive a higher radiation dose in general than adult males for the same CT technique factors. There are a number of limitations of current CT dosimetry computer codes. These include unrealistic modelling of the human anatomy, a limited number of organs and tissues for dose calculation, inability to alter patient height and weight, and non-applicability to new CT technologies. Therefore, further studies are needed to overcome these limitations and to improve CT dosimetry.
[show abstract][hide abstract] ABSTRACT: The purpose of this study was to estimate the ratio of cancers prevented to induced (benefit-risk ratio) for CT colonography (CTC) screening every 5 years from the age of 50 to 80 years.
Radiation-related cancer risk was estimated using risk projection models based on the National Research Council's Biological Effects of Ionizing Radiation (BEIR) VII Committee's report and screening protocols from the American College of Radiology Imaging Network's National CT Colonography Trial. Uncertainty intervals were estimated using Monte Carlo simulation methods. Comparative modeling with three colorectal cancer microsimulation models was used to estimate the potential reduction in colorectal cancer cases and deaths.
The estimated mean effective dose per CTC screening study was 8 mSv for women and 7 mSv for men. The estimated number of radiation-related cancers resulting from CTC screening every 5 years from the age of 50 to 80 years was 150 cases/100,000 individuals screened (95% uncertainty interval, 80-280) for men and women. The estimated number of colorectal cancers prevented by CTC every 5 years from age 50 to 80 ranged across the three microsimulation models from 3580 to 5190 cases/100,000 individuals screened, yielding a benefit-risk ratio that varied from 24:1 (95% uncertainty interval, 13:1-45:1) to 35:1 (19:1-65:1). The benefit-risk ratio for cancer deaths was even higher than the ratio for cancer cases. Inclusion of radiation-related cancer risks from CT examinations performed to follow up extracolonic findings did not materially alter the results.
Concerns have been raised about recommending CTC as a routine screening tool because of potential harms including the radiation risks. Based on these models, the benefits from CTC screening every 5 years from the age of 50 to 80 years clearly outweigh the radiation risks.
American Journal of Roentgenology 04/2011; 196(4):816-23. · 2.90 Impact Factor
[show abstract][hide abstract] ABSTRACT: To develop a computed tomography (CT) organ dose estimation method designed to readily provide organ doses in a reference adult male and female for different scan ranges to investigate the degree to which existing commercial programs can reasonably match organ doses defined in these more anatomically realistic adult hybrid phantoms
The x-ray fan beam in the SOMATOM Sensation 16 multidetector CT scanner was simulated within the Monte Carlo radiation transport code MCNPX2.6. The simulated CT scanner model was validated through comparison with experimentally measured lateral free-in-air dose profiles and computed tomography dose index (CTDI) values. The reference adult male and female hybrid phantoms were coupled with the established CT scanner model following arm removal to simulate clinical head and other body region scans. A set of organ dose matrices were calculated for a series of consecutive axial scans ranging from the top of the head to the bottom of the phantoms with a beam thickness of 10 mm and the tube potentials of 80, 100, and 120 kVp. The organ doses for head, chest, and abdomen/pelvis examinations were calculated based on the organ dose matrices and compared to those obtained from two commercial programs, CT-EXPO and CTDOSIMETRY. Organ dose calculations were repeated for an adult stylized phantom by using the same simulation method used for the adult hybrid phantom.
Comparisons of both lateral free-in-air dose profiles and CTDI values through experimental measurement with the Monte Carlo simulations showed good agreement to within 9%. Organ doses for head, chest, and abdomen/pelvis scans reported in the commercial programs exceeded those from the Monte Carlo calculations in both the hybrid and stylized phantoms in this study, sometimes by orders of magnitude.
The organ dose estimation method and dose matrices established in this study readily provides organ doses for a reference adult male and female for different CT scan ranges and technical parameters. Organ doses from existing commercial programs do not reasonably match organ doses calculated for the hybrid phantoms due to differences in phantom anatomy, as well as differences in organ dose scaling parameters. The organ dose matrices developed in this study will be extended to cover different technical parameters, CT scanner models, and various age groups.
Medical Physics 03/2011; 38(3):1196-206. · 2.91 Impact Factor
[show abstract][hide abstract] ABSTRACT: Epidemiological studies of medical radiation workers have found excess risks of leukemia, skin and female breast cancer in those employed before 1950 but little consistent evidence of cancer risk increases subsequently. Occupational radiation-related dose-response data and recent and lifetime cancer risk data are limited for radiologists and radiologic technologists and lacking for physicians and technologists performing fluoroscopically guided procedures. Survey data demonstrate that occupational doses to radiologists and radiologic technologists have declined over time. Eighty mostly small studies of cardiologists and fewer studies of other physicians reveal that effective doses to physicians per interventional procedure vary by more than an order of magnitude. For medical radiation workers, there is an urgent need to expand the limited information on average annual, time-trend and organ doses from occupational radiation exposures and to assess lifetime cancer risks of these workers. For physicians and technologists performing interventional procedures, more information about occupational doses should be collected and long-term follow-up studies of cancer and other serious disease risks should be initiated. Such studies will help optimize standardized protocols for radiologic procedures, determine whether current radiation protection measures for medical radiation workers are adequate, provide guidance on cancer screening needs, and yield valuable insights on cancer risks associated with chronic radiation exposure.
Radiation Research 12/2010; 174(6):793-808. · 2.70 Impact Factor
[show abstract][hide abstract] ABSTRACT: Computed tomographic colonography (CTC) has emerged as an alternative screening tool for colorectal cancer due to the potential to provide good efficacy combined with greater acceptability than optical colonoscopy or fecal occult blood testing. However, some organizations have raised concerns about the potential harms, including perforation rates and radiation-related cancer risks, and have not recommended that it currently be used as a screening tool in the general population in the US. In this article the authors review the current evidence for these potential harms from CTC and compare them to the potential harms from the alternatives including colonoscopy and double-contrast barium enema.
Gastrointestinal endoscopy clinics of North America 04/2010; 20(2):279-91.
[show abstract][hide abstract] ABSTRACT: Although radiological exams are not frequently used to diagnose unsuspected endocrine disease, computed tomography (CT) plays a significant role in today's endocrinology. Despite the known association between radiation exposure during childhood and cancer, the use of pediatric CT, which delivers non-negligible radiation doses to some organs and tissues, continues to rise sharply. The purpose of this review is to describe the current use of pediatric CT, explain basic concepts in ionizing radiation physics and dosimetry, and discuss potential risks from pediatric CT scans. Finally, we will summarize two recent programs for reducing and controlling exposure to ionizing radiation from pediatric CT: the As Low As Reasonably Achievable (ALARA) concept and the Image Gently initiative. Promoting public awareness and particularly educating referring physicians, including endocrinologists, about the potential radiation-associated risks from CT scans, is essential for reducing unnecessary radiation exposure from CT in children.
Pediatric endocrinology reviews: PER 12/2009; 7(2):29-36.
[show abstract][hide abstract] ABSTRACT: Phospholipids are key components of cellular membrane and signaling. Among cellular phospholipids, phosphoinositides, phosphorylated derivatives of phosphatidylinositol are important as a participant in essential metabolic processes in animals. However, due to its low abundance in cells and tissues, it is difficult to identify the composition of phosphoinositides. Recent advances in mass spectrometric techniques, combined with established separation methods, have allowed the rapid and sensitive detection and quantification of a variety of lipid species including phosphoinositides. In this mini review, we briefly introduce progress in profiling of cellular phosphoinositides using mass spectrometry. We also summarize current progress of matrices development for the analysis of cellular phospholipids using matrix-assisted laser desorption/ionization mass spectrometry. The phosphoinositides profiling and phospholipids imaging will help us to understand how they function in a biological system and will provide a powerful tool for elucidating the mechanism of diseases such as diabetes, cancer and neurodegenerative diseases. The investigation of cellular phospholipids including phosphoinositides using electrospray ionization mass spectrometry and matrix-assisted laser desorption/ionization mass spectrometry will suggest new insights on human diseases, and on clinical application through drug development of lipid related diseases.
Experimental and Molecular Medicine 11/2009; 42(1):1-11. · 2.57 Impact Factor
[show abstract][hide abstract] ABSTRACT: Multidetector computed tomography has been proposed as a tool for routine screening for coronary artery calcification in asymptomatic individuals. As proposed, such screening could involve tens of millions of individuals, but detailed estimates of radiation doses and potential risk of radiation-induced cancer are not currently available. We estimated organ-specific radiation doses and associated cancer risks from coronary artery calcification screening with multidetector computed tomography according to patient age, frequency of screening, and scan protocol.
Radiation doses delivered to adult patients were calculated from a range of available protocols using Monte Carlo radiation transport. Radiation risk models, derived using data from Japanese atomic bomb survivors and medically exposed cohorts, were used to estimate the excess lifetime risk of radiation-induced cancer.
The radiation dose from a single coronary artery calcification computed tomographic scan varied more than 10-fold (effective dose range, 0.8-10.5 mSv) depending on the protocol. In general, higher radiation doses were associated with higher x-ray tube current, higher tube potential, spiral scanning with low pitch, and retrospective gating. The wide dose variation also resulted in wide variation in estimated radiation-induced cancer risk. Assuming screening every 5 years from the age of 45 to 75 years for men and 55 to 75 years for women, the estimated excess lifetime cancer risk using the median dose of 2.3 mSv was 42 cases per 100 000 men (range, 14-200 cases) and 62 cases per 100 000 women (range, 21-300 cases).
These radiation risk estimates can be compared with potential benefits from screening, when such estimates are available. Doses and therefore risks can be minimized by the use of optimized protocols.
Archives of internal medicine 08/2009; 169(13):1188-94. · 11.46 Impact Factor
[show abstract][hide abstract] ABSTRACT: What is known about radiation exposure to physicians who perform cardiac interventions is reviewed and various factors that affect their exposure are discussed. There are wide variations in the radiation dose (up to 1000-fold) per procedure. Despite extensive improvements in equipment and technology, there has been little or no reduction in dose over time. The wide variation and lack of reduction in operator doses strongly suggests that more attention must be paid to factors influencing the operator dose. Numerous patient, physician and shielding factors influence the operator dose to different degrees. Operators can change some of these factors immediately, at minimal or no cost, with a substantial reduction in dose and potential cancer risk.
[show abstract][hide abstract] ABSTRACT: While the etiology of most childhood cancers is largely unknown, epidemiologic studies have consistently found an association between exposure to medical radiation during pregnancy and risk of childhood cancer in offspring. The relation between early life diagnostic radiation exposure and occurrence of pediatric cancer risks is less clear. This review summarizes current and historical estimated doses for common diagnostic radiologic procedures as well as the epidemiologic literature on the role of maternal prenatal, children's postnatal and parental preconception diagnostic radiologic procedures on subsequent risk of childhood malignancies. Risk estimates are presented according to factors such as the year of birth of the child, trimester and medical indication for the procedure, and the number of films taken. The paper also discusses limitations of the methods employed in epidemiologic studies to assess pediatric cancer risks, the effects on clinical practice of the results reported from the epidemiologic studies, and clinical and public health policy implications of the findings. Gaps in understanding and additional research needs are identified. Important research priorities include nationwide surveys to estimate fetal and childhood radiation doses from common diagnostic procedures, and epidemiologic studies to quantify pediatric and lifetime cancer risks from prenatal and early childhood exposures to diagnostic radiography, CT, and fluoroscopically guided procedures.
[show abstract][hide abstract] ABSTRACT: Cardiac catheterization procedures using fluoroscopy reduce patient morbidity and mortality compared to operative procedures. These diagnostic and therapeutic procedures require radiation exposure to patients and physicians. The objectives of the present investigation were to provide a systematic comprehensive summary of the reported radiation doses received by operators due to diagnostic or interventional fluoroscopically-guided procedures, to identify the primary factors influencing operator radiation dose, and to evaluate whether there have been temporal changes in the radiation doses received by operators performing these procedures. Using PubMed, we identified all English-language journal articles and other published data reporting radiation exposures to operators from diagnostic or interventional fluoroscopically-guided cardiovascular procedures from the early 1970's through the present. We abstracted the reported radiation doses, dose measurement methods, fluoroscopy system used, operational features, radiation protection features, and other relevant data. We calculated effective doses to operators in each study to facilitate comparisons. The effective doses ranged from 0.02-38.0 microSv for DC (diagnostic catheterizations), 0.17-31.2 microSv for PCI (percutaneous coronary interventions), 0.24-9.6 microSv for ablations, and 0.29-17.4 microSv for pacemaker or intracardiac defibrillator implantations. The ratios of doses between various anatomic sites and the thyroid, measured over protective shields, were 0.9 +/- 1.0 for the eye, 1.0 +/- 1.5 for the trunk, and 1.3 +/- 2.0 for the hand. Generally, radiation dose is higher on the left side of an operator's body, because the operator's left side is closer to the primary beam when standing at the patient's right side. Modest operator dose reductions over time were observed for DC and ablation, primarily due to reduction in patient doses due to decreased fluoroscopy/cineradiography time and dose rate by technology improvement. Doses were not reduced over time for PCI. The increased complexity of medical procedures appears to have offset dose reductions due to improvements in technology. The large variation in operator doses observed for the same type of procedure suggests that optimizing procedure protocols and implementing general use of the most effective types of protective devices and shields may reduce occupational radiation doses to operators. We had considerable difficulty in comparing reported dosimetry results because of significant differences in dosimetric methods used in each study and multiple factors influencing the actual doses received. Better standardization of dosimetric methods will facilitate future analyses aimed at determining how well medical radiation workers are being protected.
Health Physics 04/2008; 94(3):211-27. · 1.02 Impact Factor
[show abstract][hide abstract] ABSTRACT: To estimate the risk of radiation-induced lung cancer mortality from three annual low-dose lung computed tomography (CT) screens before age 55 years (starting at age 30, 40 or 50) and the mortality reduction from screening (i.e. the efficacy) needed to outweigh these risks for never and current-smokers. The risk of radiation-induced breast cancer was also estimated for women.
The Biological Effectiveness of Ionizing Radiation VII committee's risk models were used to estimate radiation risk. Lung cancer mortality rates (based on the Bach model for current and the Cancer Prevention Study for never-smokers) were used to estimate the mortality reduction needed to outweigh this risk.
For never-smokers, the estimated excess lifetime risk of radiation-induced lung cancer mortality from annual screening aged 40-42 was 1/10,000 (90% credibility interval: 0.4-3) for men and 3/10,000 (2-6) for women. For current-smokers, the estimated risks were approximately two-fold higher, with wider credibility intervals. Risks from screening age 30-32 or 50-52 years were of similar magnitude. The mortality reduction required to outweigh these risks was, for female never-smokers: 125% (40-300%) age 30-32 years, 70% (30-190%) age 40-42 years and 25% (10-70%) age 50-52 years, and for male current-smokers: 70% (20-120%) age 30-32 years, 10% (3-20%) age 40-42 years and 2% (1-4%) age 50-52 years. These figures were two to three times higher for females because of the higher radiation risks. The risk of radiation-induced breast cancer was in the range of three to six cases/10,000 females screened.
Before age 50, the mortality reduction from lung CT screening that is required to outweigh the radiation risk may be substantial, and in some cases unattainable (i.e. >100%).
Journal of Medical Screening 01/2008; 15(3):153-8. · 2.35 Impact Factor