Patient exposure in medical X-ray imaging in Europe

Effective Radiation Dose from Cone-Beam Computed Tomography Guidance during Bronchoscopic Tumour Ablation

INTRODUCTION

Endobronchial radiofrequency ablation (RFA) is a novel minimally invasive approach to management of peripheral non-small-cell lung cancer (NSCLC) in medically inoperable patients. Minimally invasive ablative techniques are generally delivered with cone-beam computed tomography (CBCT) guidance. CBCT requires a significant number of two dimensional imaging projections to be acquired which is then reconstructed as a three-dimensional cone-beam image. The objective of this study was to determine the radiation dosimetry consequent to use of CBCT guidance for bronchoscopic RFA.

METHODS

Post hoc analysis of data following bronchoscopic RFA of stage I biopsy-confirmed NSCLC performed with CBCT. Effective dose estimates for these patients were calculated using PCXMC2.0 software.

RESULTS

Ten patients underwent bronchoscopic RFA, with a median 3 (range 2-4) CBCT spins per procedure. Mean dose area product (DAP) per procedure was 7,778 μGy.m2 (±4,743) with an effective dose of 11.6 mSv (±7.4). The DAP per spin for these 10 patients varied from 83.8 to 8,625.6 μGy.m2 (effective dose range 0.15-13.81 mSv).

CONCLUSION

This is the first study to report radiation dosimetry consequent to CT guidance for bronchoscopic RFA procedures. Effective doses appear comparable to other CT fluoroscopic procedures.

Seven general radiography x-ray detectors with pixel sizes ranging from 175 to 76μm: technical evaluation with the focus on orthopaedic imaging

Aim. Flat panel detectors with small pixel sizes general can potentially improve imaging performance in radiography applications requiring fine detail resolution. This study evaluated the imaging performance of seven detectors, covering a wide range of pixel sizes, in the frame of orthopaedic applications.Material and methods. Pixel sizes ranged from 175 (detector A175) to 76μm (detector G76). Modulation transfer function (MTF) and detective quantum efficiency (DQE) were measured using International Electrotechnical Commission (IEC) RQA3 beam quality. Threshold contrast (CT) and a detectability index (d') were measured at three air kerma/image levels. Rabbit shoulder images acquired at 60 kV, over five air kerma levels, were evaluated in a visual grading study for anatomical sharpness, image noise and overall diagnostic image quality by four radiologists. The detectors were compared to detector E124.Results. The 10% point of the MTF ranged from 3.21 to 4.80 mm-1, in going from detector A175to detector G76. DQE(0.5 mm-1) measured at 2.38μGy/image was 0.50 ± 0.05 for six detectors, but was higher for F100at 0.62. High frequency DQE was superior for the smaller pixel detectors, howeverCTfor 0.25 mm discs correlated best with DQE(0.5 mm-1). Correlation betweenCTand the detectability model was good (R2= 0.964).CTfor 0.25 mm diameter discs was significantly higher for D150and F100compared to E124. The visual grading data revealed higher image quality ratings for detectors D125and F100compared to E124. An increase in air kerma was associated with improved perceived sharpness and overall quality score, independent of detector. Detectors B150, D125, F100and G76, performed well in specific tests, however only F100consistently outperformed the reference detector.Conclusion. Pixel size alone was not a reliable predictor of small detail detectability or even perceived sharpness in a visual grading analysis study.

Evaluation of four criteria in assessing third molar maturity for age estimation in Koreans

Third molar maturity is one of the major criteria for estimating human age. This study aimed to determine the most suitable third molar maturity criteria for age estimation in Koreans. The correlation between chronological age and the Demirjian, Köhler, Liversidge, and Thevissen criteria was evaluated using 900 panoramic radiographs of patients aged 15-23 years. The four criteria were applied separately to measure third molar maturity on the same radiograph. The concordance rates between third molars within the same jaw and between jaws were calculated and tested using a paired t-test. Regression was performed to observe the relationship between age and the evaluated stages for each tested criterion. The Demirjian standard showed the lowest root mean square error (1.29 years for males, 1.30 years for females) and highest adjusted R ² (0.753 for males, 0.739 for females) values; however, the differences of the values derived from other criteria were minute. In addition, the symmetry (within the same jaw) and asymmetry (between the upper and lower jaws) of third molar development, which was confirmed in previous Korean studies, was observed only in the Demirjian and Liversidge criteria. Based on the results, we can conclude that all four tested criteria are suitable for age estimation in Koreans. However, the Demirjian and Liversidge criteria can be recommended from the perspective of accurate reflection of the developmental patterns. Further research is necessary to determine whether the results of this study are consistently observed in other populations.

Diagnostic value of full-length femur radiographs in patients with neck of femur fracture and co-existing malignancy

PURPOSE

In the UK, it is common practice to obtain full-length femur radiographs in patients admitted with neck of femur fractures (NOF) and co-existing malignancy. Limited literature exists studying this topic. Our aim was to identify whether full-length femur radiographs are of diagnostic and therapeutic value in this demographic.

METHODS

A retrospective observational analysis of the patients admitted with a neck of femur fracture over a 5-year period (2015-2020) using the National Hip Fracture Database was performed at a major trauma centre. Electronic patient records were accessed to screen the NOF patients who had co-existing malignancy and subsequently underwent a full-length femur radiograph. In addition to patient demographics, we also identified the plan and whether it was affected by findings of the full-length radiograph, the operation performed, any additional investigations undertaken for malignancy, the type of cancer, complications and 1-year mortality.

RESULTS

Of the 2416 patients screened, 18% had a co-existing malignancy (n = 431). Of the 431 with underlying malignancy, 424 patients underwent a full-length femur radiograph while only seven of these radiographs identified lesions. From the seven patients with findings of metastatic deposits on full-length radiographs, none required an alternative operation to that which they normally would undergo. Furthermore, no patients required a longer stem arthroplasty or longer internal fixation. One in four fractures was associated with co-existing breast malignancy (26.5%, n = 114), followed by prostate cancer (14.8%, n = 64). Colorectal, lung, bladder and skin (squamous cell carcinoma) contributed 6-10% (n = 44, 40, 33, 29, respectively). Other malignancies contributed to the rest of the 25%.

CONCLUSION

To conclude, full-length radiographs had no diagnostic or therapeutic value in our cohort of patients regardless of the full-length femur findings.

Are dental x-rays safe? Content analysis of English and Chinese YouTube videos

Objective

This study provided a content analysis of English and Chinese YouTube videos related to dental radiation safety.

Method

The search string, entered in English and Chinese respectively, was: (dental x-ray safe). The searches were performed and exported with Apify YouTube scraper. By screening the resultant videos and their related videos (as recommended by YouTube), a total of 89 videos were screened. Finally, 45 videos (36 English and nine Chinese) were included and analyzed. The specific information regarding dental radiation was evaluated. The Patient Education Material Assessment Tool for Audiovisual Materials was used to assess understandability and actionability.

Results

There was no significant difference between the English and Chinese videos in terms of view count, like count, comment count, and video duration. Half of the videos explicitly reassured the audience that dental x-rays are safe. Two of the English videos specifically stated that dental x-rays do not cause cancers. Numerous analogies were made in regard to radiation dose, such as equivalence to taking a flight or eating some bananas. About 41.7% of the English videos and 33.3% of the Chinese videos mentioned that patients could be further protected from scatter radiation by wearing a lead apron and thyroid collar. Videos had a good understandability score (91.3) but a poor actionability score (0).

Conclusions

Some of the analogies and the claimed radiation dose were questionable. One Chinese video even wrongly stated that dental x-rays are nonionizing radiation. The videos generally did not mention their information sources or the underlying radiation protection principles.

Recent Progress and Trends in X-ray-Induced Photodynamic Therapy with Low Radiation Doses

The prominence of photodynamic therapy (PDT) in treating superficial skin cancer inspires innovative solutions for its congenitally deficient shadow penetration of the visible-light excitation. X-ray-induced photodynamic therapy (X-PDT) has been proven to be a successful technique in reforming the conventional PDT for deep-seated tumors by creatively utilizing penetrating X-rays as external excitation sources and has witnessed rapid developments over the past several years. Beyond the proof-of-concept demonstration, recent advances in X-PDT have exhibited a trend of minimizing X-ray radiation doses to quite low values. As such, scintillating materials used to bridge X-rays and photosensitizers play a significant role, as do diverse well-designed irradiation modes and smart strategies for improving the tumor microenvironment. Here in this review, we provide a comprehensive summary of recent achievements in X-PDT and highlight trending efforts using low doses of X-ray radiation. We first describe the concept of X-PDT and its relationships with radiodynamic therapy and radiotherapy and then dissect the mechanism of X-ray absorption and conversion by scintillating materials, reactive oxygen species evaluation for X-PDT, and radiation side effects and clinical concerns on X-ray radiation. Finally, we discuss a detailed overview of recent progress regarding low-dose X-PDT and present perspectives on possible clinical translation. It is expected that the pursuit of low-dose X-PDT will facilitate significant breakthroughs, both fundamentally and clinically, for effective deep-seated cancer treatment in the near future.

Advances in multiscale image processing and its effects on image quality in skeletal radiography

Multi-frequency processing (MFP) leads to enhanced image quality (IQ) of radiographs. This study is to determine the effect of third generation MFP (M3) on IQ in comparison to standard second-generation MFP (M2). 20 cadavers were examined and post-processing of radiographs was performed with both M2 and M3. Three readers blinded to the MFP used for each image independently compared corresponding image pairs according to overall IQ and depiction of bony structures and soft tissue (+ 2: notably better > 0: equal > - 2: notably worse). A significant deviation of the median grade from grade 0 (equal) (p < 0.01) for each evaluator A, B and C speaks against an equal image quality of M2- and M3-images. M3-images were categorized with better grades (+ 1, + 2) in 87.7% for overall image quality, in 90.4% for soft tissue and 81.8% for bony structures. M3 images showed significant higher averaged SNR and CNR for all investigated lower extremities than that of M2 images (0.031 < p < 0.049). The newest generation of MFP leads to significantly better depiction of anatomical structures and overall image quality than in images processed with the preceding generation of MFP. This provides increased diagnostic accuracy and further decreased radiation exposure.

Use of optically stimulated luminescence dosimeter and radiophotoliminescent glass dosimeter for dose measurement in dual-source dual-energy computed tomography

We aimed to evaluate properties of optically stimulated luminescence dosimeters (OSLDs) and radiophotoluminescent glass dosimeters (RPLDs) used in dual-source dual-energy (DE) computed tomography (DECT) dosimetry. Energy dependence was evaluated in single-energy (SE) and DE modes, and their relative dose responses differed by 3.8% and 6.6% under equivalent effective energy with OSLD and RPLD, respectively. Dose variation was evaluated using coefficients of variation of dose values from 10 dosimeters, and dose variation of OSLD and RPLD in SE mode ranged from 2.1 to 3.0% and from 2.1 to 2.8%, and those in the DE mode were 1.8 and 2.6%, respectively. Dose linearity was evaluated from 1 to 150 mGy, and linear relationships of dose response were observed between the dosimeters and the ionization chamber (correlation coefficients ≥ 0.9991). Angular dependence was evaluated from - 90° to + 90°, and it was smaller in DE mode than in SE mode for OSLD. The normalized response of RPLD was higher at ± 30° and ± 60° and lower at - 90° in SE and DE modes. This study demonstrated both OSLD and RPLD can perform dosimetry in dual-source DECT with small influence of the properties of the dosimeters compared with that in SECT.

Image quality is resilient against tube voltage variations in post-mortem skeletal radiography with a digital flat-panel detector

In recent phantom studies low-contrast detectability was shown to be independent from variations in tube voltage in digital radiography (DR) systems. To investigate the transferability to a clinical setting, the lower extremities of human cadavers were exposed at constant detector doses with different tube voltages in a certain range, as proposed in the phantom studies. Three radiologists independently graded different aspects of image quality (IQ) in a comparative analysis. The grades show no correlation between IQ and kV, which means that the readers were not able to recognize a significant IQ difference at different kV. Signal-to-noise and contrast-to-noise ratios showed no significant differences in IQ despite the kV-setting variations. These findings were observed from a limited kV range setting. Higher kV-settings resulted in lowest patient exposure at constant IQ. These results confirm the potential of DR-systems to contribute to standardization of examination protocols comparable to computed tomography. This may prevent the trend to overexpose. Further investigations in other body regions and other DR-systems are encouraged to determine transferability.

Image quality and radiation dose reduction in chest CT in pulmonary infection

PURPOSE

To evaluate the effect of dose reduction with iterative reconstruction (IR) on image quality of chest CT scan comparing two protocols.

MATERIALS AND METHODS

Fifty-nine patients were enrolled. The two CT protocols were applied using Iterative Reconstruction (ASIR™) 40% but different noise indexes, recording dose-length product (DLP) and volume computed tomography dose index (CTDI_vol). The subjective IQ was rated based on the distinction of anatomic details using a 4-point Likert scale based on the European Guidelines on Quality Criteria for CT. For each patient, two single CTs, at enrollment (group 1) and at follow-up after lowering the dose (group 2), were evaluated by two radiologists evaluating, for each examination, five different lung regions (central zone-CZ; peripheral zone-PZ; sub-pleural region-SPR; centrilobular region-CLR; and apical zone-AZ). An inter-observer agreement was expressed by weighted Cohen's kappa statistics (k) and intra-individual differences of subjective image analysis through visual grading characteristic (VGC) analysis.

RESULTS

An average 50.4% reduction in CTDI_vol and 51.5% reduction in DLP delivered were observed using the dose-reduced protocol. An agreement between observers evaluating group 1 CTs was perfect (100%) and moderate to good in group 2 examinations (k-Cohen ranging from 0.56 for PZ and AZ to 0.70 for SPR). In the VGC analysis, image quality ratings were significantly better for group 1 than group 2 scans for all regions (AUC_VGC ranging from 0.56 for CZ to 0.62). However, disagreement was limited to a score 4 (excellent)-to-score 3 (good) IQ transition; apart from a single case in PZ, both the observers scored the IQ at follow-up as 2 (sufficient) starting from a score 4 (excellent).

CONCLUSION

Dose reduction achieved in the follow-up CT scans, although a lower IQ still allows a good diagnostic confidence.

EYE LENS DOSES OF RADIOLOGY TECHNOLOGISTS WHO ASSIST PATIENTS DURING RADIOGRAPHY

The International Commission on Radiological Protection (ICRP) revised a drastic decrease of the annual eye equivalent dose limit. The present study aimed to evaluate the amounts of radiation to which the eye lenses of radiological technologists (RT) become exposed and the effects of wearing lead glasses on dose reduction while assisting patients during radiographic assessments. Lens equivalent doses (Hp(3)) were measured at the neck using personal dosemeter. In addition, Hp(3) was estimated by converting air kerma determined using small optically stimulated luminescence (OSL) dosemeters at six positions on lead glasses near the eyes and at the neck. The estimated mean Hp(3) from personal dosemeter at the neck varied from 3.92 to 18.6 mSv/y. Compare to OSL for which the dose varies from 8.95 to 54.75 mSv/y, personal dosimeter underestimate Hp(3).Therefore, Hp(3) for RT might exceed the revised eye equivalent dose limit 20 mSv/y recommended by the ICRP.

APPLICATION OF TIME-AVERAGED AND INTEGRAL-BASED MEASURE FOR MEASUREMENT RESULTS VARIABILITY REDUCTION IN GSM/DCS/UMTS SYSTEMS

Since EMF levels from wireless telecommunication networks are non-stationary and exhibit large temporal variations, the use of continuous measurements during extended periods (preferably 24 h or longer) with a data-logging system is required. Because of the short-term variations of E field, the 6-min measurements and 6-min averaged results to obtain the mean level strength at a given place appear to be dependent on the time of measurements during the day. This paper presents a new (integral-based) measure to evaluate electromagnetic exposure. The new measure is a pure physical descriptor of the amount of exposed energy density (a parameter accumulated from instantaneous power density values in time). To confirm previous observations, continuous measurements with personal exposure metre were recorded 24 h a day for two weeks at every location in urban area, 14 different locations in total. Additionally, to check temporal variations and repeatability of exposure assessment, a week of prolonged measurements was taken 6 months later, making in total three weeks of measurements at 2 locations. Day-to-day repeatability of RF-EMF exposure was analysed through the time-averaged and integral-based measure. The analysis is based on approximately 5.1 million data samples (1.7 million for each band). The ratio between the maximum and minimum instantaneous (maximum and minimum 6-min averaged) E field values during the day could reach up to 25 dB (20 dB). Therefore, great variability in the results may occur. By applying the 24 h time-averaged and integral-based measure on a 24 h data set of measurements, the variability of daily exposure could stay within ±20% of the week mean level obtained either with the time-averaged or integral-based measure. Both, the time-averaged E field and integral-based power density exposures of the general public in all locations were found to be well below the general public exposure limits of the ICNIRP guidelines.

How have advances in CT dosimetry software impacted estimates of CT radiation dose and cancer incidence? A comparison of CT dosimetry software: Implications for past and future research

Objective

Organ radiation dose from a CT scan, calculated by CT dosimetry software, can be combined with cancer risk data to estimate cancer incidence resulting from CT exposure. We aim to determine to what extent the use of improved anatomical representation of the adult human body “phantom” in CT dosimetry software impacts estimates of radiation dose and cancer incidence, to inform comparison of past and future research.

Methods

We collected 20 adult cases for each of three CT protocols (abdomen/pelvis, chest and head) from each of five public hospitals (random sample) (January-April inclusive 2010) and three private clinics (self-report). Organ equivalent and effective dose were calculated using both ImPACT (mathematical phantom) and NCICT (voxelised phantom) software. Bland-Altman plots demonstrate agreement and Passing-Bablok regression reports systematic, proportional or random differences between results. We modelled the estimated lifetime attributable risk of cancer from a single exposure for each protocol, using age-sex specific risk-coefficients from the Biologic Effects of Ionizing Radiation VII report.

Results

For the majority of organs used in epidemiological studies of cancer incidence, the NCICT software (voxelised) provided higher dose estimates. Across the lifespan NCICT resulted in cancer estimates 2.9%-6.6% and 14.8%-16.3% higher in males and females (abdomen/pelvis) and 7.6%-19.7% and 12.9%-26.5% higher in males and females respectively (chest protocol). For the head protocol overall cancer estimates were lower for NCICT, but with greatest disparity, >30% at times.

Conclusion

When the results of previous studies estimating CT dose and cancer incidence are compared to more recent, or future, studies the dosimetry software must be considered. Any change in radiation dose or cancer risk may be attributable to the software and phantom used, rather than—or in addition to—changes in scanning practice. Studies using dosimetry software to estimate radiation dose should describe software comprehensively to facilitate comparison with past and future research.

Patient Exposure during Fluoroscopy-guided Pacemaker Implantation Procedures

A pacemaker, which is used for heart resynchronization with electrical impulses, is used to manage many clinical conditions. Recently, the frequency of pacemaker implantation procedures has increased to more than 50% worldwide. During this procedure, patients can be exposed to excessive radiation exposure. Wide range of doses has been reported in previous studies, suggesting that optimization of this procedure has not been fulfilled yet. The current study evaluated patient radiation exposure during cardiac pacemaker procedures and quantified the patient effective dose. A total of 145 procedures were performed for five pacemaker procedures (VVI, VVIR, VVD, VVDR, and DDDR) at two hospitals. Patient doses were measured using the kerma-area product meter. Effective doses were estimated using software based on Monte Carlo simulation from the National Radiological Protection Board (NRPB, now The Health Protection Agency). The effective dose values were used to estimate cancer risk from the pacemaker procedure. Patient demographic data and exposure parameters for fluoroscopy and radiography were quantified. The mean patient doses ± SD per procedure (Gycm²) for VVI, VVIR, VVD, VVDR, and DDDR were 1.52 ± 0.13 (1.43-1.61), 3.28 ± 2.34 (0.29-8.73), 3.04 ± 1.67 (1.57-4.86), 6.04 ± 2.326 3.29-8.58), and 8.8 ± 3.6 (4.5-26.20), respectively. The overall patient effective dose was 1.1mSv per procedure. It is obvious that the DDDR procedure exposed patients to the highest radiation dose. Patient dose variation can be attributed to procedure type, exposure parameter settings, and fluoroscopy time. The results of this study showed that patient doses during different pacemaker procedures are lower compared to previous reported values. Patient risk from pacemaker procedure is low, compared to other cardiac interventional procedures. Patients' exposures were mainly influenced by the type of procedures and the clinical indication.

Age estimation in Portuguese population: The application of the London atlas of tooth development and eruption

Chronological age estimation from the dental parameters is becoming increasingly important. The London atlas of tooth development is the most recent developed method and represents a modification of the previous older methods. The aim of this study was to evaluate the accuracy of the London atlas for the dental age estimation in the Portuguese population. The study sample included 736 radiographic images (498 females and 238 males) of Portuguese origin, patients of Dental Clinic of Superior Institute of Health Sciences Egas Moniz and Dental Medicine Faculty, University of Lisbon. The age range of the individuals was between 3 and 24 years. Estimated age was compared with the chronological age using the paired t-test. The results showed that there was no statistically significant difference between left and right side of the jaw (p>0.05). Both sides showed an average overestimation of age by one month approximately. Moreover, the significant difference between chronological and estimated age was not observed in the females. However, the significant difference was observed in a sample coming from males (right: p=0.008; left: p=0.003). Our results showed that the London atlas can be potentially used as a tool for age estimation. However, the difference between sexes clearly suggests that separate charts should be made for each sex. Further studies, which will have as a final goal the development of a new method for age estimation using dental parameters, are needed.

PHYSICIANS' KNOWLEDGE ABOUT RADIATION DOSE AND POSSIBLE RISKS OF COMMON MEDICAL TESTS: A SURVEY IN IRAN

Recent data suggest that knowledge of radiation exposures among physicians is inadequate. This study, therefore, aimed to evaluate their knowledge of the radiation doses their patients received and awareness of associated biological risks of radiation exposure. A questionnaire in multiple-choice format consisted of four sections with a total of 10 questions based on the literature review. A total of 136 questionnaires were returned from 69 general practitioners and 67 physicians in various specialties from 10 different hospitals in the capital city of Tehran, Iran. Fifty-four percent of general practitioners and twenty-five percent of specialties declared that they are not aware of biological risks of radiation exposure. Fifty-six percent of physicians did not know the correct definition of absorbed dose. Only 33% of physicians knew the dose exposure of a chest X-ray and only 31% knew the approximate doses of various procedures relative to a chest X-ray. Forty-seven percent of physicians incorrectly distinguished the stochastic effects of radiation from the deterministic effects, and thirty-eight of physicians did not know the organs of the body that are most sensitive to ionizing radiation. Only 23.5% of physicians were aware of the one in 2000 risk of induction of fatal carcinoma from computed tomography of the abdomen. Seventy-nine percent of physicians incorrectly underestimated the contribution of nuclear and radiological tests in exposure of an average person. The mean score of the specialties trended toward being more accurate than general practitioners (4.18 ± 1.28 vs. 3.89 ± 1.46, respectively, from a potential accurate total score of 9), but these differences were not statistically significant. Among specialists, orthopedics had the highest scores. The present study demonstrated the limited knowledge of radiation exposures among general practitioners and specialists and a need to improve their knowledge by means of targeted training and re-education.

[Aspects of radiation protection during chest X-radiography]

BACKGROUND

Radiation safety in conventional X-ray diagnostics is based on the concepts of justification, optimization of an X-ray examination and limitation of the radiation exposure achieved during the examination. Optimization of an X-ray examination has to be considered as a multimodal process in which all technical components of the X-ray equipment have to be adapted to each other and also have to be adapted to the anthropometric characteristics of patients and the clinical indications.

OBJECTIVES

In this article the technical components of a conventional pediatric chest X-radiograph are presented, and recommendations for optimizing chest X-rays in children are provided.

RESULTS AND DISCUSSION

The following measures are of prime importance: correct x-ray beam limitation, using the posteroanterior projection when possible and not using anti-scatter grids in children under approximately 8 years old. In pediatric radiology chest x-rays that are taken not at the peak of inspiration can also be of some diagnostic significance. Optimization of an X-ray examination inevitably results in the limitation of radiation exposure.

Trends and patterns in the use of computed tomography in children and young adults in Catalonia - results from the EPI-CT study

BACKGROUND

Although there are undeniable diagnostic benefits of CT scanning, its increasing use in paediatric radiology has become a topic of concern regarding patient radioprotection.

OBJECTIVE

To assess the rate of CT scanning in Catalonia, Spain, among patients younger than 21 years old at the scan time.

MATERIALS AND METHODS

This is a sub-study of a larger international cohort study (EPI-CT, the International pediatric CT scan study). Data were retrieved from the radiological information systems (RIS) of eight hospitals in Catalonia since the implementation of digital registration (between 1991 and 2010) until 2013.

RESULTS

The absolute number of CT scans annually increased 4.5% between 1991 and 2013, which was less accentuated when RIS was implemented in most hospitals. Because the population attending the hospitals also increased, however, the rate of scanned patients changed little (8.3 to 9.4 per 1,000 population). The proportions of patients with more than one CT and more than three CTs showed a 1.51- and 2.7-fold increase, respectively, over the 23 years.

CONCLUSION

Gradual increases in numbers of examinations and scanned patients were observed in Catalonia, potentially explained by new CT scanning indications and increases in the availability of scanners, the number of scans per patient and the size of the attended population.

The disproportionate risk burden of CT scanning on females and younger adults in Australia: a retrospective cohort study

OBJECTIVES

To explore the interaction of computed tomography (CT) use, dose and radiation risk of Australian Medicare-funded CT scanning and the impact on cancer incidence and mortality.

METHODS

This retrospective cohort study used records of Medicare subsidised CT scans in Australia (2006/07 to 2011/12) and Australian CT dosimetry. The annual number, rate and adjusted likelihood of CT were determined for gender, age and examination type. Incident cancer and cancer-related mortality attributable to CT in Australia were estimated using lifetime attributable risk coefficients, dosimetry and scan numbers.

RESULTS

The number of CT scans increased by 36% from 2006/07 to 2011/12. Only patients aged 0-4 years did not present an increase in CT scanning rates. Females were 11% more likely to be scanned than males. Head, abdomen/pelvis and spine CT scans were the most likely areas scanned. Females were attributed 61% of both incident cancers and cancer-related mortality from 55% of scans performed. Patients aged 15-44 years were attributed 37% of incident cancers and 30% of cancer-related mortality from 26% of CT scans.

CONCLUSIONS

CT in Australia is increasing, including in groups at higher risk from ionising radiation. This presents a complex set of risk/benefit considerations for clinicians and policy makers.

Decision Making and Variation in Radiation Exposure Factor Selection by Radiologic Technologists

The goal of radiographic imaging is to produce a diagnostically useful image while minimizing patient radiation dose. This study aimed to review variations in exposure factor selection by radiologic technologists for virtual patients with varying body mass index characteristics. Eleven technologists were asked to assign exposure parameters (kVp, mAs, source-to-image receptor distance, and grid use) to 10 computer-generated patient images for each of four radiographic examinations (anteroposterior [AP] shoulder; AP lumbar spine; lateral lumbar spine; AP portable chest). The virtual patients represented five body mass index categories-underweight, healthy weight, overweight, obese, and superobese. As participants assigned exposures, their visual patterns were recorded by a Tobii TX300 eye-tracker. Significant (P < .05) correlation was found between radiographer age/experience and assignment of mAs for AP shoulder and lumbar examinations. Greater age/experience correlated with higher mAs for the AP shoulder examination, but with lower values for lumbar examinations. Strong correlations also existed between times to first fixations on relevant anatomic areas, and kVp/mAs values existed for the AP portable chest examination. Exposure selection differences related to age/experience highlight inconsistencies in the practice of exposure parameter setting. The reason for these inconsistencies requires further investigation, and how to address deficiencies in practice requires consideration to optimize safe patient care. Because of the small sample size used, further research into the relationship between visual factors and individual examinations is suggested, after the findings regarding the AP portable chest examination.

Conversion coefficients for determining organ doses in paediatric pelvis and hip joint radiography

BACKGROUND

Knowledge of organ and effective doses achieved during paediatric X-ray examinations is an important prerequisite for assessment of radiation burden to the patient.

OBJECTIVE

Conversion coefficients for reconstruction of organ and effective doses from entrance doses for pelvis and hip joint radiographs of 0-, 1-, 5-, 10-, 15- and 30-year-old patients are provided regarding the Guidelines of Good Radiographic Technique of the European Commission.

MATERIALS AND METHODS

Using the personal computer program PCXMC developed by the Finnish Centre for Radiation and Nuclear Safety (Säteilyturvakeskus STUK), conversion coefficients for conventional pelvis and hip joint radiographs were calculated by performing Monte Carlo simulations in mathematical hermaphrodite phantom models representing patients of different ages. The clinical variation of radiation field settings was taken into consideration by defining optimal and suboptimal standard field settings.

RESULTS

Conversion coefficients for the reconstruction of organ doses in about 40 organs and tissues from measured entrance doses during pelvis and hip joint radiographs of 0-, 1-, 5-, 10-, 15- and 30-year-old patients were calculated for the standard sagittal beam projection and the standard focus detector distance of 115 cm.

CONCLUSION

The conversion coefficients presented can be used for organ dose assessments from entrance doses measured during pelvis and hip joint radiographs of children and young adults with all field settings within the optimal and suboptimal standard field settings.

Dual-axis rotational coronary angiography can reduce peak skin dose and scattered dose: a phantom study

The purpose of this study was to evaluate peak skin dose received by the patient and scattered dose to the operator during dual‐axis rotational coronary angiography (DARCA), and to compare with those of standard coronary angiography (SA). An anthropomorphic phantom was used to simulate a patient undergoing diagnostic coronary angiography. Cine imaging was applied on the phantom for 2 s, 3 s, and 5 s in SA projections to mimic clinical situations with normal vessels, and uncomplicated and complicated coronary lesions. DARCA was performed in two curved trajectories around the phantom. During both SA and DARCA, peak skin dose was measured with thermoluminescent dosimeter arrays and scattered dose with a dosimeter at predefined height (approximately at the level of left eye) at the operator's location. Compared to SA, DARCA was found lower in both peak skin dose (range: 44%–82%, p < 0.001) and scattered dose (range: 40%–70%, p < 0.001). The maximal reductions were observed in the set mimicking complicated lesion examinations (82% reduction for peak skin dose, p < 0.001; 70% reduction for scattered dose, p < 0.001). DARCA reduces both peak skin dose and scattered dose in comparison to SA. The benefit of radiation dose reduction could be especially significant in complicated lesion examinations due to large reduction in X‐ray exposure time. The use of DARCA could, therefore, be recommended in clinical practice to minimize radiation dose.

PACS numbers: 87.53.‐j, 87.53.Bn, 87.59.‐e, 87.59.C‐, 87.59.cf, 87.59.Dj

Conversion coefficients for determining organ doses in paediatric spine radiography

BACKGROUND

Knowledge of organ and effective doses achieved during paediatric x-ray examinations is an important prerequisite for assessment of radiation burden to the patient.

OBJECTIVE

Conversion coefficients for reconstruction of organ and effective doses from entrance doses for segmental spine radiographs of 0-, 1-, 5-, 10-, 15- and 30-year-old patients are provided regarding the Guidelines of Good Radiographic Technique of the European Commission.

MATERIALS AND METHODS

Using the personal computer program PCXMC developed by the Finnish Centre for Radiation and Nuclear Safety (Säteilyturvakeskus STUK), conversion coefficients for conventional segmental spine radiographs were calculated performing Monte Carlo simulations in mathematical hermaphrodite phantom models describing patients of different ages. The clinical variation of beam collimation was taken into consideration by defining optimal and suboptimal radiation field settings.

RESULTS

Conversion coefficients for the reconstruction of organ doses in about 40 organs and tissues from measured entrance doses during cervical, thoracic and lumbar spine radiographs of 0-, 1-, 5-, 10-, 15- and 30-year-old patients were calculated for the standard sagittal and lateral beam projections and the standard focus detector distance of 115 cm.

CONCLUSION

The conversion coefficients presented may be used for organ dose assessments from entrance doses measured during spine radiographs of patients of all age groups and all field settings within the optimal and suboptimal standard field settings.

Conversion factors for determining organ doses received by paediatric patients in high-resolution single slice computed tomography with narrow collimation

Estimations of organ doses DT received during computed tomographic examinations are usually performed by applying conversion factors to basic dose indicators like the computed tomography dose index (CTDI) or the dose-length-product (DLP). In addition to the existing conversion factors for beam apertures of 5 mm or 10 mm, we present new DLP-DT conversion factors adapted to high-resolution CT (HRCT) examinations of infants and young children with beam apertures of the order of 1 mm and under consideration of bow tie filtration. Calculations are performed on mathematical MIRD phantoms for an age range from 0, 1, 5, 10, 15 up to (for comparison) 30 years by adapting PCXMC, a Monte Carlo algorithm originally developed by STUK (Helsinki, Finland) for dose reconstructions in projection radiography. For this purpose, each single slice CT examination is approximated by a series of corresponding virtual planar radiographies comprising all focus positions. The transformation of CT exposure parameters into exposure parameters of the series of corresponding planar radiographies is performed by a specially developed algorithm called XCT. The DLP values are evaluated using the EGSRay code. The new method is verified at a beam aperture of 10 mm by comparison with formerly published conversion factors. We show that the higher spatial resolution leads to an enhanced DLP-DT conversion factor if a small organ (e. g. thyroid gland, mammae, uterus, ovaries, testes) is exactly met by the chosen CT slice, while the conversion factor is drastically reduced if the chosen CT slice is positioned above or below the organ. This effect is utilized for dose-saving examinations with only a few single slices instead a full scan, which technique is applied in about 10% of all paediatric chest CT examinations.

Age estimation for forensic purposes in Italy: ethical issues

Age assessment in children and young adults is a relevant medicolegal issue due to the gradual increase of persons devoid of proper identification documents in European countries. Because of the illegal immigration and growing crime rates among children and adolescents, age estimation for forensic purposes is often required. The scientific research and the extensive experience of forensic experts in the last decades focused on the use of radiographic methods addressed to evaluate the degree of skeletal or dental development as the most accurate parameters to estimate the chronological age of children and adolescents. This paper analyzes the ethical issues related to age estimation procedures based on radiographic methods, showing how the ethical principles of beneficence, nonmalevolence, justice, and autonomy may be guaranteed during the execution of the age assessment in forensic practice. The procedure might be conducted in accordance with international guidelines and protocols, though they need a higher homogenization and standardization. A strong collaboration between various scientific societies of professionals (forensic odontologists, forensic pathologists, forensic anthropologist, radiologists, pediatricians, and psychologists), who have been involved in age estimation for years, is needed to reach this goal.

Diagnostic chest X-rays and breast cancer risk before age 50 years for BRCA1 and BRCA2 mutation carriers

BACKGROUND

The effects of low-dose medical radiation on breast cancer risk are uncertain, and few studies have included genetically susceptible women, such as those who carry germline BRCA1 and BRCA2 mutations.

METHODS

We studied 454 BRCA1 and 273 BRCA2 mutation carriers ages younger than 50 years from three breast cancer family registries in the United States, Canada, and Australia/New Zealand. We estimated breast cancer risk associated with diagnostic chest X-rays by comparing mutation carriers with breast cancer (cases) with those without breast cancer (controls). Exposure to chest X-rays was self-reported. Mammograms were not considered in the analysis.

RESULTS

After adjusting for known risk factors for breast cancer, the ORs for a history of diagnostic chest X-rays, excluding those for tuberculosis or pneumonia, were 1.16 [95% confidence interval (CI), 0.64-2.11] for BRCA1 mutations carriers and 1.22 (95% CI, 0.62-2.42) for BRCA2 mutations carriers. The OR was statistically elevated for BRCA2 mutation carriers with three to five diagnostic chest X-rays (P = 0.01) but not for those with six or more chest X-rays. Few women reported chest fluoroscopy for tuberculosis or chest X-rays for pneumonia; the OR estimates were elevated, but not statistically significant, for BRCA1 mutation carriers.

CONCLUSIONS

Our findings do not support a positive association between diagnostic chest X-rays and breast cancer risk before the ages of 50 years for BRCA1 or BRCA2 mutation carriers.

IMPACT

Given the increasing use of diagnostic imaging involving higher ionizing radiation doses, further studies of genetically predisposed women are warranted.

Low-dose ionising radiation from medical imaging in patients hospitalised in Internal Medicine

BACKGROUND

Medical imaging is responsible for increasing exposure to low-dose ionising radiation in the general population. The extent of exposure in specific patient populations remains to be determined.

AIM

We sought to determine the level of exposure in patients hospitalised in General Internal Medicine.

METHODS

In this retrospective cohort study, we searched the Centre Informatisé de Recherche Évaluative en Services et Soins de Santé database for adult patients hospitalised in General Internal Medicine from 1 January 2008 to 31 December 2008. We collected data on demographics, co-morbidities, and radiological and nuclear imaging. We used data from the literature to calculate an estimated annual effective dose for each patient and searched for factors associated with higher exposure.

RESULTS

One thousand one hundred eighty-seven (1187) patients were hospitalised at least once during the study period. The median age was 69 years (interquartile range 56-81) and 636 (53.6%) were men. The median annual effective dose of the whole cohort was 8.7 mSv/year. Patients aged between 55 and 80 years were exposed to a higher median effective dose compared with their younger and older counterparts (P < 0.001). Patients with cardiac, pulmonary, peripheral arterial and neoplastic disease were at higher risk of exposure to high and very high annual effective dose (P < 0.01). Patients with longer hospitalisations were at higher risk of exposure to high and very high annual effective dose (P < 0.01).

CONCLUSION

Patients hospitalised on a General Internal Medicine ward are exposed to three times more ionising radiation than the general population.

Radiation dosimetry assessment of routine CT scanning protocols used in Western Australia

Technical data on local CT practice in Western Australia were collected for five major CT providers using a self-completed questionnaire. The CTDIvol DLP and effective dose for each protocol were obtained and providers were ranked according to radiation burden for each clinical scenario. The mean, median, 75th percentile and standard deviation were calculated for both effective dose and DLP for each scenario and these values were compared with published data. CT utilisation data were used to estimate the attributable radiation dose to the WA population and the potential change in population annual effective dose according to the protocol used was estimated. We found that wide variations in technique and radiation dose exist across providers for similar examinations, producing a higher radiation burden than reported internationally. As expected, the CT protocol used dramatically affects the radiation dose received, and this has a significant effect on annual population dose. This study highlights the need for recognition and understanding of both the degree of variation in radiation dose across providers and the relatively high radiation burden afforded by protocols in use in Western Australia so that necessary dialogue can be launched for practitioner consensus on appropriate diagnostic reference levels in CT scanning.

A study of the perception of health risks among college students in China

The present survey was designed to investigate the perception of health risks among college students in China. The data are the responses of a sample of 3,069 college students at one university to surveys that include measures of several dimensions of public judgments about fifteen specific hazards. Chinese college students conveyed their concerns as falling into three broad categories: Environmental (e.g., global warming, natural catastrophes, the ozone hole, air pollution, chemical pollution, pesticides in food), Technological (e.g., nuclear power stations, thermal power, genetically modified food, medical X-rays), and Social (cigarette smoking, drinking alcohol, overtime study or work, mental stress, motor vehicle accidents). The data were collected with a self-report questionnaire. Descriptive statistics were used to illustrate the levels of perceived risk according to the percent of "high risk" responses as well as the mean response values. Generally, the hazards that were perceived as posing the greatest health risk were those belonging to the social health risks; items related to technology risks received the lowest percentage of "high health risk" rankings. Traditional environmental risks such as natural catastrophes, pollution issues (chemical pollution, air pollution), and pesticides in food were ranked as being relatively high risks. The respondents were less concerned about new emerging issues and long-term environmental risks (global warming). In this survey, motor vehicle accidents were considered to be a "high health risk" by the greatest percentage of respondents. Generally speaking, the female respondents' degree of recognition of health risks is higher than that of male respondents. Only for the item of smoking was the male respondents' degree higher than that of females. There is also a geographic imbalance in the health risk perceptions. The degree of recognition of health risks from respondents in municipalities is generally lower than that of respondents from other areas except for items such as natural disasters, smoking, medical X-rays, and mental stress, which are exceptions.

Evaluation of a dedicated MDCT protocol using iterative image reconstruction after cervical spine trauma

AIM

To evaluate radiation exposure for 64-row computed tomography (CT) of the cervical spine comparing two optimized protocols using filtered back projection (FBP) and adaptive statistical iterative reconstruction (ASIR), respectively.

MATERIALS AND METHODS

Sixty-seven studies using FBP (scanner 1) were retrospectively compared with 80 studies using ASIR (scanner 2). The key scanning parameters were identical (120 kV dose modulation, 64 × 0.625 mm collimation, pitch 0.531:1). In protocol 2, the noise index (NI) was increased from 5 to 25, and ASIR and the high-definition (HD) mode were used. The scan length, CT dose index (CTDI), and dose-length product (DLP) were recorded. The image quality was analysed subjectively by using a three-point scale (0; 1; 2), and objectively by using a region of interest (ROI) analysis. Mann-Whitney U and Wilcoxon's test were used.

RESULTS

In the FBP group, the mean CTDI was 21.43 mGy, mean scan length 186.3 mm, and mean DLP 441.15 mGy cm. In the ASIR group, the mean CTDI was 9.57 mGy, mean scan length 195.21 mm, and mean DLP 204.23 mGy cm. The differences were significant for CTDI and DLP (p < 0.001) and scan length (p = 0.01). There was no significant difference in the subjective image quality (p > 0.05). The estimated mean effective dose decreased from 2.38 mSv (FBP) to 1.10 mSv (ASIR).

CONCLUSION

The radiation dose of 64-row MDCT can be reduced to a level comparable to plain radiography without loss of subjective image quality by implementation of ASIR in a dedicated cervical spine trauma protocol. These results might contribute to an improved relative risk-to-benefit ratio and support the justification of CT as a first-line imaging tool to evaluate cervical spine trauma.

Swiss population exposure to radiation by interventional radiology in 2008

The aim of this study was to investigate the radiation exposure of the Swiss population to interventional procedures. A nationwide survey was conducted in Switzerland. The annual effective dose per capita due to interventional procedures was found to be 0.14 mSv, corresponding to 12% of the total dose. Coronary angiography and percutaneous coronary interventions were found to be the most frequent and the most irradiating interventional procedures, accounting for 52% of the total examination frequency and 64% of the dose delivered to the population. Switzerland stands at the same level as other countries in terms of effective dose per capita due to interventional radiology.

The radiation issue in cardiology: the time for action is now

The "radiation issue" is the need to consider possible deterministic effects (e.g., skin injuries) and long-term cancer risks due to ionizing radiation in the risk-benefit assessment of diagnostic or therapeutic testing. Although there are currently no data showing that high-dose medical studies have actually increased the incidence of cancer, the "linear-no threshold" model in radioprotection assumes that no safe dose exists; all doses add up in determining cancer risks; and the risk increases linearly with increasing radiation dose. The possibility of deterministic effects should also be considered when skin or lens doses may be over the threshold. Cardiologists have a special mission to avoid unjustified or non-optimized use of radiation, since they are responsible for 45% of the entire cumulative effective dose of 3.0 mSv (similar to the radiological risk of 150 chest x-rays) per head per year to the US population from all medical sources except radiotherapy. In addition, interventional cardiologists have an exposure per head per year two to three times higher than that of radiologists. The most active and experienced interventional cardiologists in high volume cath labs have an annual exposure equivalent to around 5 mSv per head and a professional lifetime attributable to excess cancer risk on the order of magnitude of 1 in 100. Cardiologists are the contemporary radiologists but sometimes imperfectly aware of the radiological dose of the examination they prescribe or practice, which can range from the equivalent of 1-60 mSv around a reference dose average of 10-15 mSv for a percutaneous coronary intervention, a cardiac radiofrequency ablation, a multi-detector coronary angiography, or a myocardial perfusion imaging scintigraphy. A good cardiologist cannot be afraid of life-saving radiation, but must be afraid of radiation unawareness and negligence.

Population exposure to ionising radiation from CT examinations in Aosta Valley between 2001 and 2008

Recent and continuous advances in CT, such as the development of multislice CT, have promoted a rapid increase in its clinical application. Today, CT accounts for approximately 10% of the total number of medical radiographic procedures worldwide. However, the growing performance of the new CT generations have increased not only the diagnostic opportunities, but also the radiation dose to the patient. The relative contribution to the collective radiation dose is now estimated to be approximately 50%. Several papers have been published concerning the intensive use of CT and its contribution to the collective dose. However, most of the literature concerns the years 1997-2003 and the dosimetric evaluations are generally limited to the main standard protocols (chest, head and abdomen), deriving the effective dose by the simple application of the diagnostic reference levels. Only specific dosimetric analyses of single and innovative procedures have been published recently. Moreover, few data comes from Italian radiology departments. This paper aims to bridge these gaps. Firstly, it characterises in terms of measured CT dose index (CTDI) two last-generation scanners of the Radiological Department of Aosta Hospital. Secondly, it evaluates the effective dose from most of the CT examinations performed from 2001 to 2008 to compare protocols and technologies in line with the suggestions of the 2007 Recommendations of the International Commission on Radiological Protection, Publication 103. Finally, it estimates the collective dose to the population.

Dose conversion coefficients for CT examinations of adults with automatic tube current modulation

Automatic tube current modulation (TCM) is used in modern CT devices. This is implemented in the numerical calculation of dose conversion coefficients for CT examinations. For four models of adults, the female and male reference models of ICRP and ICRU and a lighter and a heavier female model, dose conversion coefficients normalized to CTDI(vol) (DCC(CT)) have been computed with a Monte Carlo transport code for CT scans with and without TCM. It could be shown for both cases that reliable values for spiral CT scans are obtained when combining the results from an appropriate set of axial scans. The largest organ DCC(CT) are presented for typical CT examinations for all four models. The impact of TCM is greatest for chest, pelvis and whole-trunk CT examinations, where with TCM the effective DCC(CT) can be 20-25% lower than without TCM. Typical organs with strong dependence on TCM are thyroid, urinary bladder, lungs and oesophagus. While the DCC(CT) of thyroid and urinary bladder are mainly sensitive to angular TCM, the DCC(CT) of lungs and oesophagus are influenced primarily by longitudinal TCM. The impact of the body stature on the effective DCC(CT) is of the same order as the effect of TCM. Thus, for CT scans in the trunk region, accurate dose values can only be obtained when different sets of DCC(CT) are employed that are appropriate for the patient's sex and stature and the actual TCM settings.

A study in Europe of patient dosimetry in diagnostic radiology: protocol development and findings

In a multi-centre study more than 600 patient measurements of patients receiving thorax radiography were performed in five European cities. Participating centres were Fulda, Liverpool, Nicosia, Passau and Sofia. The dose quantities measured were the air kerma-area product (AKAP), incident air kerma and entrance surface air kerma (ESAK). In addition, for each patient sex, age, weight, height, focus-to-film distance, focus-to-skin distance, patient thickness, kV, mAs, field size and the nominal film speed were registered. Different X-ray machines were used in the participating centres--Thoravision, flat panel detector and film screen combinations in two centres (analogue system). The tube voltages employed varied between 60 and 150 kV and the nominal film speed between 200 and 400/800. All mean dose values (ESAK and AKAP) for the different centres showed a different value for female and male populations. The differences were up to 100 % and always higher for the mean AKAP. For a thorax posteroanterior examination, the mean ESAK varied between 0.06 and 0.46 mGy and the mean AKAP varied between 60 and 690 mGy cm(2). The differences in the results obtained as well as the methodologies for multi-national, multi-centre studies will be discussed. Future perspectives for this type of study within the framework of radiation protection and quality assurance in Europe will also be discussed as well as the role and function of multi-national radiological data sets including patient dose values.

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.

What physicians think about the need for informed consent for communicating the risk of cancer from low-dose radiation

BACKGROUND

The National Institute of Environmental Health Sciences, a subsidiary of the Food and Drug Administration, has declared that X-ray radiation at low doses is a human carcinogen.

OBJECTIVE

The purpose of our study was to determine if informed consent should be obtained for communicating the risk of radiation-induced cancer from radiation-based imaging.

MATERIALS AND METHODS

Institutional review board approval was obtained for the prospective survey of 456 physicians affiliated with three tertiary hospitals by means of a written questionnaire. Physicians were asked to state their subspecialty, number of years in practice, frequency of referral for CT scanning, level of awareness about the risk of radiation-induced cancer associated with CT, knowledge of whether such information is provided to patients undergoing CT, and opinions about the need for obtaining informed consent as well as who should provide information about the radiation-induced cancer risk to patients. Physicians were also asked to specify their preference among different formats of informed consent for communicating the potential risk of radiation-induced cancer. Statistical analyses were performed using the chi-squared test.

RESULTS

Most physicians stated that informed consent should be obtained from patients undergoing radiation-based imaging (71.3%, 325/456) and the radiology department should provide information about the risk of radiation-induced cancer to these patients (54.6%, 249/456). The informed consent format that most physicians agreed with included modifications to the National Institute of Environmental Health Services report on cancer risk from low-dose radiation (20.2%, 92/456) or included information on the risk of cancer from background radiation compared to that from low-dose radiation (39.5%, 180/456).

CONCLUSION

Most physicians do not know if patients are informed about cancer risk from radiation-based imaging in their institutions. However, they believe that informed consent for communicating the risk of radiation-induced cancer should be obtained from patients undergoing radiation-based imaging.

A cohort study of childhood cancer incidence after postnatal diagnostic X-ray exposure

Ionizing radiation is an established cause of cancer, yet little is known about the health effects of doses from diagnostic examinations in children. The risk of childhood cancer was studied in a cohort of 92.957 children who had been examined with diagnostic X rays in a large German hospital during 1976-2003. Radiation doses were reconstructed using the individual dose area product and other exposure parameters, together with conversion coefficients developed specifically for the medical devices and standards used at the radiology department. Newly diagnosed cancers occurring between 1980 and 2006 were determined through record linkage to the German Childhood Cancer Registry. The median radiation dose was 7 microSv. Eight-seven incident cases were found in the cohort: 33 leukemia, 13 lymphoma, 10 central nervous system tumors, and 31 other tumors. The standardized incidence ratio (SIR) for all cancers was 0.99 (95% CI: 0.79-1.22). No trend in the incidence of total cancer, leukemia or solid tumors with increasing radiation dose was observed in the SIR analysis or in the multivariate Poisson regression. Risk did not differ significantly in girls and boys. Overall, while no increase in cancer risk with diagnostic radiation was observed, the results are compatible with a broad range of risk estimates.

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.

Effective doses in radiology and diagnostic nuclear medicine: a catalog

Medical uses of radiation have grown very rapidly over the past decade, and, as of 2007, medical uses represent the largest source of exposure to the U.S. population. Most physicians have difficulty assessing the magnitude of exposure or potential risk. Effective dose provides an approximate indicator of potential detriment from ionizing radiation and should be used as one parameter in evaluating the appropriateness of examinations involving ionizing radiation. The purpose of this review is to provide a compilation of effective doses for radiologic and nuclear medicine procedures. Standard radiographic examinations have average effective doses that vary by over a factor of 1000 (0.01-10 mSv). Computed tomographic examinations tend to be in a more narrow range but have relatively high average effective doses (approximately 2-20 mSv), and average effective doses for interventional procedures usually range from 5-70 mSv. Average effective dose for most nuclear medicine procedures varies between 0.3 and 20 mSv. These doses can be compared with the average annual effective dose from background radiation of about 3 mSv.