Medical Diagnostic Examinations Research Articles

Effective doses and risks from medical diagnostic x-ray examinations for male and female patients from childhood to old age

The consideration of risks from medical diagnostic x-ray examinations and their justification commonly relies on estimates of effective dose, although the quantity is actually a health-detriment-weighted summation of organ/tissue-absorbed doses rather than a measure of risk. In its 2007 Recommendations, the International Commission on Radiological Protection (ICRP) defines effective dose in relation to a nominal value of stochastic detriment following low-level exposure of 5.7 × 10−2 Sv−1, as an average over both sexes, all ages, and two fixed composite populations (Asian and Euro-American). Effective dose represents the overall (whole-body) dose received by a person from a particular exposure, which can be used for the purposes of radiological protection as set out by ICRP, but it does not provide a measure that is specific to the characteristics of the exposed individual. However, the cancer incidence risk models used by ICRP can be used to provide estimates of risk separately for males and females, as a function of age-at-exposure, and for the two composite populations. Here, these organ/tissue-specific risk models are applied to estimates of organ/tissue-specific absorbed doses from a range of diagnostic procedures to derive lifetime excess cancer incidence risk estimates; the degree of heterogeneity in the distribution of absorbed doses between organs/tissues will depend on the procedure. Depending on the organs/tissues exposed, risks are generally higher in females and notably higher for younger ages-at-exposure. Comparing lifetime cancer incidence risks per Sv effective dose from the different procedures shows that overall risks are higher by about a factor of two to three for the youngest age-at-exposure group, 0–9 yr, than for 30–39 yr adults, and lower by a similar factor for an age-at-exposure of 60–69 yr. Taking into account these differences in risk per Sv, and noting the substantial uncertainties associated with risk estimates, effective dose as currently formulated provides a reasonable basis for assessing the potential risks from medical diagnostic examinations.

The risk of cancer attributable to diagnostic medical radiation: Estimation for France in 2015

Introduction Although diagnostic medical ionizing radiation (IR) has clear clinical benefits, it is also an established carcinogen. Although the individual IR dose usually delivered from medical diagnostic procedures is small, the number of people undergoing these procedures is large. In France exposure to diagnostic medical IR represented 35% of the French total non-therapeutic IR exposure, being one of the highest exposures to diagnostic medical IR in Europe. This study quantifies the number of new cancer cases in France in 2015 attributable to lifetime IR exposure from medical imaging procedures. Methods The cancer incidence attributable to medical diagnostic IR was estimated using cumulative exposure, risk of cancer for a given dose, and cancer incidence by site. We used national frequencies of medical diagnostic examinations by sex and age reported in 2007 to estimate the lifetime cumulative organ dose exposure adjusted for changes in use of diagnostic procedures over time. The Biological Effects of Ionizing Radiation (BEIR) VII risk models were used to estimate the excess cancer risk due to IR; alongside we used cancer incidence data from the French Cancer Registries Network, FRANCIM. A minimum latency period of 10 years was assumed. Exposures from both external (X-rays, CT scans and interventional radiology) and internal sources (nuclear medicine) were considered. Results Of the 346,000 estimated new cancer cases in adults in France in 2015, 2100 cases (800 among men and 1300 among women) were attributable to diagnostic IR from external sources, representing 0.6% of all new cancer cases (0.4% for men and 0.8% for women). Furthermore, 220 new cancer cases, representing 0.1% of all cases, were attributable to diagnostic IR from internal sources. Overall, the leading cancers attributable to diagnostic medical IR in France were female breast (n = 560 cases), lung cancers (n = 500), colon (n = 290) and bladder (n = 250) cancers. In the sensitivity analyses, we found that the largest differences with the main model were observed when changing the dose-rate effectiveness. Assuming an over- or under-estimation of the dose by 30% also modified the attributable fraction. Using the UNSCEAR model instead of the BEIR VII model increased attributable fraction for all nine considered cancer sites. Conclusion The contribution of diagnostic medical IR to the cancer burden in France is small compared to other risk factors, and the benefits largely outweigh its harms quantified here. However, some of these IR-associated cancer cases may be preventable through dose optimization and more enhanced justification thorough diagnostic examination.

Investigation of radiation protection of medical staff performing medical diagnostic examinations by using PET/CT technique

Positron emission tomography (PET) is now one of the most important methods in the diagnosis of cancer diseases. Due to the rapid growth of PET/CT centres in Poland in less than a decade, radiation protection and, consequently, the assessment of worker exposure to ionising radiation, emitted mainly by the isotope 18F, have become essential issues. The main aim of the study was to analyse the doses received by workers employed in the Medical Diagnostic Centre. The analysis comprises a physicist, three nurses, three physicians, three technicians, as well as two administrative staff employees. High-sensitivity thermoluminescent detectors (TLDs) were used to measure the doses for medical staff. The personnel was classified into categories, among them employees having direct contact with the ‘source of radiation’—18FDG. The TLDs were placed on the fingertips of both hands and they were also attached at the level of eye lenses, thyroid and gonads depending on the assigned category. The highest dose of radiation was observed during the administration of the 18FDG to the patients. In the case of the physicist, the highest dose was recorded during preparation of the radiopharmaceutical—18FDG. The body parts most exposed to ionizing radiation are the fingertips of the thumb, index and middle finger.

Causal illness attributions in somatoform disorders: Associations with comorbidity and illness behavior

Objective To compare causal illness beliefs between patients with unexplained physical symptoms and different comorbid disorders and to assess the association of causal illness beliefs with illness behavior. Methods We examined a sample of 233 patients attending treatment in primary care. Inclusion criteria were “unexplained physical symptoms.” All patients were investigated using structured interviews and self-rating scales [Screening for Somatoform Symptoms (SOMS), Beck Depression Inventory (BDI), Beck Anxiety Inventory, and a 12-item instrument to assess causal attributions]. By means of factor analysis, the following illness attributions were considered: vulnerability to infection and environmental factors, psychological factors, organic causes including genetic and aging factors, and distress (including exhaustion and time pressure). Results Most patients reported multiple illness attributions. The more somatoform symptoms patients had, the more explanations in general they considered. Especially for vulnerability and organic illness beliefs, patients with somatoform symptoms had increased scores. Comorbidity with depression and with anxiety disorders was associated with more psychological attributions. Even when the influence of somatization, depression, and anxiety is controlled for, illness beliefs still showed associations with illness behavior. Organic causal beliefs and vulnerability attributions were associated with a need for medical diagnostic examinations, increased expression of symptoms, increased illness consequences, and bodily scanning. Conclusions Multiple causal attributions can coexist demonstrating different associations with comorbid depression and illness behavior.

Causal illness attributions in somatoform disordersAssociations with comorbidity and illness behavior

To compare causal illness beliefs between patients with unexplained physical symptoms and different comorbid disorders and to assess the association of causal illness beliefs with illness behavior. We examined a sample of 233 patients attending treatment in primary care. Inclusion criteria were “unexplained physical symptoms.” All patients were investigated using structured interviews and self-rating scales [Screening for Somatoform Symptoms (SOMS), Beck Depression Inventory (BDI), Beck Anxiety Inventory, and a 12-item instrument to assess causal attributions]. By means of factor analysis, the following illness attributions were considered: vulnerability to infection and environmental factors, psychological factors, organic causes including genetic and aging factors, and distress (including exhaustion and time pressure). Most patients reported multiple illness attributions. The more somatoform symptoms patients had, the more explanations in general they considered. Especially for vulnerability and organic illness beliefs, patients with somatoform symptoms had increased scores. Comorbidity with depression and with anxiety disorders was associated with more psychological attributions. Even when the influence of somatization, depression, and anxiety is controlled for, illness beliefs still showed associations with illness behavior. Organic causal beliefs and vulnerability attributions were associated with a need for medical diagnostic examinations, increased expression of symptoms, increased illness consequences, and bodily scanning. Multiple causal attributions can coexist demonstrating different associations with comorbid depression and illness behavior.

Ultrasonic probe for medical diagnostic examinations

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Ultrasonic transducer assembly for medical diagnostic examinations

An ultrasonic transducer for medical diagnostic examinations which comprises a transducer element having one surface through ultrasonic waves are emitted, an acoustic impedance matcher, and a contact member brought to contact with an object being examined and formed on the one surface of the ultrasonic transducer element. The contact member includes at least a flat plate or an acoustic lens made of a-4-methylpentene-1-base polymer which has high mechanical strength. Transducer arrays and assemblies using such polymer as a member directly contacted with human body are also described.