A MODEL FOR EVALUATING THE USE OF IMAGING IN IMAGE-GUIDED INTERVENTIONAL PROCEDURES-POSSIBLE IMPLICATIONS ON OPTIMISATION OF RADIATION PROTECTION.

The present study focuses on introducing the concept of optimisation and proposing a model, including evaluation of image quality, to be used in the clinical routines where image-guided intervention is being performed. The overall aim of the study was to develop a model for evaluating the use of imaging in X-ray-guided interventional procedures and its possible implications on optimisation of radiation protection. In the search for an adequate evaluation model, data from endovascular interventions of the aorta (EVAR procedures) were used. The procedure was schematically described in steps. Every imaging event was connected to the steps in the medical procedure and was also described with the purpose of the imaging event. Available technical, as well as procedural parameters, were studied and analysed. Data were collected from the X-ray equipment for 70 EVAR procedures and, out of these, 12 procedures were randomly selected to be recorded on video to understand the procedure better. It was possible to describe the EVAR procedures in a general way with explanations of the clinical purpose connected to each imaging event. Possible quality parameters of the procedure were identified for the imaging events (radiation dose, image quality). The model method still needs to be refined and will then be applied to clinical data and to other clinical procedures to test the validity.

Challenges assessing radiation risk in image-guided treatments-implications on optimisation of radiological protection.

The present work explores challenges when assessing organ dose and effective dose concerning image-guided treatments. During these treatments considerable x-ray imaging is employed using technically advanced angiographic x-ray equipment. Thus, the radiation dose to organs and the related radiation risk are relatively difficult to assess. This has implications on the optimisation process, in which assessing radiation dose is one important part. In this study, endovascular aortic repair treatments were investigated. Organ dose and effective dose were assessed using Monte Carlo calculations together with a detailed specification of the exposure situation and patient size. The resulting normalised organ dose and effective dose with respect to kerma-area product for patient sizes and radiation qualities representative for the patient group were evaluated. The variability and uncertainty were investigated and their possible impact on optimisation of radiation protection was discussed. Exposure parameters, source to detector distances etc varied between treatments and also varied between image acquisitions during one treatment. Thus the derived normalised organ dose and effective dose exhibited a large range of values depending greatly on used exposure parameters and patient configuration. The derived normalised values for effective dose varied approximately between 0.05 and 0.30 mSv per Gy·cm2 when taking patient sizes and exposure parameters into consideration, the values for organ doses exhibited even larger variation. The study shows a possible systematic error for derived organ doses and effective dose up to a factor of 7 if detailed exposure or patient characteristics are not known and/or not taken into consideration. The intra-treatment variability was also substantial and the normalised dose values varied up to a factor of 2 between image acquisitions during one treatment. The study shows that the use of conversion factors that are not adapted to the clinic can cause the radiation dose to be exaggerated or underestimated considerably. A conclusion from the present study is that the systematic error could be large and should be estimated together with random errors. A large uncertainty makes it difficult to detect true differences in radiation dose between methods and technology-a prerequisite for optimising radiation protection for image-guided treatments.

Eye dosimetry and protective eyewear for interventional clinicians.

Doses to the eyes of interventional clinicians can exceed 20 mSv. Various protective devices can afford protection to the eyes with the final barrier being protective eyewear. The protection provided by lead glasses is difficult to quantify, and the majority of dosimeters are not designed to be worn under lead glasses. This study has measured dose reduction factors (DRFs) equal to the ratio of the dose with no protection, divided by that when lead glasses are worn. Glasses have been tested in X-ray fields using anthropomorphic phantoms to simulate the patient and clinician. DRFs for X-rays incident from the front vary from 5.2 to 7.6, while values for orientations reminiscent of clinical practice are between 1.4 and 5.2. Results suggest that a DRF of two is a conservative factor that could be applied to personal dosimeter measurements to account for the dose reduction provided by most types of lead glasses.

A management system integrating radiation protection and safety supporting safety culture in the hospital.

Quality assurance has been identified as an important part of radiation protection and safety for a considerable time period. A rational expansion and improvement of quality assurance is to integrate radiation protection and safety in a management system. The aim of this study was to explore factors influencing the implementing strategy when introducing a management system including radiation protection and safety in hospitals and to outline benefits of such a system. The main experience from developing a management system is that it is possible to create a vast number of common policies and routines for the whole hospital, resulting in a cost-efficient system. One of the key benefits is the involvement of management at all levels, including the hospital director. Furthermore, a transparent system will involve staff throughout the organisation as well. A management system supports a common view on what should be done, who should do it and how the activities are reviewed. An integrated management system for radiation protection and safety includes key elements supporting a safety culture.

Optimisation of occupational radiological protection in image-guided interventions: potential impact of dose rate measurements.

The optimisation of occupational radiological protection is challenging and a variety of factors have to be considered. Physicians performing image-guided interventions are working in an environment with one of the highest radiation risk levels in healthcare. Appropriate knowledge about the radiation environment is a prerequisite for conducting the optimisation process. Information about the dose rate variation during the interventions could provide valuable input to this process. The overall purpose of this study was to explore the prerequisite and feasibility to measure dose rate in scattered radiation and to assess the usefulness of such data in the optimisation process.Using an active dosimeter system, the dose rate in the unshielded scattered radiation field was measured in a fixed point close to the patient undergoing an image-guided intervention. The measurements were performed with a time resolution of one second and the dose rate data was continuously timed in a data log. In two treatment rooms, data was collected during a 6 month time period, resulting in data from 380 image-guided interventions and vascular treatments in the abdomen, arms and legs. These procedures were categorised into eight types according to the purpose of the treatment and the anatomical region involved.The dose rate varied substantially between treatment types, both regarding the levels and the distribution during the procedure. The maximum dose rate for different types of interventions varied typically between 5 and 100 mSv h(-1), but substantially higher and lower dose rates were also registered. The average dose rate during a complete procedure was however substantially lower and varied typically between 0.05 and 1 mSv h(-1). An analysis of the distribution disclosed that for a large part of the treatment types, the major amount of the total accumulated dose for a procedure was delivered in less than 10% of the exposure time and in less than 1% of the total procedure time.The present study shows that systematic dose rate measurements are feasible. Such measurements can be used to give a general indication of the exposure level to the staff and could serve as a first risk assessment tool when introducing new treatment types or x-ray equipment in the clinic. For example, it could provide an indication for when detailed eye dose measurements are needed. It also gives input to risk management considerations and the development of efficient routines for other radiological protection measures.

Evaluation of the impact of a system for real-time visualisation of occupational radiation dose rate during fluoroscopically guided procedures.

Optimisation of radiological protection for operators working with fluoroscopically guided procedures has to be performed during the procedure, under varying and difficult conditions. The aim of the present study was to evaluate the impact of a system for real-time visualisation of radiation dose rate on optimisation of occupational radiological protection in fluoroscopically guided procedures. Individual radiation dose measurements, using a system for real-time visualisation, were performed in a cardiology laboratory for three cardiologists and ten assisting nurses. Radiation doses collected when the radiation dose rates were not displayed to the staff were compared to radiation doses collected when the radiation dose rates were displayed. When the radiation dose rates were displayed to the staff, one cardiologist and the assisting nurses (as a group) significantly reduced their personal radiation doses. The median radiation dose (Hp(10)) per procedure decreased from 68 to 28 µSv (p = 0.003) for this cardiologist and from 4.3 to 2.5 µSv (p = 0.001) for the assisting nurses. The results of the present study indicate that a system for real-time visualisation of radiation dose rate may have a positive impact on optimisation of occupational radiological protection. In particular, this may affect the behaviour of staff members practising inadequate personal radiological protection.

The prevalence of violence investigated in a pregnant population in Sweden.

All women registered for antenatal care within a Swedish municipality during a 6-month period were assessed regarding acts of violence. The Abuse Assessment Screen was used on two occasions during pregnancy, and once between 4 and 20 weeks after delivery. The efficacy of repeated interviews was investigated, and characteristics of abused and non-abused women were compared. The participation rate was 93% (1038 women). Physical abuse by a close acquaintance or relative during or shortly after pregnancy was reported by 1.3%, and by 2.8% when the year preceding pregnancy was included. The lifetime prevalence of emotional, physical or sexual abuse was 19.4%. Repeated questioning increased the detection of abuse. Women abused during pregnancy reported more preceding ill-health and more elective abortions than non-abused women. Intervention against sexual violence has been on the political agenda in Sweden for several decades. Even so, physical abuse is a risk factor comparable in frequency to obstetric complications such as gestational diabetes and pre-eclampsia. Routines need to be established to make questioning about violence an integral part of the standardized screening for risk factors during pregnancy.

[Infant and child mortality in the Nordic countries before 1900]. / La mortalité infantile et post-infantile dans les pays nordiques avant 1900.

The mortality decline in the Nordic countries started at the end of the 18th century with a decrease in infant and child mortality. It was not until the middle of the 19th century that adult mortality started to fall. Recent research shows that improvements in nutrient supply, medical care, sanitation and nursing, did not take place until the beginning of the 19th century, i.e. considerably later than the start of the decline in infant and child mortality. One possible explanation to the initial decline is that a change in virulence of pathogens did occur at the end of the 18th century, i.e. that the decline was caused by factors beyond human control. There is a general agreement that the decline that followed during the 19th century had multli-factoral causes. The importance of different factors is, however, still debated. To proceed with this debate there is an obvious need to construct more data series of age-specific mortality at the macro level and to make full use of family reconstitution data. The use of advanced statistical methods, such as life event analysis, will also be of crucial importance. Equally important is the quality of the data. Since the Nordic data are said to be very good, which they generally are, too little attention has been paid to the examination of its quality. One such problem is the under-reporting of infant deaths in the church books. It is vital to research on infant and child mortality, as well as on fertility, that those periods and parishes with good data are identified.

Reliability of radiographic pelvimetry. A methodological study.

The purpose of this study was to assess the reliability of radiographic pelvimetry. 48 radiologists were asked to estimate the pelvic inlet and outlet diameters from copies of 20 pelvimetry radiographs. We found that every third patient will have the sum of her pelvic outlet over- or underestimated by at least 4 mm, and 3% by more than 10 mm. The random measurement error of the sum of the pelvic outlet is about four times greater than the systematic error. The random error of the sagittal outlet diameter contributes to almost half of the total measurement error of the pelvic outlet sum. The measurement values of radiographic pelvimetry are often expressed in mm, which may give an impression of exactness that is obviously not well founded. Only in a few cases where the measurements suggest a severe feto-pelvic disproportion is it justified to do an elective cesarean section on the basis of radiographic pelvimetry only.

Radiographic pelvimetry--its use and possible radiation risk.

Radiographic pelvimetry is widely used in obstetrics. Every fourth primapara in Sweden is submitted to this radiographic examination. The frequency of the examination in the United States is estimated to a mean of 6% of all deliveries. The use of radiographic pelvimetry is now under intense debate and the missing argument in this discussion is a prospective study of an unselected group of parturients where progress and outcome of labour is referred to known pelvic dimension. Since the value of the method is questioned the frequent use of radiographic pelvimetry is justified only by an almost negligible radiation risk to the mother and her baby. Such a low risk is also an indispensable condition to allow the correct scientific evaluation of radiographic pelvimetry mentioned above. This paper presents the measurement results of absorbed radiation dose with the only radiographic pelvimetry method used in Sweden. The estimated radiation risk of the method, based on these figures, is 1 case of childhood malignancy in 50 000 pelvimetries. This corresponds to 4 years routine use of radiographic pelvimetry in Sweden. The annual incidence of childhood malignancy in Sweden is 220. The maternal risk is estimated to one tenth of the fetal risk.

Vaginal cleansing at vacuum aspiration abortion does not reduce the risk of postoperative infection.

Does a thorough vaginal cleansing with bactericidal solutions prior to induced first-trimester vacuum aspiration abortion reduce the frequency of postabortal pelvic inflammatory disease (PID)? To answer this question we compared the frequency of PID in 372 women where a thorough preoperative vaginal cleansing with a bactericidal solution was undertaken at abortion with that in 350 women where the upper part of the vagina was swabbed with a pad moistened with a 0.9% saline solution. A postoperative PID was recorded in 25 (6.7%) of the former women and in 23 (6.6%) of the latter women.