Well-nourished cystic fibrosis patients have normal mineral density, but reduced cortical thickness at the forearm.

UNLABELLED: Our goal was to assess mineral density and geometry of the cortex at the level of the forearm in adolescents and young adults with cystic fibrosis, using peripheral quantitative computed tomography. We found that density was normal, but cortical thickness significantly reduced, as well in males as in females. INTRODUCTION: Our goal was to measure bone mineral density as a volumetric density, as well as total cross-sectional area, cortical area and cortical thickness, using peripheral quantitative computed tomography (pQCT) at the forearm in adolescents and young adults with cystic fibrosis. We evaluated relationships between forearm bone measurements and body composition assessed using dual energy X-ray absorptiometry (DXA). METHODS: An XCT 2000 pQCT (Stratec, Pforzheim, Germany) and a QDR 4500 A-upgraded to Discovery DXA device (Hologic, Waltham, MA, USA) were used. RESULTS: Forty-eight patients (31 males,17 females, mean+/-SD 20+/5 years) were studied. Anthropometric features were: height 169+/- 10 cm, SDS 0.05+/-0.12, body mass index 19.8+/- 2.5 kg/m(2), SDS -0.56+/-0.14. Bone mineral density and total cross-sectional area of the forearm and body composition were normal, whereas cortical thickness was significantly reduced in males (mean Z-score - 1.22, p < 0.05), and in females (mean Z-score - 1.61, p < 0.05). Total body lean mass correlated more strongly with cortical thickness (r = 0.72, p < 0.001) than with total bone mineral density at the proximal radius (r = 0.39, p < 0.05). CONCLUSIONS: Adolescents and young adults with cystic fibrosis, presenting with only a slight degree of underweight, have at the radius a preserved bone mineral density but a reduced cortical thickness.

Comparison of double dosimetry algorithms for estimating the effective dose in occupational dosimetry of interventional radiology staff.

'Double dosimetry' i.e. measurement with two dosemeters, one located above the protective apron and one under has been recommended in interventional radiology (IR) to determine the effective dose to staff. Several algorithms have been developed to calculate the effective dose from the readings of the two dosemeters, but there is no international consensus on what is the best algorithm. In this work, a few of the most recently developed algorithms have been tested in typical IR conditions. The effective dose and personnel dosemeter readings were obtained experimentally by using thermoluminescent dosemeters in and on a Rando-Alderson phantom provided with a lead apron. In addition, the effective dose and personnel dosemeter readings were calculated by the Monte Carlo method for the same irradiation geometry. The results suggest that most of the algorithms overestimate effective dose in the selected IR conditions, but there is also a risk of underestimation by using the least conservative algorithms. Two of the algorithms seem to comply best with the chosen criteria of performance, i.e. no underestimation, minimum overestimation and close estimation of effective dose in typical IR conditions. However, it might not be justified to generalise the results. It is recommended that whenever personnel doses approach or exceed the dose limit, IR conditions should be further investigated and the possibility of over- or under-estimation of effective dose by the algorithm used should be considered.

Overview of double dosimetry procedures for the determination of the effective dose to the interventional radiology staff.

In interventional radiology, for an accurate determination of effective dose to the staff, measurements with two dosemeters have been recommended, one located above and one under the protective apron. Such 'double dosimetry' practices and the algorithms used for the determination of effective dose were reviewed in this study by circulating a questionnaire and by an extensive literature search. The results indicated that regulations for double dosimetry almost do not exist and there is no firm consensus on the most suitable calculation algorithms. The calculation of effective dose is mainly based on the single dosemeter measurements, in which either personal dose equivalent, directly, (dosemeter below the apron) or a fraction of personal dose equivalent (dosemeter above the apron) is taken as an assessment of effective dose. The most recent studies suggest that there might not be just one double dosimetry algorithm that would be optimum for all interventional radiology procedures. Further investigations in several critical configurations of interventional radiology procedures are needed to assess the suitability of the proposed algorithms.

A study of the correlation between dose area product and effective dose in vascular radiology.

The purpose of the multi-centre study was to assess dose area product (DAP) and effective dose of patients undergoing angiography of the lower limbs in Belgium and to investigate the correlation between DAP and effective dose. DAP values were measured in 12 centres and compared with the national diagnostic reference levels (DRLs). The effective dose (E) was estimated by multiplying the DAP with case-specific conversion coefficients (CCs) that were calculated with Monte Carlo software MCNP5. As a model for the patient, a mathematical hermaphrodite phantom was used. Calculations showed that tube configurations and extra Cu filtration have a large influence on these CCs. Due to the use of Cu filtration, effective dose can be twice as high for comparable DAP values. Also the use of an over-couch tube configuration is a disadvantage when compared with the under-couch tube configuration. For centres working under-couch without the use of extra Cu-filtration, the DAP values correlate very well with effective dose (Spearman's rank correlation rho ; = 0.97). For these conditions, general CCs between DAP and E were calculated. They were 0.083 mSv Gy(-1) cm(-2) (ICRP 60) and 0.065 mSv Gy(-1) cm(-2) (ICRP 103).

Diagnostic reference levels in angiography and interventional radiology: a Belgian multi-centre study.

The purpose of this study was to determine diagnostic reference levels (DRLs) for common angiographic and interventional procedures in Belgium. Dose Area Product (DAP) measurements were performed on 21 systems, (13 angiography and 4 vascular surgery centres). Type of procedure, total DAP, patient weight and height were collected on a daily basis during 1 y. The 75th percentile of the distribution of DAP values was defined as DRL. Preliminary DRLs were calculated for the three most frequent procedures for the whole population, for a weight class of patients (65-80 kg) and normalised to the standard size patient. Among them, the DRL for angiography of the lower limbs (30% of the procedures) from the whole population was 74.6 and 63.2 Gycm2 for the size corrected. The mean DAP values of each room was then compared to these DRLs.

Personal dose monitoring in hospitals: global assessment, critical applications and future needs.

It is known that medical applications using ionising radiation are wide spread and still increasing. Physicians, technicians, nurses and others constitute the largest group of workers occupationally exposed to man-made sources of radiation. Many hospital workers are consequently subjected to routine monitoring of professional radiation exposures. in the university hospital, UZ Brussel, 600 out of 4000 staff members are daily monitored for external radiation exposures. The most obvious applications of ionising radiation are diagnostic radiology, diagnostic or therapeutic use of radionuclides in nuclear medicine and external radiation therapy or brachytherapy in radiotherapy departments. Other important applications also include various procedures in interventional radiology (IR), in vitro biomedical research and radiopharmaceutical production around cyclotrons. Besides the fact that many of the staff members, involved in these applications, are not measurably exposed, detailed studies were carried out at workplaces where routine dose monitoring encounters difficulties and for some applications where relatively high occupational exposures can be found. most of the studies are concentrated around nuclear medicine applications and IR. They contain assessments of both effective dose and doses at different parts of the body. The results contribute to better characterisation of the different workplaces in a way that critical applications can be identified. Moreover, conclusions point out future needs for practical routine dose monitoring and optimisation of radiation protection.

Typetesting of physical characteristics of digital mammography systems: first experiences within the Flemish breast cancer screening programme.

To avoid the purchase of a digital mammography system by radiologists with intrinsic characteristics not able to fulfil the physical-technical quality requirements of the acceptance tests of the European guidance document, typetesting of digital equipment was introduced in the organisation and legislation of the Flemish breast cancer screening programme. Typetesting is performed for two types of instrumentation: systems for image capture and -processing and systems for image presentation. Typetesting is finalised or ongoing for eight DR systems and four CR systems. Eight workstations were or are submitted to the typetesting for image presentation. Experiences gained in typetesting of systems for image capture and -processing up to now show that the contrast-detail analysis of CDMAM phantom imaging and the homogeneity tests are most stringent. In general DR performs better than CR in imaging performance. Typetesting for image presentation has shown no difference in quality between CRT and LCD monitors. Furthermore, 3 MP monitors also pass the tests. However, to get the full resolution capabilities of the image capture system zooming in and scrolling over the image is necessary, which is time-consuming in clinical practice. Finally, we emphasize that typetesting involves also an evaluation of a set of clinical images by the working party of radiologists and that succeeding in typetesting does not mean that a particular system passes automatically the acceptance testing. A perfect tuning of the system and the coupling to a high quality X-ray system is necessary as well.