Search

Slot-scanning technology is nowadays a valid solution for the follow-up of chronic musculoskeletal disorders on children and adolescent patients, but there is no commercial software designed for simulating this X-ray beam geometry. PC Program for X-ray Monte Carlo (PCXMC) is a widespread Monte Carlo software developed for dose computation in projection radiography. In this study, experimental measurements were performed to evaluate its applicability in examinations with a slit-beam device. Physical phantoms corresponding to an adult and a 5-y-old child with calibrated thermoluminescent dosemeters were used for experiments. Different simulation approaches were investigated. Differences between measured and calculated organ doses ranged from −95 to 67% and were statistically significant for almost all organs. For both patients, PCXMC underestimated the effective dose of about 25%. This study suggests that PCXMC is not suited for organ dose evaluation in examinations with slot-scanning devices. It is still a useful tool for effective dose estimation when a proper correction factor is applied. [ABSTRACT FROM AUTHOR]

Background: To investigate associations between patient characteristics, intraprocedural complexity factors, and radiation exposure to patients during endovascular abdominal aortic aneurysm repair (EVAR)., Methods: Elective standard EVAR procedures between January 2015 and December 2020 were retrospectively analyzed. Patient characteristics and intraprocedural data (i.e., type of device, endograft configuration, additional procedures, and contralateral gate cannulation time [CGCT]) were collected. Dose area product (DAP) and fluoroscopy time were considered as measurements of radiation exposure. Furthermore, effective dose (ED) and doses to internal organs were calculated using PCXMC 2.0 software. Descriptive statistics, univariable, and multivariable linear regression were applied to investigate predictors of increased radiation exposure., Results: The 99 patients were mostly male (90.9%) with a mean age of 74 ± 7 years. EVAR indications were most frequently abdominal aortic aneurysm (93.9%), penetrating aortic ulceration (2.0%), focal dissection (2.0%), or subacute rupture of infrarenal abdominal aortic aneurysm (2.0%). Median fluoroscopy time was 19.6 minutes (interquartile range [IQR], 14.1-29.4) and median DAP was 86,311 mGy cm 2 (IQR, 60,160-130,385). Median ED was 23.2 mSv (IQR, 17.0-34.8) for 93 patients (93.9%). DAP and ED were positively correlated with body mass index (BMI) and CGCT. Kidneys, small intestine, active bone marrow, colon, and stomach were the organs that received the highest equivalent doses during EVAR. Higher DAP and ED values were observed using the Excluder endograft, other bi- and tri-modular endografts, and EVAR with ≥2 additional procedures. Multivariable linear regression analysis revealed that BMI, ≥2 additional procedures during EVAR, and CGCT were independent positive predictors of DAP and ED levels after accounting for endograft type., Conclusions: Patient-related and procedure-related factors such as BMI, ≥2 additional procedures during EVAR, and CGCT resulted predictors of radiation exposure for patients undergoing EVAR, as quantified by higher DAP and ED levels. The main intraprocedural factor that increased radiation exposure was CGCT. These data can be of importance for better managing radiation exposure during EVAR., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Introduction: Antegrade sclerotherapy (Tauber) effectively treats varicocele. However, fluoroscopy exposes young males to ionizing radiation. We aimed to evaluate radiation exposure and surgical outcomes after the Tauber procedure., Materials and Methods: We retrospectively analysed data from 251 patients. Dose area product (DAP) and fluoroscopy time were recorded. The effective dose was calculated with the PCXMC software. Descriptive statistics and linear regression tested the association between clinical predictors and radiation exposure., Results: Median (IQR) age and body mass index (BMI) were 14 (13-16) years and 20.1 (17.9-21.6) kg/m². Five (2.1%) patients developed clinical recurrence and two (0.81%) developed complications. Median fluoroscopy time and DAP were 38.5 (27.7-54.0) s and 89.6 (62.5-143.9) cGy*cm 2 . The effective dose was 0.19 (0.14-0.31) mSv. Fluoroscopy time was higher in patients with collateral veins (41 (26-49) s vs. 36 (31-61) s, p = 0.02). The median amount of sclerosing agent (SA) used was 3 (3-4) ml. DAP was higher when SA > 3 mL was used (101.4 (65-183) cGy*cm 2 vs. 80.5 (59-119) cGy*cm 2 ; p < 0.01). At univariable linear regression, age, BMI, operative time and SA > 3 mL were associated with higher DAP (all p < 0.01). At multivariable linear regression, only BMI (beta 12.9, p < 0.001) and operative time (beta 1.9, p < 0.01) emerged as predictors of higher DAP, after accounting for age and SA > 3 mL., Conclusions: The Tauber procedure is safe and associated with low effective doses. Operative time and the patient's BMI independently predict a higher radiation dose.

Purpose: Placenta previa is a major cause of maternal morbidity and mortality, associated to a high risk of peripartum hemorrhage and hysterectomy. We aimed to verify if prophylactic intraoperative uterine artery embolization in patients with placenta previa and at least one additional risk of bleeding (major placenta previa), can reduce hemorrhage, need for blood transfusions, peripartum hysterectomy and maternal morbidity., Materials and Methods: We enrolled 76 patients with major placenta previa; a specific multidisciplinary protocol was designed for management, including ultrasound evaluation, hospitalization at 34 weeks, antenatal corticosteroids and scheduled cesarean section at 35-36 weeks. 44 patients (control group or CTR) were treated with elective cesarean section, 32 patients (embolized group or EMB) underwent selective catheterization of bilateral uterine arteries before cesarean section and subsequent uterine embolization. In both cases cesarean section was performed by a senior surgeon., Results: Significant differences were found in term of intraoperative blood loss (CTR: 1431 ml; EMB: 693 ml); despite an high percentage of CTR patients had a bleeding greater than 1000 ml (56%), the need for blood transfusion was not significantly different between the two groups. Time of surgery was higher in the EMB group, considering that embolization procedure required approximatively 30 min. Three patients from the CTR group needed hysterectomy and ICU admission, compared to none in the EMB group. Duration of hospitalization and neonatal outcome were similar. Uterine embolization was not related to any short or long-term complications; return to normal menses and preservation of fertility were confirmed at follow up., Conclusions: Our results are promising, although we believe that a major contribution is referable to the multidisciplinary approach rather than the procedure itself. Nevertheless, we demonstrated the feasibility and safety of preventive uterine embolization in patients with placenta previa; in order to establish its prophylactic role in the prevention of peripartum hemorrhage, randomized trial should be carried out, on a larger population.

Background: Women with aesthetic prostheses must be included in the target population of mammography screening programmes. Breast implants are radiopaque and partially obscure the breast tissue. This can be avoided with the use of the Eklund technique, which causes an increased radiation exposure. In this study, augmented women undergoing a dedicated protocol within a population-based screening programme were compared according to selected indicators with the standard screening population. Essential dosimetric parameters and their time trend were also assessed., Materials and Methods: The study was conducted in a screening centre in Milan in the years 2009-2016. The screening protocol for women with breast implants included a double-read mammography with the Eklund views, ultrasound and clinical breast examination., Results: A total of 28,794 women were enrolled, including 588 (2%) women with breast implants and 28,206 (98%) undergoing the standard screening protocol. The invasive assessment rate was 9.0‰ for women with breast implants vs. 15‰ in the standard cohort. The surgical referral rate was 2.2% vs. 0.9%. The detection rate was similar in the two groups (4.0 and 4.5‰, respectively). There were significant differences in the average glandular dose according to the mammography equipment. The use of the Eklund views increased over time., Conclusions: Screening of augmented women according to a specific protocol in the contexts of population-based programmes is feasible. Observed differences in screening indicators relative to the standard screening population require further research. The increasing use of Eklund views probably results from quality assurance measures associated with screening programmes.

Purpose: To compare outcomes of two different miniaturized percutaneous nephrolithotomy (PCNL) techniques: minimally invasive PCNL (MIP) with the vacuum cleaner effect and vacuum-assisted mini-PCNL (vmPCNL). Materials and Methods: Data from 104 (66.7%) patients who underwent vmPCNL and 52 (33.3%) patients who underwent MIP at a single tertiary referral academic center between January 2016 and December 2019 were analyzed. Patient demographics and peri- and postoperative data were recorded, and propensity score matching was performed. Descriptive statistics and linear regression models were used to identify variables associated with operative time (OT) and patient effective dose. Logistic regression analyses were used to identify factors associated with infectious complications and stone-free (SF) status. Results: Patient demographics and stone characteristics were comparable between groups. vmPCNL was associated with shorter OT ( p  < 0.001), fluoroscopy time, and patient effective dose (4.2 mSv vs 7.9 mSv; p  < 0.001). A higher rate of infectious complications was found in the MIP group (25.0% vs 7.7%, p  < 0.01). Linear regression analysis showed that stone volume, multiple stones, and MIP procedure (all p values ≤0.02) were associated with longer OT. Similarly, OT and the MIP procedure ( p  ≤ 0.02) were associated with higher patient effective dose. Logistic regression analysis revealed that the stone volume, positive preoperative bladder urine culture, and MIP procedure (all p values ≤0.02) were associated with postoperative infectious complications. vmPCNL was not associated with the SF rate. Conclusions: Mini-PCNL performed with continuous active suction is associated with lower rates of infectious complications, shorter OT, and lower patient effective dose than MIP.

Background: In the recent years, clinical progress and better medical assistance for pregnant women, together with the introduction of new complex technologies, has improved the survival of preterm infants. However, this result requires frequent radiological investigations mostly represented by thoracic and abdominal radiographs in incubators. This document was elaborated by an expert panel Italian inter-society working group (Radiologists, Paediatricians, Medical Physicists) with the aim to assist healthcare practitioners in taking choices involving radiation exposures of new-born infants and to provide practical recommendations about justification and optimization in Neonatal Intensive Care Units. The adherence to these practice recommendations could ensure a high quality and patient safety. More complex and less common radiological practice, such as CT scan or fluoroscopy have been excluded., Methods: The consensus was reached starting from current good practice evidence shared by four scientific societies panel: AIFM (Italian Association of Physics in Medicine), SIN (Italian Neonatology Society), SIP (Italian Paediatric Society), SIRM (Italian Medical Radiology Society) in order to guarantee good standard practices for every professional involved in Neonatal Intensive Care Units (NICU). The report is divided into clinical and physical-dosimetric sections: clinical Indications, good practice in radiological exposures, devices, exposure parameters and modalities, patient positioning and immobilization, Reference Diagnostic Levels, operators and patient's radiation protection. Another important topic was the evaluation of the different incubators in order to understand if the consequences of the technological evolution have had an impact on the increase of the dose to the small patients, and how to choose the best device in terms of radiation protection. At the end the working group faced the problem of setting up the correct communication between clinicians and parents following the most recent indications of the international paediatric societies., Results: Taking into account the experience and expertise of 10 Italian Centres, the guideline sets out the criteria to ensure a high standard of neonatal care in NICU about procedures, facilities, recommended equipment, quality assurance, radiation protection measures for children and staff members and communication on radiation risk., Conclusions: This document will allow a standardization of the approach to the exposures in NICU, although oriented to a flexible methodology.

Purpose: Interventional cardiology procedures, during which live images are acquired, involve exposure to x-rays. The use of fluoroscopy can cause high radiation doses to patients and operators because of the prolonged duration of x-ray emission. For this reason, special attention and constant vigilance represent challenges for commissions and groups of experts in the field. The purpose of this study is to establish local diagnostic reference levels (DRLs) for these procedures, to improve radiological practice, and to optimize radiation doses., Methods: This work was carried out in two university hospitals and two private medical facilities in Rabat, the capital of Morocco, during the period 2017-2018. The study concerns 657 interventional cardiology procedures (457 coronary angiography [CA] and 200 percutaneous transluminal coronary angioplasty [PTCA]), performed by 11 cardiologists on different installations in 5 catheterization rooms. The data collected for each procedure were patient age, height and weight, dosimeter indicators in terms of dose area product (P KA ), total air kerma at the reference point (K ar ), fluoroscopy time (FT), and the number of frames, together with the primary beam parameters as kV and total mAs. The proposed DRLs were set from the 75th percentile of the P KA and FT., Results: The mean of P KA for CA and PTCA procedures were 29.2 Gy∗cm 2 and 70.4 Gy∗cm 2 , respectively, the mean of fluoroscopy time were 4.0 min and 12.17 min for 334 and 685 frames, respectively. Results for the local DRLs were 37.3 and 87.1 Gy cm 2 for P KA and 4.48 and 16.15 min for FT, corresponding to CA and PTCA procedures., Conclusion: This work focuses on proposing local DRLs in Morocco for CA and PTCA procedures. The results show that the values found conform with those of international studies., (Copyright © 2020. Published by Elsevier Inc.)

Background: The impact of surgical experience on radiation exposure (RE) during endourological procedures has been poorly investigated., Objective: To assess the impact of surgical experience on fluoroscopy time (FT) and RE during retrograde intrarenal surgery (RIRS)., Design, Setting, and Participants: The study included 140 patients who underwent RIRS performed either by a senior surgeon (expertise of >100 RIRSs) (group A) or by two junior residents (expertise of <15 RIRSs) (group B) between January 2016 and May 2018., Outcome Measurements and Statistical Analysis: We tested the hypothesis that surgical experience had a limited impact on RE during RIRS. To adjust for potential baseline confounders, propensity-score matching was performed. Descriptive statistics and linear regression models tested the association between clinical variables and FT and patients' effective doses., Results and Limitations: There was no significant difference between the two groups for baseline, intraoperative, and postoperative characteristics. Overall FT (p=0.97) and effective dose (p=0.79) did not differ between groups. A statistically significant association was found between male sex (all p<0.03), stone burden (all p<0.001), operative time (all p<0.003), and postoperative double-J placement (all p<0.02) with both FT and effective dose. Linear multivariable analysis revealed that body mass index was significantly associated with effective dose (p=0.002). Similarly, longer operative time (all p<0.03) and double-J placement (all p<0.04) were significantly associated with increased FT and effective dose., Conclusions: Surgical experience has a limited impact on FT and RE during RIRS. Longer operative time and double-J placement were associated with increased FT and effective dose., Patient Summary: In this study, we assessed whether surgical experience affects fluoroscopy time and patient's effective dose during retrograde intrarenal surgery (RIRS). We found that radiation exposure (RE) was not affected by surgeon's experience and that the standardisation of the surgical technique at the beginning of the learning curve of young surgeons may represent the key factor in reducing RE during RIRS., (Copyright © 2018 European Association of Urology. Published by Elsevier B.V. All rights reserved.)

Background: To manage and analyse dosimetric data provided by computed tomography (CT) scanners from four Italian hospitals., Methods: A radiation dose index monitoring (RDIM) software was used to collect anonymised exams stored in a cloud server. Since hospitals use different names for the same procedure, digital imaging and communications in medicine (DICOM) tags more appropriate to describe exams were selected and associated to study common names (SCNs) from a radiology playbook according to scan region and use of contrast media. Retrospective analysis was carried out to describe population and to evaluate dosimetric indexes and inaccuracies associated with SCNs., Results: More than 400 procedures were clustered into 95 SCNs, but 78% of exams on adults were described with only 10 SCNs. Median values of dose-length product (DLP) and volumetric CT dose index (CTDI vol ) for three analysed SCNs were in agreement with those previously published. The percentage of inaccuracies does not heavily affect the dosimetric analysis on the whole cloud, since variations in median values reached at most 8%., Conclusions: Implementation of a cloud-based RDIM software and related issues were described, showing the strength of the chosen playbook-based clustering and its usefulness for homogeneous data analysis. This approach may allow for optimisation actions, accurate assessment of the risk associated with radiation exposure, comparison of different facilities, and, last but not least, collection of information for the implementation of the 2013/59 Euratom Directive.

Objective: We compared the image quality and radiation dose of flat-panel CT (FPCT) and multi-slice CT (MSCT) performed respectively with an angiographic unit and a 128-slice CT scanner. We investigated whether the higher spatial resolution of FPCT translated into higher image quality and we sought to eliminate inter-subject variability by scanning temporal bone specimens with both techniques., Materials and Methods: Fifteen temporal bone specimens were imaged with FPCT and MSCT. Two neuroradiologists experienced in otoradiology evaluated 30 anatomical structures with a 0-2 score; 18 structures important from a clinical perspective were assigned a twofold value in calculation of the overall score. The radiation dose was calculated through the use of an anthropomorphic phantom., Results: The image quality was significantly higher for FPCT than MSCT for 10 of the 30 anatomical structures; the overall score was also significantly higher for FPCT (p = 0.001). The equivalent dose of the two techniques was very similar, but with different effective doses to the organs., Conclusion: FPCT performed on an angiographic unit provides higher image quality in temporal bone assessment compared to MSCT performed on a 128-slice CT scanner thanks to its higher spatial resolution, with comparable equivalent doses but different effective doses to the organs., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Background: In a neonatal intensive care unit (NICU), preterm infants are often exposed to a large number of radiographic examinations, which could cause adjacent neonates, family caregivers and staff members to be exposed to a dose amount due to scatter radiation., Objective: To provide information on scatter radiation exposure levels in a NICU, to compare these values with the effective dose limits established by the European Union and to evaluate the effectiveness of radiation protection devices in this setting., Materials and Methods: Radiation exposure levels due to scatter radiation were estimated by passive detectors (thermoluminescent dosimeters) and direct dosimetric measurements (with a dose rate meter); in the latter case, an angular map of the scatter dose distribution was achieved., Results: The dose due to scatter radiation to staff in our setting is approximately 160 μSv/year, which is markedly lower than the effective dose limit for workers established by the European Union (20 mSv/year). The doses range between 0.012 and 0.095 μSv/radiograph. Considering a mean hospitalization period of 3 months and our NICU workload, the corresponding scatter radiation dose to an adjacent patient and/or his/her caregiver is at most 40 μSv., Conclusion: For distances greater than 1 m from the irradiation field, both scatter dose absorbed by a staff member during a year and that by an adjacent patient and/or his/her caregiver during hospitalization is less than 1 mSv, which is the exposure limit for public members in a year.

Purpose: To determine the frequency of unindicated CT phases and the resultant excess of absorbed radiation doses to the uterus and ovaries in women of reproductive age who have undergone CT for non-traumatic abdomino-pelvic emergencies., Materials and Methods: We reviewed all abdomino-pelvic CT examinations in women of reproductive age (40 years or less), between 1 June 2012 and 31 January 2015. We evaluated the appropriateness of each CT phase on the basis of clinical indications, according to ACR appropriateness criteria and evidence-based data from the literature. The doses to uterus and ovaries for each phase were calculated with the CTEXPO software, taking into consideration the size-specific dose estimate (SSDE) after measuring the size of every single patient., Results: The final cohort was composed of 76 female patients with an average age of 30 (from 19 to 40 years). In total, 197 CT phases were performed with an average of 2.6 phases per patient. Out of these, 93 (47%) were unindicated with an average of 1.2 inappropriate phases per patient. Unindicated scans were most frequent for appendicitis and unlocalized abdominal pain. The excesses of mean radiation doses to the uterus and ovaries due to unindicated phases were, respectively, of 38 and 33 mSv per patient., Conclusion: In our experience, unindicated additional CT phases were numerous with a significant excess radiation dose without an associated clinical benefit. This excess of radiation could have been avoided by widespread adoption of the ACR appropriateness criteria and evidence-based data from the literature.

Background and Purpose: Cross-sectional imaging of the temporal bone is challenging because of the complexity and small dimensions of the anatomic structures. We evaluated the role of flat panel angiography in the cross-sectional imaging of the temporal bone by comparing its image quality and radiation dose with a 64-section multisection CT scanner., Materials and Methods: We retrospectively collected 29 multisection CT and 29 flat panel angiography images of normal whole-head temporal bones. Image quality was assessed by 2 neuroradiologists, who rated the visualization of 30 anatomic structures with a 3-point ordinal scale. The radiation dose was assessed with an anthropomorphic phantom., Results: Flat panel angiography showed better image quality than multisection CT in depicting the anterior and posterior crura of the stapes, the footplate of the stapes, the stapedius muscle, and the anterior ligament of the malleus ( P < .05). In contrast, multisection CT showed better image quality than flat panel angiography in assessing the tympanic membrane, the bone marrow of the malleus and incus, the tendon of the tensor tympani, the interscalar septum, and the modiolus of the cochlea ( P < .05). Flat panel angiography had a significantly higher overall image quality rating than multisection CT ( P = .035). A reduction of the effective dose of approximately 40% was demonstrated for flat panel angiography compared with multisection CT., Conclusions: Flat panel angiography shows strengths and weaknesses compared with multisection CT. It is more susceptible to artifacts, but due to the higher spatial resolution, it shows equal or higher image quality in assessing some bony structures of diagnostic interest. The lower radiation dose is an additional advantage of flat panel angiography., (© 2017 by American Journal of Neuroradiology.)

Introduction: The differential diagnosis of malignancy in small foci of microcalcifications or in extremely small nodes can be difficult. We carried out a retrospective analysis of integrated mammographic and US results, correlated with histologic data, to assess the limitations of each method and to optimize and benign/malignant ratio., Materials and Methods: Our series consisted of 485 nonpalpable breast lesions submitted to histologic examination after vegetable charcoal marking. We gave each lesion an 0-5 score according to the degree of diagnostic doubt/suspicion after mammography and US, which results were correlated with histologic data to assess the carcinoma frequency in the various groups identified., Results: The analysis of mammographic and US images showed that the most frequent mammographic alteration in the lesions submitted to biopsy was an isolated cluster of microcalcifications (40.99%): of these, 36.86% were neoplastic. The nodules submitted to biopsy, which were 29.81% of the total, showed a cancer rate (36.80%) very similar to that of the microcalcifications. The carcinoma rate rose to 37.93% when the microcalcifications were associated with nodes. The highest carcinoma rates, i.e., 52.94% and 66.66%, respectively, were found in parenchymal distortions, either isolated or associated with microcalcifications, which however were only 7.03% and 3.10%, respectively, of the total number of cases., Discussion and Conclusions: Our study showed that: 1) a highly suspicious US result must be seriously considered when a negative mammography has poor intrinsic contrast; 2) a highly suspicious US image with a little suspicious good contrast mammography requires further confirmation before surgery is planned; 3) when the mammographic finding is mid-to-highly suspicious, further investigations are needed even if US is negative. To conclude, even though the histologic examination of nonpalpable breast lesions involves performing a biopsy, we believe this is acceptable when performed on an outpatient basis, under local anesthesia and removing a limited amount of tissue only. The benign/malignant ratio ranges 2 to 1.5: if it is further reduced (below 1.5), there will be the risk of missing some early neoplastic lesions.

The present paper reports an updated dosimetry of dental radiology since it presents the data relative to 7 radiological techniques. The doses to 9 organs were measured on a Randoman phantom using TLD (4 in each chosen cavity) for lenses, tongue, cervical vertebrae (C2), thyroid, ovaries, uterus and testes. The examinations were subsequently repeated after applying X-ray shields to the phantom. The main conclusions follow: a) local doses are never negligible but can be really high, especially for tongue (1.880 mGy), thyroid (1.011 mGy), and C2 (0.699 mGy); b) X-ray shields for lenses, ovaries, uterus and testes have proven to be unnecessary; in a more general context, X-ray shields should be evaluated by the Health Physics Dept., especially relative to radiation leaks from the X-ray tube. As for the thyroid, X-ray shields have proven very useful but can result in repeated acquisitions because of possible interference with the radiological image; c) technicians' risk, in the present experimental conditions, does not exceed the threshold values recommended by Italian laws. At any rate, the use of fixed or mobile shieldings should always be evaluated while keeping in mind the specific working conditions in radiology departments.

According to recent surveys made by the International Commission on Radiological Protection (ICRP) and the World Health Organization (WHO), it has been estimated that in temperate regions people spend only 20% of their time outdoors and spend the remaining 80% indoors (homes, schools, other buildings). It is therefore important to establish whether radiation sources exist inside buildings in order to assess risk for the population. The 238U and 232Th radioactive chains are of particular importance because of Radon and Radon daughter production and 40K as component of building materials. It has been estimated that about 4.5% of lung cancers observed in the population are associated with exposure to Radon daughters. In order to comply with international regulations it is estimated that 1.5% of the existing dwellings in temperate regions need to be improved.

Patient protection against ionizing radiation has become more and more important and the subject has been included in all the latest ICRP publications. Recently a 50 microns Niobium filter (NIOBI-X) has come out, which, installed on tungsten anode X-ray apparatuses, allows patient dose reduction by absorbing the radiation which does not contribute to the image. In order to verify the NIOBI-X actual effect on image quality and on patient dose reduction, image resolution, image contrast and patient exposure (air-Kerma) were measured using a bone-equivalent stepped wedge. The NIOBI-X, added to the total filtration of the X-ray apparatus, allows an air-Kerma reduction of about 50% from 60 to 130 kV. In the case of bone-equivalent material exposure the filter causes a slight contrast loss and does not affect, or even improves, image resolution. Before choosing the NIOBI-X filter for all the X-ray apparatuses a cost-benefit analysis should of course be made by evaluating results and cost related to other kinds of filter. With particular regard to Aluminium filters, whose prices are far lower than Niobium ones, it has to be pointed out that: 1) in order to have the same air-Kerma reduction the Aluminium filter thickness must be quite heavy (2.8 mm) which causes practical problems of use; 2) the Aluminium filter causes image quality loss especially at lower kVs.