Air trapping in Wegener's granulomatosis: an additional finding on expiratory chest HRCT.

PURPOSE: This study was undertaken to assess the presence and extent of air trapping (AT) on high-resolution computed tomography (HRCT) in patients with Wegener's granulomatosis (WG) and to correlate the finding with the inspiratory pattern and bronchial/bronchiolar involvement. MATERIALS AND METHODS: Twenty-one patients (7 M/14 F) with WG underwent inspiratory and expiratory HRCT. Images were evaluated for the presence and extent of AT and for airway involvement (bronchi/bronchioles); the predominant HRCT pattern was also documented. The attenuation difference was measured between the areas of AT on expiration and the same areas on inspiration in order to verify the finding of AT. The extent of AT was calculated by visual scoring and correlated with the predominant inspiratory patterns and bronchial/bronchiolar involvement. RESULTS: AT was found in seven patients (33.3%) and its extent ranged between 3% and 70% (mean 15.8±7). Two patients showed no lesions on inspiratory HRCT, and the only finding was AT on expiration. The attenuation difference between areas of AT on expiration and the same areas on inspiration ranged between 32 and 89 HU. Inspiratory HRCT was pathological in 19 patients (90.4%), and the principal lung patterns were nodular, cavitary or noncavitary (n=7, 38.9%); ground-glass opacities (n=5, 26.3%); masses (n=3, 15.8%); fibrotic (n=3, 15.8%); and consolidation with air bronchogram (n=1, 5.3%). Bronchial and bronchiolar involvement was found in 14 and five patients, respectively. No statistically significant correlation was found between AT extent and the findings on inspiration. In addition, there were no specific patterns that caused higher or lower scores of AT. Moreover, when bronchial or bronchiolar involvement was absent, the mean AT score was statistically significantly higher. CONCLUSIONS: Areas of AT represent a new and indirect HRCT finding--and in rare cases the only finding--of pulmonary WG. The nonsignificant correlation between AT extent and inspiratory findings may suggest AT as an additional HRCT finding in patients with WG.

Infantile fibromatosis of the mandible: a case report.

We report an aggressive tumour in a 5-year-old girl causing facial disfigurement. Imaging confirmed a solid, diffusely enhancing mass at the right internal pterygoid muscle, infiltrating the adjacent bone. Surgical excision and reconstruction of the mandible were performed. Histology revealed aggressive infantile fibromatosis. No recurrence was noted 7 months later. Infantile fibromatosis may mimic malignancies and should be considered in aggressive mandibular soft tissue masses, in order to carefully plan biopsy and reconstructive surgery.

Determination of the weighted CT dose index in modern multi-detector CT scanners.

The aim of the present study was to (a) evaluate the underestimation in the value of the free-in-air (CTDI(air)) and the weighted CT dose index (CTDI(w)) determined with the standard 100 mm pencil chamber, i.e. the CTDI(100) concept, for the whole range of nominal radiation beam collimations selectable in a modern multi-slice CT scanner, (b) estimate the optimum length of the pencil-chamber and phantoms for accurate CTDI(w) measurements and (c) provide CTDI(w) values normalized to free-in-air CTDI for different tube-voltage, nominal radiation beam collimations and beam filtration values. The underestimation in the determination of CTDI(air) and CTDI(w) using the CTDI(100) concept was determined from measurements obtained with standard polymethyl-methacrylate (PMMA) phantoms and arrays of thermoluminescence dosimeters. The Monte Carlo N-Particle transport code was used to simulate standard CTDI measurements on a 16-slice CT scanner. The optimum pencil-chamber length for accurate determination of CTDI(w) was estimated as the minimum chamber length for which a further increase in length does not alter the value of the CTDI. CTDI(w)/CTDI(air) ratios were determined using Monte Carlo simulation and the optimum detector length for all selectable tube-voltage values and for three different values of beam filtration. To verify the Monte Carlo results, measured values of CTDI(w)/CTDI(air) ratios using the standard 100 mm pencil ionization chamber were compared with corresponding values calculated with Monte Carlo experiments. The underestimation in the determination of CTDI(air) using the 100 mm pencil chamber was less than 1% for all beam collimations. The underestimation in CTDI(w) was 15% and 27% for head and body phantoms, respectively. The optimum detector length for accurate CTDI(w) measurements was found to be 50 cm for the beam collimations commonly employed in modern multi-detector (MD) CT scanners. The ratio of CTDI(w)/CTDI(air) determined using the optimum detector length was found to be independent of beam collimation. Percentage differences between measured and calculated corresponding CTDI(w)/CTDI(air) ratios were always less than 8% for head and less than 5% for body PMMA phantoms. In conclusion, the CTDI(air) of MDCT scanners may be measured accurately with a 100 mm pencil chamber. However, the CTDI(100) concept was found to be inadequate for accurate CTDI(w) determination for the wide beam collimations commonly used in MDCT scanners. Accurate CTDI(w) determination presupposes the use of a pencil chamber and PMMA phantoms at least 50 cm long.

Preoperative imaging staging of rectal cancer.

Carcinomas of the rectum are associated with a significant local and distant recurrence rate. Not all patients are appropriate candidates for preoperative radiation therapy. Preoperative identification of those most likely to benefit from neoadjuvant therapy is important. There is no general consensus on the role of endorectal ultrasonography, computed tomography (CT), and magnetic resonance imaging (MRI) in staging patients with rectal cancer. Although the tumor stage is an important prognostic factor, preoperative assessment is associated with prediction of the circumferential resection margin. Newer developments such as coils, sequences and gradients in MRI, evolution of multidetector CT and new contrast media, allow for an algorithm selection aiming at the best diagnostic options for patients. The present review will discuss the current role of the various imaging modalities in staging carcinomas of the rectum.

Detection of colorectal cancer hepatic metastases with contrast-enhanced ultrasound: comparison with conventional B-mode ultrasound.

The aim of this study was to assess whether contrast-enhanced ultrasound (CE-US) could provide improved diagnostic information in detecting liver metastases from colorectal cancer as compared to B-mode non-enhanced ultrasound (B-US). 32 patients (M/F 23/9, age range 48-82 years, mean 58.2 years) under chemotherapy for colorectal cancer were examined with B-US and CE-US using a second-generation ultrasound contrast agent and a dedicated protocol for contrast detection. The presence of focal liver lesions along with the number, size, pre- and post-contrast sonographic features were recorded digitally. Lesion conspicuity with a three-grade scoring scale was performed on both techniques and contrast intensity measurements were calculated for each focal lesion. CE-US detected 17% more metastases in patient-by-patient and lesion-by-lesion analysis. A statistically significant difference was found between the scoring mean values with regard to conspicuity of the lesions. Accurate characterization of the liver lesions was achievable only with contrast-enhanced technique. A quantitative contrast intensity measurement method confirmed the invariably washing-out vascular pattern in all metastases at sinusoidal-parenchymal liver phase. In conclusion, CE-US is superior to B-US and provides an effective tool in the investigation of colorectal cancer liver metastases.

Experimental determination of the effect of detector size on profile measurements in narrow photon beams.

The aim of this work is to investigate experimentally the detector size effect on narrow beam profile measurements. Polymer gel and magnetic resonance imaging dosimetry was used for this purpose. Profile measurements (Pm(s)) of a 5 mm diameter 6 MV stereotactic beam were performed using polymer gels. Eight measurements of the profile of this narrow beam were performed using correspondingly eight different detector sizes. This was achieved using high spatial resolution (0.25 mm) two-dimensional measurements and eight different signal integration volumes A X A X slice thickness, simulating detectors of different size. "A" ranged from 0.25 to 7.5 mm, representing the detector size. The gel-derived profiles exhibited increased penumbra width with increasing detector size, for sizes >0.5 mm. By extrapolating the gel-derived profiles to zero detector size, the true profile (Pt) of the studied beam was derived. The same polymer gel data were also used to simulate a small-volume ion chamber profile measurement of the same beam, in terms of volume averaging. The comparison between these results and actual corresponding small-volume chamber profile measurements performed in this study, reveal that the penumbra broadening caused by both volume averaging and electron transport alterations (present in actual ion chamber profile measurements) is a lot more intense than that resulted by volume averaging effects alone (present in gel-derived profiles simulating ion chamber profile measurements). Therefore, not only the detector size, but also its composition and tissue equivalency is proved to be an important factor for correct narrow beam profile measurements. Additionally, the convolution kernels related to each detector size and to the air ion chamber were calculated using the corresponding profile measurements (Pm(s)), the gel-derived true profile (Pt), and convolution theory. The response kernels of any desired detector can be derived, allowing the elimination of the errors associated with narrow beam profile measurements.

Occupational exposure in the electrophysiology laboratory: quantifying and minimizing radiation burden.

Fluoroscopically guided procedures in the electrophysiology room, such as radiofrequency catheter ablation and implantation of cardiac resynchronization devices, may result in high radiation exposure of electrophysiologists and assisting staff. Our aim was to provide accurate and applicable data on occupational doses to the electrophysiology laboratory personnel. We exposed fluoroscopically an anthropomorphic phantom at three projections common in electrophysiology studies. For each exposure, scattered radiation was measured at 182 sites of the cardiology room at four body levels. Effective dose values, eye lens, skin and gonadal doses to the laboratory staff were calculated. Our study has shown that a procedure requiring 40 min of fluoroscopy yields a maximum effective dose of 129 microSv and a maximum value of gonadal dose of 56.8 microSv to staff using a 0.35 mm lead-equivalent apron. A conservative estimate of the electrophysiologist's annual maximum permissible workload is 155 procedures. Staff effective dose values vary by a factor of 40 due to positioning during fluoroscopy and by a factor of 11 due to radiation protection equipment. Undercouch protective shields may reduce gonadal doses up to 98% and effective dose up to 25%. Consequently, radiation levels in the electrophysiology room are not negligible. Mitigation of occupational exposure is feasible through good fluoroscopy and working practices.

Chest radiography and tuberculosis case-finding in asymptomatic native and immigrant populations in Greece.

SETTING: A university hospital in southern Greece. OBJECTIVE: To determine the prevalence of tuberculosis (TB) and other clinically significant conditions in routine chest X-rays (CXRs) of asymptomatic Greeks and immigrants in Greece. DESIGN: Prospective study. METHODS: CXRs of 4338 asymptomatic persons (56.8% Greeks, 43.2% immigrants, 18-74 years of age) were examined by two experienced chest radiologists blinded to identifying data. Abnormalities were recorded and the final radiological diagnosis was established by consensus. Results were statistically analysed. RESULTS: The majority (94.7%) of the CXRs were reported as normal. Clinically significant findings were reported in four cases (0.08%). No case of active TB was depicted. The incidence of old TB was higher in the Greek-born group than among the immigrants, although the difference was not statistically significant. CONCLUSION: The low prevalence of TB in the Greek-born group implies that radiographic screening in that group presents an unnecessary risk and should possibly be abandoned. Our study does not confirm noticeably higher rates of TB in immigrants in comparison to the native Greek population. However, larger prospective studies are required to confirm this finding.

The effect of z overscanning on patient effective dose from multidetector helical computed tomography examinations.

z overscanning in multidetector (MD) helical CT scanning is prerequisite for the interpolation of acquired data required during image reconstruction and refers to the exposure of tissues beyond the boundaries of the volume to be imaged. The aim of the present study was to evaluate the effect of z overscanning on the patient effective dose from helical MD CT examinations. The Monte Carlo N-particle radiation transport code was employed in the current study to simulate CT exposure. The validity of the Monte Carlo simulation was verified by (a) a comparison of calculated and measured standard computed tomography dose index (CTDI) dosimetric data, and (b) a comparison of calculated and measured dose profiles along the z axis. CTDI was measured using a pencil ionization chamber and head and body CT phantoms. Dose profiles along the z axis were obtained using thermoluminescence dosimeters. A commercially available mathematical anthropomorphic phantom was used for the estimation of effective doses from four standard CT examinations, i.e., head and neck, chest, abdomen and pelvis, and trunk studies. Data for both axial and helical modes of operation were obtained. In the helical mode, z overscanning was taken into account. The calculated effective dose from a CT exposure was normalized to CTDI(free in air). The percentage differences in the normalized effective dose between contiguous axial and helical scans with pitch = 1, may reach 13.1%, 35.8%, 29.0%, and 21.5%, for head and neck, chest, abdomen and pelvis, and trunk studies, respectively. Given that the same kilovoltage and tube load per rotation were used in both axial and helical scans, the above differences may be attributed to z overscanning. For helical scans with pitch = 1, broader beam collimation is associated with increased z overscanning and consequently higher normalized effective dose value, when other scanning parameters are held constant. For a given beam collimation, the selection of a higher value of reconstructed image slice width increases the normalized effective dose. In conclusion, z overscanning may significantly affect the patient effective dose from CT examinations performed on MD CT scanners. Therefore, an estimation of the patient effective dose from MD helical CT examinations should always take into consideration the effect of z overscanning.

Organ and effective dose conversion coefficients for radiographic examinations of the pediatric skull estimated by Monte Carlo methods.

The objective of the present work was to provide precise effective and organ dose data for radiographic examinations of the skull performed on pediatric patients. To accomplish this, the MCNP4C2 transport code was utilized and 18 mathematical anthropomorphic phantoms, representing ages from a newborn child to a 17-year-old adolescent, were developed. Three common projections, anterior-posterior, posterior-anterior and lateral, were considered. The results consist of effective and organ radiation doses normalized to the entrance surface dose. Normalized data are presented for a wide range of peak kilovoltages and beam filtration values so that doses for any X-ray unit can be calculated. Both organ and effective dose values showed an inverse correlation with age. Good agreement was observed between the normalized effective doses produced in this study and values derived from calculations based on the National Radiological Protection Board coefficients for specific mathematical phantoms representing 1-, 5-, 10- and 15-year-old children. In the present work, dose data for nine mathematical phantoms representing 0-, 1-, 2-, 3-, 4-, 5-, 6-, 9- and 14-year-old pediatric patients were provided for estimation of organ and effective doses delivered to pediatric patients from radiographic examinations of the skull.

Therapeutic external irradiation in women of reproductive age: risk estimation of hereditary effects.

Exposure of women of childbearing age to ionizing radiation may result in induction of genetic disorders in future generations. This study aims to estimate the risk of hereditary effects attributable to therapeutic external irradiation in women. An anthropomorphic phantom was used to simulate radiotherapy in female patients and ovarian dose was measured for irradiation of brain, breast and lung cancer, and for treatment of Hodgkin's disease. These malignancies are among the most common tumours presenting in women of reproductive age. Dose measurements were undertaken using thermoluminescent dosemeters and all exposures were made with 6 MV X-ray beams. The dose to ovaries was found to be 2-3 cGy, 8-11 cGy and 11-15 cGy depending on the distance from the primary irradiation field during radiotherapy of brain, breast and lung cancer, respectively. The corresponding ovarian dose resulting from treatment of supradiaphragmatic and infradiaphragmatic Hodgkin's disease was 18-25 cGy and 128-356 cGy, respectively. A small excess risk of genetic diseases of (1-15) x 10(-4) was estimated for radiotherapy above the diaphragm. Pelvic irradiation resulted in an increased risk of hereditary effects of (77-214) x 10(-4).

Determination of dose-area product from panoramic radiography using a pencil ionization chamber: normalized data for the estimation of patient effective and organ doses.

The aims of the present study were (a) to investigate the potential of pencil ionization chamber to be used for the determination of dose-width product (DWP) and dose-area product (DAP) from panoramic radiographic exposures and (b) to provide data normalized to DAP for the determination of patient effective and gonadal dose from panoramic radiography performed in any laboratory. A pencil ionization chamber commonly used to measure CT dose index (CTDI) in CT scanners was employed to determine DWP for various combinations of panoramic exposure settings at the beam exit slit of a Cranex Tome panoramic x-ray unit (Soredex, Helsinki, Finland). DWP values were also measured using an array of thermoluminescence dosimeters. Reproducibility of the DWP measurement was tested. The effect of milliamperage and kilovoltage of panoramic exposures on DWP was investigated. DAP was estimated using the value of DWP measured using the pencil ionization chamber and the beam exit slit length measured using dosimetric film attached on the beam exit slit. A Rando anthropomorphic phantom appropriately loaded with thermoluminescent dosimeters (TLDs) was used to obtain organ dose and effective dose values from panoramic radiography. Reproducibility of DWP determination using the proposed method was better than 1.5%. DWP was found to be linearly related to milliamperage (r>0.999, p<0.001) and to kilovoltage raised in a power ranging from 2.18 to 2.55. DWP measured using the pencil chamber was found to be up to 11% higher than the corresponding values determined using TLD array. The panoramic exposure obtained with settings appropriate for the typical adult patient was found to result in 0.008 mSv patient effective dose, 0.0002 mGy gonadal dose, and 11.3 cGy cm2 DAP. The use of a pencil ionization chamber is proposed for the determination of DWP and DAP from panoramic radiographic exposures. Normalized data over DAP were provided for the determination of patient effective and gonadal dose from panoramic radiography.

Quantitative ultrasound measurements in children and adolescents with: type 1 diabetes.

The aim of the current study was to evaluate bone status at the radius and phalanx in children and adolescents with type 1 diabetes by using quantitative ultrasound (QUS) measurements. Thirty pediatric patients, 16 male and 14 female, with type 1 diabetes of duration of 5 to 177 months and mean (+/- SD) age 11.3 +/- 4.6 years were studied. QUS measurements were carried out using the Sunlight Omnisense 7000 S device. Speed of sound (SOS) was measured at the radius and tibia. Diabetic control was assessed by glycosylated hemoglobin (HbA(1c)) measurements. Male and female patients with type 1 diabetes did not have significantly different SOS or HbA(1c) values. SOS Z-scores at both the radius and tibia were negatively associated with duration of disease ( r = -0 41 and r = -0.37 for the radius and tibia respectively, P < 0.05 for both correlations). Seven of 15 patients with duration of disease of >6 years had diminished SOS, defined as Z-score of <-1, at either the radius or tibia. SOS measurements at the radius showed moderate correlation with SOS at the tibia ( r = 0.58, P < 0.00 l). There was no correlation between SOS and HbA(1c). In conclusion, SOS Z-scores at both the radius and tibia show a significant negative correlation with duration of insulin-dependent diabetes in children. No relation was found between SOS and metabolic control of young diabetic patients.

Bilateral variation in radial bone speed of sound.

The aims of this study were to: (a) examine differences in speed of sound (SOS) between the right (SOS(R)) and left (SOS(L)) radius; (b) detect bone loss following proximal forearm fracture by SOS measurement at the radius; and (c) compare SOS(L) and bone mineral density (BMD) of one-third, mid-distal, ultra-distal and total region of the left radius. Two hundred eighty-seven Caucasian women (mean age 60.4+/-6.7 years) participated in this study. All subjects were right-handed. Twenty-seven women (mean age 63.6+/-8.0 years) had suffered a high-energy fracture of the right or left forearm. The SOS was assessed using a quantitative ultrasound device, whereas BMD was measured by dual energy X-ray absorptiometry (DXA). The SOS(R) was significantly higher than SOS(L) (4047.5+/-121.0 vs 4026.3+/-113.4 m/s; p<0.001). The contralateral absolute difference was 1.94% (95% confidence intervals: 1.73-2.15%). In women who had suffered a fracture of their right forearm, SOS(R) was not significantly higher than SOS(L )(3989.9+/-141.8 vs 3985.0+/-151.1 m/s), whereas the bilateral difference was reduced to 1.45%. In women with a previous fracture of the left forearm, SOS(R) was significantly higher than SOS(L) (4076.9+/-92.8 vs 3992.6+/-124.0 m/s; p<0.01) and the bilateral difference was increased to 2.61%. Of the 260 subjects without fracture, 155 had greater SOS in the right radius, 102 had greater SOS in the left radius and 3 patients had equal values of SOS in both bones. Calculated correlations between SOS and BMD were weak to moderate ( r=0.27-0.41; p<0.0001 for all comparisons). The SOS measurements should be performed on both radial bones. A high-energy forearm fracture results in a decrease in SOS measured at the radius. Radial-bone SOS measurements cannot predict forearm BMD.

Conceptus radiation dose assessment from fluoroscopically assisted surgical treatment of hip fractures.

Our aims in the present study were to (a) provide normalized dose data for the estimation of the conceptus dose from fluoroscopically assisted surgical treatment of hip fractures carried out during all trimesters of pregnancy and (b) estimate the conceptus radiation dose and risks associated with fluoroscopy during a typical treatment of hip fracture performed on a pregnant woman. Conceptus doses normalized to entrance surface dose (ESD) or dose area product (DAP) were obtained with the help of anthropomorphic phantoms simulating pregnancy in the three trimesters of gestation. ESD and conceptus dose measurements were carried out using thermoluminescent dosimeters. DAP to conceptus dose conversion factors were estimated for the first, second and third trimesters of gestation. Conceptus dose data normalized to ESD were also estimated to investigate whether these conversion factors may be used for procedures carried out in x-ray units not equipped with a DAP meter. Fluoroscopically assisted surgical treatments were performed in 18 women. The projections involved in these procedures are (a) posteroanterior (PA) and (b) lateral crosstable 45 degrees (LC). Radiation doses for a potential conceptus were estimated by using normalized dose data obtained in phantoms. The results consist of tabulated dose data normalized to DAP or ESD for the estimation of a conceptus dose. An important finding of this study was that the total DAP of a procedure, instead of the individual DAP values of each projection, could be used for the accurate estimation of the conceptus dose. Conceptus doses calculated using dose data normalized to ESD are about 23% higher compared to those estimated using data normalized to DAP. This discrepancy may be attributed to the contribution of scattering radiation from PA projection to ESD measurement of LC projection and vice versa. Therefore, dose data normalized to ESD do not provide accurate conceptus dose estimation. Doses normalized to DAP showed a dependence on (a) tube potential and (b) tube filtration. Data are provided to extent the doses normalized to DAP for the standard spectrum to other tube voltages and filtrations. The maximum dose for a potential conceptus was 0.425 mGy for a patient irradiated for 50 seconds during the PA projection and for 40 seconds during the LC projection. Although the total duration of fluoroscopy is usually less than 2 minutes during a typical procedure, screening time as long as 14 minutes has been reported in the literature for treatment of complex fractures. The relationship between conceptus dose and fluoroscopy time found in the current study showed that, in these cases, the radiation dose received by a conceptus may exceed 1 mGy. In conclusion, an accurate estimation of conceptus doses associated with fluoroscopically assisted surgical treatment of hip fractures can be made using the DAP normalized dose data provided in this study. Conceptus doses from a typical procedure is less than 1 mGy during all trimesters.

Late changes in barium sulfate aspiration: HRCT features.

Aspiration of barium sulfate occurs accidentally. Lung reaction is usually mild in the early phase due to inert character of the substance and long-term reactions or late toxicities are not expected. Little if any fibrotic response is speculated. We present a case with barium aspiration, studied by high-resolution computed tomography (HRCT) 1 year after the event, as late pulmonary sequelae studied by CT have not been described yet, to the best of our knowledge. The HRCT revealed thickened interlobular septa, subpleural lines, subpleural cysts, and centrilobular micronodules along with barium particles in a subpleural distribution. Those findings indicated that barium is capable of producing mild though silent clinically fibrosis.

Can radial bone mineral density and quantitative ultrasound measurements reduce the number of women who need axial density skeletal assessment?

The purpose of this study was to investigate the clinical usefulness of forearm bone mineral density (BMD) and speed of sound (SOS) at the phalanx and radius as pre-selection tests to identify women with low BMD at the axial skeleton. BMD was measured by dual-energy X-ray absorptiometry (DXA) in the forearm, lumbar spine and femoral neck. SOS at the radius and phalanx was measured using a multisite quantitative ultrasound (QUS) device. Measurements were performed on 524 consecutive women referred for the assessment of BMD. Women with a T-score <-1 and T-score < or =-2.5 at either spine or femoral neck were identified, and T-score cut-off values for the forearm DXA and QUS variables were determined. Cut-off values for the forearm BMD estimated to detect normal women and those with T-score <-1 at the axial skeleton identified a total of 82% of subjects with 91% certainty. Cut-off values for the forearm BMD determined to detect women with T-score >-2.5 and those with osteoporosis allowed the identification of 62% of the study population with 90% certainty. Cut-off values for the phalangeal and radial SOS estimated to detect normal women and those with T-score <-1 at the axial skeleton identified a total of 49% and 1% of subjects, respectively. Cut-off values estimated for QUS variables to detect women with T-score >-2.5 and those with osteoporosis at the axial skeleton either failed to detect subjects with sufficient certainty (phalangeal SOS) or detected a negligible percentage of patients (radial SOS). In conclusion, forearm BMD may be used as a pre-selection test to identify women with low BMD at the axial skeleton, thus enabling reduction of the number of women who need axial BMD assessment. SOS of the phalanges and radius appears to have less value in the detection of the women with low axial BMD.

Sedations and analgesia in patients undergoing percutaneous transhepatic biliary drainage.

AIM: To present our experience using intravenous sedoanalgesia for percutaneous biliary drainage. MATERIALS AND METHODS: This study comprised 100 patients, all of whom were continuously monitored [electrocardiogram (ECG), blood pressure, pulse oxymetry] and received an initial dose of 2mg midazolam followed by 0.02 mg fentanyl. Before every anticipated painful procedure, a maintenance dose of 0.01 mg fentanyl was administered. If the procedure continued and the patient became aware, another 1mg midazolam was given. This was repeated if patients felt pain. A total dose of 0.08 mg fentanyl and 7 mg midazolam was never exceeded. Immediately after the procedure, the nurse was asked to evaluate patients' pain score. The patients were asked 3h later to complete a visual 10-degree pain score scale. RESULTS: The average dose of fentanyl and midazolam was 0.042 mg (0.03-0.08 mg) and 4.28 mg (2-7 mg), respectively. Only one patient recorded the procedure as painful. The scores given by the attending nurse (1-7 points, mean 2.9) correlated well with those given by the patients (1-6 points, mean 2.72). No complications were noted. CONCLUSION: According to our experience, interventional radiologists practising biliary procedures can administer low doses of midazolam and minimize the doses of fentanyl, without loss of adequate sedation and analgesia.

Risk estimation of radiation-induced thyroid cancer from treatment of brain tumors in adults and children.

The purpose of this study was to estimate the risk of thyroid cancer induction attributable to brain radiation therapy in adult and pediatric patients. An anthropomorphic phantom was used to simulate treatment of brain tumors with two lateral opposed fields. Thyroid dose was measured using thermoluminescent dosimeters. Phantom measurements were performed for all possible field sizes that may be applied during brain radiotherapy in adults and children. The dependence of the thyroid dose on the distance from the irradiation field and on the presence of beam modifiers in the primary beam was investigated. All phantom exposures were generated with a 6 MV photon beam. Thyroid dose was found to vary from 9.6 to 89.4 cGy and from 8.0 to 194.0 cGy depending upon the field size used and the thyroid location in respect to the field edge for adults and children respectively. The excess relative risk of thyroid cancer induction for exposed children was estimated to be 0.6-14.9. The corresponding excess relative risk for adults was 0.1-1.1. The introduction of lead blocks or wedges into the primary beam may result in a considerable increase of the risk of thyroid cancer due to the increase of the thyroid dose. This study shows that brain radiotherapy during childhood may be associated with an increased risk of secondary thyroid cancer while the risk in adult patients is much smaller.