Effective dose for kidney-ureter-bladder plain radiography, intravenous urography, and abdominal computed tomography scan: A phantom study.

Abdominal colic pain or hematuria is suspected to be caused by urinary tract stones. Commonly used X-ray examinations include kidney-ureter-bladder plain radiography (KUB), intravenous urography (IVU), and abdominal computed tomography (CT). In this study, a high-sensitivity thermoluminescent dosimeter (TLD) was embedded in a Rando phantom to directly measure organ dose and evaluate effective dose. During each experiment, 139 TLD measurement points that cover almost all organs (as recommended by the ICRP 103 report) were examined. Red bone-marrow and remainder tissues have a high tissue weighting factor (0.12), and they are widely distributed. In the phantom, 34 TLDs and 31 TLDs were embedded in the red bone-marrow and remainder tissues to improve the accuracy and representativeness of organ doses. The detailed organ dose distributions for KUB, IVU, and abdominal CT are presented. The effective doses for KUB and IVU were 0.22 and 1.51 mSv, respectively, and those for two abdominal CTs were 8.21 and 9.27 mSv. This experiment presents a conversion factor of 0.0177 mSv·mGy-1 cm-1 for the abdominal CT examination, which differs from most of the conversion factors obtained through the Monte Carlo simulation method.

Ambient and personnel occupational dose assessment in a Hospital's PET/CT center.

This study used thermoluminescent dosimeters (TLDs) to measure cumulative radiation doses in a PET/CT center. It covered 18 areas and four personnel groups. Because the isolated lead shielding separated the patients from the nurses, wearing protective clothing when injecting radiopharmaceuticals was unnecessary. Fingertip doses of the dispensing and nurse groups were below the occupational limit. Current radiopharmaceutical transportation and injection operations in this PET/CT center provide considerable radiation protection to medical personnel.

Effective dose for multiple and repeated radiation examinations in donors and recipients of adult-to-adult living donor liver transplants at a single center.

PURPOSE: To evaluate the effective doses received by donors and recipients, identify effective dose contributions, and make risk assessments. MATERIALS AND METHODS: It was a retrospective study. 100 Donors and 100 recipients were enrolled with an operative day from March 2016 to August 2017. The dose was analyzed for all radiation-related examinations over a period of 2 years, 1 year before and 1 year after the LDLT procedure. The effective doses of plain X-rays, CT, fluoroscopy, and nuclear medicine per patient were simulated by a Monte Carlo software, evaluated by the dose-length product conversion factors, evaluated by the dose-area product conversion factors, and evaluated by the activity conversion factors, respectively. The risks of radiation-induced cancer were assessed on the basis of the ICRP risk model. RESULTS: The median effective doses were 71 (range: 30-186) mSv for donors and 147 (32-423) mSv for recipients. The radiation examinations were mainly performed in the last three months of preoperative period to first month of postoperative period for recipients and donors. The HCC recipients received a higher effective dose, 195 (64-423) mSv, than those with other indications. The median radiation-induced cancer risk was 0.38 % in male and 0.48 % in female donors and was 0.50 % in male and 0.58 % in female recipients. CONCLUSION: Donors and recipients received a large effective dose, mainly from the CT scans. To reduce effective doses should be included in future challenges in some living donor liver transplants centers that often use CT examinations.

RADIATION DOSE DISTRIBUTION OF A PLAIN RADIOGRAPHY ROOM AND COMPUTED TOMOGRAPHY ROOM IN A VETERINARY HOSPITAL.

Thermoluminescent dosemeters (TLDs) were attached to the walls of a plain radiography room and a computed tomography (CT) room, control rooms and corridors to measure the radiation dose. The types of animals scanned and scan parameters were analysed. Dogs and cats accounted for the largest proportion of animals, a combined total of 96.0%. Distributions of tube voltage and tube current-time product are presented. In the CT room, the dose at the angle of the gantry opening was higher than that on either side of the gantry. The study developed equations that may be useful to assess the dose for staff standing in radiography rooms. The personal annual doses for the controlled and uncontrolled areas were lower than the recommended dose limit. The annual doses for personnel and nonworkers were also within the acceptable level for radiation safety.

The Population Effective Dose of Medical Computed Tomography Examinations in Taiwan for 2013.

PURPOSE: To evaluate the annual effective dose per capita attributed to computed tomography (CT) examinations in 2013 and to predict the population effective dose from 2000 to 2013 in Taiwan. METHODS: A CT examination database collected from 30 hospitals was divided into 22 procedures and classified into six regions: head, neck, chest, abdomen, pelvis, and other, respectively. The effective doses in different regions were evaluated by dose-length product (DLP) multiplied by conversion factors. RESULTS: The CT scan dose parameters were collected from 4,407 patients. For the six scanned regions, the percentages of patients scanned were: head (39.8%), neck (3.9%), chest (23.3%), abdomen (26.7%), pelvis (4.8%), and other (1.6%), respectively. The DLPs per patient (mGy·cm/patient) were head (1,071±225), neck (1,103±615), chest (724±509), abdomen (1,315±550), pelvis (1,231±620) and other (1,407±937), respectively. The number of CT examinations increased rapidly, with an average annual growth rate of 7.6%. The number of CT examinations in 2013 was 2.6 times that in 2000. The population effective dose was 0.30 mSv per capita in 2000 and increased to 0.74 mSv per capita in 2013, with an annual growth rate of 7.2%. The growth trend indicates that the effective dose will continue to rise in Taiwan. CONCLUSION: Some strategies should be applied to cope with this growth. Defining the CT dose reference level stipulated in official recommendations and encouraging the use of iterative reconstruction imaging instead of filtered back-projection imaging could be a useful method for optimizing the effective dose and image quality.

Scattered radiation doses absorbed by technicians at different distances from X-ray exposure: Experiments on prosthesis.

UNLABELLED: This work aimed to investigate the spatial distribution of scattered radiation doses induced by exposure to the portable X-ray, the C-arm machine, and to simulate the radiologist without a shield of lead clothing, radiation doses absorbed by medical staff at 2 m from the central exposure point. MATERIAL AND METHOD: With the adoption of the Rando Phantom, several frequently X-rayed body parts were exposed to X-ray radiation, and the scattered radiation doses were measured by ionization chamber dosimeters at various angles from the patient. Assuming that the central point of the X-ray was located at the belly button, five detection points were distributed in the operation room at 1 m above the ground and 1-2 m from the central point horizontally. RESULTS: The radiation dose measured at point B was the lowest, and the scattered radiation dose absorbed by the prosthesis from the X-ray's vertical projection was 0.07 ±0.03 µGy, which was less than the background radiation levels. The Fluke biomedical model 660-5DE (400 cc) and 660-3DE (4 cc) ion chambers were used to detect air dose at a distance of approximately two meters from the central point. The AP projection radiation doses at point B was the lowest (0.07±0.03 µGy) and the radiation doses at point D was the highest (0.26±0.08 µGy) .Only taking the vertical projection into account, the radiation doses at point B was the lowest (0.52 µGy), and the radiation doses at point E was the highest (4 µGy).The PA projection radiation at point B was the lowest (0.36 µGy) and the radiation doses at point E was the highest(2.77 µGy), occupying 10-32% of the maximum doses. The maximum dose in five directions was nine times to the minimum dose. When the PX and the C-arm machine were used, the radiation doses at a distance of 2 m were attenuated to the background radiation level. The radiologist without a lead shield should stand at point B of patient's feet. Accordingly, teaching materials on radiation safety for radiological interns and clinical technicians were formulated.

Ambient and Personal Effective Dose Assessment at the International Arrival Hall of Taichung Airport in Taiwan.

Ambient monitor and phantom studies were carried out in the international arrival hall of Taichung Airport, Taiwan. A total of 172 thermoluminescent dosimeters (TLDs) were used for ambient monitoring. The sites of the export conveyor, the outward face of the x-ray scanning chamber, and the x-ray image monitor were assessed as low-radiation areas because the possible annual effective doses were 0.12, 0.39, and 0.16 mSv, all less than 1 mSv per year. In addition, a phantom filled with 126 TLDs was used to simulate a 10-year-old child being exposed by the x-ray baggage scanner. The effective dose was evaluated as 3.39 ± 0.33 µSv/scan, using the tissue weighting factor of the International Commission on Radiological Protection (ICRP) 103 report. This figure is a useful reference should a person be accidentally scanned by the x-ray baggage scanner.

Concurrent and convergent validity of the mobility- and multidimensional-hierarchical disability categorization models with physical performance in community older adults.

A valid, time-efficient and easy-to-use instrument is important for busy clinical settings, large scale surveys, or community screening use. The purpose of this study was to validate the mobility hierarchical disability categorization model (an abbreviated model) by investigating its concurrent validity with the multidimensional hierarchical disability categorization model (a comprehensive model) and triangulating both models with physical performance measures in older adults. 604 community-dwelling older adults of at least 60 years in age volunteered to participate. Self-reported function on mobility, instrumental activities of daily living (IADL) and activities of daily living (ADL) domains were recorded and then the disability status determined based on both the multidimensional hierarchical categorization model and the mobility hierarchical categorization model. The physical performance measures, consisting of grip strength and usual and fastest gait speeds (UGS, FGS), were collected on the same day. Both categorization models showed high correlation (γs = 0.92, p < 0.001) and agreement (kappa = 0.61, p < 0.0001). Physical performance measures demonstrated significant different group means among the disability subgroups based on both categorization models. The results of multiple regression analysis indicated that both models individually explain similar amount of variance on all physical performances, with adjustments for age, sex, and number of comorbidities. Our results found that the mobility hierarchical disability categorization model is a valid and time efficient tool for large survey or screening use.

Surveyed data for structural shielding calculations of radiographic x-ray installations in Taiwan.

The use of surveyed data on the x-ray tube workloads and clinical exposure parameters was suggested in NCRP Report No. 147 for the structural shielding design of medical x-ray installations. To guide the shielding design of radiographic x-ray rooms in Taiwan, a large-scale survey was conducted to collect information required for the computations of the transmissions from broad x-ray beams through shielding materials. Surveyed data were collected during one week from 10,750 projections of 6,657 examinations in 13 radiographic rooms from nine hospitals. This survey was the first time that this type of clinical data has been collected in Taiwan on a large scale. The surveyed total workload was divided into separate contributions from x-ray projections directed at the floor, the wall bucky, and all barriers (used for secondary barriers). Based on the surveyed workload distributions, the unshielded air kerma per patient at 1 m from the source was calculated by the PCXMC program using surveyed x-ray tube parameters on the generator waveform, anode material, target angle, and filtration. Subsequently, the transmissions of x-rays through different barrier materials were computed by considering the average workloads and the average workloads plus one standard deviations. The latter computations were for a sensitivity study to find the influence of workload variations in different hospitals on the shielding requirements. All surveyed data and calculated results were compared with corresponding values given in NCRP 147 to analyze the radiographic imaging differences between Taiwan and U.S.

A reliability study for standing functional reach test using modified and traditional rulers.

The purposes of the study were (1) to estimate the standing reach distance, test-retest, and interrater reliability of the functional reach test using traditional and modified rulers and (2) to evaluate the difference in the scores based on one trial, the mean of two or of three trials. Sixty-four individuals (M age = 36.3 yr., SD = 19.5, range = 19 to 70 years; 24 men, 40 women) volunteered to participate. Differences in measurements were examined. The intraclass correlation coefficient (ICC) was used to assess the test-retest and interrater reliability. Analysis indicated that the reach score measured by the rulers were not statistically significantly different, but the three measurements were significantly different. Reliability estimates were similar for the two mean scores, the mean of two trials (ICC2,2 = 0.87-1.00) or three trials (ICC2,3 = 0.89-1.00). The standard error of measurement (SEM) was always smaller when the modified ruler was used than when the traditional ruler was used. Performance with the modified ruler is an alternative to that with a traditional ruler. The mean of two trials as a measure of performance of reach distance when standing is recommended with either ruler.

Gait speed measure: the effect of different measuring distances and the inclusion and exclusion of acceleration and deceleration.

The purposes of this study were to examine the effects of different distances and the inclusion and exclusion of acceleration and deceleration distances on the measurement of self-paced and fastest gait speeds in younger and older adults. The self-paced and fastest gait speeds of younger and older adults were measured over 4-m and 10-m walkways with the acceleration and deceleration distances included and excluded in the measuring distance. The results indicated gait speeds (both self-paced and fastest) measured over different distances were comparable only if a distance for acceleration and deceleration was excluded from the measuring distance to obtain stable and comparable gait speeds. Similar results were found for younger and older groups.