Determination Of Radiation Dose Research Articles

Radiation Doses in Routine CT Examinations for Adult Patients in Saudi Arabia: A Systematic Review.

Computed tomography (CT) is an important imaging technique that produces detailed cross-sectional images for diagnosing medical conditions. However, the associated radiation exposure raises concerns. Establishing diagnostic reference levels (DRLs) helps identify unusual radiation doses and optimize exposure while maintaining diagnostic image quality. The purpose of this systematic review is to review the radiation doses received by adult patients in the head, chest, abdomen, pelvis, abdomen-pelvis (AP), and combined chest, abdomen, and pelvis (CAP) CT scans in Saudi Arabia. A search was conducted in several databases including PubMed and Google Scholar to identify studies that have established DRLs or determined radiation dose for adult CT examinations. Only studies that specifically assessed DRLs in actual adult patients were considered for inclusion. Out of a total of 31 articles that were identified as eligible, 13 were included after a thorough screening process. The values of CTDIv, DLP, and effective doses were determined. The review discovered that CTDIv and DLP were the most frequently used dosimetric quantities. The mean values in terms of CTDIv for head, chest, abdomen, pelvis, AP, and CAP ranged from 40.67 to 61.80 mGy, 5.80 to 14.90 mGy, 8.60 to 16.15 mGy, 10.80 to 17.35 mGy, 14.10 to 16.84 mGy, and 12.00 to 22.94 mGy, respectively. The mean values in terms of DLP for head, chest, abdomen, pelvis, AP, and CAP ranged from 757 to 1212 mGy.cm, 243 to 657 mGy.cm, 369.5 to 549 mGy.cm, 379.6 to 593 mGy.cm, 658 to 940.43 mGy.cm, and 740 to 1493.8 mGy.cm, respectively. There is a fluctuation in radiation dose among CT centers, highlighting a need to provide proper education and training to radiographers. It is recommended to establish a universally accepted standardized protocol based on weight, equivalent diameter, or cross-sectional area for accurate comparisons with national and international DRLs.

Establishment and Application of a Radiation Dose Rate Model for Nuclear Medicine Examinees.

Traditional methods for determining radiation dose in nuclear medicine include the Monte Carlo method, the discrete ordinate method, and the point kernel integration method. This study presents a new mathematical model for predicting the radiation dose rate in the vicinity of nuclear medicine patients. A new algorithm was created by combining the physical model of "cylinder superposition" of the human body with integral analysis to assess the radiation dose rate in the vicinity of nuclear medicine patients. The model accurately predicted radiation dose rates within distances of 0.1-3.0 m, with a deviation of less than 11% compared to observed rates. The model demonstrated greater accuracy at shorter distances from the radiation source, with a deviation of only 1.55% from observed values at 0.1 m. The model proposed in this study effectively represents the spatial and temporal distribution of the radiation field around nuclear medicine patients and demonstrates good agreement with actual measurements. This model has the potential to serve as a radiation dose rate alert system in hospital environments.

Saccharomyces Cerevisiae as a Model Organism for Retrospective Impedance Biodosimetry.

Previous studies have shown that measuring changes in electrical impedance that follow radiation-induced suppression of metabolic activity in irradiated yeast cells can be used to determine radiation dose. The current work investigates the radiation response of Saccharomyces cerevisiae cells by using metabolic activity of cells as a damage indicator. Impedance biodosimetry was examined as a method to evaluate the radiation response of yeast cells. Active lab-grade dry yeast cells were used as the biological material as these samples are simple to handle and have a long shelf-life. A novel dosimeter design has been developed with a strict fabrication method and measurement procedure to ensure reproducible measurements are possible. Prepared yeast samples were irradiated to doses from 0.5 to 8 Gy using a 137Cs source, and a dose response curve was developed that showed a linear relationship of dose with changes in impedance measurements. Fading of the impedance signal was also investigated, and it was shown that there was no noticeable fading of the impedance signal over a period of 7 mo. Finally, the lowest detectable limit measured using this methodology was determined to be 300 mGy. This work presents an alternative retrospective dosimetry technique that can be used at a high scale and low cost following large-scale radiological accidents.

Radiation dose to multidisciplinary staff members during complex interventional procedures

IntroductionComplex interventional radiology procedures involve extensive fluoroscopy and image acquisition while staff are in-room. Monitoring occupational radiation dose is crucial in optimization. The purpose was to determine radiation doses received by staff involved in complex interventional procedures performed in a dedicated vascular or neuro intervention room. MethodsIndividual real-time radiation dose for all staff involved in vascular and neuro-interventional procedures in adult patients was recorded over a one-year period using wireless electronic dosimeters attached to the apron thyroid shield. A reference dosimeter was attached to the C-arm near the tube housing to measure scattered, unshielded radiation. Radiology staff carried shoulder thermo-luminescent dosimeters with monthly read-out to monitor dose over time. ResultsOccupational radiation dose was measured in 99 interventional procedures. In many cases prostate artery embolization procedures exposed radiologists to high radiation doses with a median of 15.0 μSv and a very large spread, i.e. 0.2–152.5 μSv. In all procedures except uterine fibroid embolization radiographers were exposed to lower doses than those of radiologists, with endovascular aortic repair being the procedure with highest median exposure to assisting radiographers, i.e. 2.2 μSv ranging from 0.1 to 36.1 μSv. Median radiation dose for the reference dosimeter was 670 μGy while median staff dose for all procedures combined was 3.2 μGy. ConclusionRadiation doses for multiple staff were determined and the ratio between staff dose and reference dosimeter indicated proper use of shielding in general. Some high-dose procedures may need further optimization for certain staff members, especially those not primarily employed in radiology. Implications for practiceThe study provides benchmark doses that may be used widely in audits and in the ongoing effort to optimize radiation protection for staff in interventional radiology.

Radiation exposure and cancer risk of pediatric head CT scans: Impact of age and scanning parameters

Computed tomography (CT) is a widely utilized imaging technique in various medical applications due to the advanced technology that allows the diagnosis of diseases efficiently. The aims of this study were (1) to assess the radiation dose and the probability of cancer incidence for pediatric head CT scans, and (2) to analyze the influence of age and other scanning parameters on radiation dose. A total of 224 pediatric patients, ranging in age from newborn to 18 years, were collected from three main hospitals in Saudi Arabia. The patient data were divided into four age groups: Group 1 (0 to < 1 year old), Group 2 (1 to < 5 years old), Group 3 (5 to < 10 years old), and Group 4 (10 to < 18 years old). Initially, descriptive statistics were conducted for the values of volume CT dose index (CTDIvol), dose-length product (DLP), effective dose, and probability of lifetime cancer risk. This was followed by applying the Kruskal-Wallis H and the Mann-Whitney U tests to investigate the influence of age and other scanning parameters, namely tube voltage, slice thickness, and the use of automatic tube current modulation (ATCM), on radiation dose. It has been found that as the age of patients increased, there was a corresponding increase in CTDIvol and DLP values and a decrease in effective doses and lifetime cancer risk. The patient's age accounted for 33.4% and 34.9% of the variations in CTDIvol and DLP, respectively, while tube voltage (kVp) settings accounted for 25.8% and 24.9%, respectively. There was an increase of 22.3% in CTDIvol reported for patients scanned with a slice thickness of 2 mm compared to those scanned at 2.5 mm, and a 2.2% dose increase between slice thicknesses of 2.5 mm and 5 mm. Radiation doses in the surveyed hospitals fall within acceptable limits. Further studies in Saudi Arabia should focus on evaluating patient doses based on the actual sizes, which determine radiation doses for pediatric CT imaging more accurately.

An Analytical Study to Determine Dose-Volume Threshold for Radiation Induced Hypothyroidism.

Objective: To determine radiation dose volume threshold in predicting the development of hypothyroidism in cancer patients following neck irradiation. Methods: This is a cross sectional follow up study for patients who had been previously irradiated, prior to enrolment in the study. We have done thyroid dose-volumetric analysis on 120 histologically proven cancer patients in the age group of 18-75 years who received neck irradiation as a part of their definitive or adjuvant radiotherapy with three-dimensional conformal or intensity-modulated radiotherapy technique (3D -CRT or IMRT) and completed at least six months post-radiotherapy. Primary tumor sites included carcinoma or lymphoma of the head and neck, breast, cervical, and upper thoracic esophagus, requiring neck irradiation. Results: The proportion of patients who tested positive for Radiation induced hypothyroidism (RIHT) was found to be 40%, with clinical hypothyroidism and subclinical hypothyroidism being 25.8% and 14.2%, respectively. Time to develop hypothyroidism peaks around two years. Mean thyroid gland dose (Dmean) >28 Gy, thyroid gland volume receiving 40 Gy dose (i.e. V40) >49% and age <50 years were found to be significant risk factors for the development of RIHT on binary logistic regression. RT dose >50 Gy and thyroid gland volume spared from 40 Gy (i.e. VS40) < 2.12cm3 were statistically significant predictors for RIHT on chi-square and (Receiver operating characteristic) ROC curve analysis respectively but not on regression analysis. Conclusion: Dose-volume threshold for the thyroid gland as Dmean <28 Gy and V40 <49% may prevent the development of RIHT.

Quantitative analysis of 99mTc-pertechnetate thyroid uptake with a large-field CZT gamma camera: feasibility and comparison between SPECT/CT and planar acquisitions

PurposeThe main objective of this study was to evaluate the ability of a large field Cadmium Zinc Telluride (CZT) camera to estimate thyroid uptake (TU) on single photon emission computed tomography (SPECT) images with and without attenuation correction (Tomo-AC and Tomo-NoAC) compared with Planar acquisition in a series of 23 consecutive patients. The secondary objective was to determine radiation doses for the tracer administration and for the additional Computed Tomography (CT) scan.MethodsCross-calibration factors were determined using a thyroid phantom, for Planar, Tomo-AC and Tomo-NoAC images. Then Planar and SPECT/CT acquisitions centered on the thyroid were performed on 5 anthropomorphic phantoms with activity ranging from 0.4 to 10 MBq, and 23 patients after administration of 79.2 ± 3.7 MBq of [99mTc]-pertechnetate. We estimated the absolute thyroid activity (AThA) for the anthropomorphic phantoms and the TU for the patients. Radiation dose was also determined using International Commission on Radiological Protection (ICRP) reports and VirtualDoseTMCT software.ResultsCross-calibration factors were 66.2 ± 4.9, 60.7 ± 0.7 and 26.5 ± 0.3 counts/(MBq s), respectively, for Planar, Tomo-AC and Tomo-NoAC images. Theoretical and estimated AThA for Planar, Tomo-AC and Tomo-NoAC images were statistically highly correlated (r < 0.99; P < 10–4) and the average of the relative percentage difference between theoretical and estimated AThA were (8.6 ± 17.8), (− 1.3 ± 5.2) and (12.8 ± 5.7) %, respectively. Comparisons between TU based on different pairs of images (Planar vs Tomo-AC, Planar vs Tomo-NoAC and Tomo-AC vs Tomo-NoAC) showed statistically significant correlation (r = 0.972, 0.961 and 0.935, respectively; P < 10–3). Effective and thyroid absorbed doses were, respectively (0.34CT + 0.95NM) mSv, and (3.88CT + 1.74NM) mGy.ConclusionAThA estimation using Planar and SPECT/CT acquisitions on a new generation of CZT large-field cameras is feasible. In addition, TU on SPECT/CT was as accurate as conventional planar acquisition, but the CT induced additional thyroid exposure.Trial registration Name of the registry: Thyroid Uptake Quantification on a New Generation of Gamma Camera (QUANTHYC). Trial number: NCT05049551. Registered September 20, 2021—Retrospectively registered, https://clinicaltrials.gov/ct2/show/record/NCT05049551?cntry=MC&draw=2&rank=4.

THE DEVELOPMENT OF GAMMA RADIATION DOSIMETERS REAL-TIME NETWORK-BASED SENSOR WIRELESS IEEE 802.15.4 PROTOCOL

Several studies have been carried out on the development of real-time gamma radiation dosimeter based on the wireless sensor network (WSN) protocol IEEE 802.15.4. WSN technology can be adopted to develop a gamma radiation dose monitoring system on a large scale due to its real-time, centralized, efficient, and relatively low-cost attributes. This study aims to develop a personal radiation dosimeter that can collect data from the measurement results of several sensor nodes or multi-sensors. The measurement results of radiation dose values from many radiation workers are sent to a coordinator node consisting of the Xbee module and Arduino as a microcontroller. The system test is compared with a calibrated dosimeter reading and is expected to be one of the instruments for determining radiation dose in real-time. It can also reduce the risk of receiving a radiation dose that exceeds the threshold allowed by the ionizing control agency and a program in radiation protection. Changes in the intensity of radiation emitted by Cs-137 (gamma radiation) are carried out by varying each detector's distance to the source, which indirectly varies the value of the dose rate received by the detector. This relationship is shown from the value of R2 = 0.99, which indicates a strong correlation between changes in the dose given to the detector's response being developed. The system built is efficient, inexpensive, and collecting radiation exposure data can monitor radiation exposure received by workers in real-time. This technique can help speed up reporting of radiation exposure received by radiation workers.

Simulation of Leksell Gamma Knife-4C System with Different Phantoms Using PHITS and Geant4

This study used PHITS and Geant4 code packages to simulate a Leksell Gamma Knife system in order to determine radiation dose distribution in two types of phantoms. The results observed in the water phantom with configurations of single source and 201 sources are in good accord with the prior research, including both simulation and experiment. Several characteristics of Leksell Gamma Knife 4C, such as dose profiles, output factor, FWHM, and penumbra size, are calculated based on Monte Carlo simulations, which show the best consistency with other results. The output factors for collimators of 14 mm, 8 mm, and 4 mm are 0.984, 0.949, and 0.872, respectively. The simulation results with an adult mesh-type reference phantom reveal considerable similarities with the established radiosurgery plans. It indicates that the absorbed dose in brain tumors was highest when utilizing the 18 mm collimator and subsequently reduced with collimator size to 0.65, 0.25, and 0.5 with the 14 mm, 8 mm, and 4 mm collimators, respectively. The absorbed dose has a very low value for other essential organs and decreases with distance from the brain tumor. These findings may explain why the dose to organs decreases linearly as target distance, volume, and collimator size increase.

Determining baseline radiation levels in marine biota – A comparison of SE Queensland commercial species

Limited data exists on the contribution to radiological dose to members of the public from ingestion of radioactivity in seafood in the Australian diet. There is also a lack of data available to assess the radiological dose to marine fauna in Australian waters. Natural and anthropogenic radionuclides and trace metals were measured in the edible flesh of prawns to determine the radiological dose to humans. The remaining tissues were combined and analysed to enable uptake and environmental radiological doses to be assessed. Although in international studies, the edible flesh is generally measured to determine radiation dose or ingestion of trace metals, the effects of preparation and cooking techniques are rarely assessed. In this study, cooking and preparation techniques that may influence the radiological dose to humans were assessed. Eggs were also removed from a selected number of samples to assess the potential dose in sensitive developmental tissues and possible implications for environmental effects. Order of magnitude differences in 210Po activity concentrations and Cd concentrations were observed between whole animals and the edible flesh of Australian caught King (Melicertus spp.) and Tiger (Penaeus spp.) prawns, with the hepatopancreas primarily responsible for this difference. Most 210Po was unsupported by 210Pb and activity concentrations of all other radionuclides measured (137Cs, 210Pb, 226Ra, 232Th, and 238U) were very low. The major contribution to radiation dose via the ingestion pathway and to the organism itself was from 210Po. Cooking techniques that may lead to leaching of 210Po from the hepatopancreas could substantially increase the radiological dose from ingestion of this isotope. Organism dose estimates using different input assumptions in the radiological assessment tool “ERICA”, including site-specific tissue activity concentrations with site- or region-specific media concentrations, were compared with ERICA default distribution coefficients (Kd) and concentration ratios.

Al2O3:C optically stimulated luminescence dosimetry for evaluation of potential factors contributing to entrance skin doses received by liver cancer patients undergoing Transarterial Chemoembolization

Transarterial Chemoembolization (TACE) has been accepted as an effective technique that can be practically used for liver cancer treatment due to its outstanding benefits for patients with large, infiltrative, and multifocal tumors that cannot be surgically removed. However, this invasive image-guided technique may potentially result in higher radiation doses than general diagnostic radiology. Radiation-induced skin injury caused by excessive exposure to X-rays during fluoroscopically guided procedures has been previously reported. Therefore, dose assessment during TACE examination is relevant to minimize radiological hazards and reduce patient distress.The study aims to 1) quantify the magnitude of radiation doses received in TACE treatments, 2) evaluate potential factors contributing to an increase of the entrance skin dose, and 3) demonstrate an improved image-guided procedure for reducing radiation doses while maintaining high X-ray image quality. The study was carried out employing an anthropomorphic phantom to determine radiation dose using a standard commercial optically stimulated luminescence dosimeter (OSLD). Experimental data was collected from 370 patients under three specific image-guided techniques. They include 1) abdomen frontal 3 fps procedure where a pathway of blood flow was created using an image acquisition rate of three frames per second (fps), 2) navigation where a blood vessel roadmap was created with subtraction of bones and organs, and 3) fluoroscopy where X-ray beams were continuously delivered to a target for creating real-time images with no interference removed. Analysis of variance was used to demonstrate the difference of the mean entrance skin doses (ESDs) among the three imaging techniques. A multiple regression model was also used to investigate potential factors contributing to the increased ESDs.The study confirms that the ESDs received by TACE patients using these three imaging techniques are not significantly different. Moreover, the statistical-based model shows that the five main factors obtained from the exposure parameters and patient dosimetric data contribute to the patient ESDs. They include 1) the dose area product (DAP), 2) fluoroscopy time, 3) X-ray tube voltage, 4) X-ray tube current, and 5) total diagnostic images. All information is reported based on the machine DICOM-RDSR (Digital Imaging and Communication in Medicine – Radiation Dose Structured Report) data after completed examinations. Finally, the ANOVA test confirms that this simplified model can be used to estimate the radiation doses received by TACE patients, accounting for a 95% confidence interval.

Correlation between X-ray tube current exposure time and X-ray photon number in GATE.

X-ray image quality relies heavily on the emitted X-ray photon number which depends on X-ray tube current and exposure time. To accurately estimate the absorbed dose in an imaging protocol, it is better to simulate the X-ray imaging with a Monte Carlo platform such as GATE (Geant4 Application for Tomographic Emission). Although input of GATE is the X-ray photon number of the simulated X-ray tube, it lacks a good way to setup the photon number for a desired X-ray tube current setting. To provide a method to correlate the experimental X-ray tube current exposure time and the X-ray photon number in GATE. The accumulated radiation dose of a micro-computed tomography (CT) X-ray tube was recorded at different current exposure times with a general-purpose ion chamber. GATE was used to model the experimental microCT imaging system and calculate the total absorbed dose (cGy) in the sensitive volume of the ion chamber with different X-ray photon numbers. Linear regression models are used to establish a correlation between the estimated X-ray photon number and the X-ray tube settings. At first, one model establishes the relationship between the experimentally measured dose and the X-ray tube setting. Then, another model establishes a relationship between the simulated dose and the X-ray number in GATE. At last, by correlating these two models, a regression model to estimate the X-ray output number from an experimental X-ray tube setting (mAs) is obtained. For a typical micro-CT scan, the X-ray tube is operated at 50 kVp and 0.5 mA for a 500 ms exposure time per projection (0.25 mAs). For these X-ray imaging parameters, the X-ray number per projection is estimated to be 3.613×106 with 1.0 mm Al filter. The findings of this work provide an approach to correlate the experimental X-ray tube current exposure time to the X-ray photon number in the GATE simulation of the X-ray tube to more accurately determine radiation dose for an imaging protocol.

Serial Bone Density Changes in Women Undergoing Pelvic (Chemo) Radiation: Results From the PARCER Trial

Pelvic irradiation leads to substantial dose to the pelvic girdle. However, bone density loss as a function of radiation therapy dose and time has not been investigated. This study was undertaken to evaluate such a dose-response relationship. Women undergoing pelvic radiation therapy for cervix cancer within a phase 3 trial were included. The study necessitated 2 computed tomography imaging sets acquired at least 12 months apart in patients with no evidence of relapse. All images were transferred to the treatment planning system to determine radiation dose and Hounsfield unit (HU). Across the entire lumbopelvic region (lumbar 1-5 [L1-5] vertebrae, pubic symphysis, femur, acetabulum, greater trochanter, and anterior-superior iliac spine) multiple regions were defined to measure radiation therapy dose and HU. Bone health was categorized as normal if >130 HU, osteopenic at 110 to 130 HU, and osteoporotic <110 HU at baseline and follow-up. Univariate analysis was performed to test the effect of various factors on HU. Further interaction among radiation therapy dose, time, and HU was assessed using a linear mixed model. Overall, 132 of 300 patients were eligible. The median age was 49 (42-56) years. With a prescription dose of 50 Gy, the L1 and L2 vertebrae received a median dose of 1.2 and 4 Gy, respectively, and L3-5 received 10 to 50 Gy. At 24 months, median HU loss at L4-5 was 45 HU (interquartile range, 34-77 HU). Out of the 132 patients, at baseline 96% had normal bone health. However, at the last follow-up, 3% of patients had normal bone health, 12% developed osteopenia, and 85% developed osteoporosis (P < .001). There were no patient- or treatment-related factors predicted for HU loss on univariate analysis. HU loss >60 to 70 was observed at >45 Gy at L5 vertebra (60-70 HU, P < .02) and >15 Gy at L4 vertebra (33 HU; P=.04). Dose-response relationship is observed between radiation dose and bone mineral density loss. Prospective studies are needed to corroborate these observations and design future interventions.

Using the genetic algorithm to detect kinetic parameters of thermoluminescence glow curves

The study estimates the kinetic parameters of the thermoluminescence (TL) glow curves by the genetic algorithm (GA) combined with finding the peak by interacting between the computer mouse and the screen. TL curve peak parameters are calculated by the peak shape (PS) or initial rise (IR) method according to the general order kinetics (GOK) model. TL curves are simulated using Python software and installed library packages. Trapping parameters of the obtained TL glow curves are evaluated through the figure of merit (FOM) values. The FOM values of the small showed that that this method is very suitable and promising as a tool that can be widely applied in the analysis and processing of TL curves. The results of the study will serve as the basis for detecting irradiated foods, determining the age of antiques, and determining radiation doses.

Evaluation of the Radiation Dose of an Embryo/Fetus during Lymphoscintigraphy (Sentinel Lymph Node Mapping) in Pregnant Patients with Breast Cancer

Purpose: To develop a method for evaluation of the radiation dose of an embryo/fetus during lymphoscintigraphy (sentinel lymph node mapping) in pregnant patients with breast cancer.Material and methods: Two pregnant women (aged 43 and 30) with breast cancer stage IIA (T2N0M0), during the second trimester of pregnancy. We used a lymphotropic colloidal radiopharmaceutical labeled with 99mTc. To evaluate the radiation dose of an embryo, each patient had 6 individual dosimeters, which were placed around the abdomen using an elastic bandage at equal distances around the abdomen. Additionally, we placed the 7th dosimeter, it was placed near the injection site (under the mammary gland). After installing individual dosimeters, radiocolloid was injected into the affected mammary gland at four points (periareolar). The administered activity of radiopharmaceutical was 32.5 MBq, and 51.5 MBq. Lymphoscintigraphy was performed 1 hour after injection. First patient underwent sector resection of the left breast with SLN biopsy. The second patient underwent right mastectomy with SLN biopsy and breast reconstruction surgery using a tissue expander.Results: Based on the results of the study, the dose rate was calculated, on the basis of which the fetal radiation doses were calculated in both patients. Comparison of the mathematical data of both patients shows that, the calculated and experimental values of radiation exposure to the fetus during the radionuclide study of sentinel lymph nodes practically coincide. The obtained data shows that during pregnancy (280 days) the embryo/fetus will accumulate a natural radiation background dose of 1960 μSv, which is 2 times higher than the dose from the radionuclide study of sentinel lymph nodes. Thus these results verify the safety of SLN biopsy technology in pregnancy.Conclusion: 1. Radionuclide diagnostic studies of pregnant women determine radiation doses to the embryo/fetus that do not cause any radiation-induced effects in the prenatal period, and the probability of the occurrence of stochastic radiation-induced effects is several times lower than the incidence of endogenous cancers. 2. Radionuclide examination of sentinel lymph nodes appears to be safe for the fetus when conducted in pregnant women diagnosed with breast cancer. 3. In Russian Federation this method is used for the first time in pregnant women with diagnosed breast cancer. This technology has not been previously described in Russian literature.

Determining Radiation Doses of Critical Normal Tissues for Stereotactic Body Radiotherapy (SBRT) of Central Lung Tumors

While respiratory motion is included in the definition of target volumes for lung SBRT, delineation of organs at risk (OARs) and dose calculation are typically performed on average intensity projection images (AIP). This approach often misses structural detail during contouring due to motion blurring on AIP. Including respiratory motion in the dose calculation for OARs will result in more accurate dose assessment, which is necessary to establish reliable dose-effect relationships, particularly for SBRT of central lung tumors with a high risk of critical side effects.For 17 centrally-located lung tumors, clinical 4DCT-based SBRT treatment plans (BED≥100 Gy in 76%) were created for both AIP and mid ventilation image (MidV, 30% breathing phase) and contour sets. Internal GTVs were produced via GTV propagation over all breathing phases. OARs were outlined on both AIP and MidV images according to RTOG 0813. Both plans were also recalculated on all 10 breathing phases and registered back deformably to the MidV to assess differences in the accumulated OAR doses over the full breathing cycle. MidV was selected over the AIP as the reference image for comparison as it does not suffer from motion blurring.Volumes were, on average, larger on AIP than MidV image sets for all OARs by 3-15% (P < 0.05 for heart, lungs, great vessels (GV)), except the esophagus. Mean differences ± SDs in the max doses (Gy) between respiration-averaged MidV and AIP plans were for proximal bronchial tree (PBT) 2.26 ± 2.11, heart 2.24 ± 2.89, GV 1.71 ± 1.12, esophagus 1.38 ± 1.1, spinal cord 1.11 ± 0.67, and trachea 0.71 ± 1.16. Doses were significantly different for heart Dmean/10cc/15cc (P = 0.03/0.03/0.04). Relative to MidV plans, AIP plans resulted in higher max doses for PBT in 11/17 (65%) plans, 9/17 (53%) for esophagus, GV and spinal cord, and 5/17 (29%) for heart and trachea. Max dose differences > 5 Gy were observed for GV and PBT in 2/17 (12%) and for heart in 3/17 (18%) of individual plans. Superior-inferior carina motion ranged from 0.32 to 0.73 cm. No significant correlations between dose differences and carina motion were identified.Though limited by a small sample size, this study represents a comprehensive assessment of OAR doses for SBRT planning of centrally located lung tumors including the effects of respiratory motion. We often observed only small differences in dose delivered to central OARs. However, clinically relevant differences ≥ 5 Gy were observed in individual patients for PBT, GV and heart, resulting in over- or underestimation of the actual OAR dose over the full breathing cycle when using AIP-based planning. We therefore recommend MidV image-based OAR dose assessment to develop reliable dose-effect relationships for central lung OARs.D.A. Cooper: None. L. Padilla: None. A. Watson: None. K. Neiderer: None. B. Smith: None. E. Weiss: Research Grant; NIH. royalties; UpToDate.

Understanding radiographic decision-making when imaging obese patients: A Think-Aloud study.

IntroductionThe incidence of obesity has been steadily rising over the last few decades and is having a significant impact upon the health system. In radiography, a particular challenge of imaging obese patients is implementing the as low as reasonably achievable (ALARA) principle when determining radiation dose, and technical and patient‐care adaptations. This study aimed to better understand the decision‐making strategies of experienced radiographers in determining imaging and exposure factor selection in the context of imaging obese patients.MethodsThis study employed a ‘think‐aloud,’ methodology, and eight experienced diagnostic radiographers working in clinical education were recruited to perform routine AP abdominal X‐ray projections on an anthropomorphic phantom. They were asked to simultaneously verbalise emerging thoughts as they considered positioning, exposure selection and image evaluation. This process was repeated with three different phantom sizes, each representing an increased BMI from ‘healthy,’ to, ‘morbidly obese.’ Audio recordings were transcribed and interpreted via Bowman’s (1997) theory of radiographic judgement and decision‐making.ResultsAnalysis of interview transcripts identified 12 key concepts considered by experienced radiographers. Differences in radiographic concepts were considered when imaging phantoms of different sizes was demonstrated. A shift from segmental (e.g. positioning) to more environmental factors (e.g. patient comfort) and an increase in the number of verbal considerations with increasing phantom size were identified. The shift in focus of decision‐making stages identified the greater need to consider contextual factors such as patient comfort and repeatability when imaging obese patients.ConclusionExperienced radiographers find imaging obese patients challenging and alter their perception of image quality to accommodate for patient presentation. The findings will help inform future research, practice guidelines and learning resources to provide optimal imaging and care for obese patients, especially for student education.

Methodology for determining radiation dose distribution of strontium-90 applicators for veterinary intraoperatory betatherapy

Betatherapy is a modality within brachytherapy that uses beta radiation applicators, which are used in the treatment of superficial injuries. With the advancement of therapeutic techniques, new clinical protocols in veterinary medicine will be established. In this sense, betatherapy appears as an important option for performing radiotherapy procedures and, consequently, further studies are necessary to define the clinical oncological protocols. Therefore, the aim of this study was to present a methodology for determining the dose distribution of beta radiation from strontium-90 (90Sr) applicators for use in intraoperative radiotherapy in veterinary medicine. Planar radiation dose distributions from three 90Sr applicators were analyzed using radiographic films, which were exposed to beams from sources at different exposure times. The optical density (O.D.) of the radiation field was verified with a digital densitometer. After scanning the films, using the ImageJ software, the brightness intensities (BI) for the radiation exposure fields were measured. The analysis of the radiation dose distribution of the betatherapy applicators, produced results similar to those already described in the literature. The use of the ImageJ software, as well as the O.D. obtained, helped in the analysis of dosimetric studies. The behavior of the dose-effect curves provided a better understanding of the homogeneity of the radiation field in the treatment plan and, therefore, the radiation dose distributions in the treatment fields indicate the use of these types of applicators in veterinary radiotherapy procedures.

Assessment of radiation dose level in farm soils of mission quarters, Wukari, Taraba State, Nigerian

The study has assessed the amount of radiation exposed to farm soils in mission quarters Wukari, Taraba State. Assessment of radiation dose level is very important, especially in soil since man depends on Soil for his food. Assessment of radiation will help to know the radiation dose in the soil. The objective of this work is to determine radiation dose in soils and to provide necessary information of human health risks associated with radioactivity in soil and its effects on plant materials as well as human being. Different soil samples were collected and the Radiation Alert Inspector EXP, was used to measure the level of radiation exposure in the soil samples. The results showed low amount of radiation dose level. The average dose values ranging between 0.035±0.097 to 0.333±0.289, an absorbed dose rate ranging between 3.50 x 10-8±0.097 to 3.33 x 10-7±0.289 and annual dose rate ranging between 0.059±0.097 to 0.758±0.289. These results revealed that the dose rates do not exceed the recommended values by International Commission on Radiological Protection (ICRP) is 1mSvyr1 for the general public. It is less and in compliance with the recommended radiation dose level. Therefore do not pose a significant health hazard. The radiation dose level has no negative effect on both the plants and the dwellers. Therefore the study area is safe for human activities.

Hybrid Operating Room System for the Treatment of Thoracic and Abdominal Aortic Aneurysms: Evaluation of the Radiation Dose Received by Patients.

In recent years, endovascular treatment of aortic aneurysms has attracted considerable attention as a promising alternative to traditional surgery. Hybrid operating room systems (HORSs) are increasingly being used to perform endovascular procedures. The clinical benefits of endovascular treatments using HORSs are very clear, and these procedures are increasing in number. In procedures such as thoracic endovascular aortic repair (TEVAR) and endovascular aortic repair (EVAR), wires and catheters are used to deliver and deploy the stent graft in the thoracic/abdominal aorta under fluoroscopic control, including DSA. Thus, the radiation dose to the patient is an important issue. We determined radiation dose indicators (the dose–area product (DAP) and air karma (AK) parameters) associated with endovascular treatments (EVAR and TEVAR) using a HORS. As a result, the mean ± standard deviation (SD) DAPs of TEVAR and EVAR were 323.7 ± 161.0 and 371.3 ± 186.0 Gy × cm2, respectively. The mean ± SD AKs of TEVAR and EVAR were 0.92 ± 0.44 and 1.11 ± 0.54 Gy, respectively. The mean ± SD fluoroscopy times of TEVAR and EVAR were 13.4 ± 7.1 and 23.2 ± 11.7 min, respectively. Patient radiation dose results in this study of endovascular treatments using HORSs showed no deterministic radiation effects, such as skin injuries. However, radiation exposure during TEVAR and EVAR cannot be ignored. The radiation dose should be evaluated in HORSs during endovascular treatments. Reducing/optimizing the radiation dose to the patient in HORSs is important.