Dose Calculator Research Articles

Synchrotron CT dosimetry for wiggler operation at reduced magnetic field and spatial modulation with bow tie filters.

The Australian Synchrotron Imaging and Medical Beamline (IMBL) uses a superconducting multipole wiggler (SCMPW) source, dual crystal Laue monochromator and 135 m propagation distance to enable imaging and computed tomography (CT) studies of large samples with mono-energetic radiation. This study aimed to quantify two methods for CT dose reduction: wiggler source operation at reduced magnetic field strength, and beam modulation with spatial filters placed upstream from the sample. Transmission measurements with copper were used to indirectly quantify the influence of third harmonic radiation. Operation at lower wiggler magnetic field strength reduces dose rates by an order of magnitude, and suppresses the influence of harmonic radiation, which is of significance near 30 keV. Beam shaping filters modulate the incident beam profile for near constant transmitted signal, and offer protection to radio-sensitive surface organs: the eye lens, thyroid and female breast. Their effect is to reduce the peripheral dose and the dose to the scanned volume by about 10% for biological samples of 35-50 mm diameter and by 20-30% for samples of up to 160 mm diameter. CT dosimetry results are presented as in-air measurements that are specific to the IMBL, and as ratios to in-air measurements that may be applied to other beamlines. As CT dose calculators for small animals are yet to be developed, results presented here and in a previous study may be used to estimate absorbed dose to organs near the surface and the isocentre.

Machine learning-enhanced stochastic uncertainty and sensitivity analysis of the ICRP human respiratory tract model for an inhaled radionuclide

The International Commission on Radiological Protection (ICRP) has developed the reference Human Respiratory Tract Model (HRTM), detailed in ICRP Publications 66 and 130, to estimate the deposition and clearance of inhaled radionuclides. These models utilize reference anatomical and physiological parameters for particle deposition (PD). Biokinetic models further estimate retention and excretion of internalized particulates, aiding the derivation of inhalation dose coefficients (DC). This study aimed to assess variability in deterministic131I biokinetic and dosimetry models through stochastic analysis using the updated HRTM from ICRP Publication 130. The complexities of the ICRP PD model were reconstructed into a new, independent computational model. Comparison with reference data for total PD fractions for reference worker, solely a nose breather, covering activity median aerodynamic diameters from 0.3μm to 20μm, showed a 1.04% relative and 0.7% absolute difference, demonstrating good agreement with ICRP deposition fractions. The deterministic DC module was reconstructed in Python and expanded for stochastic analysis, systematically expanding deposition components from HRTM and assigning probability distribution functions to uncertain parameters. These were integrated into an in-house stochastic radiological exposure dose calculator, utilizing latin hypercube sampling. A case of an occupational radionuclide intake was explored, in which biodistribution and committed effective DC (CEDC) were computed for131I type F, considering a lognormal particle size distribution with a median of 5μm. Results showed the published ICRP reference CEDC marginally exceeds the 75th percentile of observed samples, with log-gamma distribution as the best-fit probability distribution. A Random Forest regression model with SHapley Additive exPlanations was employed for sensitivity analysis to predict feature importance. The analysis identified the HRTM particle transport rates scaling factor, followed by the aerodynamic deposition efficiency in the alveolar interstitial region as the most impactful parameters. This study offers a unique stochastic approach on inhaled particulate metabolism, enhancing radiation consequence management, medical countermeasures, and dose reconstruction for epidemiological studies.

A multicentric, randomized, controlled clinical trial to study the impact of bedside model-informed precision dosing of vancomycin in critically ill children—BENEFICIAL trial

BackgroundVancomycin is a commonly prescribed antibiotic to treat serious Gram-positive infections in children. The efficacy of vancomycin is known to be directly related to the pharmacokinetic/pharmacodynamic (PK/PD) index of the area under the concentration–time curve (AUC) divided by the minimal inhibitory concentration (MIC) of the pathogen. In most countries, steady-state plasma concentrations are used as a surrogate parameter for this target AUC/MIC, but this practice has some drawbacks. Hence, AUC-based dosing using model-informed precision dosing (MIPD) tools has been proposed for increasing the target attainment rate and reducing vancomycin-related nephrotoxicity. Solid scientific evidence for these claimed benefits is lacking in children. This randomized controlled trial aims to investigate the large-scale utility of MIPD dosing of vancomycin in critically ill children.MethodsParticipants from 14 neonatal intensive care, pediatric intensive care, and pediatric hemo-oncology ward units from 7 hospitals are randomly allocated to the intervention or standard-of-care comparator group. In the intervention group, a MIPD dosing calculator is used for AUC-based dosing, in combination with extra sampling for therapeutic drug monitoring in the first hours of treatment, as compared to standard-of-care. An AUC24h between 400 and 600 is targeted, assuming an MIC of 1 mg/L. Patients in the comparator group receive standard-of-care dosing and monitoring according to institutional guidelines. The primary endpoint is the proportion of patients reaching the target AUC24h/MIC of 400–600 between 24 and 48 h after the start of vancomycin treatment. Secondary endpoints are the proportion of patients with (worsening) acute kidney injury during vancomycin treatment, the proportion of patients reaching target AUC24h/MIC of 400–600 between 48 and 72 h after the start of vancomycin treatment, time to clinical cure, ward unit length-of-stay, hospital length-of-stay, and 30-day all-cause mortality.DiscussionThis trial will clarify the propagated benefits and provide new insights into how to optimally monitor vancomycin treatment in critically ill children.Trial registrationEudract number: 2019–004538-40. Registered on 2020–09-08ClinicalTrials.gov NCT046666948. Registered on 2020–11-28

Adapting general anaesthesia for a patient with class III obesity and obstructive sleep apnoea undergoing day case laparoscopic cholecystectomy: A case report.

This report describes the anaesthesia provided for a class III obese patient with obstructive sleep apnoea, undergoing an elective laparoscopic cholecystectomy. Several adaptations were required to provide safe anaesthesia. A McGrath video laryngoscopy was utilised for intubation. The patient was positioned in the ramped position, thereby increasing time to desaturation on induction of anaesthesia. Pressure controlled ventilation - volume guaranteed mode was selected for ventilation to provide consistent tidal volumes. An increased level of positive end-expiratory pressure was utilised to minimise atelectasis. Drug doses were carefully considered and calculated with the aid of The Society for Obesity and Bariatric Anaesthesia dose calculator. The airway management adaptations provided an unobstructed view for intubation. Peak airway pressures during surgery remained within safe limits and no atelectasis was evident postoperatively. Pain was kept under control and desaturation was avoided during postanaesthetic care. The patient was discharged home later that evening.

Evaluation of the predictive performance of an online voriconazole dose calculator in children.

The dosing of voriconazole is challenging in pediatrics. One approach to improve the dosing is through the use of Bayesian concentration-guided dosing software. Our study assessed the predictive performance of a freely available online voriconazole dose calculator in pediatric patients "NextDose" ( https://www.nextdose.org/ ). Per each dose calculator, we predicted voriconazole concentrations. We did both a priori and a posteriori Bayesian predictions. A total of 51 patients were included in this study. For a priori predictions, bias was + 26% while imprecision was 70%. For a posteriori predictions, bias and imprecision were 0.01% and 46%. In conclusion, the available online dose calculator was overpredicting the concentrations before voriconazole observations were available. However, with just one measured concentration, the predictions improved with minimal bias and an acceptable level of imprecision. There is a need for more prospective studies evaluating the use of voriconazole dosing calculators in the pediatric population to assess if they can improve the achievement of therapeutic target concentrations compared to standard of care.

An automated dispensing cabinet alert influences anesthesia provider medication preparation in a remifentanil waste reduction initiative

Study ObjectiveTo decrease the occurrence of remifentanil waste of 1 mg or more (1 full vial) by 25 % in our surgical division while maintaining satisfaction of 60 % of providers by using a remifentanil mixing workflow. DesignA time series–design quality improvement initiative targeted preventable remifentanil waste. A period of active interventions, followed by a pause and reinstatement of a system intervention, was used to validate its effectiveness. SettingAn academic medical center in the US with 1219 inpatient beds, performing 144,418 surgical cases in 2019 and 127,341 surgical cases in 2020, in 148 operating rooms. InterventionsIndividual- and system-level interventions provided education on the issues of preventable waste, access to a remifentanil dose calculator, and an automated dispensing cabinet (ADC) alert to halt wasteful practice. MeasurementsPreventable remifentanil waste was identified as disposing of intravenous infusion bags containing 1 mg or more or 1 full vial or more of unused medication. Data were retrieved from ADC reports. A preimplementation and postimplementation survey of anesthesia providers assessed workflow attitudes, perceptions, and satisfaction surrounding remifentanil mixing. Main ResultsPreventable remifentanil waste (≥1 mg or ≥ 1 full vial) decreased significantly from 22.0 % of cases using remifentanil at baseline to 16.7 % of cases using remifentanil (odds ratio, 0.71; 95 % CI, 0.60–0.84; P < .001) during the final data collection. Individual-level interventions of education, remifentanil dose calculator, and practice champions did not significantly affect waste while unpaired from the system intervention of the ADC alert. ConclusionsThe implementation of an ADC alert reduced preventable remifentanil waste among anesthesia providers.

Creation of a novel vancomycin dosing protocol in the electronic medical record and the use of analytics to show improved patient safety

AbstractVancomycin dosing guidelines recommend using first‐order analytic calculations or Bayesian software along with two drug concentrations at steady state to confirm an area under the serum concentration versus time curve (AUC24), which is safe and efficacious for the treatment of serious methicillin‐resistant Staphylococcus aureus (MRSA) infections. Evidence supporting optimal vancomycin dosing for empiric or nonserious MRSA infections is sparse. A systemwide vancomycin dosing protocol applying the latest guidelines and a novel dosing strategy to estimate AUC was created by a large, multicenter healthcare organization. A dosing calculator was embedded in the electronic medical record, and an analytics tool was created to monitor the incidence and predictors of vancomycin‐associated acute kidney injury (VA‐AKI). The incidence of VA‐AKI was tracked over time and between hospitals to identify opportunities to reduce variation. This article describes the implementation of the vancomycin protocol and the use of informatics to ensure patient safety.

Optimize and Thrive: An Electronic Health Record Optimization Program Case Study.

Although electronic health record optimization programs are common in healthcare organizations, a dearth of published evaluations of these programs exists. Little is known about the ability of optimization programs to handle flooding requests for change and achieve their objectives of cost savings, value, quality of care, and efficiency. This program evaluation reviewed one organization's electronic health record clinical optimization program. The evaluation examines the implementation of the insulin dosing calculator project at five hospitals within a large nonprofit healthcare organization using interviews, project documents, reported insulin dosing errors, and workflow observation to determine if the program provides sufficient structure and processes to successfully implement large optimization projects and achieve the project's desired outcomes. This evaluation finds that the optimization program processes support the implementation of large projects. The program can improve the planning of human resources to increase productivity and reduce waste. A clearer definition of meaningful project outcomes at the onset would allow the program to measure and communicate its accomplishments across the organization.

Determination of Diagnostic Reference Level in Dose-Area Product (DAP) and Evaluation of Dosimetry in Chest x-ray Examination at Bingerville Mother-Child Hospital, Cote D’Ivoire

X-rays have an undeniable advantage in medicine, especially for diagnosis. However, their use is not without risk. Following numerous studies carried out by the International Atomic Energy Agency and learned societies, it has been recommended to strengthen the principle of optimization in diagnostic radiology by implementing Diagnostic Reference Levels. The purpose of this study is to determine diagnostic reference levels (DRLs) in order to evaluate radiological practices and to reduce doses received by patients for frontal chest examination at the Bingerville Mother-Child Hospital (MCH). The work was carried out on a sample of 110 patients at the Mother and Child Hospital in Bingerville. We used a generator and a tube for the production of X-rays. The dose-area product (DAP) value was obtained using a dose calculator built into the generator. The determination of the DRLs in DAP (cGy.cm²) was made with the 75th percentile statistical method and yielded the following result of 14.32 cGy.cm². Comparing our DRL value with those obtained elsewhere, as well as comparing the median DAP from the present study with the DRLs in Abidjan and at the national level, radiological practices are satisfactory for frontal chest examination. However, after analysis of some radiological parameters used, it appears that efforts need to be made by acting on the kV, mAs, diaphragm and the filtration.

Radiation exposure of patients from computed tomography for COVID-19 diagnosis

BackgroundDuring the global Coronavirus Disease 2019 (COVID-19) pandemic, numerous computed tomography (CT) scans were conducted to assess pulmonary abnormalities associated with COVID-19. A number of studies have contributed to our current understanding of radiation doses in the context of chest CT scans for COVID-19 diagnosis, but there remains a discernible gap in the literature regarding organ-level dose assessments. Materials and methodsWe estimated organ and effective dose for the COVID-19-related chest CT patients in the following three steps. First, we collected CTDIvol and DLP from the literature published during and after COVID-19 pandemic period. Second, we developed the probability density functions (PDFs) for the CTDIvol and the starting location of CT scans by age groups from which 1000 sets of patient and technique parameters were created. With CT organ dose calculation software, National Cancer Institute dosimetry system for CT (NCICT), we calculated 1000 sets of plausible organ and effective doses and evaluated summary statistics for the patient population. ResultsThe standard dose protocol administered approximately five times higher CTDIvol (5.4 mGy) to patients undergoing COVID-19-related chest CT scans compared to the low dose protocol (1.1 mGy). The median lung dose (11.8 mGy) for the 1-year-old patients was about 1.5 times greater than that (7.8 mGy) of the adult patients. We found that 75% of whole COVID-19-related CT patients would have received effective doses less than 6.4 mSv and 1.5 mSv when scanned by standard dose and low dose protocols, respectively. ConclusionWe evaluated the distribution of organ and effective dose for the COVID-19-related chest CT patients worldwide by collecting comprehensive data of CTDIvol for the COVID-19-related chest CT scans from the literature and combining them with NCICT organ dose calculator. While past studies have predominantly reported basic CT dose descriptors, our work takes it a step further by reporting organ-level doses and effective doses. Subsequent research endeavors could involve enhancing the precision of radiation dose assessment through the collection of a subset of electronic CT records.

A Randomized Trial Comparing Standard of Care to Bayesian Warfarin Dose Individualization.

The quality of warfarin treatment may be improved if management is guided by the use of models based upon pharmacokinetic-pharmacodynamic theory. A prospective, two-armed, single-blind, randomized controlled trial compared management aided by a web-based dose calculator (NextDose) with standard clinical care. Participants were 240 adults receiving warfarin therapy following cardiac surgery, followed up until the first outpatient appointment at least 3 months after warfarin initiation. We compared the percentage of time spent in the international normalized ratio acceptable range (%TIR) during the first 28 days following warfarin initiation, and %TIR and count of bleeding events over the entire follow-up period. Two hundred thirty-four participants were followed up to day 28 (NextDose: 116 and standard of care: 118), and 228 participants (114 per arm) were followed up to the final study visit. Median %TIR tended to be higher for participants receiving NextDose guided warfarin management during the first 28 days (63 vs. 56%, P = 0.13) and over the entire follow-up period (74 vs. 71%, P = 0.04). The hazard of clinically relevant minor bleeding events was lower for participants in the NextDose arm (hazard ratio: 0.21, P = 0.041). In NextDose, there were 89.3% of proposed doses accepted by prescribers. NextDose guided dose management in cardiac surgery patients requiring warfarin was associated with an increase in %TIR across the full follow-up period and fewer hemorrhagic events. A theory-based, pharmacologically guided approach facilitates higher quality warfarin anticoagulation. An important practical benefit is a reduced requirement for clinical experience of warfarin management.

Verification of the utility of the gonadotropin starting dose calculator in progestin-primed ovarian stimulation: A comparison of empirical and calculated controlled ovarian stimulation.

To validate the effectiveness of a gonadotropin starting dose calculator for progestin-primed ovarian stimulation (PPOS), we conducted a study comparing the outcomes of oocyte retrieval between a group assigned gonadotropin doses via the calculator and a control group, where doses were determined by the clinician's empirical judgment. Patients underwent controlled ovarian stimulation (COS) using the PPOS method, followed by oocyte retrieval. We assessed and compared the results of COS and oocyte retrieval in both groups. Additionally, we examined the concordance rate between the number of oocytes actually retrieved and the target number of oocytes in each group. The calculated group demonstrated a significantly higher number of preovulation follicles and a higher ovarian sensitivity index than the control group. Furthermore, the discrepancy between the target and actual number of oocytes retrieved was notably smaller in the calculated group. The concordance rate between the target and actual number of oocytes was significantly greater in the calculated group. The gonadotropin starting dose calculator proved to be effective within the PPOS protocol, offering a reliable method for predicting the approximate number of oocytes to be retrieved, irrespective of the COS protocol employed.

Use of Computerized Physician Order Entry with Clinical Decision Support to Prevent Dose Errors in Pediatric Medication Orders: A Systematic Review.

Prescribing is a high-risk task within the pediatric medication-use process and requires defenses to prevent errors. Such system-centric defenses include electronic health record systems with computerized physician order entry (CPOE) and clinical decision support (CDS) tools that assist safe prescribing. The objective of this study was to examine the effects of CPOE systems with CDS functions in preventing dose errors in pediatric medication orders. This study followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 criteria and Synthesis Without Meta-Analysis (SWiM) items. The study protocol was registered in PROSPERO (CRD42021277413). The final literature search on MEDLINE (Ovid), Scopus, Web of Science, and EMB Reviews was conducted on 10 September 2023. Only peer-reviewed studies considering both CPOE and CDS systems in pediatric inpatient or outpatient settings were included. Study selection, data extraction, and evidence quality assessment (JBI critical appraisal tool assessment and GRADE approach) were carried out by two individual reviewers. Vote counting method was used to evaluate the effects of CPOE-CDS systems on dose errors rates. A total of 17 studies published in 2007-2021 met the inclusion criteria. The most used CDS tools were dose range check (n = 14), dose calculator (n = 8), and dosing frequency check (n = 8). Alerts were recorded in 15 studies. A statistically significant reduction in dose errors was found in eight studies, whereas an increase of dose errors was not reported. The CPOE-CDS systems have the potential to reduce pediatric dose errors. Most beneficial interventions seem to be system customization, implementing CDS alerts, and the use of dose range check. While human factors are still present within the medication use process, further studies and development activities are needed to optimize the usability of CPOE-CDS systems.

Impact of a Mobile App (LoAD Calc) on the Calculation of Maximum Safe Doses of Local Anesthetics: Protocol for a Randomized Controlled Trial.

Local anesthetics (LAs) are regularly used to alleviate pain during medical or surgical procedures. Their use is generally considered safe, but exceeding the maximum recommended doses can lead to LA systemic toxicity, a rare but potentially lethal complication. Determining maximum safe doses is therefore mandatory before performing local anesthesia, but rules are often unclear and the factors affecting dose calculation are numerous. Mobile health apps have been shown to help clinical decision-making, but most currently available apps present significant limitations. The Local Anesthetics Dose Calculator (LoAD Calc) app was designed to overcome these limitations by taking all relevant parameters into account. Before deploying this app in a clinical setting, it should be tested to determine its effectiveness and whether clinicians would be willing to use it. The primary objective will be to evaluate the effectiveness of the LoAD Calc app through written simulated cases. The secondary objective will be to determine whether physicians find this app easier, faster, and safer than the methods they generally use. We describe a parallel-group randomized controlled trial protocol. Anesthesiologists working at the Geneva University Hospitals will be invited to participate. Participants will be asked to compute the maximum dose of LA in 10 simulated clinical cases using 3 different LAs. The maximum safe dose will be determined manually using the same calculation rules that were used to develop LoAD Calc, without using the app itself. An overdose will be considered any dose higher than the correct dose, rounded to the superior integer, while an underdose will be defined as the optimal calculated dose minus 20%, rounded to the inferior integer. Randomization will be stratified according to current position (resident vs registrar). The participants allocated to the LoAD Calc (experimental) group will use the LoAD Calc app to compute the maximum safe LA doses. Those allocated to the control group will be asked to use the method they generally use. The primary outcome will be the overall overdose rate. Secondary outcomes will include the overdose rate according to ideal and actual body weight and to each specific LA, the overall underdose rate, and the time taken to complete these calculations. The app's usability will also be assessed. A sample size of 46 participants will be needed to detect a difference of 10% with a power of 90%. Thus, a target of 50 participants was set to allow for attrition and exclusion criteria. We expect recruitment to begin during the winter of 2023, data analysis in the spring of 2024, and results by the end of 2024. This study should determine whether LoAD Calc, a mobile health app designed to compute maximum safe LA doses, is safer and more efficient than traditional LA calculation methods. PRR1-10.2196/53679.

Evaluation of organ and effective doses using anthropomorphic phantom: A comparison between experimental measurement and a commercial dose calculator

IntroductionThe aim of this study was to experimentally measure organ doses for computed tomography (CT) procedures using thermoluminescence dosimeters (TLDs) on a RANDO anthropomorphic phantom and verify the measured doses using CT-Expo software. MethodsThe phantom was irradiated using clinical CT scan protocols routinely used for specific procedures in the radiology department. Fifty TLD chips were used in this study. The scanning parameters (kVp, mA, s) used to scan the phantom were used as input parameters for CT-Expo dose estimations. ResultsThe TLD measured organ doses varied between 3.97 mGy for the esophagus and 56.22 mGy for the brain. High doses were recorded in the brain (37.80–56.22 mGy) and the eye lens (29.94–36.16 mGy). Comparing the organ dose measurements between TLD and CT-Expo, the maximum organ dose difference was obtained for the eye lens. A comparison between the two methods for the other organs were all less than 32 %. The effective doses from the TLD measurements for the head, chest, and abdominopelvic CT examinations were 2.78, 6.67, and 17 mSv, respectively and CT-Expo were 2.20, 10.30, and 16.70 mSv, respectively. ConclusionThe experimental and computational results are comparable, and the reliability of the TLD measurements and CT-Expo dose calculator has been proven. Implications for studyA reason for the difference in dose measurements between the two methods has been attributed to the dissimilarity in the organ position in the Rando anthropomorphic phantom and the standard mathematical phantom used by CT-Expo. The experimental and computational results have been found to be comparable.

Automated Workflow for Calculating the Collective and Average Effective Doses of Galactic Cosmic Radiation Received by Pilots in Taiwan from 2006 to 2021.

On the basis of statistical data obtained from publicly available annual civil aviation reports, we developed an automated workflow for estimating the overall radiation exposure of aircraft pilots caused by galactic cosmic radiation. The workflow comprises several data-processing scripts that work with the batch analysis capability built in the NTHU Flight Dose Calculator . This method can quickly provide best possible estimates of the annual collective and average effective doses received by pilots of various airlines because all passenger, cargo, and charter flights operated that year were considered rather than some selected flights. The workflow and its implementation as well as analysis of results for the period of 2006-2021 are discussed herein. The results revealed that in 2019, six airlines in Taiwan operated 479 separate flight segments with 226 aircraft. The collective effective dose received by all 2,986 pilots was approximately 5,536 person-mSv; hence, the average individual effective dose was 1.85 mSv. During the COVID-19 pandemic, the doses decreased by more than half. In 2020, the collective effective dose received by all 2,936 pilots decreased sharply to 2,527 person-mSv, corresponding to an average effective dose per pilot of only 0.86 mSv. During 2006-2019, the annual average effective dose per pilot in Taiwan was between 1.65 and 2.71 mSv, and the average effective dose rate per flight hour was 3.15 μSv h. -1.

A New Software for the Calculation of Eye-lens Dosimetry Quantities Based on Dose-rate Coefficients.

In the last decade, the International Commission on Radiological Protection recommended a reduction in the annual limits to the dose to the lens of the eye from 150 mSv to 20 mSv y-1, averaged over defined periods of 5 y, with no single year exceeding 50 mSv. To assist the health physics community in this task, many groups have calculated protection and operational fluence dose coefficients. This led to the publication of multiple coefficient tables that were calculated for arrays of different parameters, including particle type, angle of incidence, target phantom models, presence or absence of secondary charged particle equilibrium, etc. The coefficients available in the literature include protection dose values calculated in a realistic eye model and operational values calculated in a simplified cylindrical head phantom at a point 3 mm below the surface. This paper reports on a simple Windows™ application that was written to aid health physics professionals in accessing and using the large body of available protection and operational eye-lens data. The application is called the Eye-Lens Dose Calculator, as it also performs calculations of the eye-lens dose for radionuclides, where the complete emissions of the selected radionuclides are considered. Test cases show that there is good agreement between the calculated protection and operational dose quantities when radionuclide emission characteristics are considered.

Novel method for calculating the effective dose using size-specific dose estimates conversion factors in abdomen-pelvis computed tomography.

We propose a novel method for calculating the effective dose that closely reflects the individual attenuation, utilizing two conversion coefficients. A total of 180 adult patients who underwent abdomen-pelvis computed tomography were categorized into six groups based on sex and body type. The effective dose was calculated by multiplying the dose-length product with the effective dose conversion coefficient and the size-specific dose estimate conversion factor. The effective dose calculated using a simulation-based dose calculator (WAZA-ARI) was employed as the reference value. The following values, obtained through both methods, were compared within each category: distribution of the effective dose, median effective dose, and relative difference in median effective dose across additional body mass index (BMI) categories. For male patients, no significant disparity was observed in the median effective doses calculated using the two methods. The relative differences in median effective doses across additional BMI categories ranged from -5 to 6%. Conversely, among female patients, the median effective dose calculated using our method slightly undercut that calculated using WAZA-ARI, with relative differences ranging from -16 to -9%. Additionally, relative differences in median effective dose across additional BMI categories ranged from -18 to -7%. The median effective dose differed slightly depending on the calculation method because of the different reference phantoms applied in dose calculations. Our proposed method is sensitive to individual size and helps compute a size-specific effective dose.

Application of a warfarin dosing calculator to guide individualized dosing versus empirical adjustment after fixed dosing: a pilot study.

Background: Warfarin has a narrow therapeutic window and individual variation, and patients require regular follow-up and monitoring of the International Normalized Ratio (INR) for dose adjustment. The calculation method of Warfarin Dosing Calculator (WDC) software is based on the European and American populations, and its accuracy in the Chinese population is yet to be verified. Objective: This study was to evaluate the feasibility of applying Warfarin Dosing Calculator software intervention in a real-world clinical research setting in China. Methods: The pilot study divided the included patients after valve replacement into an experimental group and a control group, with 38 cases in each group. In the control group, the initial dose was fixed at 2.5mg/d and the dose was adjusted empirically during the study period; in the experimental group, the Warfarin Dosing Calculator software was applied to guide the dosing, and patients in both groups were followed up for 3months. Analysis of the incidence anticoagulation outcomes and excessive anticoagulation events in both groups. Kaplan-Meier survival curves were used to analyze the correlation between different dosing regimens and first International Normalized Ratio attainment, and Logrank tests were performed. Results: The mean time required for first International Normalized Ratio compliance in the experimental group was 4.38days less than in the control group, and the mean number of tests was 1.43 less (p < 05). Time in therapeutic range (TTR) was significantly higher in the experimental group than in the control group (p < 05). Kaplan-Meier survival curve analysis showed that the first International Normalized Ratio attainment rate was significantly higher in the experimental group than in the control group (p = 01). No major bleeding events occurred in either group, but other excessive anticoagulation events (INR>3.5 and minor bleeding) were significantly reduced in the experimental group compared with the control group (p < 05). Conclusion: Application of Warfarin Dosing Calculator software to guide individualized warfarin dosing may be better than a fixed dose of 2.5mg/d. It may be shorten the time to first International Normalized Ratio attainment, and the attainment rate in the same time, and can better improve the mean Time in therapeutic range level value and reduce excessive anticoagulation events, which improves the safety of warfarin anticoagulation therapy in clinical practice. Clinical Trial Registration: https://www.chictr.org.cn/showproj.html?proj=52793, ChiCTR2000032393.

NCIRF: an organ dose calculator for patients undergoing radiography and fluoroscopy

Background. It is critical to monitor the radiation dose delivered to patients undergoing radiography and fluoroscopy to prevent both acute and potential long-term adverse health effects. Accurate estimation of organ doses is essential to ensuring that radiation dose is maintained As Low As Reasonably Achievable. We developed a graphical user interface-based organ dose calculation tool for pediatric and adult patients undergoing radiography and fluoroscopy examinations. Methods. Our dose calculator follows the four sequential steps. First, the calculator obtains input parameters related to patient age and gender, and x-ray source data. Second, the program creates an input file describing the anatomy and material composition of a phantom, x-ray source, and organ dose scorers for Monte Carlo radiation transport using the user input parameters. Third, a built-in Geant4 module was developed to import the input file and to calculate organ absorbed doses and skeletal fluences through Monte Carlo radiation transport. Lastly, active marrow and endosteum doses are derived from the skeletal fluences and effective dose is calculated from the organ and tissue doses. Following benchmarking with MCNP6, we conducted some benchmarking calculations calculated organ doses for an illustrative cardeiac interventional fluoroscopy and compared the results with those from an existing dose calculator, PCXMC. Results. The graphical user interface-based program was entitled National Cancer Institute dosimetry system for Radiography and Fluoroscopy (NCIRF). Organ doses calculated from NCIRF showed an excellent agreement with those from MCNP6 in the simulation of an illustrative fluoroscopy exam. In the cardiac interventional fluoroscopy exam of the adult male and female phantoms, the lungs received relatively greater doses than any other organs. PCXMC based on stylistic phantoms overall overestimated major organ doses calculated from NCIRF by up to 3.7-fold (active bone marrow). Conclusion. We developed an organ dose calculation tool for pediatric and adult patients undergoing radiography and fluoroscopy examinations. NCIRF could substantially increase the accuracy and efficiency of organ dose estimation in radiography and fluoroscopy exams.