Organ Doses Research Articles

Evaluating Factors Affecting Mean Glandular Dose in Mammography: Insights from a Retrospective Study in Dubai

Background/Objective: This study evaluates the mean glandular dose (MGD) in mammography screening for women aged 40–69 in Dubai, based on a retrospective analysis of a dose survey involving 2599 participants. Methods: MGD was calculated using the Dance formula. Results: The average MGD was 0.96 ± 0.39 mGy for mediolateral oblique (MLO) views and 0.81 ± 0.33 mGy for craniocaudal (CC) views. Weak inverse correlations were found between age and organ dose (OD) for both views, while a direct relationship was observed between breast thickness and entrance skin dose (ESD). In adjusted models, ESD was strongly associated with MGD (β = 1.04, 95% CI: 0.97, 1.09), while OD showed a moderate association (β = 0.44, 95% CI: 0.40, 0.49). Significant variations in ESD, OD, and MGD were noted across age groups and breast thicknesses. Conclusions: Lower MGD indicates reduced radiation exposure risk, while higher MGD in MLO views suggests improved imaging quality. Monitoring and optimizing MGD are essential for enhancing patient safety and screening efficacy.

Monte Carlo Simulation of Organ Absorbed Dose of Worker's Radiation Exposure in Bone Scintigraphy

Objectives: This study examines individual organ doses and the impact of ionizing radiation sources on effective radiation doses. Methods: In the research, the ICRP-defined adult standing phantom was used as the phantom material in the Visual Monte Carlo Dose Calculation Program (VMC). Subsequently, the incurred doses were calculated by defining different doses, distances, and durations for the 99mTc radioactive source. Results: Exposure times were set at 5 minutes and 20 minutes in comparison. The results indicated that for 5 minutes and 20 minutes at 360 cm, doses remained below the ICRP recommended annual dose limit of 5.7 µSv/h for occupational exposure. Conclusion: Organ absorbed and effective doses varied with exposure time and source-phantom distance. To optimize radiation exposure, people working in radiation fields must make an increased effort to reduce radiation doses following the ALARA principles. Keywords: Effective dose, absorbed dose, VMC software, Monte Carlo

Simulation of the shielding effect of lead apron undergoing chest CT scan.

Lead aprons are used to reduce radiation dose to patients. As the distance between the lead apron and the edge of the scan range increases, organ dose is expected to decrease, but with increasing scattered radiation dose in the body. By simulation, this work aims at estimate whether the organ dose increases due to the scattered radiation in the body with lead apron. A standard-sized male and a female phantom is used to simulate organ doses of chest scans in various lead apron shielding situations. Simulations in this work considered different distance between the edge of the 0.35-mm lead apron and the edge of the scan range. For the female phantom, the dose to the gonads was significantly reduced (56% on average), but not as much as men (78% on average). However, the amount of dose reduction is small for male and female phantoms (0.0082mGy/100mAs and 0.0160mGy/100mAs).

Attempt to re-estimate organ doses of victims in non-homogeneous exposure accident by means of the state-of-the-art Mesh-type Reference Computational Phantom-a case study of an IR-192 source accident.

An attempt was made to estimate organ doses of a victim in a high-dose non-homogeneous exposure accident caused by a sealed 192Ir gamma-ray source. The Gilan accident was selected as a case study. Organ doses including testis, red bone marrow and so on were properly estimated by applying the Monte Carlo calculation with the state-of-the-art adult male Mesh type Reference Computational Phantom. By introducing a complicated exposure scenario, the dose distribution on the right chest of the victim in the Gilan accident could be reproduced to a certain extent.

CTNI-63. RHENIUM (186RE) OBISBEMEDA (RHENIUM NANOLIPOSOME,186RNL) FOR THE TREATMENT OF LEPTOMENINGEAL METASTASES (LM): SUMMARY OF THE PHASE 1 DOSE ESCALATION STUDY AND PHASE 2 ADMINISTERED DOSE SELECTION

Abstract BACKGROUND Leptomeningeal metastases (LM) is a devastating systemic cancer complication most often seen with breast, lung, and melanoma, with limited treatment options and poor survival. Rhenium (186Re) Obisbemeda (186RNL) provides the combination of effective therapeutic beta radiation, simultaneous gamma-decay for imaging, and ~90-hour physical half-life for optimal radiation delivery. A summary of the Phase 1 dose escalation study, expected to be completed, will be presented. METHODS ReSPECT-LM is a Phase 1 dose escalation study for patients with LM from any primary cancer. Adult patients are given a single dose of 186RNL via intraventricular catheter (Ommaya reservoir) in an outpatient setting to determine the maximum tolerated/feasible dose (MTD/MFD), safety, and tolerability. Seven administered dose cohorts in a 3 + 3 design, from 6.6 mCi to 109.96 mCi, were anticipated. RESULTS For the first 5 cohorts, doses were well-tolerated; most AEs were Grade 1 and 2 with 1 DLT (Cohort 5) at time of abstract submission. CSF tumor cell enumeration assays were performed with a maximum reduction over baseline seen at Day 28. Radiation absorbed doses were calculated for the ventricles, cranial subarachnoid space, and spinal fluid and showed a linear increase with administered dose, with liver and spleen remaining low. Neurological symptoms were reported to improve. We expect the Phase 1 conclusion and the RP2D to be determined for conference reporting; additionally, based on duration of benefit seen during the Phase 1, a multidose paradigm will be initiated to extend benefit. CONCLUSION A single dose of 186RNL for patients with LM has been well-tolerated, with high absorbed doses to the treatment area, acceptable organ doses, and promising clinical improvement and reductions in tumor cell count. Phase 2 is expected to begin enrollment by Q4 2024. Additionally, based on these data, a Phase 1 multidose study is planned to be initiated this year.

Estimation and analysis of S values for131I using pediatric mesh type reference computational phantoms.

This study examines the effect of paediatric mesh-type reference computational phantoms on organ S values resulting from radioiodine (131I) intake. Using Geant4, we estimated131I S values for 30 radiosensitive target tissues due to emission from the thyroid (Target ← Thyroid) in these phantoms. Our results show that S values differ between male and female phantoms of the same age and S values also decrease as phantom age increases. The male-to-female S value ratio typically varies within 10%, with larger differences observed for the esophagus, extra-thoracic regions, muscles, bladder, and sex organs. On average, S values for mesh phantoms are approximately 17% higher than those for voxel phantoms, with larger discrepancies for organs remodelled separately in mesh phantoms. The study provides organ S values for the paediatric population due to131I exposure from the thyroid, based on reference mesh-type computational phantoms, enhancing organ doses estimation in emergency situations and during radioiodine treatment.

EFFECTIVE DOSE ANALYSIS IN ABDOMEN AP EXAMINATION PATIENTS WITH CALDOSE_X VERSION 5.0

This study evaluates radiation dose exposure during diagnostic radiology procedures using X-rays and their potential risks, including cancer, to optimize radiation safety through the CALDose_X software that calculates the absorbed organ dose, effective dose, and cancer risk, according to the lowest possible achievable (ALARA) principle. This study used a quantitative experimental design to evaluate the impact of filter thickness variations on Entrance Surface Air Kerma (ESAK) and effective dose by analyzing data from 54 patients undergoing AP Abdominal X-ray examinations. The results showed that the effective dose to the abdominal organs varied with exposure factors and Focus to Detector Distance (FDD), where the colon wall had the highest sensitivity with doses ranging from 0.030 mSv to 0.126 mSv, followed by the stomach and pancreas. Increasing kV, mAs, and FDD increased the effective dose, emphasizing the importance of careful dose management. This study concluded that exposure factors and FDD affect the effective dose received by the abdominal organs, with recommendations to monitor patient doses, revise national diagnostic reference levels, and establish standard protocols with health authorities. Keywords: CALDose_X, X-ray Exposure Factor, patient dose, ESAK, Effective Dose, Abdomen AP.

Evaluation of radiation dose and cancer risk for paediatric digital radiography in a Moroccan hospital

Pediatric radiography is the first line of most diagnostic examinations and an effective tool that provides important information about the patient's health status.This study aims to investigate the Entrance Surface Dose (ESD) and organ doses for pediatric patients undergoing imaging procedures of the abdomen, chest, pelvis, and nasopharynx using Optically Stimulated Luminescence Dosimeters OSLDs and an anthropomorphic phantom.An ATOM pediatric 5-year-old phantom was imaged using a Digital Radiography (DR) based on similar conditions of routine radiography (exposure parameters kVp, mAs, SID: Source Image receptor Distance). The OSLDs were inserted at the appropriate sites to measure localized doses in the sensitive organs.The results showed that the entrance surface doses for the pediatric patients were 0.17 ± 0.03 mGy, 0.10 ± 0.00 mGy, 0.46 ± 0.00 mGy, and 0.42 ± 0.02 mGy, respectively, for the abdomen (AP), chest (AP), pelvis (AP), and nasopharynx (LAT). The range of organ doses were 0.05-0.45 mGy, 0.01-0.44 mGy, 0.13-1.05 mGy, and 0.084 -0.99 mGy for the abdomen, chest, pelvis, and nasopharynx examination, respectively. Effective doses (ED) were 0.088 ± 0.021 mSv, 0.011 ±0.004 mSv, 0.058 ±0.007 mSv, and 0.044 ±0.024 mSv for the abdomen, chest, pelvis, and nasopharynx examination, respectively.The likelihood of cancer, as determined by the ICRP health risk model with a rate of 500 cases per 10,000 person-Sv (5% per sievert), estimated that a 0.015 case of health risk (0.3 person-Sv × 5% per sievert) may in the future be attributable to four X-ray pediatric procedures conducted in 2022.The ESD, ED, and organ dose values are deemed acceptable compared to those reported in the literature. Although the risk of incidence and mortality from cancer during life is minimal, it should not be ignored.

Development of a novel automated algorithm for patient dosimetry in computed tomography: a step towards the facilitation of size-specific dose estimates and organs dosimetry estimations in a busy clinical workflow

Abstract Accurate dosimetry in computed tomography (CT) is essential for patient safety and effective radiation management. This study presents the development of an automated algorithm designed to enhance patient dosimetry by facilitating size-specific dose estimates (SSDE) and organ dose estimations. Utilizing a Python-based script, the proposed method integrates advanced image preprocessing, contour detection, and mathematical calculations to quantify key metrics from CT images. This automated approach addresses the limitations of manual measurement techniques. A retrospective analysis was conducted on CT axial images from examinations acquired with an 80-detector scanner. The algorithm processes DICOM images, converts pixel values to Hounsfield Units, applies Gaussian smoothing, windowing, and thresholding, followed by morphological operations to refine segmentation. It measures the water equivalent diameter (Dw) and estimates both region SSDE and organ doses, incorporating tissue attenuation. Validation was performed using an adult anthropomorphic ATOM phantom, with organ doses measured by optically stimulated luminescence dosimeters. The results demonstrated the algorithm's potential in estimating SSDE and organ doses. Validation of the automated method revealed strong correlations for Dw and SSDE between the proposed method and manual measurements of five expert reviewers ranging from 0.86 to 0.99 for determination coefficient. Comparative analysis of organ doses showed close agreement between results from experimental setup against the proposed algorithm. The automated algorithm estimated brain dose with a mean of 21.8 mGy, while measurements from the ATOM phantom and CT Expo indicated 19.74 mGy and 23.05 mGy, respectively. For lung doses, the automated algorithm estimated 12.5 mGy compared to 11.0 mGy from the ATOM phantom and 13.1 mGy from CT Expo. Liver doses were measured at 12.7 mGy by the automated method, versus 12.1 mGy from the ATOM phantom and 11.1 mGy from CT Expo. This study shows the potential of automated image analysis techniques in enhancing dosimetry accuracy in CT examinations.

Influence of X-ray spectrum and bowtie filter characterisation on the accuracy of Monte Carlo simulated organ doses: Validation in a whole-body CT scanning mode

PurposeFor patient-specific CT dosimetry, Monte Carlo dose simulations require an accurate description of the CT scanner. However, quantitative spectral information and information on the bowtie filter material and shape from the manufacturer is often not available. In this study, the influence of different X-ray spectra and bowtie filter characterisation methods on simulated CT organ doses is studied. MethodsUsing ImpactMC, organ doses of whole-body CTs were simulated in twenty adult whole-body voxel models, generated from PET/CT examinations previously conducted in these patients. Simulated CT organ doses based on the manufacturer X-ray spectra and bowtie filter data were compared with those obtained using alternative characterisation models, including spectrum generators and experimentally measured dose data. A total of four different X-ray spectra and one bowtie filter model were defined based on these data. ResultsFor all X-ray spectra and bowtie filter combinations, estimated CT organ doses are within 6% from those resulting from simulations with the CT characterisation models provided by the manufacturer. While varying the bowtie filter model results in CT organ dose differences smaller than 1%, dose differences up to 6% are observed when X-ray spectra are not based on the quantitative data from the manufacturer. ConclusionsEstimated organ doses slightly depend on the applied CT characterisation model. When manufacturer’s data are not available, half-value layer and dose measurements provide sufficient input to obtain equivalent X-ray spectra and bowtie filter profiles, respectively.

Diagnostic performance of digital tomosynthesis for postoperative assessment of acetabular fractures and pelvic ring injuries.

Digital tomosynthesis (DTS) has broad non-orthopaedic applications and has seen limited use within orthopaedics for imaging of the wrist. The utility of DTS for assessing reduction and hardware placement following operative treatment of pelvic ring injuries and acetabular fractures has not previously been investigated. All operatively treated acetabular fractures and pelvic ring injuries that underwent surgical fixation within a one-year time span received both a computed tomography (CT) scan and a DTS scan as part of their routine postoperative imaging workup. Three orthopaedic traumatologists independently reviewed the images for face-value clinical utility. Radimetrics and PCXMC software were utilized on a subset of the study population's DTS and CT studies to calculate the effective and organ radiation doses delivered. 52 patients (22 acetabular fractures, 22 pelvic ring injuries, 7 pelvic ring and acetabular fractures, 2 femoral head & acetabular fractures) were included. DTS was considered adequate to assess reduction 83% of the time, hardware position 83% of the time, and sufficient to replace the CT scan 67% of the time. DTS was associated with an 8.3 times lower effective radiation dose than CT. All organ doses were lower for DTS than CT. DTS appears to have face-value clinical utility for assessing reduction and hardware position following surgical treatment of acetabular fractures and pelvic ring injuries. Given that DTS is associated with significantly lower radiation doses to patients, further study utilizing more objective criteria is warranted.

Preclinical Aspects of [89Zr]Zr-DFO-Rituximab: A High Potential Agent for Immuno-PET Imaging.

An early diagnosis of cancer can lead to choosing more effective treatment and increase the number of cancer survivors. In this study, the preparation and preclinical aspects of [89Zr]Zr-DFO-Rituximab, a high-potential agent for PET imaging of Non- Hodgkin Lymphoma (NHL), were evaluated. DFO was conjugated to rituximab monoclonal antibody (mAb), and DFO-rituximab was successfully labeled with zirconium-89 (89Zr) at optimized conditions. The stability of the complex was assessed in human blood serum and PBS buffer. Radioimmunoreactivity (RIA) of the radioimmunoconjugate (RIC) was evaluated on CD20-overexpressing Raji cell line and CHO cells. The biodistribution of the radiolabeled mAb was studied in normal and tumorbearing rodents. Finally, the absorbed dose in human organs was estimated. The radiolabeled compound was prepared with radiochemical purity (RCP) >99% (RTLC) and a specific activity of 180±1.8 GBq/g. The RCP of the final complex PBS buffer and human blood serum was higher than 95%, even after 48 h post incubation. The RIA assay demonstrated that more than 63% of the radiolabeled compound (40 ng/ml, 0.5 mL) was bound to 5×106 Raji cells. The biodistribution of the final product in tumor-bearing mice showed a high accumulation of the RIC in the tumor site in all intervals post-injection. Tumor/ non-target ratios were increased over time, and longer imaging time was suggested. The dosimetry data indicated that the liver received the most absorbed dose after the complex injection. [89Zr]Zr-DFO-Rituximab represents a significant advancement in the field of oncological imaging and offers a robust platform for both diagnostic and therapeutic applications in the management of B-cell malignancies.

Construction of new polygon mesh-type phantoms based on adult Japanese voxel phantoms.

To construct adult Japanese phantoms applicable to individual exposure dose assessments, we created adult Japanese polygon mesh-type male (JPM) and female (JPF) phantoms through modification of the adult Japanese voxel phantoms, JM-103 (male) and JF-103 (female). The body sizes and masses of organs, tissues, and organ contents in JPM and JPF were adjusted to the Japanese averages, except for those unimportant for radiation protection or risks. The JPM and JPF data were converted to tetrahedral mesh-type data and incorporated into the Particle and Heavy Ion Transport code System (PHITS) for dose calculations. The dosimetric characteristics of the JPM and JPF phantoms were validated by calculating their effective doses in the anterior-posterior geometry for the external irradiation of photons with energies of 0.01-20 MeV and compared with those of JM-103 and JF-103 or the reference values given in ICRP Publication 116. The results confirmed no problems applying JPM and JPF to dose assessments in adult Japanese subjects. Furthermore, it was found that JPM and JPF can also accurately calculate the absorbed doses for entire organs and high radiosensitive cell regions with thin, small, and complicated structures.

The Australian paediatric brachytherapy experience: A pathway to a national programme.

Paediatric cancers are rare, and most children requiring radiation therapy receive external beam radiation (EBRT). Although EBRT may offer organ preservation compared to surgery, it can be associated with significant late effects. Image-guided brachytherapy is a highly specialised technique offering both organ preservation and dose conformity to minimise late toxicity. This is a retrospective mono-institutional review of paediatric brachytherapy in one of the largest paediatric centres in Australia. Outcomes and toxicities are presented as well as brachytherapy versus proton plan comparison in four patients. A total of 14 patients were treated with adjuvant brachytherapy between 2012 and 2022. The predominant histology was rhabdomyosarcoma, and all patients had pelvic tumours. High-dose rate (HDR) brachytherapy was given for 13 patients with one patient receiving low-dose rate (LDR) brachytherapy. Only one grade three late toxicity was reported and two patients developed metastatic disease within one year of completion of treatment. The brachytherapy plan was superior to protons in two of four patients and equivocal in one patient. This is the first Australian publication of a paediatric brachytherapy series from a single institution. This retrospective series demonstrates the feasibility and safety of brachytherapy in paediatric pelvic tumours. The initial work presented here demonstrates the value of a comprehensive radiation plan review in selecting the optimal modality for an individual paediatric patient.

First-in-human study of dosimetry, safety and efficacy for [177Lu]Lu-P15-073: a novel bisphosphonate-based radioligand therapy (RLT) agent for bone metastases.

Bisphosphonates are pivotal in managing bone tumors by inhibiting bone resorption. This study investigates the therapeutic potential of [177Lu]Lu-P15-073, a novel bisphosphonate, for radioligand therapy (RLT) in bone metastases. Ten patients (age 35 to 75) with confirmed bone metastases underwent therapy with a single dose of [177Lu]Lu-P15-073 (1,225 ± 84 MBq, or 33 ± 2 mCi). Prior to treatment, bone metastases were verified via [99mTc]Tc-MDP bone scans. Serial planar whole-body scans monitored biodistribution over a 14-day period. Dosimetry was assessed for major organs and tumor lesions, while safety was evaluated through blood biomarkers and pain scores. Serial planar whole-body scans demonstrated rapid and substantial accumulation of [177Lu]Lu-P15-073 in bone metastases, with minimal uptake in blood and other organs. The absorbed dose in the critical organ, red marrow, was measured at (0.034 ± 0.010 mSv/MBq), with a notably low normalized effective dose (0.013 ± 0.005 mSv/MBq) compared to other 177Lu-labeled bisphosphonates. Persistent high uptake in bone metastases was observed, resulting in elevated tumor doses (median 3.12Gy/GBq). Patients exhibited favorable tolerance to [177Lu]Lu-P15-073 therapy, with no new instances of side effects. Additionally, 87.5% (7/8) of patients experienced a significant reduction in pain scale (numerical rating scale, NRS, from 5.1 ± 2.3 to 3.0 ± 1.8). The tumor-background ratio (TBRmean) of [99mTc]Tc-MDP correlated significantly with [177Lu]Lu-P15-073 uptake (P < 0.01), indicating its potential for prediction of absorbed dose. This study demonstrates the safety, dosimetry, and efficacy of a single therapeutic dose of [177Lu]Lu-P15-073 in bone metastases. The treatment was well-tolerated with no severe adverse events. These findings suggest that [177Lu]Lu-P15-073 holds promise as a novel RLT agent for bone metastases.

Comparing organ and effective dose of various CT localizer acquisition strategies: A Monte Carlo study.

CT examinations commonly start with the acquisition of one or two localizer radiographs (2D localizers). Recently, a manufacturer introduced the option to perform a heavily filtrated low-dose helical scan as a localizer acquisition. To compare the dose of one or two 2D localizer acquisitions to the dose of a 3D localizer acquisition, one cannot simply compare the CTDIs of the different acquisition techniques, because of the use of different geometries and spectra. To compare the organ and effective dose for various CT localizer acquisition techniques. A Geant4-based Monte Carlo simulation, replicating a clinical wide-area CT scanner was developed and validated. Various localizer acquisition strategies were simulated: Anterior-posterior (AP) alone, PA alone, combined AP+lateral (LAT), and PA+LAT 2D localizers, and an Ag-filtered 3D localizer acquisition. Validation was performed by measuring and simulating CTDI100 in both the periphery and the center of a CTDI phantom. The software was subsequently used to estimate organ and effective doses for localizers for chest, abdomen+pelvis, and the combined chest, abdomen, and pelvis exams. As representations of patients, eight ICRP computational phantoms (adult, 15-, 10-, and 5-year, both male and female) and five female and five male XCAT phantoms with various BMIs were used. The dose of the various strategies was compared to the current clinically-implemented AP+LAT localizers. CTDI100-measurements and simulations within the CTDI-phantom differs by a maximum of 8.1% and by an average of 0.9%. For chest, the average effective doses for AP, PA, AP+LAT, and the 3D localizer are 0.10, 0.07, 0.32, and 0.22 mSv, respectively. The organ dose to the breast varies the most across the various localizer strategies and is, on average, 0.17, 0.03, 0.44, and 0.33 mGy, in the same order. For abdomen, the average effective doses are 0.11, 0.07, 0.36, and 0.25 mSv for the AP, PA, AP+LAT and the 3D localizer, respectively. The organ dose to the stomach varies the most across the various localizers and is on average 0.14, 0.08, 0.58, and 0.30 mGy, in the same order. The PA-only localizer results in the lowest organ dose to the most radiosensitive organs and the lowest effective dose. For the chest exam, compared to AP+LAT, the PA+LAT results in a 7±2% effective dose reduction (mean±standard deviation), while the 3D localizer results in a 21±3% effective dose reduction. Using AP or PA only would result in 69±2% and 76±2% reduction, respectively. For the abdomen exam, also compared to AP+LAT, PA+LAT results in 6±2% effective dose reduction, while the 3D localizer results in a 20±5% reduction. Using AP or PA only would result in 69±5% and 76±4% reduction, respectively. Using a PA localizer results in a lower or equivalent organ dose in the most radiosensitive organs, and a lower effective dose compared to an AP localizer for both chest and abdomen+pelvis exams. Compared to a two-localizer strategy, the 3D localizer results in a lower effective dose in both the chest and abdomen+pelvis region.

Radiation exposure of astronauts following an intense solar particle event: analysis and comparison of doses in male and female voxel phantoms.

According to NASA's plans, a human travel to the Moon is planned by the end of 2025 with the Artemis II mission, and humans should land on the Moon again in 2026. Exposure to space radiation is one of the main risks for the crew members; while for these short missions the doses from galactic cosmic rays would be relatively low, the possible occurrence of an intense solar particle event (SPE) represents a major concern, especially considering that in 2025 the Sun activity will be at its peak. Quantifying the amount and the effects of such exposure is therefore crucial, to identify shielding conditions that allow respecting the dose limits established by the various space agencies. By exploiting an interface between the BIANCA biophysical model and the FLUKA Monte Carlo radiation transport code, in this work we implemented a male and a female voxel phantom and we calculated absorbed doses and Gy-Eq doses in the various tissues/organs, as well as effective doses, following exposure to the August 1972 SPE, the most intense event of the modern era. The calculations were performed respect the organ dose limits for 30 d missions. A detailed comparison between male and female doses was then carried out, also considering that the Artemis II crew will include a woman. The results showed that female doses tend to be higher than male doses, especially with light shielding. This should be taken into account in mission design, also considering that, in a typical lunar mission, up to 15% of time may be spent in extra-vehicular activities, and thus with light shielding. More generally, this work outlines the importance of performing separate calculations for male and female astronauts when dealing with radiation doses and effects.

Cardiac Radiation Exposure and Incident Cancer: challenges and opportunities.

Use of radiological procedures has enormously advanced cardiology. People with heart disease are exposed to ionizing radiation. Exposure to ionizing radiation increases lifetime cancer risk with a dose-proportional hazard according to the linear no-threshold model adopted for radioprotection purposes. In the United States, the average citizen accumulates a median annual medical radiation exposure of 2.29 millisievert (mSv) per year per capita as of the radiologic year 2016, corresponding to the dose exposure of 115 chest X-rays. Cardiology studies often involve high exposures per procedure accounting for approximately 30% to 50% of cumulative medical radiation exposures. Malignancy is more incident in the most radiosensitive organs receiving the largest organ dose from cardiac interventions and cardiovascular imaging testing, such as the lung, bone marrow, and female breast. The latency period between radiation exposure and cancer is thought to be at least 2 years for leukemia and 5 years for all solid cancers, and differences are more likely to emerge in cardiology studies with longer follow-up and inclusion of non-cardiovascular endpoints such as cancer incidence. In cardiological studies, excess cancers are observed 3 to 12 years following exposure, with longer follow-up times showing greater differences in cancer incidence. The presumed associated excess cancer risk needs greater study. These exposures provide a unique opportunity to expand our knowledge of the relationship between exposure to ionizing radiation and cancer risk. Future trials comparing interventional fluoroscopy versus optimal medical therapy or open surgery should include a cancer incidence endpoint.

Image quality and radiation dose from pediatric abdomen-pelvis CT scans

Introduction: The aim of this study is to assess the organ doses, effective dose, image quality, and the potential risk of developing radiation-related cancer in children undergoing computed tomography (CT) scans of the abdomen-pelvis. Methods: The research involved 219 pediatric patients (129 males and 90 females) who underwent an abdomen-pelvic CT examination. The patients were categorized into four age groups: &lt;1, 1-4, 5-9, and 10-14 years old. The NCICT software version 3.0 was utilized to estimate the organ doses and effective dose. Estimation of cancer incidence risks were conducted according to the Biological Effects of Ionizing Radiation (BEIR) VII report. The image quality was evaluated by measuring the level of noise, as well as the signal-to-noise ratio, and contrast-to-noise ratio. Results: The colon received the highest organ dose in all age groups. The risk of all cancers was 75.38 per 100,000 for the &lt;1 age group, and it decreased to 56.10 for the 10-14 age group. The cancer risks were statistically higher for females (p &lt; 0.05). The mean noise values for the liver, aorta, and paraspinal muscle were found to be 9.08, 11.04, and 8.21, respectively. Conclusion: The findings of present study indicate that pediatric abdomen-pelvis CT examinations carry a potential risk of cancer that should not be disregarded. Consequently, it is crucial to prioritize radiation protection measures in children compared to adults.

Patient radiation risk reduction by controlling the tube start angle in single and dual source spiral CT scans: A simulation study.

Organ doses in spiral CT scans depend on the tube startangle. To determine the effective dose in single source CT (SSCT) and dual source CT (DSCT) scans as a function of tube start angle and spiral pitch value to identify the dose reduction potential by selecting the optimal startangle. Using Monte Carlo simulations, dose values for different tube positions with an angular increment of and a longitudinal increment of were simulated over a range of with collimations of , , and . The simulations were performed for the thorax region of six adult patients based on clinical CT data. From the resulting dose distributions, organ doses and effective dose were determined as a function of tube angle and longitudinal position. Using these per-view dose data, the individual organ doses, as well as the total effective dose, were determined for spiral scans with and without tube current modulation (TCM) with pitch values ranging from 0.5 to 1.5 for SSCT and up to 3.0 for DSCT. The dose of the best and worst tube start angle in terms of dose was determined and compared to the mean dose over all tube startangles. With increasing pitch and collimation, the dose variations from the effective dose averaged over all start angles increase. While for a collimation of , the variations from the mean dose value stay below for SSCT, we find that for a spiral scan with a pitch of 3.0 for DSCT with TCM and collimation of , the dose for the best starting angle is on average lower than the mean value and lower than the maximumvalue. Variation of the tube start angle in spiral scans exhibits substantial differences in radiation dose especially for high pitch values and for high collimations. Therefore, we suggest to control the tube start angle to minimize patientrisk.