Patient Radiation Dose Research Articles

Twelve-month outcome of robotic assisted PCI

Abstract Background Robotics in interventional cardiology (R-PCI) is a technique with high potential for optimising the outcome of patients with coronary heart disease. In order to compare R-PCI with conventional, manual PCI (M-PCI), it is necessary to analyse both the index procedure during the initial hospital stay and, in particular, the long-term outcome. Methods We report twelve-month follow up data of our prospective FRiK registry, started in mid 2021. This registry focuses on success rates and safety, radiation dose of patients and personnel as well as long-term outcome (after 6 and 12 months). Moreover, R-PCI is compared with M-PCI in these categories. Results 73 patients received R-PCI. PCI success rate was 100%, with 17.8% requiring manual assistance. Rate of complications (MACE - major adverse cardiovascular events) was 0%. Compared with 152 M-PCI patients, treated by the same interventionalists, there was a higher median procedural time (diagnostic and intervention) 102.5 (82.8-123.5) min vs. 73 (51-101.5) (p<0.001) and fluoroscopy time 18.3 (14.4-26.6) min vs. 16.2 (9.8-23.4) min (p=0.037) in R-PCI patients. However, there was no significant difference between the dose-area product 4062 (2337-5990) cGycm² vs. 3747 (2238-5904) cGycm² (p=0.878) and contrast volume use 180 (140-250) ml vs. 180 (135-235) ml (p=0.370, figure 1). Twelve months after the intervention, all patients in both groups were alive. R-PCI and M-PCI had comparable rates of rehospitalisation (11.4% vs. 8.1%, p=0.903) and unscheduled PCI (4.3% vs. 2.7%, p=0.932, figure 2). Target vessel failure occurred in one vs. two patients in the R-PCI and M-PCI group, respectively (1.4% vs. 1.3%, p=0.932). Conclusion R-PCI showed a high success rate, low rates for need of manual assistance, and a very high safety profile without any complications. Also at 12-month follow-up, R-PCI was comparable to the M-PCI in all categories.Comparison of procedural characteristicsComparison of twelve-month outcome

Optimisation of cone beam CT radiotherapy imaging protocols using a novel 3D printed head and neck anthropomorphic phantom

Objective.This study aimed to optimise Cone Beam Computed Tomography (CBCT) protocols for head and neck (H&N) radiotherapy treatments using a 3D printed anthropomorphic phantom. It focused on precise patient positioning in conventional treatment and adaptive radiotherapy (ART).Approach.Ten CBCT protocols were evaluated with the 3D-printed H&N anthropomorphic phantom, including one baseline protocol currently used at our centre and nine new protocols. Adjustments were made to milliamperage and exposure time to explore their impact on radiation dose and image quality. Additionally, the effect on image quality of varying the scatter correction parameter for each of the protocols was assessed. Each protocol was compared against a reference CT scan. Usability was assessed by three Clinical Scientists using a Likert scale, and statistical validation was performed on the findings.Main results. The work revealed variability in the effectiveness of protocols. Protocols optimised for lower radiation exposure maintained sufficient image quality for patient setup in a conventional radiotherapy pathway, suggesting the potential for reducing patient radiation dose by over 50% without compromising efficacy. Optimising ART protocols involves balancing accuracy across brain, bone, and soft tissue, as no single protocol or scatter correction parameter achieves optimal results for all simultaneously.Significance.This study underscores the importance of optimising CBCT protocols in H&N radiotherapy. Our findings highlight the potential to maintain the usability of CBCT for bony registration in patient setup while significantly reducing the radiation dose, emphasizing the significance of optimising imaging protocols for the task in hand (registering to soft tissue or bone) and aligning with the as low as reasonably achievable principle. More studies are needed to assess these protocols for ART, including CBCT dose measurements and CT comparisons. Furthermore, the novel 3D printed anthropomorphic phantom demonstrated to be a useful tool when optimising CBCT protocols.

Establishing Local Diagnostic Reference Levels for Head Computed Tomography Examinations

Background/Objectives: Head Computed Tomography (CT) is an essential diagnostic tool for identifying brain pathologies and visualizing blood vessels. However, CT exposes patients to ionizing radiation, making it necessary to establish local diagnostic reference levels (DRLs) to ensure patient safety. This study aimed to establish DRLs for head CT scans and assess the influence of patient characteristics on radiation dose. Methods: A retrospective analysis was conducted on 2043 non-contrast and 488 contrast-enhanced head CT scans performed between 1 July 2023 and 31 March 2024 using a SIEMENS SOMATOM Definition Edge machine. Computed Tomography Dose Index (CTDIvol) and Dose-Length Product (DLP) values were analyzed, with DRLs set at the 75th percentile. The influence of gender, height, and weight on radiation dose was also evaluated. Results: The DRL for both non-contrast and contrast-enhanced scans was 58.18 mGy for CTDIvol and 1018.11 mGy·cm for DLP per acquisition. Total DLP was 2046.09 mGy·cm for contrast-enhanced and 1027.99 mGy·cm for non-contrast scans. No significant correlation was found between patient characteristics and radiation dose, allowing for a uniform DRL to be established. Conclusions: Uniform DRLs were successfully established for head CT scans, ensuring safe radiation doses for both non-contrast and contrast-enhanced studies. The lack of correlation between patient-specific factors and dose supports the use of standardized DRLs, contributing to optimized radiation safety in head CT diagnostics.

Evaluation of automatic tube current modulation in a CT scanner using a customised homogeneous phantom

Objective.The introduction of automatic tube current modulation (ATCM) has resulted in complex relationships between scanner parameters, patient body habitus, radiation dose, and image quality. ATCM adjusts tube current based on x-ray attenuation variations in the scan region, and overall patient dose depends on a combination of factors. This work aims to develop mathematical models that predict CT radiation dose and image noise in terms of attenuating diameter and all relevant scanner parameters.Approach.A homogenous phantom, equipped with the features to conduct discrete and continuous adaption tests, was developed to model ATCM in a Philips CT scanner. Scanner parameters were varied based on theoretical dose relationships, and a MATLAB script was developed to extract data from DICOM images. R statistical software was employed for data analysis, plotting, and regression modelling.Main Results.Phantom data provided the following insights: Median tube current decreased by 81% as tube potential varied from 80 kVp to 140 kVp. Doubling the DoseRight Index (DRI) from 12 to 24, at 24 cm diameter, produced a 294% increase in mA and a 46% decrease in noise. Mean mA increased by 53% whilst mean noise increased by 5.7% as helical pitch increased from 0.6 to 0.925. Changing rotation time from 0.33s to 0.75s gave a 56% reduction in mean mA and no change in image noise. Increasing detector collimation (n×T) resulted in higher tube currents and lower output image noise values, asnandTwere varied independently. Interpreting these results to apply transformations relevant to each independent variable produced models for tube current and noise with adjusted R-squared values of 0.965 and 0.912, respectively.Significance.The models developed more accurately predict radiation dose and image quality for specific patients and scanner settings. They provide imaging professionals with a practical tool to optimize scan protocols according to patient diameters and clinical objectives.

Diagnostic reference levels for the city of Moscow during X-ray examinations

Diagnostic reference levels are one of the effective tools for optimizing patient radiation doses in diagnostic radiology. The staff of domestic radiology departments does not have an understanding of the development process and use of diagnostic reference levels during X-ray examinations, although this tool is a generally accepted in practice abroad. The article shows the experience of forming regional diagnostic reference levels based on measurements provided by the accredited testing laboratory of the Scientific and Practical Clinical Center for Diagnostics and Telemedicine Technologies of the Moscow Healthcare Department. The diagnostic reference levels for radiography in Moscow were developed for eight of the most common types of examinations based on the operation of 216 digital X-ray machines. The resulting levels, expressed in the dose-area product (cGy-cm2) and effective dose (mSv), were compared with the local diagnostic reference levels for the Ryazan region, Russia, and national diagnostic reference levels for other countries. The analysis showed continuity in the values. Some types of studies have been optimized. The developed diagnostic reference levels are the quality performance indicators foe diagnostic radiology departments and will be used to optimize a patient radiation dose during diagnostic studies in Moscow.

S668 FLIP Distensibility Index Correlates With Radiation Dose in Cancer Patients With Radiation Exposure and Dysphagia

S668 FLIP Distensibility Index Correlates With Radiation Dose in Cancer Patients With Radiation Exposure and Dysphagia

429 - Early Radiation Dose Warning System Improves Patient Safety And Radiation Dose Optimization In Neuro Interventional Procedures At Professor Ngoerah Public Hospital, Bali, Indonesia

429 - Early Radiation Dose Warning System Improves Patient Safety And Radiation Dose Optimization In Neuro Interventional Procedures At Professor Ngoerah Public Hospital, Bali, Indonesia

Effects of Head and Neck Cancer Radiotherapy on Cricothyroid Membrane Related Dimensions.

Radiation treatment can modify soft tissue dynamics depending on the extent and location of irradiation. We hypothesized that head and neck radiotherapy caused alterations in cricothyroid membrane (CTM) related dimensions. Primary objective was to evaluate changes in the cricothyroid membrane height (CTMH) and skin-to-CTM distance (STCD) in patients who underwent radiation treatment for head and neck cancers. Pre- and post-head-and-neck cancer-radiated computed tomography (CT) scans were analyzed retrospectively. The patients' demographics (age, sex, body mass index, cancer location), radiation dose and laterality, time from radiation initiation to CT scan assessments were summarized. CTMH and STCD were measured from pre-and post-radiation CT scans. Pre- and post-radiation comparisons were conducted using a paired t-test, or Wilcoxon signed-rank test if more appropriate. Chi-squared or Fisher's Exact test were used for categorical variables. Among 231 study patients, who underwent head and neck radiotherapy in our institution 73.2% were males, and the median age of total population was 66years (31-93). The median BMI was 25.2kg/m2 (13.8-47.2). The median time from first radiation dose to CT scan assessment was 29.5months (2-115).The median pre- and post-radiation CTMH were 8.7mm (3-16.2) and 7.5mm (3.1-14.3) respectively. The median pre- and post-radiation STCD were 11.7mm (2.9-71.1) and 10.2mm (3.9-38) respectively. In summary our patient population had significant reduction of cricothyroid membrane related dimensions following head-and-neck radiotherapy, which can limit the localization of the cricothyroid membrane. Retrospective cohort study.

TCT-554 Patient Radiation Dose During Bifurcation Percutaneous Coronary Intervention

TCT-554 Patient Radiation Dose During Bifurcation Percutaneous Coronary Intervention

Evaluation of X-ray Beam Collimation in Adult Chest Radiography.

Restricting the irradiated volume can reduce X-ray scattering incidents on the image receptor. Proper X-ray collimation during medical imaging reduces a patient's dose while improving image quality. Even though the patient radiation dose due to chest X-ray imaging is low, the 'as low as reasonably achievable' (ALARA) principle should be satisfied, especially for young patients. To evaluate the accuracy of collimation in digital chest radiography. Ninety-eight chest radiographs were studied retrospectively from February 2021 to December 2021. Chest images were collected from three main centers in the Madinah region of Saudi Arabia. The ratio of the field of interest area to the field of view (FOV) was measured and calculated to determine the accuracy of X-ray beam collimation. Out of 98 chest radiographs enrolled in the study, 87.8% (n=80) were adequately collimated, while 12.2% (n=18) were rejected due to inadequate collimation. The ratio of the field of interest collimated area of chest radiographs was 0.547, which indicated an acceptable value. Among the three centers, Center 2 showed higher, significant, adequate collimation than Center 1 (P<0.001) and Center 3 (P=0.007). There was a significant gender difference in collimation levelsas the level of collimation of female chest radiographs is inferior to that of males (P>0.001). The collimation of chest radiographs among the three centers was adequate. Based on the study findings, the X-ray beam collimation was sufficient, indicating good optimization and no unnecessary radiation exposure to patients and staff. The collimation of chest radiographs in females was significantly inferior to that of males.

How Effective is Deep Inspiration Breath Hold in Minimizing Cardiac Doses During Hybrid Radiotherapy Treatment for Left-Sided Breast Cancer with Comprehensive Regional Nodes?

In the context of left breast cancer radiotherapy, long term cardiopulmonary toxicity has been well-documented, significant efforts have been undertaken to mitigate such toxicity by using 4D gating, deep inspiration breath-hold(DIBH) and active breath control(ABC) techniques. To evaluate and compare the cardio-pulmonary radiation doses incurred during postmastectomy radiotherapy (PMRT) in two distinct breathing conditions such as DIBH and Free Breathing (FB), with a specific focus on the left chest wall with comprehensive regional nodal irradiation. A prospective dosimetric study was conducted on 15 patients who received adjuvant loco-regional radiotherapy of chest-wall (CW), supraclavicular fossa(SCF), and internal mammary region(IMC), with or without axilla. Two sets of planning CT scans were taken in DIBH and FB conditions. The dosimetric difference between DIBH CT and FB CT plans analyzed using Wilcoxon signed-rank test, employing SPSS software version 21.0. Comparison of DIBH and FB parameters for target coverage revealed a statistically significant advantage with DIBH in SCF(D95, V90, p<0.017) and IMC(D98, V90 & V95, p<0.03). Dosimetric characteristics of heart and LAD exhibited statistically significant lower doses with DIBH (V20, V25, and Dmean, p<0.001) compared to FB plans. Lung doses were similar with no discernible advantage of one technique over the other. Other OARs such as contralateral breast (p=0.027) and esophagus (p=0.001) received lower doses with the DIBH technique while the spinal cord (p=0.691) and thyroid(p=0.496) showed no significant difference. Maximum heart distance (p= 0.001), central lung distance (p= 0.011) and Haller index (p= 0.001) exhibited statistical significance between the two techniques, whereas chest wall separation showed no significant statistical difference (p=0.629). DIBH demonstrates a substantial reduction in cardiac and LAD doses compared to the FB technique. This study underscores the efficacy of DIBH as a viable strategy for mitigating cardiac and LAD radiation doses in left-sided breast cancer patients undergoing PMRT of chest wall with comprehensive regional nodes.

2058: prospective correlation research on shoulder radiation dose and impairment in breast cancer patients

2058: prospective correlation research on shoulder radiation dose and impairment in breast cancer patients

Comparative study of image quality and radiation dose in thoracic-abdominal-pelvic CT Enhancement with different tube voltages and reconstruction algorithms

ObjectivesTo evaluate the image quality and radiation dose in thoracic-abdominal-pelvic computed tomography enhancement using ATVM (Automatic Tube Voltage Modulation)coupled with AIIR versus routine tube voltage combined with Karl-3D IR. The optimal noise level for the AIIR in thoracic-abdominal-pelvic CT enhancement was also determined. MethodsGroup A was scanned using ATVM, and images were reconstructed using AIIR with 1–5 noise levels. Group B was scanned and reconstructed using the fixed tube voltage (120 kVp) combined with Karl 3D level 5 IR. The image quality of the reconstructed images of AIIR with 1–5 noise levels were compared and the best image reconstruction noise level for AIIR was preferred. Image quality and radiation dose were statistically analyzed for group A (best image reconstruction noise level for AIIR) and group B. ResultsAIIR level 3 is the optimal noise level for CT-enhanced image reconstruction of the thorax, abdomen, and pelvis. The mean SNR, CNR, and subjective evaluation of AIIR level 3 Group A images were better than those of Karl 3D level 5 Group B images (p < 0.05). The mean SSDE and the mean ED of the AIIR Group A patients were reduced by 46% and 41%, respectively, compared with those of Group B. ConclusionsATVM technology combined with the AIIR algorithm improved image quality and reduced patient radiation dose in thoracic-abdominal-pelvic CT scans. The optimal noise level for the reconstruction of high-quality arterial and venous-phase images was AIIR level 3.

One-year outcome of robotical vs. manual percutaneous coronary intervention.

Robotic-assisted percutaneous coronary intervention (R-PCI) is a promising technology for optimizing the treatment of patients with coronary heart disease. For a better understanding of the potential of R-PCI in clinical routine compared to conventional manual PCI (M-PCI) both initial treatment success of the index procedure and long-term outcome have to be analysed. Prospective evaluation from the FRiK (DRKS00023868) registry of all R-PCI cases with the CorPath GRX Cardiology by Siemens Healthineers and Corindus in the Freiburg University Heart Center between 04/2022 and 03/2023. Index procedure success and safety, radiation dose of patients and personnel, and 1-year outcome will be reported. Findings will be compared to a prospective control group of M-PCI patients treated by the same team of interventionalists during the same observation period. Seventy patients received R-PCI and were included in the registry. PCI success rate was 100%, with 19% requiring manual assistance. No complications (MACE-major adverse cardiovascular events) occurred. Compared with 70 matched-pair M-PCI patients, there was a higher median procedural time (103min vs. 67min, p < 0.001) and fluoroscopy time (18min vs. 15min, p = 0.002), and more contrast volume was used (180 ml vs. 160ml, p = 0.041) in R-PCI vs. M-PCI patients. However, there was no significant difference of the dose-area product (4062 vs. 3242 cGycm2, p = 0.361). One year after the intervention, there was no difference in mortality, rehospitalisation, unscheduled PCI or target vessel failure. Health-related quality of life evaluation 6 and 12months after the index procedure (NYHA, CCS, SAQ7 and EQ-5D-5L) was similar in both groups. R-PCI is feasible and safe. Compared to M-PCI, index procedure success rate is high, safety profile is favourable, and manual assistance was required in only few cases. At 1-year follow-up results for R-PCI vs. M-PCI considering mortality, rehospitalisation, morbidity and target vessel failure were equal.

Systematic Review and Meta-Analysis of Adjuvant Radiation Dose for Pediatric Patients (≤22 years) with Nonmetastatic Intracranial Ependymomas

Ependymomas are the third most common brain tumors in children. Standard of care is surgery followed by adjuvant radiotherapy. Controversy in the literature still exists over optimal radiotherapy dose. We completed a systematic review and meta-analysis to determine the optimal dose for local control (LC), event-free survival (EFS), and overall survival (OS) in pediatric patients. We searched MEDLINE (PubMed), Cochrane Database of Systematic Reviews, and Web of Science through January 2024. We included cohort studies that compared adjuvant radiotherapy of ≤54Gy to >54Gy in pediatric patients (≤22 years) with non-metastatic intracranial ependymomas. We assessed study quality using the Newcastle-Ottawa Quality Assessment Scale of Cohort Studies. We pooled studies using a random effects meta-analysis for hazard ratios (HR), 95% confidence intervals (CI), and assessed statistical heterogeneity via I2. When HRs were unavailable, we transformed risks using established methods. We narratively summarized qualitative outcomes. Seven studies met our inclusion criteria, covering a combined 1321 patients. Studies included a range of doses from 45-66.6Gy. Compared with >54Gy, we found no difference in LC for those receiving ≤54Gy (HR=0.83, 95% CI 0.56-1.24, I2=49.1%), in EFS (HR=1.02, 95% CI 0.95-1.09, I2=0.00%), and OS (HR=0.99, 95% CI 0.82-1.20, I2=37.5%). Two studies reported on subtotal resection by radiotherapy dose, neither study reporting statistical differences in LC, EFS, or OS, though the number of patients was small (n≤30). Five studies reported on late effects, with brainstem radionecrosis, radiation-induced vasculopathy, and secondary tumors being the most frequent. Overall study quality was high, though lower scores were consistently seen in comparability of cohorts. No studies reported on molecular subgroups. We found no difference in LC, EFS, or OS for those treated with ≤54Gy compared to >54Gy. There was insufficient data to complete a subgroup meta-analysis on radiotherapy dosing based on extent of resection or molecular subgroups.

Establishment of Indonesian Diagnostic Reference Levels for Mammography and Dental Radiography for Use as Medical Exposure Optimization Tools

Diagnostic Reference Level (DRL) is a dose value that will be an indicator in optimizing patient radiation protection. This study aims to determine the national DRL value in Indonesia when examining patients using mammography and dental radiography. The method used in this study combines quantitative research and descriptive analysis. The patient radiation dose data used comes from the 2019 to 2024 dose survey from health facilities in Indonesia for each type of mammography and dental radiography examination. Based on data analysis, it has been proposed to be adopted as an Indonesian DRL value for dental radiography for the types of examinations Panoramic - Standard for pediatric patients and Cephalo - LAT, Panoramic - Standard, Panoramic - Front, Panoramic - Bitewing, Intraoral - Periapical Anterior, and Intraoral - Periapical molars in adult patients. The Indonesian DRL value for mammography for Cranial-Caudal and Mediolateral-Oblique examination types is also proposed. The proposed value to become Indonesia's DRL will be agreed upon and determined to be Indonesia's DRL value and will be applied for five years. After five years, a review was done to update Indonesia's DRL value. BAPETEN needs to guide the form of more intensive socialization and assistance to increase awareness and compliance in carrying out optimization through the use of DRL as well as compliance in recording and reporting patient radiation dose data to the National Patient Radiation Dose Data Information System (Si-INTAN). Keywords: Diagnostic Reference Level (DRL), optimization of radiation protection, radiation protection of patients, X-ray mammography, X-ray dental radiography

Analysis of Radiation Dose Rate and Evaluation of Whole Body Scan SPECT/CT Images in Thyroid Carcinoma Radioablation Patients Using Radioisotope 131I

The incidence rate of thyroid carcinoma shows an increasing trend from year to year. One method for treating thyroid carcinoma is radioablation therapy using 131I. The use of 131I must be carried out in accordance with radiation safety regulations to avoid undesirable radiation dose rates. Therefore, research was conducted to analyze the radiation dose rate emitted by patients, obtain the relationship between body mass index (BMI) and the emitted dose rate, and evaluate whole body scan images of Single-Photon Emission Computed Tomography (SPECT/CT) of thyroid carcinoma radioablation patients. The research was carried out by measuring the patient's radiation dose rate using a surveymeter. The sample used was 53 patients who met the inclusion criteria and were not included in the exclusion criteria. The patient is isolated until it is safe to leave the hospital, then the therapy is evaluated by means of a whole body scan using SPECT/CT. Region of Interest (ROI) was carried out on the thyroid, stomach, liver, large intestine and bladder. On the third day the patient's dose rate value was below 70 μSv/h so that the patient could go home safely in accordance with radiation protection regulations. The average dose rate value for obese patients was higher compared to patients with low, normal and excess BMI. The high organ radiation count value for whole body SPECT/CT scan patients is caused by several factors such as the absorption of 131I by organs and the buildup of radioisotopes in organs.

Photoneutron production mechanisms, their characteristics, and shielding strategies in high-energy linac environment: A review

Radiotherapy, a mainstay cancer treatment for patients worldwide, utilizes medical linear accelerators (linacs) with photon energies ranging from 4 MV to 25 MV. However, concerns arise at higher energies (>6 MV, particularly >10 MV). These high-energy photons interact with high-atomic number materials in the linac head and collimation system, generating unwanted neutrons through (γ,n) reactions. This neutron contamination, present in both photon and electron beams, is a significant issue. Neutrons, with their high Linear Energy Transfer (LET), are more effective at causing clustered DNA damage (single and double-strand breaks). These neutrons not only impact shielding requirements in treatment rooms but also increase out-of-field radiation doses for patients receiving high-energy photon therapy. Therefore, for radiotherapy treatments exceeding 6 MV, additional precautions become crucial, including enhanced door shielding and optimized treatment planning. This review discusses in detail the multifaceted aspects of neutron production and shielding requirements during radiotherapy.

Evaluating spectral performance for quantitative contrast-enhanced breast CT with a GaAs based photon counting detector: a simulation approach

Quantitative contrast-enhanced breast computed tomography (CT) has the potential to improve the diagnosis and management of breast cancer. Traditional CT methods using energy-integrated detectors and dual-exposure images with different incident spectra for material discrimination can increase patient radiation dose and be susceptible to motion artifacts and spectral resolution loss. Photon Counting Detectors (PCDs) offer a promising alternative approach, enabling acquisition of multiple energy levels in a single exposure and potentially better energy resolution. Gallium arsenide (GaAs) is particularly promising for breast PCD-CT due to its high quantum efficiency and reduction of fluorescence x-rays escaping the pixel within the breast imaging energy range. In this study, the spectral performance of a GaAs PCD for quantitative iodine contrast-enhanced breast CT was evaluated. A GaAs detector with a pixel size of 100 μm, a thickness of 500 μm was simulated. Simulations were performed using cylindrical phantoms of varying diameters (10 cm, 12 cm, and 16 cm) with different concentrations and locations of iodine inserts, using incident spectra of 50, 55, and 60 kVp with 2 mm of added aluminum filtration and and a mean glandular dose of 10 mGy. We accounted for the effects of beam hardening and energy detector response using TIGRE CT open-source software and the publicly available Photon Counting Toolkit (PcTK). Material-specific images of the breast phantom were produced using both projection and image-based material decomposition methods, and iodine component images were used to estimate iodine intake. Accuracy and precision of the proposed methods for estimating iodine concentration in breast CT images were assessed for different material decomposition methods, incident spectra, and breast phantom thicknesses. The results showed that both the beam hardening effect and imperfection in the detector response had a significant impact on performance in terms of Root Mean Squared Error (RMSE), precision, and accuracy of estimating iodine intake in the breast. Furthermore, the study demonstrated the effectiveness of both material decomposition methods in making accurate and precise iodine concentration predictions using a GaAs-based photon counting breast CT system, with better performance when applying the projection-based material decomposition approach. The study highlights the potential of GaAs-based photon counting breast CT systems as viable alternatives to traditional imaging methods in terms of material decomposition and iodine concentration estimation, and proposes phantoms and figures of merit to assess their performance.

Deep-learning-based Attenuation Correction for 68Ga-DOTATATE Whole-body PET Imaging: A Dual-center Clinical Study.

Attenuation correction is a critical phenomenon in quantitative positron emission tomography (PET) imaging with its own special challenges. However, computed tomography (CT) modality which is used for attenuation correction and anatomical localization increases patient radiation dose. This study was aimed to develop a deep learning model for attenuation correction of whole-body 68Ga-DOTATATE PET images. Non-attenuation-corrected and computed tomography-based attenuation-corrected (CTAC) whole-body 68Ga-DOTATATE PET images of 118 patients from two different imaging centers were used. We implemented a residual deep learning model using the NiftyNet framework. The model was trained four times and evaluated six times using the test data from the centers. The quality of the synthesized PET images was compared with the PET-CTAC images using different evaluation metrics, including the peak signal-to-noise ratio (PSNR), structural similarity index (SSIM), mean square error (MSE), and root mean square error (RMSE). Quantitative analysis of four network training sessions and six evaluations revealed the highest and lowest PSNR values as (52.86±6.6) and (47.96±5.09), respectively. Similarly, the highest and lowest SSIM values were obtained (0.99±0.003) and (0.97±0.01), respectively. Additionally, the highest and lowest RMSE and MSE values fell within the ranges of (0.0117±0.003), (0.0015±0.000103), and (0.01072±0.002), (0.000121±5.07xe-5), respectively. The study found that using datasets from the same center resulted in the highest PSNR, while using datasets from different centers led to lower PSNR and SSIM values. In addition, scenarios involving datasets from both centers achieved the best SSIM and the lowest MSE and RMSE. Acceptable accuracy of attenuation correction on 68Ga-DOTATATE PET images using a deep learning model could potentially eliminate the need for additional X-ray imaging modalities, thereby imposing a high radiation dose on the patient.