Acceptable Radiation Dose Research Articles

Cone-beam x-ray luminescence computed tomography (CB-XLCT) prototype development and performance evaluation.

This study developed a prototype for a rotational cone-beam x-ray luminescence computed tomography (CB-XLCT) system, considering its potential application in pre-clinical theranostic imaging. A geometric calibration method applicable to both imaging chains (XL and CT) was also developed to enhance image quality. The results of systematic performance evaluations were presented to assess the feasibility of commercializing XLCT technology. Monte Carlo GATE simulation was performed to determine the optimal imaging conditions for nanophosphor particles (NPs) irradiated by 70 kV x-rays. We acquired a low-dose transmission x-ray tube and designed a prone positioning platform and a rotating gantry, using mice as targets from commercial small animalμ-CT systems. We then employed the image cross-correlation (ICC) automatic geometric calibration method to calibrate XL and CT images. The performance of the system was evaluated through a series of phantom experiments with a linearity of 0.99, and the contrast-to-noise ratio (CNR) between hydroxyl-apatite (HA) and based epoxy resin is 19.5. The XL images of the CB-XLCT prototype achieved a Dice similarity coefficient (DICE) of 0.149 for a distance of 1 mm between the two light sources. Finally, the final XLCT imaging results were demonstrated using the Letter phantoms with NPs. In summary, the CB-XLCT prototype developed in this study showed the potential to achieve high-quality imaging with acceptable radiation doses for small animals. The performance of CT images was comparable to current commercial machines, while the XL images exhibited promising results in phantom imaging, but further efforts are needed for biomedical applications.

Unlocking the Potential of Ultra-High Dose Fractionated Radiation for Effective Treatment of Glioblastoma in Mice.

Background: Current radiotherapy regimens for glioblastoma (GBM) have limited efficacy and fails to eradicate tumors. Regenerative medicine brings hope for repairing damaged tissue, opening opportunities for elevating the maximum acceptable radiation dose. In this study, we explored the effect of ultra-high dose fractionated radiation on tumor responses and brain injury in immunocompetent mice which can better mimic the tumor-host interactions observed in patients. We also evaluated the role of the hypoxia-inducible factor-1 alpha under radiation as potential target for combating radiation-induced brain injury. Methods: Naïve and Hif-1α+/- heterozygous mice received a fractionated daily dose of 20 Gy for three or five consecutive days. Magnetic resonance imaging (MRI) and histology were performed to assess brain injury post-radiation. The 2×105 human GBM1 luciferase-expressing cells were transplanted with tolerance induction protocol. Fractionated radiotherapy was performed during the exponential phase of tumor growth. Bioluminescence imaging, MRI, and immunohistochemistry staining were performed to evaluate tumor growth dynamics and radiotherapy responses. Additionally, animal lifespan was recorded. Results: Fractionated radiation of 5×20 Gy induced severe brain damage, starting 3 weeks after radiation. All animals from this group died within 12 weeks. In contrast, later onset and less severe brain injury were observed starting 12 weeks after radiation of 3×20 Gy. It resulted in complete GBM eradication and survival of all treated animals. Furthermore, Hif-1α+/- mice exhibited more severe vascular damage after fractionated radiation of 3×20 Gy. Conclusion: Ultra-high dose fractionated 3×20 Gy radiation has the potential to fully eradicate GBM cells at the cost of only mild brain injury. The Hif-1α gene is a promising target for ameliorating vascular impairment post-radiation, encouraging the implementation of neurorestorative strategies.

Photon-Counting Detector CT With Denoising for Imaging of the Osseous Pelvis at Low Radiation Doses: A Phantom Study.

BACKGROUND. Photon-counting detector (PCD) CT may allow lower radiation doses than used for conventional energy-integrating detector (EID) CT, with preserved image quality. OBJECTIVE. The purpose of this study was to compare PCD CT and EID CT, reconstructed with and without a denoising tool, in terms of image quality of the osseous pelvis in a phantom, with attention to low radiation doses. METHODS. A pelvic phantom comprising human bones in acrylic material mimicking soft tissue underwent PCD CT and EID CT at various tube potentials and radiation doses ranging from 0.05 to 5.00 mGy. Additional denoised reconstructions were generated using a commercial tool. Noise was measured in the acrylic material. Two readers performed independent qualitative assessments that entailed determining the denoised EID CT reconstruction with the lowest acceptable dose and then comparing this reference reconstruction with PCD CT reconstructions without and with denoising, using subjective Likert scales. RESULTS. Noise was lower for PCD CT than for EID CT. For instance, at 0.05 mGy and 100 kV with tin filter, noise was 38.4 HU for PCD CT versus 48.8 HU for EID CT. Denoising further reduced noise; for example, for PCD CT at 100 kV with tin filter at 0.25 mGy, noise was 19.9 HU without denoising versus 9.7 HU with denoising. For both readers, lowest acceptable dose for EID CT was 0.10 mGy (total score, 11 of 15 for both readers). Both readers somewhat agreed that PCD CT without denoising at 0.10 mGy (reflecting reference reconstruction dose) was relatively better than the reference reconstruction in terms of osseous structures, artifacts, and image quality. Both readers also somewhat agreed that denoised PCD CT reconstructions at 0.10 mGy and 0.05 mGy (reflecting matched and lower doses, respectively, with respect to reference reconstruction dose) were relatively better than the reference reconstruction for the image quality measures. CONCLUSION. PCD CT showed better-quality images than EID CT when performed at the lowest acceptable radiation dose for EID CT. PCD CT with denoising yielded better-quality images at a dose lower than lowest acceptable dose for EID CT. CLINICAL IMPACT. PCD CT with denoising could facilitate lower radiation doses for pelvic imaging.

Assessing Patterns of Practice in Early-Stage Lung Cancer Radiation Therapy: Findings from a Large Statewide Consortium Study on Hypofractionation

There are many different acceptable radiation dose and fractionation regimens for the treatment of early-stage non-small cell lung cancer (NSCLC), including hypofractionation (HypoRT). There are limited data supporting when to use HypoRT. We investigated which factors led physicians to choose HypoRT rather than stereotactic body radiation therapy (SBRT) or conventional fractionation (CRT) for early-stage NSCLC patients in a statewide consortium. We examined patients with T1-3N0M0 NSCLC treated at multiple institutions in a statewide consortium from January 2012-July 2022. We classified treatments as SBRT if 5 fractions or fewer, HypoRT if 6-20 fractions, and CRT if 1.8-2 Gy per fraction (Gy/Fx) for 25 or greater fractions. We excluded patients between 20 and 25 fractions as most appeared to be CRT that did not finish treatment (5% of total). We then performed a classification tree using age, race, gender, smoking status, T stage, PTV within 2cm of esophagus, PTV within 2cm of heart, and concurrent chemotherapy as covariates with a three-variable output (SBRT, HypoRT, and CRT). We excluded ECOG as it was not significant on initial analysis and was missing for 100 patients. We also reran the classification tree without CRT as an output to better discriminate between SBRT and HypoRT. A total of 418 patients were included in the analysis. 184 patients had T1, 123 with T2, and 111 with T3 tumors. In total, 228 patients underwent SBRT (median 50 Gy), 51 patients HypoRT (median 60 Gy), and 139 CRT (median 63 Gy). Covariates significant for discriminating between all three treatment regimens included T2, T3 vs T1, PTV within 2cm of the esophagus, and T3 vs T2. 94% of T1 patients were treated with SBRT. Among T2 and T3 patients, those within 2cm of the esophagus were significantly more likely to be treated with CRT or HypoRT (80% vs 15%). Patients with T3 tumor not within 2cm of the esophagus, were more likely to be treated with CRT or HypoRT than the T2 patients (85% vs 36%). Patients treated with CRT were also more likely to receive chemotherapy, particularly for T3 tumors (80% received concurrent chemotherapy). Excluding CRT as an output variable, proximity to the heart became significant in addition to the other previously described covariates. Notably, the branch with the highest likelihood of HypoRT were patients with T2/T3 tumors within 2 cm of both the esophagus and heart (94% HypoRT vs 6% SBRT). Patients with tumors not close to central structures but with T3 rather than T2 tumors were more likely to be treated with HypoRT as well (62% vs 38%). Based on this large prospective real-world data of early-stage NSCLC, larger tumors and those located near central structures are more likely to be treated with HypoRT. The patient's age, performance status, race, and smoking status were not significant in this analysis. Additional analysis on outcomes and toxicity related to treatments is underway.

Introducing Paediatric Radiology As A Subspecialty In Pakistan: Bridging The Gap In Healthcare.

Madam, Radiology is a rapidly progressing field that significantly contributes to disease diagnosis and treatment monitoring. Recent advancements in the field have improved evidence-based medicine for patient care. Despite substantial growth in Pakistan, limited opportunities for sub-specialisation training in radiology are available in Pakistan. Just a few institutions offer training in sub-specialties such as women's imaging, neurologic radiology, interventional radiology, and body imaging. There has been significant evolution in pediatric radiology, which has now emerged as a distinct field requiring solid foundations. Unfortunately, due to undefined training opportunities, pediatric radiology is being neglected in Pakistan. Pediatric radiology requires specialized training due to anatomical variations and unique disease presentations in children. Even senior general radiologists may lack confidence when reporting pediatric cases. Radiology demands updated knowledge and expertise in diagnostic tools, making it challenging to keep up. Reporting pitfalls in pediatrics differ from adults due to varying growth patterns and myelination making expert knowledge essential for accurate reporting in multiple conditions. The acceptable radiation doses and protocols for imaging studies are also different, considering children’s susceptibility to ionizing radiation3. The European Society of Radiology highlighted the importance of integrating pediatric radiology training4. Many other countries, including the USA and Europe, have sub-specializations and accreditations despite having lower proportions of children in their populations compared to Pakistan. Advocacy movements for pediatric radiology have also emerged in other developing nations like Nigeria5. Pakistan is a largely populated country, with approximately 35% being pediatric population and multiple radiological cases being reported daily. It seems a gross neglect not to cater specifically to such a large proportion of the people. Therefore, there is a dire need to recognize pediatric radiology as a formal subspeciality that requires redrafting of the curriculum. The subspecialty should focus on a particular area and offer comprehensive and consistent training to interested individuals.

Sparse2Noise: Low-dose synchrotron X-ray tomography without high-quality reference data

BackgroundSynchrotron radiation computed tomography (SR-CT) holds promise for high-resolution in vivo imaging. Notably, the reconstruction of SR-CT images necessitates a large set of data to be captured with sufficient photons from multiple angles, resulting in high radiation dose received by the object. Reducing the number of projections and/or photon flux is a straightforward means to lessen the radiation dose, however, compromises data completeness, thus introducing noises and artifacts. Deep learning (DL)-based supervised methods effectively denoise and remove artifacts, but they heavily depend on high-quality paired data acquired at high doses. Although algorithms exist for training without high-quality references, they struggle to effectively eliminate persistent artifacts present in real-world data. MethodsThis work presents a novel low-dose imaging strategy namely Sparse2Noise, which combines the reconstruction data from paired sparse-view CT scan (normal-flux) and full-view CT scan (low-flux) using a convolutional neural network (CNN). Sparse2Noise does not require high-quality reconstructed data as references and allows for fresh training on data with very small size. Sparse2Noise was evaluated by both simulated and experimental data. ResultsSparse2Noise effectively reduces noise and ring artifacts while maintaining high image quality, outperforming state-of-the-art image denoising methods at same dose levels. Furthermore, Sparse2Noise produces impressive high image quality for ex vivo rat hindlimb imaging with the acceptable low radiation dose (i.e., 0.5 Gy with the isotropic voxel size of 26 μm). ConclusionsThis work represents a significant advance towards in vivo SR-CT imaging. It is noteworthy that Sparse2Noise can also be used for denoising in conventional CT and/or phase-contrast CT.

Prospective evaluation of low-dose multiphase hepatic computed tomography for detecting and characterizing hepatocellular carcinoma in patients with chronic liver disease

BackgroundKnowing the lowest acceptable radiation dose of multiphase hepatic CT may allow us to reduce the radiation dose for detecting HCC.PurposeTo prospectively assess the image quality and diagnostic performance of low-dose and ultra-low-dose multiphase hepatic computed tomography using a dual-source CT scanner.MethodsThree reconstructed different dose scan images (standard-dose, low-dose, and ultra-low-dose) of hepatic multiphase CT were obtained from 67 patients with a dual-source CT scanner. The image quality and the diagnostic performance of the three radiation dose CT scans of the hepatic focal lesion (≥ 0.5 cm) were analyzed by two independent readers using the Liver Imaging Reporting and Data System.ResultsQualitative image quality and signal-to-noise ratio were significantly different among the radiation doses (p < 0.001). In total, 154 lesions comprising 32 hepatocellular carcinomas (HCC) and 122 non-HCC were included. The sensitivities of SDCT, LDCT, and ULDCT were 90.6%(29/32), 81.3%(26/32), and 56.2%(18/32), respectively. The accuracies of SDCT, LDCT, and ULDCT were 98.1%(151/154), 96.1%(148/154), and 89.6%(138/154), respectively. On per-lesion analysis, SDCT and LDCT did not show significantly different sensitivity and accuracy in diagnosing HCC (p = 0.250 and 0.250).ConclusionsThe diagnostic performance of dynamic hepatic LDCT with 33% reduced radiation dose in comparison to SDCT would be acceptable even though its image quality was qualitatively and quantitatively inferior. However, few HCCs could be overlooked. Therefore, with caution, radiation dose reduction by one-third could be implemented for follow-up CT scans for patients suspected of having HCC with caution and further studies are needed in the future.

Development of acceptable quality radiation dose levels for common computed tomography examinations: A focused multicenter study in United Arab Emirates.

PurposeDiagnostic Reference Level (DRL) is a practical tool for radiation dose optimization, yet it does not indicate the patient size or image quality. The Acceptable Quality Dose (AQD) introduced to address the limitations of the DRLs and it is based on image quality, radiation dose, and patient weight. The aim of this study is to establish the AQD for adult patients' undergoing Computed Tomography (CT) examinations (Head, chest, abdomen).MethodsThis study is conducted in the four main hospitals at the Ministry of Health and Prevention. Patient information and exposure parameters were extracted. All the acceptable images are scored for their quality assessments. Data is classified as seven weight groups, <50, 50–59, 60–69, 70–79, 80–89, 90–99, and ≥100 kg. The mean ± SD, median, and 75th are calculated for the CTDIvol and DLP for each weight group per examination.ResultsOut of 392, 358 CT examinations are scored with acceptable quality. The median CTDIvol values for the weight groups are obtained as 24.6, 25.4, 25.4, 25.0, 26.0, 27.0, and 29.0 mGy. Moreover, median DLP values are obtained as 576.7, 601.0, 616.5, 636.1, 654.0, 650.0, 780.0, and 622.5 mGy.cm, respectively, for head CT without Contrast Media (CM). Similar calculation for head CT with (CM), chest without CM, abdomen without CM, and chest and abdomen (with and without CM) CTs are presented.ConclusionImages with bad, unacceptable and higher than necessary qualities contribute to increasing patient dose and increasing the DRLs. The AQD for the selected examinations were lower than the proposed DRLs in the United Arab Emirates. The integration of image quality and patients size in the assessment of the AQD values provide effective model to compare radiation dose indices within facility and compare with others. The obtained results may be useful in terms of improving dose and the diagnostic quality in the national and international levels.

Image quality and radiation doses of volumetric 320-row computed tomography angiography with prospective electrocardiogram-gating in the assessment of coronary arteries in neonates and infants.

Diagnostic imaging of coronary arteries is required in neonates and infants suspected of congenital or acquired coronary artery anomalies and in pre- and postoperative assessment of complex congenital heart diseases (CHD). Our study aimed to evaluate the image quality of volumetric 320-row computed tomography angiography (CTA) with prospective electrocardiogram (ECG)-gating for coronary arteries in neonates and infants with heart diseases, analyze factors influencing image quality and assess a radiation dose related to the procedure. The study included 110 CTA performed in neonates and infants with CHD. CTA was performed in 37 girls and 73 boys at a median (interquartile range [IQR]) age of 3.0 (0.5-5.0) months, median (IQR) body weight of 5 (3.66-6.5) kg, and median heart rate (HR) of 133 (92-150) beats per minute. The orifices of the left coronary artery were visible in 100% of CTA, the orifices of the right coronary arteries were visible in 96%, whereas all coronary segments were assessable in 45% of CTA. Patients with non-diagnostic segments were significantly younger, median (IQR) age of 2.0 (0.21-5.00) months, had lower body weight of 4.6 (3.45-6.07) kg and faster HR of 136.5 (120-150) beats per minute (P <0.05) than patients with diagnostic image quality in all segments (4.0, 2-6 months, 6.0, 4.2-7 kg, and 130; 110-150 beats per minute, respectively; P <0.05). CTA performed with volumetric 320-row prospective ECG-gating allows for good visibility of the coronary arteries with an acceptable radiation dose. Children aged >15 days, with body weight >4.85 kg and HR <130 beats per minute are good candidates for excellent quality non-invasive CTA of all segments of coronary arteries.

Current situation survey for establishing personally acceptable radiation dose limits for nuclear disaster responders.

When responding to disasters, emergency preparedness is essential to ensure that disaster activities are performed smoothly, safely and efficiently. Investigations on the Fukushima accident revealed that lack of preparedness, poor communication and unsuitable emergency measures contributed to an inadequate emergency response to the nuclear disaster. In this study, we conducted a questionnaire survey on the establishment of a personal radiation exposure dose among Disaster Medical Assistance Team (DMAT) members in Japan who might be involved in the initial response to a nuclear disaster. Establishing personal exposure doses for personnel can encourage emergency preparedness and inform decisions on appropriate role assignments during nuclear response activities. Valid responses were obtained from 178 participants, and the response distribution was as follows: ‘Already have own acceptable dose standard,’ 16 (9%); ‘Follow own institution’s standard (and know its value),’ 30 (17%); ‘Follow own institution’s standard (but do not know its value),’ 59 (33%); ‘Haven’t decided,’ 63 (35%) and ‘Don’t understand question meaning,’ 10 (6%). We also assessed intention to engage in nuclear disaster activities among respondents via engagement intent scores (EIS) and found that participants who had established personal exposure standards had significantly higher EIS scores than those who had not decided or who did not understand the question. Thus, educating potential nuclear disaster responders on personal exposure doses may contribute to a higher intention to engage in emergency responses and improve preparedness and response efficiency.

Evaluation of Breast Galactography Using Digital Breast Tomosynthesis: A Clinical Exploratory Study.

Objectives: To compare the application value of digital breast tomosynthesis (DBT) and full-field digital mammography (FFDM) in breast galactography. Materials and Methods: A total of 128 patients with pathological nipple discharge (PND) were selected to undergo galactography. DBT and FFDM were performed for each patient after injecting the contrast agent; the radiation dose of DBT and FFDM was calculated, and the image quality was evaluated in consensus by two senior breast radiologists. Histopathologic data were found in 49 of the 128 patients. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for both FFDM- and DBT-galactography were calculated using histopathologic results as a reference standard. Data were presented as percentages along with their 95% confidence intervals (CI). Results: The average age of the 128 patients was 46.53 years. The average glandular dose (AGD) of DBT-galactography was slightly higher than that of FFDM-galactography (p < 0.001). DBT-galactography was 30.7% higher than FFDM-galactography in CC view, while DBT-galactography increased by 21.7% compared with FFDM-galactography in ML view. Regarding catheter anatomic distortion, structure detail, and overall image quality groups, DBT scores were higher than FFDM scores, and the differences were significant for all measures (p < 0.05). In 49 patients with pathological nipple discharge, we found that the DBT-galactography had higher sensitivity, specificity, PPV, and NPV (93.3%, 75%, 97.7%, and 50%, respectively) than FFDM-galactography (91.1%, 50%, 95.3%, and 33.3%, respectively). Conclusions: Compared to FFDM-galactography, within the acceptable radiation dose range, DBT-galactography increases the sensitivity and specificity of lesion detection by improving the image quality, providing more confidence for the diagnosis of clinical ductal lesions.

Comparison of Effects of Radiofrequency Ablation of Liver Cancer Guided by CT Images Based on Deep Learning Algorithm

Objective. To investigate the paper radiofrequency ablation (RFA) CT-guided feasibility of hepatocellular carcinoma (primary liver cancer) treatment, safety, and clinical efficacy of the use of deep learning algorithms. Method. A total of 47 cases of primary liver cancer patients were included: 21 cases of CT-guided liver lesions in line with RFA (C-CT group) and, in the same period, 26 cases of spiral CT-guided liver lesions in line with RFA (S-CT group). Two groups of patients were recorded immediately after the total operation time and ablation time, the acceptable radiation dose was observed in the incidence of postoperative complications of 7d, and the postoperative hospital stay was recorded to evaluate the efficacy of the treatment of lesions in 1, 3, and 6 months after RFA. Results. All 47 patients were successful; two technical success rates were 100%. There was a significant difference ( P &lt; 0.05) in the total operation time groups, ablation time, and acceptable radiation dose. And there was no significant difference ( P &lt; 0.05) in postoperative complications of 7d groups, postoperative hospital stay, and local disease control. There was a significant difference ( P &lt; 0.05) in the S-CT group, seven ablation residual or recurrent lesions during the follow-up ratio of 26.9%, and C-CT groups compared with only 14.3%. Conclusion. CT-guided RFA treatment of primary liver cancer patients is safe, effective, and superior to the conventional spiral CT-guided ablation lesion site-specific terms.

Extramedullary Relapsed Multiple Myeloma Treatment With 177Lu-Labeled CXCR4 Endoradiotherapy and Dosimetric Results.

We created our first national clinical protocol of 177Lu-CXCR4 therapy for patient who have failed to respond to current therapy options. We also calculated the kidney, liver, and tumor dosimetry. The kidney's mean absorbed dose was calculated to be 0.45 Gy/GBq, the calculated radiation absorbed dose of the liver was 0.63 Gy/GBq, and the radiation absorbed doses of the tumors vary between 9.2 and 82 Gy/GBq. 177Lu-CXCR4 therapy produced a promising clinical response in our patient in acceptable radiation dose limits as a treatment option in heavily pretreated patients with advanced multiple myeloma.

X-ray Phase-Contrast Computed Tomography for Soft Tissue Imaging at the Imaging and Medical Beamline (IMBL) of the Australian Synchrotron

The Imaging and Medical Beamline (IMBL) is a superconducting multipole wiggler-based beamline at the 3 GeV Australian Synchrotron operated by the Australian Nuclear Science and Technology Organisation (ANSTO). The beamline delivers hard X-rays in the 25–120 keV energy range and offers the potential for a range of biomedical X-ray applications, including radiotherapy and medical imaging experiments. One of the imaging modalities available at IMBL is propagation-based X-ray phase-contrast computed tomography (PCT). PCT produces superior results when imaging low-density materials such as soft tissue (e.g., breast mastectomies) and has the potential to be developed into a valuable medical imaging tool. We anticipate that PCT will be utilized for medical breast imaging in the near future with the advantage that it could provide better contrast than conventional X-ray absorption imaging. The unique properties of synchrotron X-ray sources such as high coherence, energy tunability, and high brightness are particularly well-suited for generating PCT data using very short exposure times on the order of less than 1 min. The coherence of synchrotron radiation allows for phase-contrast imaging with superior sensitivity to small differences in soft-tissue density. Here we also compare the results of PCT using two different detectors, as these unique source characteristics need to be complemented with a highly efficient detector. Moreover, the application of phase retrieval for PCT image reconstruction enables the use of noisier images, potentially significantly reducing the total dose received by patients during acquisition. This work is part of ongoing research into innovative tomographic methods aimed at the introduction of 3D X-ray medical imaging at the IMBL to improve the detection and diagnosis of breast cancer. Major progress in this area at the IMBL includes the characterization of a large number of mastectomy samples, both normal and cancerous, which have been scanned at clinically acceptable radiation dose levels and evaluated by expert radiologists with respect to both image quality and cancer diagnosis.

Impact of tumor anatomic characteristics on patient radiation dose during transarterial chemoembolization

Objective: The aim of the study was to determine the association between anatomic tumor characteristics and the radiation dose in patients with hepatocellular carcinoma undergoing transarterial chemoembolization (TACE). Materials and Methods: A retrospective study was performed over a 42 months period. A total of 51 TACE procedures were included in the study. Information collected included: Gender, BMI, height, weight, cumulative dose area product (KAP), cumulative reference air kerma (RAK), maximum tumor diameter, multinodular tumors, and embolization material. Parametric univariate and simple linear regression analysis were used to determine associations between quantitative variables. Results: A total of 51 procedures in 37 patients, 19 women (51%) and 18 men (49%), with a mean age of 56 years (±17.3 years) and a mean BMI of 24 kg/m2 were included in the study. Overall, patient radiation dose was as follows: Mean KAP of 542.2 Gy* cm2 (±307 Gy* cm2) with a mean RAK of 2930.2 mGy (±1776.5 mGy). Higher patient radiation doses were observed in men (581.6 ± 262.9 Gy* cm2 vs. 497.8 ± 350.5 Gy* cm2) (P = 0.06) and in patients with higher BMIs (KAP: r = 0.37 [P = 0.01]; RAK: r = 0.4 [P = 0.01]). Patients with multinodular disease were found with lower radiation dose according to RAK (1710.7 ± 1118.6 mGy vs. 3227.7 ± 1789.1 mGy, P = 0.03). Furthermore, logistic regression analysis demonstrated that patients with multinodular disease received 10% lower dose, according to RAK, when compared to patients with single tumors (odds ratio 1.001, 95% confidence interval [CI], 1–1.002) (P = 0.02). Conclusion: TACE is an effective method to treat patients with HCC that may be performed within acceptable radiation dose limits. Anatomic tumor characteristics were found to be associated with patient radiation dose. Interestingly, multi-tumor disease was found to cause a radiation dose reduction of 10%.

Cardiac Computed Tomography for Comprehensive Coronary Assessment: Beyond Diagnosis of Anatomic Stenosis.

Cardiac computed tomography angiography (CCTA) has evolved into a versatile imaging modality that can depict atherosclerosis burden, determine functional significance of a stenotic lesion, and guide the management and treatment of stable coronary artery disease.1 With newer-generation scanners, diagnostic CCTA can be obtained in the majority of patients with a very acceptable radiation dose. We discuss the ability of CCTA to provide comprehensive assessment of a patient with suspected CAD, including functional techniques of stress-rest myocardial perfusion assessment using a vasodilator and a purely post-processing approach that assesses fractional flow reserve derived by CCTA. In addition, recent data validated the role of CCTA in managing stable patients with chest pain and suspected CAD, serving as a gatekeeper for invasive coronary angiogram as well as optimizing the preprocedural planning of percutaneous coronary revascularization and coronary artery bypass surgery.

Identification of amyloid plaques in the brain using an x-ray photon-counting strip detector.

Brain aggregates of β amyloid (βA) protein plaques have been widely recognized as associated with many neurodegenerative diseases, and their identification can assist in the early diagnosis of Alzheimer’s disease. We investigate the feasibility of using a spectral x-ray coherent scatter system with a silicon strip photon-counting detector for identifying brain βA protein plaques. This approach is based on differences in the structure of amyloid, white and grey matter in the brain. We simulated an energy- and angular-dispersive X-ray diffraction system with an x-ray pencil beam and Silicon strip sensor, energy-resolving detectors. The polychromatic beam is geometrically focused toward a region of interest in the brain. First, the open-source MC-GPU code for Monte Carlo transport was modified to accommodate the detector model. Second, brain phantoms with and without βA were simulated to assess the method and determine the radiation dose required to obtain acceptable statistical power. For βA targets of 3, 4 and 5 mm sizes in a 15-cm brain model, the required incident exposure was about 0.44 mR from a 60 kVp tungsten spectrum and 3.5 mm of added aluminum filtration. The results suggest that the proposed x-ray coherent scatter technique enables the use of high energy x-ray spectra and therefore has the potential to be used for accurate in vivo detection and quantification of βA in the brain within acceptable radiation dose levels.

Investigation of HZE particle fluxes as a space radiation hazard for future Mars missions

Manned Mars missions planned in the near future of very low solar activity period and hence higher than acceptable radiation doses due mainly to the Galactic Cosmic Rays (GCR), would require special techniques and technological development for maintaining the good health of the astronauts. The present study is an attempt to make an assessment and characterise the coming years in terms of solar activity and space radiation environment especially due to the abundance of highly energetic heavy ions (known as HZE charged particles). These HZE particle fluxes constitute a major hazard to the astronauts and also to the critical electronic components of the spacecraft. Recent data on the HZE species (from B to Ni) obtained from ACE spacecraft shows a clear enhancement of the particle fluxes between the solar cycle 23 and solar cycle 24 (~between SSN peaks 2002 and 2014) due to the persisting low sunspot numbers of the latter cycle. The peak values of these cosmic ray fluxes occur with a time lag of about a year of the corresponding minimum value of the sunspots of a particular 11-year cycle which is pseudo-periodic in nature. This is demonstrated by the Fourier and Wavelet transform analyses of the long duration (1700–2018) yearly mean sunspot number data. The same time series data is also used to train a Hybrid Regression Neural Network (HRNN) model to generate the predicted yearly mean sunspot numbers for the solar cycle 25 (~2019–2031). The wavelet analysis of this new series of annual sunspot numbers including the predictions up to the end of 2031 shows a clear trend of continuation of the low solar activity and hence continuation of very high HZE fluxes prevailing in Solar cycle 24 into the solar cycle 25 and perhaps beyond.

Transverse and longitudinal segmented forward hadron calorimeters with SiPMs light readout for future fixed target heavy ion experiments

Forward hadron calorimeters with transverse and longitudinal segmentation are developed for upgraded NA61/SHINE [BM@N] and future CBM experiments at CERN, JINR and FAIR respectively. The main purpose of these calorimeters is to provide an event-by-event measurements of centrality and reaction plane orientation in ion collisions. Hadron calorimeters in all these experiments are composed of sampling lead/scintillator modules. The light collection from longitudinal sections in modules is provided by Wave-Length Shifting (WLS) fibers embedded in scintillator plates. Micropixel photodetectors MPPCs are used for light detection. The light yield measured at muons beam for these modules is about 8 - 10 ph.el./MeV. Performance of the supermodule composed of these modules has been studied at proton beam energies 1.5 - 150 GeV at CERN. Radiation conditions at high heavy ion beam rates are studied by FLUKA simulations for calorimeters geometry optimization aimed to get acceptable radiation doses and neutron fluence both for the scintillator plates and for photodetectors in these experiments.

Intra- and inter-rater reliability in a comparative study of cross-sectional and spiral computed tomography pelvimetry methods.

BackgroundDifferent low-dose computed tomography (CT) pelvimetry methods can be used to evaluate the size of birth canal before delivery. CT pelvimetry might generate an acceptable low fetal radiation dose but its measurement accuracy is unknown.PurposeTo investigate intra- and inter-rater measurement reliability of cross-sectional and two spiral CT pelvimetry methods: standard spiral and short spiral.Material and MethodsTen individuals (age ≥60 years, body mass index ≥30 kg/m2) having a CT scan of the abdomen also had CT pelvimetry scans. Three radiologists made independent measurements of each pelvimetry method on two occasions and also in consensus for a reference pelvimetry computed from the standard-dose CT scan of the abdomen. Inter- and intra-rater reliability was analyzed by intraclass correlation coefficient.ResultsMeasurements in the short spiral pelvimetry demonstrated excellent intra- and inter-rater reliability, intraclass correlation coefficient ≥0.93, and good to excellent 95% confidence interval 0.87–0.99. Corresponding results of the standard spiral and cross-sectional pelvimetry showed good to excellent intraclass correlation coefficient ≥0.85 and ≥0.76, and 95% confidence interval was least good and moderate 0.73–0.98 and 0.59–0.97, respectively. Intraclass correlation coefficient between reference pelvimetry and other CT methods showed analogous results.ConclusionThe short spiral pelvimetry demonstrated high and best reliability in comparison to other methods. Standard spiral method showed also good measurement reliability but the short spiral pelvimetry generates lower fetal radiation dose. This method might be suitable for measurements at narrow pelvis. Patient acceptance and attitude to CT pelvimetry should be investigated.