scholarly journals Impact of the dosimetry approach on the resulting 90Y radioembolization planned absorbed doses based on 99mTc-MAA SPECT-CT: is there agreement between dosimetry methods?

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Verónica Morán ◽  
Elena Prieto ◽  
Lidia Sancho ◽  
Macarena Rodríguez-Fraile ◽  
Leticia Soria ◽  
...  
Keyword(s):  
Absorbed Dose ◽  
Poor Correlation ◽  
Partition Model ◽  
Substantial Impact ◽  
Dose Volume Histograms ◽  
Absorbed Doses ◽  
Voxel Dosimetry ◽  
Pre Treatment ◽  
90Y Radioembolization ◽  
The Impact

Abstract Background Prior radioembolization, a simulation using 99mTc-macroaggregated albumin as 90Y-microspheres surrogate is performed. Gamma scintigraphy images (planar, SPECT, or SPECT-CT) are acquired to evaluate intrahepatic 90Y-microspheres distribution and detect possible extrahepatic and lung shunting. These images may be used for pre-treatment dosimetry evaluation to calculate the 90Y activity that would get an optimal tumor response while sparing healthy tissues. Several dosimetry methods are available, but there is still no consensus on the best methodology to calculate absorbed doses. The goal of this study was to retrospectively evaluate the impact of using different dosimetry approaches on the resulting 90Y-radioembolization pre-treatment absorbed dose evaluation based on 99mTc-MAA images. Methods Absorbed doses within volumes of interest resulting from partition model (PM) and 3D voxel dosimetry methods (3D-VDM) (dose-point kernel convolution and local deposition method) were evaluated. Additionally, a new “Multi-tumor Partition Model” (MTPM) was developed. The differences among dosimetry approaches were evaluated in terms of mean absorbed dose and dose volume histograms within the volumes of interest. Results Differences in mean absorbed dose among dosimetry methods are higher in tumor volumes than in non-tumoral ones. The differences between MTPM and both 3D-VDM were substantially lower than those observed between PM and any 3D-VDM. A poor correlation and concordance were found between PM and the other studied dosimetry approaches. DVH obtained from either 3D-VDM are pretty similar in both healthy liver and individual tumors. Although no relevant global differences, in terms of absorbed dose in Gy, between both 3D-VDM were found, important voxel-by-voxel differences have been observed. Conclusions Significant differences among the studied dosimetry approaches for 90Y-radioembolization treatments exist. Differences do not yield a substantial impact in treatment planning for healthy tissue but they do for tumoral liver. An individual segmentation and evaluation of the tumors is essential. In patients with multiple tumors, the application of PM is not optimal and the 3D-VDM or the new MTPM are suggested instead. If a 3D-VDM method is not available, MTPM is the best option. Furthermore, both 3D-VDM approaches may be indistinctly used.

scholarly journals Yttrium-90 Quantitative Phantom Study Using Digital Photon Counting PET

2021 ◽  
Author(s):  
Joey Labour ◽  
Philippe Boissard ◽  
Thomas Baudier ◽  
Fouzi Khayi ◽  
David Kryza ◽  
...  
Keyword(s):  
Photon Counting ◽  
Branching Ratio ◽  
Absorbed Dose ◽  
Dose Volume Histograms ◽  
Quantitative Pet ◽  
Acquisition Duration ◽  
Filter Size ◽  
Digital Photon Counting ◽  
The Impact ◽  
Imaging Conditions

Abstract Background: PET imaging of 90Y-microspheres distribution following radioembolisation is a challenging task due to the count-starved statistics from the low branching ratio producing e+/e- pairs during 90Y decay. The recent PET systems using silicon photo-multipliers technology has shown better 90Y image quality compared to photo-multiplier tubes. The aim of the present study was to quantitatively evaluate the impact of 90Y imaging conditions and reconstruction parameters on the dosimetry calculations using a digital photon counting PET.Methods: Quantitative PET and dosimetry accuracy were evaluated using two uniform cylindrical phantoms specific for PET calibration validation. A body phantom with an 9:1 hot sphere-to-background ratio was scanned at different activity concentrations of 90Y. Reconstructions were performed using OSEM algorithm with varying parameters. Time-of-flight and point-spread function modellings were included in all reconstructions. Absorbed dose calculations were carried out using Voxel S-Values convolution and were compared to reference Monte Carlo simulations. Dose-volume histograms and root-mean-square deviations were used to evaluate reconstruction parameter sets. Thanks to listmode data, datasets for phantoms and patients were rebinned into varying lengths of time to assess the influence of acquisition duration on the calculation of absorbed dose. Results: A 2 mm full width at half maximum post-reconstruction Gaussian filter size can be used for image reconstruction, keeping the same accuracy as when no filter is applied for dosimetry purposes and reducing noise. Larger filter sizes should not be used. An acquisition duration of more than 10 min/bed reduces image noise but has no significant impact in the quantification of phantom and patient data for the digital photon counting PET. 3 iterations with 10 subsets was found suitable for large spheres whereas 1 iteration with 30 subsets could improve dosimetry for smaller spheres. Conclusion: The choice of iterations and subsets combination depends on the size of the spheres. However, one should be careful on this choice, depending on the imaging conditions and setup. This study can be useful in this choice for future studies for more accurate 90Y post-dosimetry using a digital photon counting PET.

scholarly journals Simplification of Dosimetry in 90Y-Radioembolization Therapy Using Dual Planar Images.

2021 ◽  
Author(s):  
mohammad abuqbeitah ◽  
Özgür Akdağ ◽  
mustafa demir ◽  
sertaç asa ◽  
kerim sönmezoğlu
Keyword(s):  
Scatter Correction ◽  
Absorbed Dose ◽  
Whole Body ◽  
Whole Body Scan ◽  
Body Scan ◽  
Absorbed Doses ◽  
Significant Difference ◽  
Lung Shunt ◽  
The Impact ◽  
Healthy Liver

Abstract Aim: The purpose was to provide practical and effective method for performing 90Y dosimetry with 99mTc-MAA. The impact of scatter and attenuation correction (AC) on the injected 90Y activity and absorbed doses to critical organs was also further target beyond this study.Material and Methods: 18 patients (F: 3, M: 15) were subjected to 90Y therapy. 99mTc-MAA (111-222 MBq) was injected into the targeted liver, followed by a whole-body scan (WBS) with peak-window at 140 keV (15% width), and one down-scatter window. SPECT/CT scan was acquired over the lungs and liver regions. The lung shunt fractions were fashioned from the standard WBS, scatter corrected WBS, only scatter corrected SPECT and SPECT/CT with attenuation and scatter correction. The absorbed doses to tumor and surrounding healthy tissue were estimated with alternative approaches involving AC-SC (SPECT/CT), NoAC-SC (SPECT), NoAC-NoSC+LSF (SC-WBS), AC-SC+LSF (WBS), and NoAC-NoSC+LSF (WBS).Results: The average LSF deviations between the standard LSF and those obtained from AC-SC, NoAC-SC, and SC-WBS was -50% (-29/-71), -32%(-8/-67), and -45%(-13/80), respectively. The prescribed 90Y activity (GBq/Gy) was decreased by a range of 2-11%, 1-9%, and 2-7% with using LSFs from AC-SC, NoAC-SC, SC-WBS images. The absorbed dose to tumour and healthy liver tissue were calculated as 112±90 Gy and 30±18 Gy/GBq by AC-SC (SPECT/CT), 117±108 and 30±22 by NoAC-SC (SPECT), 110±100 and 31±21 Gy/GBq by NoAC-NoSC+LSF (SC-WBS), 106±84 and 28±17 Gy/GBq by AC-SC+LSF (WBS), while the absorbed dose was 90±85 and 28±20 Gy/GBq by using NoAC-NoSC+ LSF (WBS). Overall, no significant difference (p< 0.05) in the tomour and the health liver dose between all the approaches with/and without scatter correction. However, the scatter correction caused a significant difference in the lung shunt fractions (p <0.05).Conclusion: Scatter correction has a significant effect on the lung shunt fractions, planned activity and number of 90Y treatments. However, a minimal or negligible change was occurred on the absorbed dose to tumours and surrounding healthy liver. The good agreement between SPECT/CT approach, and scatter corrected whole-body scan might be practical and effective route for 90Y dosimetry.

scholarly journals Impact of contouring methods on pre-treatment and post-treatment dosimetry for the prediction of tumor control and survival in HCC patients treated with selective internal radiation therapy

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Guillaume Nodari ◽  
Romain Popoff ◽  
Jean Marc Riedinger ◽  
Olivier Lopez ◽  
Julie Pellegrinelli ◽  
...  
Keyword(s):  
Absorbed Dose ◽  
Normal Liver ◽  
Post Treatment ◽  
Tumor Control ◽  
Clinical Workflow ◽  
Liver Uptake ◽  
Advanced Hcc ◽  
Dose Metrics ◽  
Pre Treatment ◽  
The Impact

Abstract Introduction The aim of this study was to evaluate the impact of the contouring methods on dose metrics and their predictive value on tumor control and survival, in both situations of pre-treatment and post-treatment dosimetry, for patients with advanced HCC treated with SIRT. Methods Forty-eight patients who underwent SIRT between 2012 and 2020 were retrospectively included in this study. Target volumes were delineated using two methods: MRI-based contours manually drawn by a radiologist and then registered on SPECT/CT and PET/CT via deformable registration (Pre-CMRI and Post-CMRI), 99mTc-MAA-SPECT and 90Y-microspheres-PET 10% threshold contouring (Pre-CSPECT and Post-CPET). The mean absorbed dose (Dm) and the minimal absorbed dose delivered to 70% of the tumor volume (D70) were evaluated with both contouring methods; the tumor-to-normal liver uptake ratio (TNR) was evaluated with MRI-based contours only. Tumor response was assessed using the mRECIST criteria on the follow-up MRIs. Results No significant differences were found for Dm and TNR between pre- and post-treatment. TNR evaluated with radiologic contours (Pre-CMRI and Post-CMRI) were predictive of tumor control at 6 months on pre- and post-treatment dosimetry (OR 5.9 and 7.1, respectively; p = 0.02 and 0.01). All dose metrics determined with both methods were predictive of overall survival (OS) on pre-treatment dosimetry, but only Dm with MRI-based contours was predictive of OS on post-treatment images with a median of 23 months for patients with a supramedian Dm versus 14 months for the others (p = 0.04). Conclusion In advanced HCC treated with SIRT, Dm and TNR determined with radiologic contours were predictive of tumor control and OS. This study shows that a rigorous clinical workflow (radiologic contours + registration on scintigraphic images) is feasible and should be prospectively considered for improving therapeutic strategy.

scholarly journals In Silico Validation of MCID Platform for Monte Carlo-Based Voxel Dosimetry Applied to 90Y-Radioembolization of Liver Malignancies

2021 ◽  
Vol 11 (4) ◽  
pp. 1939
Author(s):  
Alessia Milano ◽  
Alex Vergara Gil ◽  
Enrico Fabrizi ◽  
Marta Cremonesi ◽  
Ivan Veronese ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Liver Tumors ◽  
Absorbed Dose ◽  
Patient Specific ◽  
Liver Malignancies ◽  
Functional Images ◽  
Geant4 Code ◽  
Voxel Dosimetry ◽  
90Y Radioembolization ◽  
Real Patients

The aim was the validation of a platform for internal dosimetry, named MCID, based on patient-specific images and direct Monte Carlo (MC) simulations, for radioembolization of liver tumors with 90Y-labeled microspheres. CT of real patients were used to create voxelized phantoms with different density and activity maps. SPECT acquisitions were simulated by the SIMIND MC code. Input macros for the GATE/Geant4 code were generated by MCID, loading coregistered morphological and functional images and performing image segmentation. The dosimetric results obtained from the direct MC simulations and from conventional MIRD approach at both organ and voxel level, in condition of homogeneous tissues, were compared, obtaining differences of about 0.3% and within 3%, respectively, whereas differences increased (up to 14%) introducing tissue heterogeneities in phantoms. Mean absorbed dose for spherical regions of different sizes (10 mm ≤ r ≤ 30 mm) from MC code and from OLINDA/EXM were also compared obtaining differences varying in the range 7–69%, which decreased to 2–9% after correcting for partial volume effects (PVEs) from imaging, confirming that differences were mostly due to PVEs, even though a still high difference for the smallest sphere suggested possible source description mismatching. This study validated the MCID platform, which allows the fast implementation of a patient-specific GATE simulation, avoiding complex and time-consuming manual coding. It also points out the relevance of personalized dosimetry, accounting for inhomogeneities, in order to avoid absorbed dose misestimations.

The Digital Divide and K-12 Student Computer Use

10.28945/2926 ◽  
2005 ◽  
Author(s):  
James N. Morgan ◽  
Craig A. VanLengen
Keyword(s):  
Digital Divide ◽  
Computer Use ◽  
Census Data ◽  
Internet Access ◽  
Demographic Characteristics ◽  
The Internet ◽  
Substantial Impact ◽  
Limited Basis ◽  
K 12 ◽  
The Impact

The divide between those who have computer and Internet access and those who do not appears to be narrowing, however overall statistics may be misleading. Measures of computer availability in schools often include cases where computers are only available for administration or are available only on a very limited basis (Gootman, 2004). Access to a computer and the Internet outside of school helps to reinforce student learning and emphasize the importance of using technology. Recent U.S. statistics indicate that ethnic background and other demographic characteristics still have substantial impact on the availability and use of computers by students outside of the classroom. This paper examines recent census data to determine the impact of the household on student computer use outside of the classroom. Encouragingly, the findings of this study suggest that use of a computer at school substantially increases the chance that a student will use a computer outside of class. Additionally, this study suggests that computer use outside of the classroom is positively and significantly impacted by being in a household with adults who either use a computer at work or work in an industry where computers are extensively used.

scholarly journals Pre-treatment clinical and gene expression patterns predict developmental change in early intervention in autism

2021 ◽  
Author(s):  
Michael V. Lombardo ◽  
Elena Maria Busuoli ◽  
Laura Schreibman ◽  
Aubyn C. Stahmer ◽  
Tiziano Pramparo ◽  
...  
Keyword(s):  
Gene Expression ◽  
Treatment Outcome ◽  
Early Intervention ◽  
Developmental Change ◽  
Expression Patterns ◽  
Gene Expression Patterns ◽  
Time In Treatment ◽  
Pre Treatment ◽  
Blood Leukocyte ◽  
The Impact

AbstractEarly detection and intervention are believed to be key to facilitating better outcomes in children with autism, yet the impact of age at treatment start on the outcome is poorly understood. While clinical traits such as language ability have been shown to predict treatment outcome, whether or not and how information at the genomic level can predict treatment outcome is unknown. Leveraging a cohort of toddlers with autism who all received the same standardized intervention at a very young age and provided a blood sample, here we find that very early treatment engagement (i.e., <24 months) leads to greater gains while controlling for time in treatment. Pre-treatment clinical behavioral measures predict 21% of the variance in the rate of skill growth during early intervention. Pre-treatment blood leukocyte gene expression patterns also predict the rate of skill growth, accounting for 13% of the variance in treatment slopes. Results indicated that 295 genes can be prioritized as driving this effect. These treatment-relevant genes highly interact at the protein level, are enriched for differentially histone acetylated genes in autism postmortem cortical tissue, and are normatively highly expressed in a variety of subcortical and cortical areas important for social communication and language development. This work suggests that pre-treatment biological and clinical behavioral characteristics are important for predicting developmental change in the context of early intervention and that individualized pre-treatment biology related to histone acetylation may be key.

scholarly journals Time-to-Treatment in Oral Cancer: Causes and Implications for Survival

Cancers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 1321
Author(s):  
Constanza Saka-Herrán ◽  
Enric Jané-Salas ◽  
Antoni Mari-Roig ◽  
Albert Estrugo-Devesa ◽  
José López-López
Keyword(s):  
Oral Cancer ◽  
Previous Treatment ◽  
Diagnostic Procedures ◽  
Original Data ◽  
Primary Treatment ◽  
Medical Attention ◽  
Time Interval ◽  
Pre Treatment ◽  
The Impact ◽  
Lack Of Knowledge

The purpose of this review was to identify and describe the causes that influence the time-intervals in the pathway of diagnosis and treatment of oral cancer and to assess its impact on prognosis and survival. The review was structured according to the recommendations of the Aarhus statement, considering original data from individual studies and systematic reviews that reported outcomes related to the patient, diagnostic and pre-treatment intervals. The patient interval is the major contributor to the total time-interval. Unawareness of signs and/or symptoms, denial and lack of knowledge about oral cancer are the major contributors to the process of seeking medical attention. The diagnostic interval is influenced by tumor factors, delays in referral due to higher number of consultations and previous treatment with different medicines or dental procedures and by professional factors such as experience and lack of knowledge related to the disease and diagnostic procedures. Patients with advanced stage disease, primary treatment with radiotherapy, treatment at an academic facility and transitions in care are associated with prolonged pre-treatment intervals. An emerging body of evidence supports the impact of prolonged pre-treatment and treatment intervals with poorer survival from oral cancer.

scholarly journals Comparison of Selected Immune and Hematological Parameters and Their Impact on Survival in Patients with HPV-Related and HPV-Unrelated Oropharyngeal Cancer

Cancers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 3256
Author(s):  
Adam Brewczyński ◽  
Beata Jabłońska ◽  
Agnieszka Maria Mazurek ◽  
Jolanta Mrochem-Kwarciak ◽  
Sławomir Mrowiec ◽  
...  
Keyword(s):  
Prognostic Factors ◽  
Oropharyngeal Cancer ◽  
Hematological Parameters ◽  
White Blood Cells ◽  
Post Treatment ◽  
Neutrophil Lymphocyte Ratio ◽  
Lymphocyte Ratio ◽  
Hpv Status ◽  
Pre Treatment ◽  
The Impact

Several immune and hematological parameters are associated with survival in patients with oropharyngeal cancer (OPC). The aim of the study was to analyze selected immune and hematological parameters of patients with HPV-related (HPV+) and HPV-unrelated (HPV-) OPC, before and after radiotherapy/chemoradiotherapy (RT/CRT) and to assess the impact of these parameters on survival. One hundred twenty seven patients with HPV+ and HPV− OPC, treated with RT alone or concurrent chemoradiotherapy (CRT), were included. Patients were divided according to HPV status. Confirmation of HPV etiology was obtained from FFPE (Formalin-Fixed, Paraffin-Embedded) tissue samples and/or extracellular circulating HPV DNA was determined. The pre-treatment and post-treatment laboratory blood parameters were compared in both groups. The neutrophil/lymphocyte ratio (NLR), platelet/lymphocyte ratio (PLR), monocyte/lymphocyte ratio (MLR), and systemic immune inflammation (SII) index were calculated. The impact of these parameters on overall (OS) and disease-free (DFS) survival was analyzed. In HPV+ patients, a high pre-treatment white blood cells (WBC) count (>8.33 /mm3), NLR (>2.13), SII (>448.60) significantly correlated with reduced OS, whereas high NLR (>2.29), SII (>462.58) significantly correlated with reduced DFS. A higher pre-treatment NLR and SII were significant poor prognostic factors for both OS and DFS in the HPV+ group. These associations were not apparent in HPV− patients. There are different pre-treatment and post-treatment immune and hematological prognostic factors for OS and DFS in HPV+ and HPV− patients. The immune ratios could be considered valuable biomarkers for risk stratification and differentiation for HPV− and HPV+ OPC patients.

scholarly journals Review on Urban Heat Island in China: Methods, Its Impact on Buildings Energy Demand and Mitigation Strategies

2021 ◽  
Vol 13 (2) ◽  
pp. 762
Author(s):  
Liu Tian ◽  
Yongcai Li ◽  
Jun Lu ◽  
Jue Wang
Keyword(s):  
Energy Consumption ◽  
Urban Heat Island ◽  
Building Energy ◽  
Design Stage ◽  
Heat Island ◽  
Building Energy Consumption ◽  
Rapid Urbanization ◽  
Substantial Impact ◽  
Urban Heat ◽  
The Impact

High population density, dense high-rise buildings, and impervious pavements increase the vulnerability of cities, which aggravate the urban climate environment characterized by the urban heat island (UHI) effect. Cities in China provide unique information on the UHI phenomenon because they have experienced rapid urbanization and dramatic economic development, which have had a great influence on the climate in recent decades. This paper provides a review of recent research on the methods and impacts of UHI on building energy consumption, and the practical techniques that can be used to mitigate the adverse effects of UHI in China. The impact of UHI on building energy consumption depends largely on the local microclimate, the urban area features where the building is located, and the type and characteristics of the building. In the urban areas dominated by air conditioning, UHI could result in an approximately 10–16% increase in cooling energy consumption. Besides, the potential negative effects of UHI can be prevented from China in many ways, such as urban greening, cool material, water bodies, urban ventilation, etc. These strategies could have a substantial impact on the overall urban thermal environment if they can be used in the project design stage of urban planning and implemented on a large scale. Therefore, this study is useful to deepen the understanding of the physical mechanisms of UHI and provide practical approaches to fight the UHI for the urban planners, public health officials, and city decision-makers in China.

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