There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

Co-Planar Stereotaxic Atlas of the Human Brain—3-Dimensional Proportional System: An Approach to Cerebral Imaging, J. Talairach, P. Tournoux. Georg Thieme Verlag, New York (1988), 122 pp., 130 figs. DM 268

“Unpaired Image-to-Image Translation using Cycle-Consistent Adversarial Networks”の学習報告

NOTE The report of the Committee without its annexes appears as Official Records of the General Assembly, Sixty-third Session, Supplement No. 46. The designations employed and the presentation of material in this publication do not imply the expression of any opinion whatsoever on the part of the Secretariat of the United Nations concerning the legal status of any country, territory, city or area, or of its authorities, or concerning the delimitation of its frontiers or boundaries. The country names used in this document are, in most cases, those that were in use at the time the data were collected or the text prepared. In other cases, however, the names have been updated, where this was possible and appropriate, to reflect political changes. Scientific Annexes Annex A. Medical radiation exposures Annex B. Exposures of the public and workers from various sources of radiation INTROdUCTION 1. In the course of the research and development for and the application of atomic energy and nuclear technologies, a number of radiation accidents have occurred. Some of these accidents have resulted in significant health effects and occasionally in fatal outcomes. The application of technologies that make use of radiation is increasingly widespread around the world. Millions of people have occupations related to the use of radiation, and hundreds of millions of individuals benefit from these uses. Facilities using intense radiation sources for energy production and for purposes such as radiotherapy, sterilization of products, preservation of foodstuffs and gamma radiography require special care in the design and operation of equipment to avoid radiation injury to workers or to the public. Experience has shown that such technology is generally used safely, but on occasion controls have been circumvented and serious radiation accidents have ensued. 2. Reviews of radiation exposures from accidents have been presented in previous UNSCEAR reports. The last report containing an exclusive chapter on exposures from accidents was the UNSCEAR 1993 Report [U6]. 3. This annex is aimed at providing a sound basis for conclusions regarding the number of significant radiation accidents that have occurred, the corresponding levels of radiation exposures and numbers of deaths and injuries, and the general trends for various practices. Its conclusions are to be seen in the context of the Committee's overall evaluations of the levels and effects of exposure to ionizing radiation. 4. The Committee's evaluations of public, occupational and medical diagnostic exposures are mostly concerned with chronic exposures of …

sources and effects of ionizing radiation

The RECIST criteria are used in computed tomography (CT) imaging to assess changes in tumour burden induced by cancer therapeutics throughout treatment. One of its requirements is frequent measurement of lesion diameters , which is often time consuming for clinicians. We aimed to study clinician-interactive AI, defined as deep learning models that use image annotations as input to assist in radiological measurements. Two annotation types are compared in their enhancement of predictive capabilities: mouse clicks in the tumour region, and bounding boxes surrounding lesions. The model architectures compared in this study are the U-Net, V-Net, AH-Net, and SegRes-Net. Models were trained and tested using a non-small cell lung cancer dataset from the cancer imaging archive (TCIA) consisting of CT scans and corresponding gold-standard lesion segmentations inferred from PET/CT scans. Mouse clicks and bounding boxes, representing clinician input, were artificially generated. The absolute percent error between predicted and ground truth diameters was computed for each model architecture. Bounding box annotations yielded mean absolute percent errors of 4.9 ± 2.1 %, 7.8 ± 3.4 %, 5.6 ± 2.4 % and 5.6 ± 2.3 %, respectively, whereas models using clicks annotations yielded 17.0 ± 7.9 %, 19.8 ± 9.3 %, 21.4 ± 10.9 % and 18.1 ± 7.9%. The corresponding mean dice scores across all model architectures were 0.883 ± 0.004 and 0.760 ± 0.012 for bounding box and click annotations respectively. Models were then implemented in an AI pipeline for clinical use at the BC cancer agency using the Ascinta software package; click annotations yielded qualitatively better results than bounding box annotations.

Clinician-interactive AI for RECIST measurements in CT imaging

The modulation transfer function (MTF) is the technical description of spatial resolution for most imaging systems. the MTF describes how well an imaging system processes signal [1,4]. There are several methods for calculation of MTF that can be categorized in theoretical and experimental methods. In this study, in order to compare the performance of five different commercial CT scanner, an experimental method was used to calculate MTF in all scanners. The MTF curves were calculated for both axial and helical scanning mode and also for different slice thickness. The method for experimental measurement of MTF which called SD method is based on calculation of the standard deviation (SD) of CT numbers in different regions of scanned phantom and determination of coefficient modulation. The results calculated in this study using simple experimental measurements were in good agreement with published technical specification by manufacturers [5].

Experimental Measurement of Modulation Transfer Function (MTF) in Five Commercial CT Scanners

Over the past few decades, there have been significant advances in medical imaging, which have modernized the assessment of a large number of disorders and provided high accuracy. The advent of X-ray CT in 1973 unlocked a new-fangled era in structural imaging, which has improved over the years to further increase the number of clinical applications using this very powerful modality [1]. This technology had a profound impact on clinical practice and proved to be valuable in almost every disorder, predominantly in situations where surgical intervention is required for optimal patient management. Subsequent to the introduction of CT, MRI became the major spotlight owing to its high soft tissue contrast, which enabled the investigation of soft tissue abnormalities, mostly in the central nervous and musculoskeletal systems [2, 3]. For virtually all neurological diseases, MRI has become and still is the preferred modality for detection and accurate characterization of the underlying disorder. Similarly, MR provided superior value for the characterization of many musculoskeletal abnormalities owing to its high spatial and contrast resolutions that enables improved lesion detectability in this organ system.

Multimodality Molecular Imaging: A Futuristic Outlook

Continuous Bed Motion (CBM) acquisition mode enables the simultaneous estimation of compartmental and graphical analysis kinetic parameters in whole-body (WB) dynamic PET imaging. Lesion detectability is one of the important characteristics when developing novel image acquisition protocols. In this work, we used clinical dynamic WB 18F-FDG PET/CT studies to compare lesion detectability between Patlak graphical analysis and full compartmental modeling derived using a previously proposed methodology for hybrid macro- and micro-parametric imaging. The performance of these approaches in the context of lesion detection and false positive identification was compared to conventional static standardized uptake value (SUV) imaging. This study was conducted on 8 clinical whole-body 18F-FDG PET/CT studies injected with 3.5 MBq/kg of 18F-FDG. The total scan time including dynamic WB imaging lasted 80 minutes. An in-house developed MATLAB code was utilized to derive the micro- and macro-parametric maps. In total, 104 lesions were detected, among which 47 located in the bed position where all quantitative parameters were calculated, thus enabling comparative analysis. The evaluation encompassed visual interpretation performed by expert physicians as well as quantitative and statistical analysis. High correlation coefficients were observed between SUVmax and Kimax derived from generalized linear least square (GLLS) approach as well as Ki generated by Patlak graphical analysis. Moreover, three biopsy-proven malignant lesions located in the liver were not visible on static SUV images and Patlak maps while they were depicted on K 1 and k 2 maps. Our results demonstrate that full compartmental modeling has the potential to provide complementary information and in some cases more accurate diagnosis than conventional static SUV imaging and even Patlak graphical analysis.

Clinical assessment of lesion detectability in dynamic whole-body PET imaging using compartmental and Patlak parametric mapping

Abstract Background Selective internal radiation therapy with 90 Y radioembolization aims to selectively irradiate liver tumours by administering radioactive microspheres under the theragnostic assumption that the pre-therapy injection of 99m Tc labelled macroaggregated albumin ( 99m Tc-MAA) provides an estimation of the 90 Y microspheres biodistribution, which is not always the case. Due to the growing interest in theragnostic dosimetry for personalized radionuclide therapy, a robust relationship between the delivered and pre-treatment radiation absorbed doses is required. In this work, we aim to investigate the predictive value of absorbed dose metrics calculated from 99m Tc-MAA (simulation) compared to those obtained from 90 Y post-therapy SPECT/CT. Results A total of 79 patients were analysed. Pre- and post-therapy 3D-voxel dosimetry was calculated on 99m Tc-MAA and 90 Y SPECT/CT, respectively, based on Local Deposition Method. Mean absorbed dose, tumour-to-normal ratio, and absorbed dose distribution in terms of dose-volume histogram (DVH) metrics were obtained and compared for each volume of interest (VOI). Mann–Whitney U-test and Pearson’s correlation coefficient were used to assess the correlation between both methods. The effect of the tumoral liver volume on the absorbed dose metrics was also investigated. Strong correlation was found between simulation and therapy mean absorbed doses for all VOIs, although simulation tended to overestimate tumour absorbed doses by 26%. DVH metrics showed good correlation too, but significant differences were found for several metrics, mostly on non-tumoral liver. It was observed that the tumoral liver volume does not significantly affect the differences between simulation and therapy absorbed dose metrics. Conclusion This study supports the strong correlation between absorbed dose metrics from simulation and therapy dosimetry based on 90 Y SPECT/CT, highlighting the predictive ability of 99m Tc-MAA, not only in terms of mean absorbed dose but also of the dose distribution. 

/pdf/predictive-value-of-99mtc-maa-based-dosimetry-in-29wd9dfm.pdf

Habib Zaidi

Papers

Clinician-interactive AI for RECIST measurements in CT imaging

Experimental Measurement of Modulation Transfer Function (MTF) in Five Commercial CT Scanners

Multimodality Molecular Imaging: A Futuristic Outlook

Clinical assessment of lesion detectability in dynamic whole-body PET imaging using compartmental and Patlak parametric mapping

Predictive value of 99mTc-MAA-based dosimetry in personalized 90Y-SIRT planning for liver malignancies