Phase-contrast imaging for body composition measurement

PurposeIn this paper, we propose a novel method for human body composition measurement, especially for the bone mineral density (BMD) measurement. The proposed method, using the absorption and differential phase information retrieved from X-ray grating-based interferometer (XGBI) to measure the BMD, has potential to replace dual-energy X-ray absorptiometry (DEXA), which is currently widely used for body composition measurement.MethodsThe DEXA method employs two absorption images acquired at two different X-ray spectra (high energy and low energy) to calculate the human body composition. In this paper, a new method to calculate BMD using a single X-ray measurement is proposed. XGBI is a relatively new X-ray technique that provides absorption, phase and scattering information simultaneously using a single X-ray spectrum. With the absorption and differential phase information retrieved from XGBI, BMD can be measured using only one single X-ray spectrum. Numerical simulations are performed with a body phantom of bone (Cortical, ICRU-44) surrounded by soft tissue (Soft, ICRU-44). BMD is calculated with both the DEXA method and the proposed method.ResultsResults show that BMD can be measured accurately with the proposed method; moreover, better signal-to-noise ratio (SNR) is obtained compared to DEXA.ConclusionWith the proposed method, BMD can be measured with XGBI setup. Further, the proposed method can be realized using current X-ray phase-contrast imaging (XPCI) apparatus without any hardware modification, suggesting that this technique can be a promising supplementary function to current XPCI equipment.     

Imaging performance of phase-contrast breast computed tomography with synchrotron radiation and a CdTe photon-counting detector

PurposeWithin the SYRMA-CT collaboration based at the ELETTRA synchrotron radiation (SR) facility the authors investigated the imaging performance of the phase-contrast computed tomography (CT) system dedicated to monochromatic in vivo 3D imaging of the female breast, for breast cancer diagnosis.MethodsTest objects were imaged at 38 keV using monochromatic SR and a high-resolution CdTe photon-counting detector. Signal and noise performance were evaluated using modulation transfer function (MTF) and noise power spectrum. The analysis was performed on the images obtained with the application of a phase retrieval algorithm as well as on those obtained without phase retrieval. The contrast to noise ratio (CNR) and the capability of detecting test microcalcification clusters and soft masses were investigated.ResultsFor a voxel size of (60 μm)³, images without phase retrieval showed higher spatial resolution (6.7 mm⁻¹ at 10% MTF) than corresponding images with phase retrieval (2.5 mm⁻¹). Phase retrieval produced a reduction of the noise level and an increase of the CNR by more than one order of magnitude, compared to raw phase-contrast images. Microcalcifications with a diameter down to 130 μm could be detected in both types of images.ConclusionsThe investigation on test objects indicates that breast CT with a monochromatic SR source is technically feasible in terms of spatial resolution, image noise and contrast, for in vivo 3D imaging with a dose comparable to that of two-view mammography. Images obtained with the phase retrieval algorithm showed the best performance in the trade-off between spatial resolution and image noise.     

Calculating the target exposure index using a deep convolutional neural network and a rule base

PurposeThe objective of this study is to determine the quality of chest X-ray images using a deep convolutional neural network (DCNN) and a rule base without performing any visual assessment. A method is proposed for determining the minimum diagnosable exposure index (EI) and the target exposure index (EIt).MethodsThe proposed method involves transfer learning to assess the lung fields, mediastinum, and spine using GoogLeNet, which is a type of DCNN that has been trained using conventional images. Three detectors were created, and the image quality of local regions was rated. Subsequently, the results were used to determine the overall quality of chest X-ray images using a rule-based technique that was in turn based on expert assessment. The minimum EI required for diagnosis was calculated based on the distribution of the EI values, which were classified as either suitable or non-suitable and then used to ascertain the EIt.ResultsThe accuracy rate using the DCNN and the rule base was 81%. The minimum EI required for diagnosis was 230, and the EIt was 288.ConclusionThe results indicated that the proposed method using the DCNN and the rule base could discriminate different image qualities without any visual assessment; moreover, it could determine both the minimum EI required for diagnosis and the EIt.     

Role of “the frame cycle time” in portal dose imaging using an aS500-II EPID

IntroductionThis paper evaluates the role of an acquisition parameter, the frame cycle time “FCT”, in the performance of an aS500-II EPID.Materials and methodsThe work presented rests on the study of the Varian EPID aS500-II and the image acquisition system 3 (IAS3). We are interested in integrated acquisition using asynchronous mode. For better understanding the image acquisition operation, we investigated the influence of the “frame cycle time” on the speed of acquisition, the pixel value of the averaged gray-scale frame and the noise, using 6 and 15 MV X-ray beams and dose rates of 1–6 Gy/min on 2100 C/D Linacs.ResultsIn the integrated mode not synchronized to beam pulses, only one parameter the frame cycle time “FCT” influences the pixel value. The pixel value of the averaged gray-scale frame is proportional to this parameter. When the FCT <55 ms (speed of acquisition V_f/s > 18 frames/s), the speed of acquisition becomes unstable and leads to a fluctuation of the portal dose response. A timing instability and saturation are detected when the dose per frame exceeds 1.53 MU/frame. Rules were deduced to avoid saturation and to optimize this dosimetric mode.ConclusionThe choice of the acquisition parameter is essential for the accurate portal dose imaging.     

Simulation of scanner- and patient-specific low-dose CT imaging from existing CT images

PurposeSimulating low-dose Computed Tomography (CT) facilitates in-silico studies into the required dose for a diagnostic task. Conventionally, low-dose CT images are created by adding noise to the projection data. However, in practice the raw data is often simply not available. This paper presents a new method for simulating patient-specific, low-dose CT images without the need of the original projection data.MethodsThe low-dose CT simulation method included the following: (1) computation of a virtual sinogram from a high dose CT image through a radon transform; (2) simulation of a ‘reduced’-dose sinogram with appropriate amounts of noise; (3) subtraction of the high-dose virtual sinogram from the reduced-dose sinogram; (4) reconstruction of a noise volume via filtered back-projection; (5) addition of the noise image to the original high-dose image. The required scanner-specific parameters, such as the apodization window, bowtie filter, the X-ray tube output parameter (reflecting the photon flux) and the detector read-out noise, were retrieved from calibration images of a water cylinder. The low-dose simulation method was evaluated by comparing the noise characteristics in simulated images with experimentally acquired data.ResultsThe models used to recover the scanner-specific parameters fitted accurately to the calibration data, and the values of the parameters were comparable to values reported in literature. Finally, the simulated low-dose images accurately reproduced the noise characteristics in experimentally acquired low-dose-volumes.ConclusionThe developed methods truthfully simulate low-dose CT imaging for a specific scanner and reconstruction using filtered backprojection. The scanner-specific parameters can be estimated from calibration data.     

Quantization accuracy of short-duration respiratory-gated PET/CT acquisitions

PurposePET/CT acquisitions are affected by physiological motion, which lowers the quantization accuracy. Respiratory-gated PET/CT methods require a long acquisition time, which may not be compatible with the clinical schedule. The objective of the present study was to assess the quantization accuracy of short-duration, respiratory-gated PET acquisitions and processing with the “CT-based” methodology developed in our laboratory.MethodsQuantization accuracy was first assessed in a phantom study. A standard (“Ungated”) PET/CT acquisition was followed by a 10-minute list-mode acquisition with simultaneous respiratory signal recording and a short breath-hold CT scan (BH-CT). These acquisitions were repeated 10 times. For the CT-based images, we reconstructed (i) 10 full-duration (FD-CT-based) volumes that took account of all events recorded in the position defined by BH-CT and (ii) 10 short-duration (SD-CT-based) volumes based on only 30 seconds of selected events. Using these volumes, we performed a bias–variance analysis to assess the effects of respiration-motion reduction and the counting statistics on the quantization accuracy. We also applied Ungated, FD- and SD-CT-based methods to 16 patients (21 pulmonary lesions) and measured the maximum standardized uptake (SUVmax) values.ResultsThe bias values were 71%, 40% and 44% for Ungated, FD- and SD-CT-based images, respectively. In the clinical study, there was a statistically significant difference in SUVmax between Ungated images and both the CT-Based images (p < 0.02) but not between the FD-CT-Based and SD-CT-Based images (p = 0.42).ConclusionOur findings demonstrated that the additional acquisition time required by the CT-based method can be reduced without altering quantitative accuracy.     

Faisabilité et intérêt d’un nouvel algorithme de reconstruction des images TEP-18FDG (AW OSEM DR) pour la délimitation des volumes cibles en radiothérapie. À propos d’un cas de néoplasie ORL

ObjectiveWe compared two reconstruction methods for 18fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography (PET) images with “attenuation weighted ordered subset expectation maximization” using either the manufacturer-provided (AW-OSEM) or a “Detector response” (AW-OSEM DR) tomographic operator. We looked at the feasibility of using the latter reconstruction for radiotherapy target volumes definition in cancers of the superior aero-digestive tract (VADS). In this preliminary study, we first assessed the spatial resolution of images obtained with AW-OSEM and AW-OSEM DR on a Biograph™ 6, and secondly target volumes of radiotherapy “Gross Tumor Volume” (GTV), “Clinical Target Volume” (CTV) and “Planning Target Volume” (PTV) obtained with each of these reconstruction methods.Material and methodsThe spatial resolution was measured on a test object containing 4 radioactive point sources. Furthermore, radiotherapy target volumes have been defined with the software Eclipse™ on injected scanner (CT IV) and PET/CT (PET AW-OSEM and PET AW-OSEM DR) images.ResultsSpatial resolution was improved with AW-OSEM DR algorithm reconstruction compared to images obtained with AW-OSEM reconstruction (from 7.5 mm down to 5.4 mm for the highest reduction). GTV from AW-OSEM DR reconstruction with 42 and 50% of the “Standard uptake value maximum” (SUVmax) semi-automatic threshold (1.2 and 0.7 cm³ respectively) were lower than those obtained with AW-OSEM (3.6 and 2.2 cm³ respectively). They were also lower than GTV defined with CT IV (5.5 cm³). It was the same for CTV and PTV.ConclusionThis study showed that AW-OSEM DR reconstruction method allows less impaired spatial resolution than AW-OSEM. In the case of radiotherapy target volumes delineation, AW-OSEM DR may decrease the GTV, CTV and PTV and therefore the risk of side effects associated with organs at risk.     

Image quality assessment of an iterative reconstruction algorithm applied to abdominal CT imaging

PurposeTo compare the noise and accuracy on images of the whole porcine liver acquired with iterative reconstruction (IMR, Philips Healthcare, Cleveland, OH, USA) and filtered back projection (FBP) methods.Materials and methodsWe used non-enhanced porcine liver to simulate the human liver and acquired it 100 times to obtain the average FBP value as the ground-truth. The mean and the standard deviation (“inter-scan SD”) of the pixel values on the 100 image acquisitions were calculated for FBP and for three levels of IMR (L1, L2, and L3). We also calculated the noise power spectrum (NPS) and the normalized NPS for the 100 image acquisitions.ResultsThe spatial SD for the porcine liver parenchyma on these slices was 9.92, 4.37, 3.63, and 2.30 Hounsfield units with FBP, IMR-L1, IMR-L2, and IMR-L3, respectively. The detectability of small faint features was better on single IMR than single FBP images. The inter-scan SD value for IMR-L3 images was 53% larger at the liver edges than at the liver parenchyma; it was only 10% larger on FBP images. Assessment of the normalized NPS showed that the noise on IMR images was comprised primarily of low-frequency components.ConclusionIMR images yield the same structure informations as FBP images and image accuracy is maintained. On level 3 IMR images the image noise is more strongly suppressed than on IMR images of the other levels and on FBP images.     

Interobserver And Intraobserver Agreement In Parathyroid Scintigraphy: How Can Parathyroid Scintigraphy Be Made More Reliable?

ObjectiveTo determine the intraobserver and interobserver agreement levels in the evaluation of technetium Tc 99m sestamibi parathyroid scintigraphic images.MethodsNinety-eight patients with hyperparathyroidism were included in the study, and their parathyroid images were evaluated by 4 experienced nuclear medicine observers. The 98 cases were evaluated twice by each observer within an interval of 2 weeks. The evaluations were performed directly on workstations with use of digital images. A questionnaire was completed by each observer. The presence of a lesion, the number and the localizations of the lesions, and whether the lesion was clear or doubtful were all evaluated. Cohen kappa statistics and total agreement percentages were calculated by using SPSS version 11.0 software.ResultsThe 4 observers performed 8 different evaluations and identified a minimum of 38 and a maximum of 43 cases with a parathyroid lesion (or lesions). Both the intraobserver and the interobserver agreements were “very good” for the presence of a parathyroid lesion. The intraobserver agreement was also “very good” and the interobserver agreement was “good” (for only 1 pair of observers) or “very good” for the evaluation of the number of parathyroid lesions. The intraobserver agreement was “very good” or “good” and the interobserver agreement was “good” for the lesion localization and for the presence of a doubtful lesion.ConclusionParathyroid scintigraphy seems to be an observer independent method in the detection of a parathyroid lesion, in the determination of the number of lesions, and in the localizations of the lesions. The measured high agreement between observers increases the reliability of parathyroid scintigraphy. (Endocr Pract. 2012;18: 538-548)     

PET textural features stability and pattern discrimination power for radiomics analysis: An “ad-hoc” phantoms study

PurposeThe analysis of PET images by textural features, also known as radiomics, shows promising results in tumor characterization. However, radiomic metrics (RMs) analysis is currently not standardized and the impact of the whole processing chain still needs deep investigation. We characterized the impact on RM values of: i) two discretization methods, ii) acquisition statistics, and iii) reconstruction algorithm. The influence of tumor volume and standardized-uptake-value (SUV) on RM was also investigated.MethodsThe Chang-Gung-Image-Texture-Analysis (CGITA) software was used to calculate 39 RMs using phantom data. Thirty noise realizations were acquired to measure statistical effect size indicators for each RM. The parameter η² (fraction of variance explained by the nuisance factor) was used to assess the effect of categorical variables, considering η² < 20% and 20% < η² < 40% as representative of a “negligible” and a “small” dependence respectively. The Cohen’s d was used as discriminatory power to quantify the separation of two distributions.ResultsWe found the discretization method based on fixed-bin-number (FBN) to outperform the one based on fixed-bin-size in units of SUV (FBS), as the latter shows a higher SUV dependence, with 30 RMs showing η² > 20%. FBN was also less influenced by the acquisition and reconstruction setup: with FBN 37 RMs had η² < 40%, only 20 with FBS. Most RMs showed a good discriminatory power among heterogeneous PET signals (for FBN: 29 out of 39 RMs with d > 3).ConclusionsFor RMs analysis, FBN should be preferred. A group of 21 RMs was suggested for PET radiomics analysis.     

Electron cryo-microscopy for elucidating the dynamic nature of live-protein complexes

BackgroundRecent innovations in the field of electron cryo-microscopy (cryo-EM) have achieved structure determination of target macromolecules at “near-atomic resolution”. In addition, cryo-EM has the potential to deal with proteins in multiple conformations in close to physiological conditions.Scope of reviewThis is an overview of the latest technical and methodological developments in cryo-EM, especially key features for elucidating the dynamic nature of specimens.Major conclusionsIt is now possible to elucidate “near-atomic resolution” structures by selecting “well-behaved” particles in Single Particle Analysis (SPA) of cryo-EM images.General significanceCurrently, cryo-EM is utilized actively as an alternative to X-ray crystallography to obtain high-resolution structures of macromolecules, especially those which are hard to crystalize. One possible reason for difficulty in crystallization could be the dynamic nature of the specimen. New developments in the field of cryo-EM will make it possible to deal with specimen heterogeneity and reveal the dynamic nature of specimens.     

Actividad de la micafungina contra las biopelículas de Candida

BackgroundMost recalcitrant infections are associated to colonization and microbial biofilm development. These biofilms are difficult to eliminate by the immune response mechanisms and the current antimicrobial therapy.AimTo describe the antifungal of micafungin against fungal biofilms based in the scientific and medical literature of recent years.MethodsWe have done a bibliographic retrieval using the scientific terms “micafungin”, “activity”, “biofilm”, “Candida”, “Aspergillus”, “fungi”, “mycos”*, susceptibility, in PubMed/Medline from the National Library of Medicine from 2006 to 2009.ResultsMost current antifungal agents (amphotericin B and fluconazole) and the new azole antifungals have no activity against fungal biofilms. However, micafungin and the rest of echinocandins are very active against Candida albicans, Candida dubliniensis, Candida glabrata, and Candida krusei biofilms but their activities are variable and less strong against Candida tropicalis and Candida parapsilosis biofilms. Moreover, they have not activities against the biofilms of Cryptococcus y Trichosporon.ConclusionsThe activity of micafungin against Candida biofilms gives more strength to its therapeutic indication for candidaemia and invasive candidiasis associated to catheter, prosthesis and other biomedical devices.     

Image Alignment for Tomography Reconstruction from Synchrotron X-Ray Microscopic Images

A synchrotron X-ray microscope is a powerful imaging apparatus for taking high-resolution and high-contrast X-ray images of nanoscale objects. A sufficient number of X-ray projection images from different angles is required for constructing 3D volume images of an object. Because a synchrotron light source is immobile, a rotational object holder is required for tomography. At a resolution of 10 nm per pixel, the vibration of the holder caused by rotating the object cannot be disregarded if tomographic images are to be reconstructed accurately. This paper presents a computer method to compensate for the vibration of the rotational holder by aligning neighboring X-ray images. This alignment process involves two steps. The first step is to match the “projected feature points” in the sequence of images. The matched projected feature points in the - plane should form a set of sine-shaped loci. The second step is to fit the loci to a set of sine waves to compute the parameters required for alignment. The experimental results show that the proposed method outperforms two previously proposed methods, Xradia and SPIDER. The developed software system can be downloaded from the URL, http://www.cs.nctu.edu.tw/~chengchc/SCTA or http://goo.gl/s4AMx.     

Basic tests in mammography as a tool in quality improvement

BackgroundMammography is a radiological diagnostic method which relies on an X-ray examination of breasts and is a process involving the use of low-dose amplitude-X-rays (usually around 0.7 mSv). Combining the use of small doses and high quality images requires extensive quality protocols, part of them being included in regulations adopted by the Minister of Health.AimThe aim of this study was to check the usefulness and efficacy of selected quality tests associated with mammography.Material/methodsThe study was performed in the mammography service of the Greater Poland Cancer Centre in Poznan. Following equipment was used: densitometer, sensitometer, mammographic scales, electronic scales, thermometer, hygrometer, PMMA plates, Europhantom, screen film contact phantom, viewing boxes and magnifying glasses. The methods were based on basic mammography tests. Quality control in mammography demands: clean darkroom, marked and clean cassettes, clean viewing boxes with homogenous light.ResultsThe results of the “Development Process” test show that each sensitometer has to be used with an appropriate densitometer. Phantoms with abnormal structures cannot be used to “AEC System – Solidity exposure” test. “Compression – The force of compression” test may only be carried out with suitable scales and compressible material. Analysis of rejected films shows that the main reasons for rejection were wrong collimation and underexposure.ConclusionEvery quality control in mammography provides essential information about the functioning of a laboratory. Apart from recommended standard sterility, it should be remembered that equipment should always be adjusted and repaired.     

Image quality characteristics for virtual monoenergetic images using dual-layer spectral detector CT: Comparison with conventional tube-voltage images

PurposeTo investigate the image quality characteristics for virtual monoenergetic images compared with conventional tube-voltage image with dual-layer spectral CT (DLCT).MethodsHelical scans were performed using a first-generation DLCT scanner, two different sizes of acrylic cylindrical phantoms, and a Catphan phantom. Three different iodine concentrations were inserted into the phantom center. The single-tube voltage for obtaining virtual monoenergetic images was set to 120 or 140 kVp. Conventional 120- and 140-kVp images and virtual monoenergetic images (40–200-keV images) were reconstructed from slice thicknesses of 1.0 mm. The CT number and image noise were measured for each iodine concentration and water on the 120-kVp images and virtual monoenergetic images. The noise power spectrum (NPS) was also calculated.ResultsThe iodine CT numbers for the iodinated enhancing materials were similar regardless of phantom size and acquisition method. Compared with the iodine CT numbers of the conventional 120-kVp images, those for the monoenergetic 40-, 50-, and 60-keV images increased by approximately 3.0-, 1.9-, and 1.3-fold, respectively. The image noise values for each virtual monoenergetic image were similar (for example, 24.6 HU at 40 keV and 23.3 HU at 200 keV obtained at 120 kVp and 30-cm phantom size). The NPS curves of the 70-keV and 120-kVp images for a 1.0-mm slice thickness over the entire frequency range were similar.ConclusionVirtual monoenergetic images represent stable image noise over the entire energy spectrum and improved the contrast-to-noise ratio than conventional tube voltage using the dual-layer spectral detector CT.     

Optimization of image quality and accuracy of low iodine concentration quantification as function of kVp pairs for abdominal imaging using dual-source CT: A phantom study

PurposeTo determine the suitable kVp pair for optimal image quality of the virtual monochromatic images (VMIs) and iodine quantification accuracy at low concentration, using a third generation dual-source CT (DSCT).Materials and methodsMulti-energy CT phantoms with and without body rings were scanned with a DSCT using four kVp pairs (tube “A”/“B” voltage): 100/Sn150, 90/Sn150, 80/Sn150 and 70/Sn150 kVp. The reference mAs was adjusted to obtain a CTDI_vol close to 11 mGy. HU values accuracy (RMSD_HU), noise (SD) and contrast-to-noise ratio (CNR) of iodine inserts of 0.5, 1, 2 and 5 mg/mL concentrations were assessed on VMIs at 40/50/60/70 keV. Iodine quantification accuracy was assessed using the RMSD_iodine and iodine bias (IB_iodine).ResultsThe RMSD_HU decreased when the tube “A” voltage increased. The mean noise value increased significantly with tube “A” voltage (p < 0.001) but decreased between 80/Sn150 and 90/Sn150 kVp for the small phantom (1.1 ± 0.1%; p = 0.047). The CNR significantly decreased with tube “A” voltage (p < 0.001), except between 80/Sn150 and 90/Sn150 kVp for all inserts and between 90/Sn150 kVp and 100/Sn150 kVp for the 1.0 and 0.5 mg/mL inserts in the large phantom. In the small phantom, no significant difference was found between 80/Sn150 kVp and 90/Sn150 kVp for all inserts and between 80/Sn150, 90/Sn150 and 100/Sn150 kVp for the 1 and 0.5 mg/mL inserts. The RMSD_iodine and IB_iodine decreased as the tube “A” voltage of the kVp pair increased.ConclusionThe kVp pair of 70/Sn150 led to better image quality in VMIs and sufficient iodine accuracy.     

Lung tumors on multimodal radiographs derived from grating-based X-ray imaging – A feasibility study

PurposeThe purpose of this study was to assess whether grating-based X-ray imaging may have a role in imaging of pulmonary nodules on radiographs.Materials and methodsA mouse lung containing multiple lung tumors was imaged using a small-animal scanner with a conventional X-ray source and a grating interferometer for phase-contrast imaging. We qualitatively compared the signal characteristics of lung nodules on transmission, dark-field and phase-contrast images. Furthermore, we quantitatively compared signal characteristics of lung tumors and the adjacent lung tissue and calculated the corresponding contrast-to-noise ratios.ResultsOf the 5 tumors visualized on the transmission image, 3/5 tumors were clearly visualized and 1 tumor was faintly visualized in the dark-field image as areas of decreased small angle scattering. In the phase-contrast images, 3/5 tumors were clearly visualized, while the remaining 2 tumors were faintly visualized by the phase-shift occurring at their edges. No additional tumors were visualized in either the dark-field or phase-contrast images. Compared to the adjacent lung tissue, lung tumors were characterized by a significant decrease in transmission signal (median 0.86 vs. 0.91, p = 0.04) and increase in dark-field signal (median 0.71 vs. 0.65, p = 0.04). Median contrast-to-noise ratios for the visualization of lung nodules were 4.4 for transmission images and 1.7 for dark-field images (p = 0.04).ConclusionLung nodules can be visualized on all three radiograph modalities derived from grating-based X-ray imaging. However, our initial data suggest that grating-based multimodal X-ray imaging does not increase the sensitivity of chest radiographs for the detection of lung nodules.     

Visual processing of pictures

Word responses have been used to dedde whether pictures of expressive faces or postures portray truthful expressions. Previous investigators have assumed words are used only as symbols of “meaning”. They did not appreciate the use of words as symbols of “sorting”. If one viewer calls two photographs “angry” and another viewer calls the same two photographs “happy,” the viewers may disagree in their “meanings” but they agree in their ‘sortings” both agree each photograph portrays the same expression. Sorting groups reveal how the visual system processes photographic images.     

Optimisation of reconstruction,volumetry and dosimetry for 99mTc-SPECT and 90Y-PET images: Towards reliable dose-volume histograms for selective internal radiation therapy with 90Y-microspheres

PurposeIn Selective Internal Radiation Therapy (SIRT), ^99mTc-MAA SPECT images are commonly used to predict microspheres distribution but recent works used ⁹⁰Y-microspheres PET images. Nevertheless, evaluation of the predictive power of ^99mTc-MAA has been hampered by the lack of reliable comparisons between ^99mTc-SPECT and ⁹⁰Y-PET images. Our aim was to determine the “in situ” optimisation procedure in order to reliably compare ^99mTc-SPECT and ⁹⁰Y-PET images and achieve optimal personal dosimetry.MethodsWe acquired ^99mTc-SPECT/CT and ⁹⁰Y-PET/CT images of NEMA and Jaszczak phantoms. We found the best reconstruction parameters for quantification and for volume estimations. We determined adaptive threshold curves on the volumetric reconstruction. We copied the optimised volumes on the quantitative reconstruction, named here the “cross volumes” technique. Finally, we compared ^99mTc-SPECT and ⁹⁰Y-PET Dose Volume Histograms.ResultsOur “in situ” optimisation procedure decreased errors on volumes and quantification (from −44.2% and −15.8% to −3.4% and −3.28%, respectively, for the 26.5 mL PET phantom sphere). Moreover, ^99mTc-SPECT and ⁹⁰Y-PET DVHs were equivalent only after the optimisation procedure (difference in mean dose <5% for the three biggest spheres).ConclusionsThis work showed that a preliminary “in situ” phantom study was necessary to optimise volumes and quantification of ^99mTc-SPECT and ⁹⁰Y-PET images and allowed to achieve a reliable comparison between patient treatment planning and post implant dosimetry, notably by the use of the “cross volumes” technique. Methodology developed in this work will enable robust evaluations of the predictive power of ^99mTc-SPECT, as well as dose-response relationship and side effects in SIRT treatments.     

Morningness–eveningness and performance-based emotional intelligence

The aim of the present article is to determine whether recently shown positive relationships between self-reported emotional intelligence (EI) and morningess preference exist when EI is measured with an ability-based test. In two studies (study 1: N = 206 and study 2: N = 184), we applied two different morningness–eveningness questionnaires and a performance test of EI consisting of four dimensions (perception, understanding, assimilation, managing). The two studies provided similar results indicating that “night owls” have higher EI than “larks”; specifically, evening-oriented subjects showed greater ability in emotion perception and understanding, as compared to morning-oriented individuals. The obtained results were in line with hitherto existing research on chronotype and general intelligence. The results provide further evidence for a cognitive character of ability-based EI and accentuate its different nature when compared to self-reported EI. The main findings are discussed in terms of evolutionary theories of circadian preferences, EI and mental abilities.