•Artificial intelligence is used for assessing response to therapy in rectal cancer.•Textural features extraction from high resolution 3 T MR images.•Artificial intelligence model helps personalize ...therapeutic strategy.•Decisions curves analysis confirm clinical utility.
To develop and validate an Artificial Intelligence (AI) model based on texture analysis of high-resolution T2 weighted MR images able 1) to predict pathologic Complete Response (CR) and 2) to identify non-responders (NR) among patients with locally-advanced rectal cancer (LARC) after receiving neoadjuvant chemoradiotherapy (CRT).
Fifty-five consecutive patients with LARC were retrospectively enrolled in this study. Patients underwent 3 T Magnetic Resonance Imaging (MRI) acquiring T2-weighted images before, during and after CRT. All patients underwent complete surgical resection and histopathology was the gold standard. Textural features were automatically extracted using an open-source software. A sub-set of statistically significant textural features was selected and two AI models were built by training a Random Forest (RF) classifier on 28 patients (training cohort). Model performances were estimated on 27 patients (validation cohort) using a ROC curve and a decision curve analysis.
Sixteen of 55 patients achieved CR. The AI model for CR classification showed good discrimination power with mean area under the receiver operating curve (AUC) of 0.86 (95% CI: 0.70, 0.94) in the validation cohort. The discriminatory power for the NR classification showed a mean AUC of 0.83 (95% CI: 0.71,0.92). Decision curve analysis confirmed higher net patient benefit when using AI models compared to standard-of-care.
AI models based on textural features of MR images of patients with LARC may help to identify patients who will show CR at the end of treatment and those who will not respond to therapy (NR) at an early stage of the treatment.
Charmed baryonium Cotugno, G; Faccini, R; Polosa, A D ...
Physical review letters,
04/2010, Letnik:
104, Številka:
13
Journal Article
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We reanalyze the published data on the Y(4630)-->Lambda(c) Lambda(c) and the Y(4660)-->psi(2S)pi pi with a consistent ansatz and we find that the two observations are likely to be due to the same ...state Y(B), produced via initial state radiation (ISR), with M(Y(B))=4660.7+/-8.7 MeV and Gamma(Y(B))=61+/-23 MeV. Under this hypothesis and reanalyzing the e+e- -->J/psi pi pi gamma(ISR) spectrum we find B(Y(B))-->Lambda(c) Lambda(c))/B(Y(B))-->psi(2S)pi pi)=117+/-44, B(Y(B))-->J/psi pi pi)/B(Y(B))-->psi(2S)pi pi)<0.46@90% C.L., B(Y(4350)-->J/psi pi pi)/B(Y(4350)-->psi(2S)pi pi)<3.4x10(-3)@90% C.L., and B(Y(B))-->psi(2S)sigma)/B(Y(B))-->psi(2S)f0)=2.0+/-0.3. These conclusions strongly support the hypothesis of Y(B) being the first observation of a charmed baryonium constituted by four quarks. Analyzing the mass spectrum we show that Y(4350) and Y(B) are, respectively, consistent with the ground state and first radial excitation of the l=1 state.
Abstract
One of today’s main challenges in molecular radiation therapy is to assess an individual dosimetry that allows treatment to be tailored to the specific patient, in accordance with the ...current paradigm of ‘personalized medicine’. The evaluation of the absorbed doses for tumor and organs at risk in molecular radiotherapy is typically based on MIRD schema acquiring few experimental points for the assessement of biokinetic parameters. WIDMApp, the wearable individual dose monitoring apparatus, is an innovative approach for internal dosimetry based on a wearable radiation detecting system for individual biokinetics sampling, a Monte Carlo simulation for particle interaction, and an unfolding algorithm for data analysis and integrated activity determination at organ level. A prototype of a WIDMApp detector element was used to record the photon emissions in a body phantom containing 3 spheres with liquid sources (
18
F,
64
Cu and
99
m
Tc) to simulate organs having different washout. Modelling the phantom geometry on the basis of a CT scan imaging, the Monte Carlo simulation computed the contribution of each emitting sphere to the signal detected in 3 positions on the phantoms surface. Combining the simulated results with the data acquired for 120 h, the unfolding algorithm deconvolved the detected signal and assessed the decay half-life (
T
1/2
) and initial activity values (
A
(0)) that best reproduces the observed exponential decays. A 3%–18% level of agreement is found between the actual
A
(0) and
T
1/2
values and those obtained by means of the minimization procedure based on the Monte Carlo simulation. That resulted in an estimation of the cumulated activity <15%. Moreover, WIDMApp data redundancy has been used to mitigate some experimental occurrences that happened during data taking. A first experimental test of the WIDMApp approach to internal radiation dosimetry is presented. Studies with patients are foreseen to validate the technique in a real environment.
The radiation used in hadrontherapy treatments interacts with the patient body producing secondary particles, either neutral or charged, that can be used for dose and Bragg peak monitoring and to ...provide a fast feedback on the treatment plans. Recent results obtained from the authors on simplified setups (mono-energetic primary beams interacting with homogeneous tissue-like target) have already indicated the correlation that exists between the flux of these secondaries coming from the target (e.g. protons and photons) and the position of the primary beam Bragg peak. In this paper, the measurements of charged particle fluxes produced by the interaction of a 220 MeV/u carbon ion beam at GSI, Darmstadt, with a polymethyl methacrylate target are reported. The emission region of protons (p), deuterons (d) and tritons (t) has been characterized using a drift chamber while the particle time-of-flight, used to compute the kinetic energy spectra, was measured with a LYSO scintillator. The energy released in the LYSO crystal was used for particle identification purposes. The measurements were repeated with the setup at 60° and 90° with respect to the primary beam direction. The accuracy on the fragments emission profile reconstruction and its relationship with the Bragg peak position have been studied. Based on the acquired experimental evidence, a method to monitor the dose profile and the position of the Bragg peak inside the target is proposed.
Cosmic rays have the potential to significantly affect the atmospheric composition by increasing the rate and changing the types of chemical reactions through ion production. The amount and states of ...ionization, and the spatial distribution of ions produced are still open questions for atmospheric models. To precisely estimate these quantities, it is necessary to simulate particle–molecule interactions, down to very low energies. Models enabling such simulations require interaction probabilities over a broad energy range and for all energetically allowed scattering processes.
In this paper, we focus on electron interaction with the two most abundant molecules in the atmosphere, i.e., N2 and O2, as an initial step. A set of elastic and inelastic cross section models for electron transportation in oxygen and nitrogen molecules valid in the energy range 10 eV – 1 MeV, is presented. Comparison is made with available theoretical and experimental data and a reasonable good agreement is observed. Stopping power is calculated and compared with published data to assess the general consistency and reliability of our results. Good overall agreement is observed, with relative differences lower than 6% with the ESTAR database.
•Cosmic rays ionization can significantly affect chemical reactions in the atmosphere.•The role of ions is still poorly explained by current atmospheric models.•We propose accurate physical models for electron impact interaction with N2 and O2.•We reimplemented these models in C++, and we obtained promising preliminary results.•These models will be included in Geant4-DNA in the near future.
Radio-Guided Surgery (RGS) is a nuclear medicine technique to support the surgeon during surgery towards a complete tumor resection. It is based on intraoperative detection of radiation emitted by a ...radio-pharmaceutical that bounds selectively to tumoral cells. In the past years, an approach that exploits β− emitting radiotracers has been pursued to overtake some limitations of the traditional RGS based on γ emission.
A particle detector dedicated to this application, demonstrating very high efficiency to β− particles and remarkable transparency to photons, has been thus developed. As a by-product, its characteristics suggested the possibility to utilize it with β+ emitting sources, more commonly in use in nuclear medicine. In this paper, performances of such detector on 18F liquid sources are estimated by means of Monte Carlo simulations (MC) and laboratory measurements. The experimental setup with a 18F saline solution comprised a “positron signal” spot (a 7 × 10 mm cylinder representing the tumor residual), and a surrounding “far background” volume, that represented for the detector an almost isotropic source of annihilation photons.
Experimental results show good agreement with MC predictions, thus confirming the expected performances of the detector with 18F, and the validity of the developed MC simulation as a tool to predict the gamma background determined by a diffuse source of annihilation photons.
•Radio Guided Surgery (RGS) based on β+ radiation extends its range of application.•This novel β-probe can detect 18F betas, with low annihilation photon background.•A simulation has been developed and validated to foresee the impact of background.
•Nuclear reactions are fundamental for Ion-therapy simulations.•Theoretical models running time are too long for medical applications.•We are proposing the idea of using a Deep Learning algorithm to ...emulate the model.•We obtained promising preliminary results.
A reliable model to simulate nuclear interactions is fundamental for Ion-therapy. We already showed how BLOB (“Boltzmann-Langevin One Body”), a model developed to simulate heavy ion interactions up to few hundreds of MeV/u, could simulate also 12C reactions in the same energy domain. However, its computation time is too long for any medical application. For this reason we present the possibility of emulating it with a Deep Learning algorithm.
The BLOB final state is a Probability Density Function (PDF) of finding a nucleon in a position of the phase space. We discretised this PDF and trained a Variational Auto-Encoder (VAE) to reproduce such a discrete PDF. As a proof of concept, we developed and trained a VAE to emulate BLOB in simulating the interactions of 12C with 12C at 62 MeV/u. To have more control on the generation, we forced the VAE latent space to be organised with respect to the impact parameter (b) training a classifier of b jointly with the VAE.
The distributions obtained from the VAE are similar to the input ones and the computation time needed to use the VAE as a generator is negligible.
We show that it is possible to use a Deep Learning approach to emulate a model developed to simulate nuclear reactions in the energy range of interest for Ion-therapy. We foresee the implementation of the generation part in C++ and to interface it with the most used Monte Carlo toolkit: Geant4.
The background induced by the high penetration power of the radiation is the main limiting factor of the current radio-guided surgery (RGS). To partially mitigate it, a RGS with β(+)-emitting ...radio-tracers has been suggested in literature. Here we propose the use of β(-)-emitting radio-tracers and β(-) probes and discuss the advantage of this method with respect to the previously explored ones: the electron low penetration power allows for simple and versatile probes and could extend RGS to tumours for which background originating from nearby healthy tissue makes probes less effective. We developed a β(-) probe prototype and studied its performances on phantoms. By means of a detailed simulation we have also extrapolated the results to estimate the performances in a realistic case of meningioma, pathology which is going to be our first in-vivo test case. A good sensitivity to residuals down to 0.1 ml can be reached within 1 s with an administered activity smaller than those for PET-scans thus making the radiation exposure to medical personnel negligible.
Radioguided surgery (RGS) is a medical practice which thanks to a radiopharmaceutical tracer and a probe allows the surgeon to identify tumor residuals up to a millimetric resolution in real-time. ...The employment of β− emitters, instead of γ or β+, reduces background from healthy tissues, administered activity to the patient, and medical exposure. In a previous work the possibility of using a CMOS Imager (Aptina MT9V011), initially designed for visible light imaging, to detect β− from 90Y or 90Sr sources has been established. Because of its possible application as counting probe in RGS, the performances of MT9V011 in clinical-like conditions were studied.11This work financed by Istituto Nazionale Fisica Nucleare, Italy, project CHIR2, and partially supported by Universitá degli Studi di Perugia, Italy , Fondo Ricerca di Base 2017, project SEISIPO.
Through horizontal scans on a collimated 90Sr source of different sizes (1, 3, 5, 7 mm), we have determined relationships between scan fit parameters and the source dimension, namely A quadratic correlation and a linear dependency of, respectively, signal integrated over scan interval, and maximum signal against source diameter, are determined. Horizontal scan measurements on a source, interposing collimators of different size, aim to determine relationships or correlations between scan fit parameters and source dimension. A quadratic correlation and a linear dependency of, respectively, signal integrated over scan interval, and maximum signal against source diameter are determined.
In order to get closer to clinical conditions, agar–agar phantoms containing 90Y with different dimensions and activities were prepared. A 90Y phantom is characterized by a central spot and a ring all around, for simulating both signal (tumor) and background (surrounding healthy tissue). The relationship found between scan maximum and 90Sr source diameter is then exploited to extract the concentration ratio between spot and external ring of the 90Y phantom. This observable, defined as the ratio between the tumor and the nearby healthy tissues uptake simulates the Tumor-to-Non-tumor Ratio (TNR). With the aim of evaluating the sensor’s ability to discriminate signal from background relying on the significance parameter, a further 90Y phantom, featuring a well-known and clinical-like activity will mimic the signal only condition. This result is used to extrapolate to different source sizes, after having estimated the background for various TNR. The obtained significance values suggest that the MT9V011 sensor is capable of distinguishing a signal from an estimated background, depending on the interplay among TNR, acquisition time and tumor diameter.
•A CMOS imager has been used as sensor for beta- emission from isotopes (90Y) of interest in Radioguided surgery.•Using a position scan a correlation between the source dimension and the shape of the response has been found.•The sensitivity of the sensor to tumor detection has been determined by studying the interplay among TNR, acquisition time and tumor diameter.
Organic scintillators are often chosen as radiation detectors for their fast decay time and their low Z, while inorganic ones are used when high light yields are required. In this paper we show that ...a para-terphenyl based detector has a blend of properties of the two categories that can be optimal for energy and position measurements of low-energy charged particles. Using 0.1% diphenylbutadiene doped para-terphenyl samples we measured a light attenuation length λ = 4.73 ±0.06 mm, a quenching factor for α particles Q α = (10.7 ±0.6), and a rejection power ranging between 3 - 11% for 660 keV photons, with respect to electrons of the same energy, depending on the signal threshold. A simulation based on FLUKA properly reproduces the experimental data distributions.
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