Cross-modal tumor segmentation using generative blending augmentation and self-training.

Objectives: Data scarcity and domain shifts lead to biased training sets that do not accurately represent deployment conditions. A related practical problem is cross-modal image segmentation, where the objective is to segment unlabelled images using previously labelled datasets from other imaging modalities.

Methods: We propose a cross-modal segmentation method based on conventional image synthesis boosted by a new data augmentation technique called Generative Blending Augmentation (GBA).

Predicting the Tumour Response to Radiation by Modelling the Five Rs of Radiotherapy Using PET Images.

Despite the intensive use of radiotherapy in clinical practice, its effectiveness depends on several factors. Several studies showed that the tumour response to radiation differs from one patient to another. The non-uniform response of the tumour is mainly caused by multiple interactions between the tumour microenvironment and healthy cells.

Impact of age on the Quadrella index assessing oncological and functional results after prostate brachytherapy: A 6-year analysis.

Purpose: As the oncological results of prostate brachytherapy (BT) are excellent for low-risk (LR) or favorable intermediate-risk (FIR) prostate cancer (PCa), evaluating the side effects has become a major issue, especially for young men. The objective of the study was to compare the oncologic and functional results of BT using Quadrella index for patients aged 60 or less compared with older patients.

Material And Methods: From June, 2007 to June, 2017, 222 patients, including 70 ≤ 60 years old and 152 > 60 years old, underwent BT for LR-FIR PCa, with good erectile function at baseline according to International Index of Erectile Function-5 (IIEF-5) > 16.

A machine-learning approach based on 409 treatments to predict optimal number of iodine-125 seeds in low-dose-rate prostate brachytherapy.

Purpose: Low-dose-rate brachytherapy is a key treatment for low-risk or favorable intermediate-risk prostate cancer. The number of radioactive seeds inserted during the procedure depends on prostate volume, and is not easy to predict without pre-planning. Consequently, a large number of unused seeds may be left after treatment.

Dosimetric Validation of a GAN-Based Pseudo-CT Generation for MRI-Only Stereotactic Brain Radiotherapy.

Purpose: Stereotactic radiotherapy (SRT) has become widely accepted as a treatment of choice for patients with a small number of brain metastases that are of an acceptable size, allowing for better target dose conformity, resulting in high local control rates and better sparing of organs at risk. An MRI-only workflow could reduce the risk of misalignment between magnetic resonance imaging (MRI) brain studies and computed tomography (CT) scanning for SRT planning, while shortening delays in planning. Given the absence of a calibrated electronic density in MRI, we aimed to assess the equivalence of synthetic CTs generated by a generative adversarial network (GAN) for planning in the brain SRT setting.

Toxicity in patients treated with permanent prostate brachytherapy using intraoperatively built custom-linked seeds versus loose seeds.

Purpose: Low-dose-rate brachytherapy (BT) with permanent iodine-125 radioactive seeds is a highly effective treatment option for low- and favorable intermediate-risk prostate cancer. However, optimal implantation is not always achieved due to edema or seeds loss. One way to improve seed placement is the use of stranded seeds called "intraoperatively built custom-linked seeds (IBCLS)" in an opposition to loose seeds (LS).

Minimal channel GreenLight photovaporization before permanent implant prostate brachytherapy for patients with obstructive symptoms: Technically feasible and safe.

Purpose: Brachytherapy (BrT) is a standard treatment for low-risk to favorable-intermediate-risk prostate cancer but is a relative contraindication for patients with obstructive symptoms. We aimed to assess the feasibility and urinary toxicity of a minimal photovaporization (mPVP) before implantation.

Materials And Methods: Between 04/2009 and 08/2016, 50 patients candidates for BrT but with International Prostate Symptom Score (IPSS)>15, uroflowmetry <15 mL/s, obstructive prostate or large median lobe underwent a mPVP (GreenLight Laser) at least 6 weeks (median 8.

Kilovoltage intrafraction monitoring during normofractionated prostate cancer radiotherapy.

Purpose: During radiotherapy (RT) for prostate cancer (PCa), interfraction and intrafraction movements can lead to decreased target dose coverage and unnecessary over-exposure of organs at risk. New image-guided RT techniques accuracy allows planning target volume (PTV) margins reduction. We aim to assess the feasibility of a kilovoltage intrafraction monitoring (KIM) to track the prostate during RT.

Dose to the penile bulb and individual patient anatomy are predictive of erectile dysfunction in men treated with I low dose rate brachytherapy for localized prostate cancer.

To evaluate the occurrence of erectile dysfunction at 3 years (3yED) after prostate brachytherapy (BT) and to predict 3yED after treatment based on patients and treatments characteristics. From September 2007 to July 2015, 117 men with mild or no ED [International Index of Erectile Function (IIEF-5) > 16] underwent Iodine real-time ultrasound-guided low-dose rate BT to a total dose of 160 Gy for low-risk or favorable intermediate-risk prostate adenocarcinoma, and were followed prospectively during 3 years. Median age was 63 years (51-79).

Prostate Volume Segmentation in TRUS Using Hybrid Edge-Bhattacharyya Active Surfaces.

Objective: We present a new hybrid edge and region-based parametric deformable model, or active surface, for prostate volume segmentation in transrectal ultrasound (TRUS) images.

Methods: Our contribution is threefold. First, we develop a new edge detector derived from the radial bas-relief approach, allowing for better scalar prostate edge detection in low contrast configurations.

Evaluation of the "Quadrella" at 3 years: New index to assess functional and oncological performance specific to prostate brachytherapy.

Purpose: "Quadrella" index has been recently developed to assess oncological and functional outcomes after prostate brachytherapy (PB). We aimed to evaluate this index at 1, 2, and 3 years, using validated questionnaires, assessed prospectively.

Methods And Materials: From 08/2007 to 01/2013, 193 patients underwent Iodine PB for low-risk or favorable intermediate-risk prostate adenocarcinoma.

Multi-Scale Modeling and Oxygen Impact on Tumor Temporal Evolution: Application on Rectal Cancer During Radiotherapy.

We present a multi-scale approach of tumor modeling in order to predict its evolution during radiotherapy. Within this context we focus on three different scales of tumor modeling: microscopic (individual cells in a voxel), mesoscopic (population of cells in a voxel) and macroscopic (whole tumor), with transition interfaces between these three scales. At the cellular level, the description is based on phase transfer probabilities in the cellular cycle.

Fully automatic deformable registration of pretreatment MRI/CT for image-guided prostate radiotherapy planning.

Purpose: In prostate radiotherapy, dose distribution may be calculated on CT images, while the MRI can be used to enhance soft tissue visualization. Therefore, a registration between MR and CT images could improve the overall treatment planning process, by improving visualization with a demonstrated interobserver delineation variability when segmenting the prostate, which in turn can lead to a more precise planning. This registration must compensate for prostate deformations caused by changes in size and form between the acquisitions of both modalities.

Patient positioning in radiotherapy based on surface imaging using time of flight cameras.

Purpose: To evaluate the patient positioning accuracy in radiotherapy using a stereo-time of flight (ToF)-camera system.

Methods: A system using two ToF cameras was used to scan the surface of the patients in order to position them daily on the treatment couch. The obtained point clouds were registered to (a) detect translations applied to the table (intrafraction motion) and (b) predict the displacement to be applied in order to place the patient in its reference position (interfraction motion).

DEMAT: A multi-institutional dosimetry audit of rotational and static intensity-modulated radiotherapy.

Purpose: Static beam intensity-modulated-radiation-therapy (IMRT) and/or Volumetric-Modulated-Arc-Therapy (VMAT) are now available in many regional radiotherapy departments. The aim of this multi-institutional audit was to design a new methodology based on radiochromic films to perform an independent quality control.

Methods: A set of data were sent to all participating centres for two clinical localizations: prostate and Head and Neck (H&N) cancers.

[Benefits of breathing-adapted radiation therapy for breast cancer].

Purpose: The purpose of this study was to compare free-breathing radiotherapy, end-expiration gating and end-inspiration gating for left breast cancer, with respect to the target volume coverage and dose to organs at risk.

Patients And Methods: Sixteen patients underwent 3D and 4D simulation CT. For each patient, five dosimetric plans were compared: free breathing, end-inspiration gating, end-expiration gating, and two optimised plans with a 3mm reduction of the posterior field edge to create optimised end-inspiration and end-expiration plans.

GGEMS-Brachy: GPU GEant4-based Monte Carlo simulation for brachytherapy applications.

In brachytherapy, plans are routinely calculated using the AAPM TG43 formalism which considers the patient as a simple water object. An accurate modeling of the physical processes considering patient heterogeneity using Monte Carlo simulation (MCS) methods is currently too time-consuming and computationally demanding to be routinely used. In this work we implemented and evaluated an accurate and fast MCS on Graphics Processing Units (GPU) for brachytherapy low dose rate (LDR) applications.

Monte-Carlo dosimetry for intraoperative radiotherapy using a low energy x-ray source.

Unlabelled: Intraoperative radiotherapy (IORT) is continuously gaining ground in cancer treatment. However, there is currently no planning system associated with these devices, which precludes patient-specific dose delivery optimization. The objective of this study was the development and validation of a Monte Carlo simulation (MCS)-based dosimetry platform using the Intrabeam™ system.

A review of the use and potential of the GATE Monte Carlo simulation code for radiation therapy and dosimetry applications.

In this paper, the authors' review the applicability of the open-source GATE Monte Carlo simulation platform based on the GEANT4 toolkit for radiation therapy and dosimetry applications. The many applications of GATE for state-of-the-art radiotherapy simulations are described including external beam radiotherapy, brachytherapy, intraoperative radiotherapy, hadrontherapy, molecular radiotherapy, and in vivo dose monitoring. Investigations that have been performed using GEANT4 only are also mentioned to illustrate the potential of GATE.

Evaluation of clinical IMRT treatment planning using the GATE Monte Carlo simulation platform for absolute and relative dose calculations.

Purpose: The objective of this study was to evaluate and validate the use of the Geant4 application for emission tomography (GATE) Monte Carlo simulation platform for clinical intensity modulated radiotherapy (IMRT) dosimetry studies.

Methods: The first step consisted of modeling a 6 MV photon beam linear accelerator (LINAC), with its corresponding validation carried out using percent depth dose evaluation, transverse profiles, tissue phantom ratio, and output factor on water phantom. The IMRT evaluation was performed by comparing simulation and measurements in terms of absolute and relative doses using IMRT dedicated quality assurance phantoms considering seven different patient datasets.

Accuracy of dynamic patient surface monitoring using a time-of-flight camera and B-spline modeling for respiratory motion characterization.

Time-of-flight (ToF) camera technology provides a real-time depth map of a scene with adequate frequency for the monitoring of physiological patient motion. However, dynamic surface motion estimation using a ToF camera is limited by issues such as the raw measurement accuracy and the absence of fixed anatomical landmarks. In this work we propose to overcome these limitations using surface modeling through B-splines.

[Metabolically active volumes automatic delineation methodologies in PET imaging: review and perspectives].

PET imaging is now considered a gold standard tool in clinical oncology, especially for diagnosis purposes. More recent applications such as therapy follow-up or tumor targeting in radiotherapy require a fast, accurate and robust metabolically active tumor volumes delineation on emission images, which cannot be obtained through manual contouring. This clinical need has sprung a large number of methodological developments regarding automatic methods to define tumor volumes on PET images.

Evaluation of a 3D local multiresolution algorithm for the correction of partial volume effects in positron emission tomography.

Purpose: Partial volume effects (PVEs) are consequences of the limited spatial resolution in emission tomography leading to underestimation of uptake in tissues of size similar to the point spread function (PSF) of the scanner as well as activity spillover between adjacent structures. Among PVE correction methodologies, a voxel-wise mutual multiresolution analysis (MMA) was recently introduced. MMA is based on the extraction and transformation of high resolution details from an anatomical image (MR/CT) and their subsequent incorporation into a low-resolution PET image using wavelet decompositions.

Incorporation of wavelet-based denoising in iterative deconvolution for partial volume correction in whole-body PET imaging.

Purpose: Partial volume effects (PVEs) are consequences of the limited resolution of emission tomography. The aim of the present study was to compare two new voxel-wise PVE correction algorithms based on deconvolution and wavelet-based denoising.

Materials And Methods: Deconvolution was performed using the Lucy-Richardson and the Van-Cittert algorithms.