Jean-Francois Carrier

Université de Montréal | UdeM · Department of Physics

Background. In the context of pharmacokinetic analyses, the segmentation method one uses has a large impact on the results obtained, thus the importance of transparency. Innovation. This paper introduces a graphical user interface (GUI), TRU-IMP, that analyzes time-activity curves and segmentations in dynamic nuclear medicine. This GUI fills a gap...

Objective. In diffusing alpha-emitters radiation therapy (‘Alpha DaRT’), the diffusion-leakage (DL) model is used to determine the spatial distributions of the emitters and the corresponding alpha dose, critical for a successful treatment. This work first introduces a finite volume (FV) approach to develop numerical schemes to simulate the DL model...

We describe the first microfluidic device for in vitro testing of brachytherapy (BT), with applications in translational cancer research. Our PDMS-made BT-on-chip system allows highly precise manual insertion of clinical...

Purpose The addition of interstitial (IS) needles to intra-cavitary (IC) brachytherapy applicators is associated with improved outcomes in locally advanced cervical cancers involving parametrial tumor extensions. The purpose of this work was to validate a clinical workflow involving 3D-printed caps for a commercial IC split ring applicator that ena...

The Task Group 211 report of the American Association of Physicists in Medicine (AAPM) reviewed static segmentation techniques in nuclear positronemission tomography (PET) imaging used in nuclear medicine. These methods, when applied to a dynamic image, such as the ones obtained in pharmacokinetic analyses, fail to take into account the dynamic nat...

Background Recent developments in alpha and beta emitting radionuclide therapy highlight the importance of developing efficient methods for patient‐specific dosimetry. Traditional tabulated methods such as Medical Internal Radiation Dose (MIRD) estimate the dose at the organ level while more recent numerical methods based on Monte Carlo (MC) simula...

Real-time motion management for image-guided radiation therapy interventions plays an important role for accurate dose delivery. Forecasting future 4D deformations from in-plane image acquisitions is fundamental for accurate dose delivery and tumor targeting. However, anticipating visual representations is challenging and is not exempt from hurdles...

Background For patients with a higher burden of localized prostate cancer, radiation dose escalation with brachytherapy boosts have improved cancer control outcomes at the cost of urinary toxicity. We hypothesize that a focal approach to brachytherapy boosts targeting only grossly visualized tumor volumes (GTV) combined with stereotactic radiothera...

Purpose Dosimetry calculation for diffusing alpha emitters radiation therapy (DaRT) is challenging because it needs to combine both diffusion modelling and radiation transport computation. We have developed a 3D dosimetry platform to compare standard focal Ir-192 HDR and Ra-224 DaRT dosimetry for real prostate focal brachytherapy cases. Materials...

Significance: The diagnosis and treatment of prostate cancer (PCa) are limited by a lack of intraoperative information to accurately target tumors with needles for biopsy and brachytherapy. An innovative image-guidance technique using optical devices could improve the diagnostic yield of biopsy and efficacy of radiotherapy. Aim: To evaluate the...

The clinical importance of radiotherapy in the treatment of cancer patients justifies the development and use of research tools at the fundamental, pre-clinical, and ultimately clinical levels, to investigate their toxicities and synergies with systemic agents on relevant biological samples. Although microfluidics has prompted a paradigm shift in d...

Background and purpose Advances in high-dose-rate brachytherapy to treat prostate cancer hinge on improved accuracy in navigation and targeting while optimizing a streamlined workflow. Multimodal image registration and electromagnetic (EM) tracking are two technologies integrated into a prototype system in the early phase of clinical evaluation. We...

Purpose Radioresistance, tumor microenvironment, and normal tissue toxicity from radiation limit the efficacy of radiotherapy in treating cancers. These challenges can be tackled by the discovery of new radiosensitizing and radioprotecting agents aimed at increasing the therapeutic efficacy of radiotherapy. The goal of this work was to develop a mi...

Radiotherapy (RT) and chemotherapy (CT) are the major therapeutics to treat cancer patients. Conventional in vitro 2D models are insufficient to study the combined effects of RT and CT towards optimized dose selection or drug screening. Soft-tissue sarcomas (STS) are rare cancers with profound social impacts as they affect patients of all ages. We...

Purpose: The purpose of this study is to develop and validate accurate methods for determining iodine content and virtual non contrast maps of physical parameters, such as electron density, in the context of radiotherapy. Methods: A simulation environment is developed to compare three methods allowing extracting iodine content and virtual non-co...

Purpose To compare the impact of the fusion of intraoperative transrectal ultrasound (TRUS) images with day 30 computed tomography (CT) and magnetic resonance imaging (MRI) on prostate volume and dosimetry. Methods and materials Seventy-five consecutive patients with CT and MRI obtained on day 30 with a Fast Spin Echo T2-weighted magnetic resonance...

Soft-tissue sarcoma is a disease having profound social impacts on patients of all ages. Conventional in vitro 2D models are insufficient to study the effect of radiotherapy as well as chemotherapy. Here, we develop a microfluidic device to form and culture soft-tissue sarcoma spheroids to study the combined effect of radiotherapy and chemotherapy....

The purpose of this study is to evaluate the impact of a novel tissue characterization method using dual-energy over single-energy computed tomography (DECT and SECT) on Monte Carlo (MC) dose calculations for low-dose rate (LDR) prostate brachytherapy performed in a patient like geometry. A virtual patient geometry is created using contours from a...

Purpose: To assess overall robustness and accuracy of a modified particle filter-based tracking algorithm for magnetic resonance (MR)-guided radiation therapy treatments. Methods and materials: An improved particle filter-based tracking algorithm was implemented, which used a normalized cross-correlation function as the likelihood calculation. W...

Purpose: There is an increasing interest in the evaluation of lung function from physiological images in radiation therapy treatment planning to reduce the extent of post-radiation toxicities. The purpose of this work is to retrieve reliable functional information from contrast-enhanced dualenergy computed tomography (DECT) for new applications in...

This work introduces a 2D motion prediction algorithm for lung tumors applied to dynamic MR images that combines intrafractional tumor deformations. It is developed in the context of MR-linac treatments and evaluates uniform and patient-specific margins about the gross tumor volume to optimize the tumor coverage. Seven early stage non-small cell lu...

Purpose:This study introduces a novel autocontouring algorithm based on particle filter for lung tumors. It is validated on dynamic magnetic resonance (MR) images and is developed in the context of MR-linac treatments. Methods:A sequential Monte Carlo method called particle filter is used as the main structure of the algorithm and is combined with...

Purpose:This study proposes a novel autocontouring algorithm for lung tumors based on particle filter. It is developed in the context of MR-linac treatments and is validated on in-vivo dynamic magnetic resonance images. Methods:A sequential Monte Carlo method called particle filter is combined with Otsu’s thresholding technique to contour lung tumo...

Purpose:To propose an alternate treatment plan that minimizes the dose to the functional lung tissues. In clinical situation, the evaluation of the lung functionality is typically derived from perfusion scintigraphy. However, such technique has spatial and temporal resolutions generally inferior to those of a CT scan. Alternatively, it is possible...

Purpose An improvement in tissue assignment for low‐dose rate brachytherapy (LDRB) patients using more accurate Monte Carlo (MC) dose calculation was accomplished with a metallic artifact reduction (MAR) method specific to dual‐energy computed tomography (DECT). Methods The proposed MAR algorithm followed a four‐step procedure. The first step invo...

Objective: The aim of this study was to assess and compare adjuvant chemotherapy followed by either high-dose-rate vaginal vault brachytherapy (VBT) alone or combined with pelvic external beam radiotherapy (EBRT) for International Federation of Gynaecology and Obstetrics stage 1 serous or clear cell (CC) endometrial cancer. Methods: Between 2006...

Significant efforts were invested during the last decade to accelerate PET list-mode reconstructions, notably with GPU devices. However, the computation time per event is still relatively long, and the list-mode efficiency on the GPU is well below the histogram-mode efficiency. Since list-mode data are not arranged in any regular pattern, costly ac...

The purpose of this study was to prospectively evaluate the quality of life (QoL) and pulmonary function of patients with early-stage non-small cell lung cancer treated with robotic stereotactic ablative radiation therapy (SABR). Eligible patients all had histologically confirmed stage I non-small cell lung cancer and were not surgical candidates b...

Purpose: To analyze the difference in prostate coverage and dose to the rectum in men with prostate carcinoma treated with permanent seed brachytherapy with different seed activities. Methods: Forty-nine patients treated with iodine-125 permanent seed prostate brachytherapy with low-activity seeds of 0.30-0.37 mCi were identified. For each of th...

Purpose: The objectives of this study are (1) to measure concordance of tumor position on breath-hold (BH) computed tomography (CT) scans relative to the natural tumor path during free breathing (FB) and (2) to evaluate the benefits of the breathing monitoring device Abches (Apex Medical, Tokyo) for stereotactic ablative radiotherapy (SABR) treatm...

Purpose: To investigate an automatic bronchial and vessel bifurcations detection algorithm for deformable image registration (DIR) assessment to improve lung cancer radiation treatment.

Purpose To improve Monte Carlo dose calculation accuracy through a new tissue segmentation technique with dual energy CT (DECT). Methods Electron density (ED) and effective atomic number (EAN) can be extracted directly from DECT data with a stoichiometric calibration method. Images are acquired with Monte Carlo CT projections using the user code e...

In cases where surgery is not possible for lung cancer treatment, stereotactic body radiation therapy (SBRT) may be an option. One problem when treating this type of cancer is the motion of the lungs caused by the patient's respiration. It is possible to reduce the impact of this movement with the use of respiratory gating. By combining respiratory...

Purpose: To develop a new segmentation technique using dual energy CT (DECT) to overcome limitations related to segmentation from a standard Hounsfield unit (HU) to electron density (ED) calibration curve. Both methods are compared with a Monte Carlo analysis of dose distribution. Methods: DECT allows a direct calculation of both ED and effective a...

Purpose To allow a reliable deformable image registration (DIR) method for dose calculation in radiation therapy. This work proposes a performance assessment of a morphological segmentation algorithm that generates a deformation field from lung surface displacements with 4DCT datasets. Methods From the 4DCT scans of 15 selected patients, the deep...

The accuracy of radiotherapy dose calculation relies crucially on patient composition data. The computed tomography (CT) calibration methods based on the stoichiometric calibration of Schneider et al (1996 Phys. Med. Biol. 41 111-24) are the most reliable to determine electron density (ED) with commercial single energy CT scanners. Along with the r...

The purpose of this work was to assess the stability of fiducial markers in the prostate bed and compared their use to surgical clips. In this study, 3-4 gold fiducial markers were transrectally implanted in the prostate bed of 14 patients. The stability of the fiducial markers position (fiducial markers fixity) over an EBRT course was assessed. Fu...

To determine which parameters allow for CyberKnife fiducial-less tumor tracking in stereotactic body radiation therapy (SBRT) for early-stage non-small cell lung cancer. A total of 133 lung SBRT patients were preselected for direct soft-tissue tracking based on manufacturer recommendations (peripherally located tumors ≥1.5 cm with a dense appearanc...

Determine whether fat distribution, body mass index, or clinical and dosimetric factors are associated with prostate specific antigen (PSA) bounce (PSAb) of ≥1.6 ng/mL in patients treated with permanent seed (125)I prostate brachytherapy (PB). We identified 23 patients with a PSAb of ≥1.6 ng/mL. For each patient with a bounce, at least one control...

To determine prostate volume (Pvol) changes at 3 different time points during the course of I125 permanent seed brachytherapy (PB). To assess the impact of these changes on acute urinary retention (AUR) and dosimetric outcome. We analyzed 149 hormone-naive patients. Measurements of the prostate volume were done using three-dimensional transrectal u...

Purpose: To establish the reliability of electron density (ED) mapping and tissue segmentation techniques using CT images for brachytherapy, considering stochastic and systematic Hounsfield unit (HU) variations. Methods: Most common artifacts are simulated within a Monte Carlo theoretical framework. A set of CT data is first generated with the EGSn...

Purpose: While dose calculations are typically performed using a simplistic correspondence of HU to electron density (ED), recent developments in DECT for radiotherapy could provide significant improvements in characterizing human tissues for such purpose. We aim to compare and validate two DECT mathematical formalisms and evaluate their accuracy i...

Purpose: The scope of this study is to implement an accurate Cyberknife model on a web‐based tool (WebTPS), which uses the EGSnrc Monte Carlo dose calculation engine. WebTPS will be mostly used as a reference to evaluate clinical treatment plans in highly heterogeneous phantoms. Methods: The WebTPS dose calculation module is linked to the user code...

Objective: Hemoglobin (Hb) is a prognostic factor in cervical cancer, but the underlying mechanisms remain unknown. In this study, we hypothesized that low Hb level, either before or during radiotherapy (RT), is a surrogate for a more infiltrative and therefore aggressive disease, with uterine corpus invasion and nodal metastases. Methods and mat...

The charge of Task Group 186 (TG‐186) is to provide guidance for early adopters of model‐based dose calculation algorithms (MBDCAs) for brachytherapy (BT) dose calculations to ensure practice uniformity. Contrary to external beam radiotherapy, heterogeneity correction algorithms have only recently been made available to the BT community. Yet, BT do...

During the last decade, studies have shown that 3D list-mode ordered-subset expectation-maximization (LM-OSEM) algorithms for positron emission tomography (PET) reconstruction could be effectively computed and considerably accelerated by graphics processing unit (GPU) devices. However, most of these studies rely on pre-calculated sensitivity matric...

Task group 43 (TG43)-based dosimetry algorithms are efficient for brachytherapy dose calculation in water. However, human tissues have chemical compositions and densities different than water. Moreover, the mutual shielding effect of seeds on each other (interseed attenuation) is neglected in the TG43-based dosimetry platforms. The scientific commu...

To determine the extent of gold fiducial marker (FM) migration in patients treated for prostate cancer with concurrent androgen deprivation and external-beam radiation therapy (EBRT). Three or 4 gold FMs were implanted in 37 patients with prostate adenocarcinoma receiving androgen deprivation therapy (ADT) in conjunction with 70-78 Gy. Androgen dep...

Purpose: The line‐of‐response OSEM (LOR‐OSEM) algorithm allows a PET image reconstruction from sinograms without any data compression(span=1, mashing=1). The main objective of this work is to accelerate the computation of this algorithm for modern PET scanners such as the Philips Gemini GXL by its implementation on modern GPU devices.Methods: We im...

To validate GPUMCD, a new package for fast Monte Carlo dose calculations based on the GPU (graphics processing unit), as a tool for low-energy single seed brachytherapy dosimetry for specific seed models. As the currently accepted method of dose calculation in low-energy brachytherapy computations relies on severe approximations, a Monte Carlo base...

Purpose: To present, G4DBR, a fast Geant4‐based Monte Carlo (MC)dosimetry platform for brachytherapy. The special case of low dose rate (LDR) brachytherapy is considered here. Methods: Geant4 9.3 has been used for designing a new MC platform for calculating the dose distribution in brachytherapy called G4DBR. This code is capable of dealing with th...

Purpose: The charge of Task Group 186 is to provide guidance to early adopters of model‐based dose calculation algorithms (MBDCA) for brachytherapydose calculations. Methods: Contrary to external beam radiotherapy(EBRT), the brachytherapy (BT) community has not widely adopted heterogeneity‐correction algorithms. Yet, BT dose calculation accuracy is...

The impact of tissue heterogeneity and interseed attenuation is studied in post-implant evaluation of five clinical permanent breast (103)Pd seed implants using the Monte Carlo (MC) dose calculation method. Dose metrics for the target (PTV) as well as an organ at risk (skin) are used to visualize the differences between a TG43-like MC method and mo...

Purpose: First to characterize the factors responsible for non‐unity corrections in nonstandard beam dosimetry and provide conceptual solutions to minimize corrections. Second to provide methods to estimate uncertainties accurately in nonstandard beam dosimetry and achievable levels in clinical situations. Materials:Ionization chamber response to s...

To assess the influence of fiducial marker (FM) migration on the matching quality in external beam radiation therapy (EBRT) for prostate cancer. The position of FMs were identified using on-board kV imaging (OBI) and their 3-D position established using an in-house reconstruction algorithm for 31 patients with prostate adenocarcinoma. To carry out...