Julie Turcotte - Profile on Academia.edu (original) (raw)
Papers by Julie Turcotte
Technology in cancer research & treatment, 2003
Boron neutron capture therapy (BNCT) is based on the preferential targeting of tumor cells with (... more Boron neutron capture therapy (BNCT) is based on the preferential targeting of tumor cells with (10)B and subsequent activation with thermal neutrons to produce a highly localized radiation. In theory, it is possible to selectively irradiate a tumor and the associated infiltrating tumor cells with large single doses of high-LET radiation while sparing the adjacent normal tissues. The mixture of high- and low-LET dose components created in tissue during neutron irradiation complicates the radiobiology of BNCT. Much of the complexity has been unravelled through a combination of preclinical experimentation and clinical dose escalation experience. Over 350 patients have been treated in a number of different facilities worldwide. The accumulated clinical experience has demonstrated that BNCT can be delivered safely but is still defining the limits of normal brain tolerance. Several independent BNCT clinical protocols have demonstrated that BNCT can produce median survivals in patients wi...
Le traitement cognitivo-comportemental d�une patiente atteinte du trouble d�anxi�t� g�n�ralis�e
Nous présentons ici le cas d’une patiente souffrant du trouble d’anxiété généralisée (TAG) à un d... more Nous présentons ici le cas d’une patiente souffrant du trouble d’anxiété généralisée (TAG) à un degré sévère et bénéficiant d’un traitement cognitivo-comportemental développé par notre équipe. Ce traitement validé empiriquement cible les 4 facteurs de notre modèle identifiés comme étant reliés au TAG: l’intolérance à l’incertitude, la surestimation de l’utilité de s’inquiéter, les difficultés de résolution de problèmes et l’évitement cognitif. Les stratégies thérapeutiques utilisées y sont décrites: modification de l’intolérance à l’incertitude, réévaluation de l’utilité de s’inquiéter, entraînement à la résolution de problèmes et exposition cognitive. Nous soulignons l’importance de l’application flexible du protocole de traitement.In this article, we describe the cognitive-behavioral treatment of a patient with severe generalized anxiety disorder (GAD). The treatment, which was developed by our group, targets the four components of our cognitive model of GAD: intolerance of uncertainty, positive beliefs about worry, ineffective problem solving, and cognitive avoidance. Examples of therapeutic strategies that are described include the modification of intolerance of uncertainty, the reevaluation of positive beliefs about worry, problem solving training, and cognitive exposure. Throughout the manuscript, we stress the importance of applying the treatment package in a flexible fashion.
Journal of Applied Clinical Medical Physics, 2010
The purpose of this study is to assess the temporal and reconstruction accuracy of a surface imag... more The purpose of this study is to assess the temporal and reconstruction accuracy of a surface imaging system, the GateCT under ideal conditions, and compare the device with a commonly used respiratory surrogate: the Varian RPM. A clinical CT scanner, run in cine mode, was used with two optical devices, GateCT and RPM, to detect respiratory motion. A radiation detector, GM-10, triggers the X-ray on/off to GateCT system, while the RPM is directly synchronized with the CT scanner through an electronic connection. Two phantoms were imaged: the first phantom translated on a rigid plate along the anterior-posterior (AP) direction, and was used to assess the temporal synchronization of each optical system with the CT scanner. The second phantom, consisting of five spheres translating 3 cm peak-topeak in the superior-inferior direction, was used to assess the quality of rebinned images created by GateCT and RPM. Calibration assessment showed a nearly perfect synchronization with the scanner for both the RPM and GateCT systems, thus demonstrating the good performance of the radiation detector. Results for the volume rebinning test showed discrepancies in volumes for the 3D reconstruction (compared to ground truth) of up to 36% for GateCT and up to 40% for RPM. No statistical difference was proven between the two systems in volume sorting. Errors are mainly due to phase detection inaccuracies and to the large motion of the phantom. This feasibility study assessed the consistency of two optical systems in synchronizing the respiratory signal with the image acquisition. A new patient protocol based on both RPM and GateCT will be soon started.
International Journal of Radiation OncologyBiologyPhysics
Purpose: External beam accelerated partial breast irradiation requires accurate localization of t... more Purpose: External beam accelerated partial breast irradiation requires accurate localization of the target volume for each treatment fraction. Using the concept of target registration error (TRE), the performance of several methods of target localization was compared. Methods and Materials: Twelve patients who underwent external beam accelerated partial breast irradiation were included in this study. TRE was quantified for four methods of image guidance: standard laser-based setup, kilovoltage imaging of the chest wall, kilovoltage imaging of surgically implanted clips, and three-dimensional surface imaging of the breast. The use of a reference surface created from a free-breathing computed tomography scan and a reference surface directly captured with three-dimensional video imaging were compared. The effects of respiratory motion were also considered, and gating was used for 8 of 12 patients. Results: The median value of the TRE for the laser, chest wall, and clip alignment was 7.1 mm (n = 94), 5.4 mm (n = 81), and 2.4 mm (n = 93), respectively. The median TRE for gated surface imaging based on the first fraction reference surface was 3.2 mm (n = 49), and the TRE for gated surface imaging using the computed tomographybased reference surface was 4.9 mm (n = 56). The TRE for nongated surface imaging using the first fraction reference surface was 6.2 mm (n = 25). Conclusions: The TRE of surface imaging using a reference surface directly captured with three-dimensional video and the TRE for clip-based setup were within 1 mm. Gated capture is important for surface imaging to reduce the effects of respiratory motion in accelerated partial breast irradiation. Ó 2008 Elsevier Inc.
Journal of applied clinical medical physics / American College of Medical Physics, 2011
The purpose of this study is to assess the temporal and reconstruction accuracy of a surface imag... more The purpose of this study is to assess the temporal and reconstruction accuracy of a surface imaging system, the GateCT under ideal conditions, and compare the device with a commonly used respiratory surrogate: the Varian RPM. A clinical CT scanner, run in cine mode, was used with two optical devices, GateCT and RPM, to detect respiratory motion. A radiation detector, GM-10, triggers the X-ray on/off to GateCT system, while the RPM is directly synchronized with the CT scanner through an electronic connection. Two phantoms were imaged: the first phantom translated on a rigid plate along the anterior-posterior (AP) direction, and was used to assess the temporal synchronization of each optical system with the CT scanner. The second phantom, consisting of five spheres translating 3 cm peak-to-peak in the superior-inferior direction, was used to assess the quality of rebinned images created by GateCT and RPM. Calibration assessment showed a nearly perfect synchronization with the scanner...
Practical radiation oncology
Proper positioning of patients with extremity sarcoma tumors can be challenging. A surface imagin... more Proper positioning of patients with extremity sarcoma tumors can be challenging. A surface imaging technique was utilized to quantify the setup uncertainties for sarcoma patients and to assess whether surface imaging could improve the accuracy of patient positioning. Pretreatment and posttreatment 3-dimensional (3D) surface images were obtained for 16 patients and 236 treatments. Offline surface registration was performed to quantify interfraction and intrafraction setup errors, and the required planning target volume (PTV) margins were calculated. Setup differences were also assessed using root mean square (RMS) error analysis. For intrafraction variation, the mean 3D vector shift was 2.1 mm, and the systematic and random errors were 1.3 mm or less. When using a reference surface from the first fraction, the mean interfraction setup variation (3D vector shift) was 7.6 mm. Systematic and random errors were 3-4 mm in each direction. When using a computed tomographic based reference s...
Évaluation D’Un Programme D’Aide Au Succès De Sevrage Des Benzodiazépines
Santé mentale au Québec, 2003
[Evaluation of a program to help discontinuation of benzodiazepines]
Santé mentale au Québec, 2003
The efficacy of a new cognitive-behavioral group program to help discontinuation of benzodiazepin... more The efficacy of a new cognitive-behavioral group program to help discontinuation of benzodiazepines (PASSE) was evaluated by comparison to a group receiving only social support. Both programs lasted 20 weeks commencing with a preparatory period of one month and then tapering continually during 16 subsequent weeks until discontinuation. Forty-eight participants (24 in each condition) with a diagnosis of anxiety disorder took part in the study. These two active conditions were compared with a separate group of 41 people receiving standard tapering with physician counselling only. The results post-treatment supported the hypothesis that those receiving either of the two active treatments succeeded better in discontinuing benzodiazepines than those receiving the standard treatment. Among those completing the two active programs there was no difference in outcome between the social support and the cognitive behavioral (PASSE) group. However, when the rate of dropout was considered, the c...
24 Clinical Implementation of IGRT Techniques
Radiotherapy and Oncology, 2005
Medical Physics, 2007
Interplay between organ (breathing) motion and leaf motion has been shown in the literature to ha... more Interplay between organ (breathing) motion and leaf motion has been shown in the literature to have a small dosimetric impact for clinical conditions (over a 30 fraction treatment). However, previous studies did not consider the case of treatment beams made up of many few-monitor-unit (MU) segments, where the segment delivery time (1-2 s) is of the order of the breathing period (3-5 s). In this study we assess if breathing compromises the radiotherapy treatment with IMRT segments of low number of MUs. We assess (i) how delivered dose varies, from patient to patient, with the number of MU per segment, (ii) if this delivered dose is identical to the average dose calculated without motion over the path of the motion, and (iii) the impact of the daily variation of the delivered dose as a function of MU per segment. The organ motion was studied along two orthogonal directions, representing the left-right and cranial-caudal directions of organ movement for a patient setup in the supine position. Breathing motion was modeled as sin(x), sin 4 (x), and sin 6 (x), based on functions used in the literature to represent organ motion. Measurements were performed with an ionization chamber and films. For a systematic study of motion effects, a MATLAB simulation was written to model organ movement and dose delivery. In the case of a single beam made up of one single segment, the dose delivered to point in a moving target over 30 fractions can vary up to 20% and 10% for segments of 10 MU and 20 MU, respectively. This dose error occurs because the tumor spends most of the time near the edges of the radiation beam. In the case of a single beam made of multiple segments with low MU, we observed 2.4%, 3.3%, and 4.3% differences, respectively, for sin(x), sin 4 (x), and sin 6 (x) motion, between delivered dose and motion-averaged dose for points in the penumbra region of the beam and over 30 fractions. In approximately 5-10% of the cases, differences between the motion-averaged dose and the delivered 30-fraction dose could reach 6%, 8% and 10-12%, respectively for sin(x), sin 4 (x), and sin 6 (x) motion. To analyze a clinical IMRT beam, two patient plans were randomly selected. For one of the patients, the beams showed a likelihood of up to 25.6% that the delivered dose would deviate from the motion-averaged dose by more than 1%. For the second patient, there was a likelihood of up to 62.8% of delivering a dose that differs by more than 1% from the motion-averaged dose and a likelihood of up to ~30% for a 2% dose error. For the entire five-beam IMRT plan, statistical averaging over the beams reduces the overall dose error between the delivered dose and the motion-averaged dose. For both patients there was a likelihood of up to 7.0% and 33.9% that the dose error was greater than 1%, respectively. For one of the patients, there was a 12.6% likelihood of a 2% dose error. Daily intrafraction variation of the delivered dose of more than 10% is non-negligible and can potentially lead to biological effects. We observed [for sin(x), sin 4 (x), and sin 6 (x)] that below 10-15 MU leads to large daily variations of the order of 15-35%. Therefore, for small MU segments, non-negligible biological effects can be incurred. We conclude that for most clinical cases the effects may be small because of the use of many beams, it is desirable to avoid low-MU segments when treating moving targets. In addition, dose averaging may not work well for hypo-fractionation, where fewer fractions are used. For hypo-fractionation, PDF modeling of the tumor motion in IMRT optimization may not be adequate.
SU-FF-J-128: Uncertainties in Target Volume Surrogates in Image Guided External Beam Partial Breast Irradiation
Medical Physics, 2006
SU-FF-J-60: A Video Guided Breath Hold Treatment Technique for Cardiac Sparing Breast Radiotherapy
Medical Physics, 2009
Journal of Radiation Research, 2007
Journal of Anxiety Disorders, 2012
Interpretations of negative, positive, and ambiguous situations were examined in individuals with... more Interpretations of negative, positive, and ambiguous situations were examined in individuals with generalized anxiety disorder (GAD), other anxiety disorders (ANX), and no psychiatric condition (CTRL). Additionally, relationships between specific beliefs about uncertainty (Uncertainty Has Negative Behavioral and Self-Referent Implications [IUS-NI], and Uncertainty Is Unfair and Spoils Everything [IUS-US]) and interpretations were explored. The first hypothesis (that the clinical groups would report more concern for negative, positive, and ambiguous situations than would the CTRL group) was supported. The second hypothesis (that the GAD group would report more concern for ambiguous situations than would the ANX group) was not supported; both groups reported similar levels of concern for ambiguous situations. Exploratory analyses revealed no differences between the GAD and ANX groups in their interpretations of positive and negative situations. Finally, the IUS-US predicted interpretations of negative and ambiguous situations in the full sample, whereas the IUS-NI did not. Clinical implications are discussed.
International Journal of Radiation Oncology*Biology*Physics, 2008
Purpose: External beam accelerated partial breast irradiation requires accurate localization of t... more Purpose: External beam accelerated partial breast irradiation requires accurate localization of the target volume for each treatment fraction. Using the concept of target registration error (TRE), the performance of several methods of target localization was compared. Methods and Materials: Twelve patients who underwent external beam accelerated partial breast irradiation were included in this study. TRE was quantified for four methods of image guidance: standard laser-based setup, kilovoltage imaging of the chest wall, kilovoltage imaging of surgically implanted clips, and three-dimensional surface imaging of the breast. The use of a reference surface created from a free-breathing computed tomography scan and a reference surface directly captured with three-dimensional video imaging were compared. The effects of respiratory motion were also considered, and gating was used for 8 of 12 patients. Results: The median value of the TRE for the laser, chest wall, and clip alignment was 7.1 mm (n = 94), 5.4 mm (n = 81), and 2.4 mm (n = 93), respectively. The median TRE for gated surface imaging based on the first fraction reference surface was 3.2 mm (n = 49), and the TRE for gated surface imaging using the computed tomographybased reference surface was 4.9 mm (n = 56). The TRE for nongated surface imaging using the first fraction reference surface was 6.2 mm (n = 25). Conclusions: The TRE of surface imaging using a reference surface directly captured with three-dimensional video and the TRE for clip-based setup were within 1 mm. Gated capture is important for surface imaging to reduce the effects of respiratory motion in accelerated partial breast irradiation. Ó 2008 Elsevier Inc.
A Voluntary Breath-Hold Treatment Technique for the Left Breast With Unfavorable Cardiac Anatomy Using Surface Imaging
International Journal of Radiation Oncology*Biology*Physics, 2012
Breath-hold (BH) treatments can be used to reduce cardiac dose for patients with left-sided breas... more Breath-hold (BH) treatments can be used to reduce cardiac dose for patients with left-sided breast cancer and unfavorable cardiac anatomy. A surface imaging technique was developed for accurate patient setup and reproducible real-time BH positioning. Three-dimensional surface images were obtained for 20 patients. Surface imaging was used to correct the daily setup for each patient. Initial setup data were recorded for 443 fractions and were analyzed to assess random and systematic errors. Real time monitoring was used to verify surface placement during BH. The radiation beam was not turned on if the BH position difference was greater than 5 mm. Real-time surface data were analyzed for 2398 BHs and 363 treatment fractions. The mean and maximum differences were calculated. The percentage of BHs greater than tolerance was calculated. The mean shifts for initial patient setup were 2.0 mm, 1.2 mm, and 0.3 mm in the vertical, longitudinal, and lateral directions, respectively. The mean 3-dimensional vector shift was 7.8 mm. Random and systematic errors were less than 4 mm. Real-time surface monitoring data indicated that 22% of the BHs were outside the 5-mm tolerance (range, 7%-41%), and there was a correlation with breast volume. The mean difference between the treated and reference BH positions was 2 mm in each direction. For out-of-tolerance BHs, the average difference in the BH position was 6.3 mm, and the average maximum difference was 8.8 mm. Daily real-time surface imaging ensures accurate and reproducible positioning for BH treatment of left-sided breast cancer patients with unfavorable cardiac anatomy.
International Journal of Radiation Oncology*Biology*Physics, 2005
European Neuropsychopharmacology, 2009
This double-blind study compared initial combination therapy against monotherapy using two antide... more This double-blind study compared initial combination therapy against monotherapy using two antidepressant drugs with complementary mechanisms of action on the serotonin (5-HT) and norepinephrine (NE) systems. Sixty one adult patients with a DSM-IV diagnosis of unipolar depression were randomized to receive mirtazapine (30 mg/day), paroxetine (20 mg/day), or the combination of both drugs for 6 weeks. Response at week 4 was defined as a 30% reduction in the Montgomery-Asberg Depression Rating Scale (MADRS), and at week 6 as a 50% reduction in the MADRS. Remission was defined as a reduction in the MADRS score to 10 points or less. After 4 weeks, non-responders in the monotherapy groups had their medication dose increased by 50%. After 6 weeks, non-responders on monotherapy had the second trial drug added to their current regimen. Non-responders on combination therapy had the dosage of both drugs increased by 50%. There was a significantly greater decrease in MADRS scores in the combination group compared to the monotherapy groups at days 28, 35 and 42, with a 10 point difference separating the combination from the monotherapies at day 42. Remission rates at week 6 were 19% on mirtazapine, 26% on paroxetine, and 43% on the combination. Fifteen patients in the mirtazapine arm and 10 in the paroxetine arm who did not respond had the other drug added to their current regimen, and 5 on the combination had an increase in dose of both drugs secondary to nonresponse. Of these 30 patients, approximately 50% went on to achieve remission in the subsequent 2 weeks. These results indicate that the combined use of two antidepressants was well tolerated and produced a greater improvement than monotherapy.
Healthcare Utilization Following Cognitive‐Behavioral Treatment for Panic Disorder with Agoraphobia
Cognitive Behaviour Therapy, 2005
The aim of this study was to examine the overall changes in healthcare services utilization after... more The aim of this study was to examine the overall changes in healthcare services utilization after providing an empirically supported cognitive-behavioral treatment for panic disorder with agoraphobia. Data on healthcare utilization were collected for a total of 84 adults meeting DSM-IV criteria. Participants were completers of a cognitive-behavioral treatment for panic disorder with agoraphobia. Data on utilization of healthcare services and medication were obtained from semi-structured interviews from baseline to 1-year after treatment. Results of the Friedman non-parametric analysis reveal a significant decrease in overall and mental health-related costs following treatment. This study shows a significant reduction in healthcare costs following cognitive behavior therapy for panic disorder with agoraphobia. More studies are needed to examine the potential long-term cost-offset effect of empirically supported treatments for panic disorder.
The Economic Burden of Anxiety Disorders in Canada
Canadian Psychology/Psychologie canadienne, 2004
Abstract 1. Concern over the costs of medical conditions has traditionally overshadowed interest ... more Abstract 1. Concern over the costs of medical conditions has traditionally overshadowed interest in assessing the costs of mental health problems. Recent research, however, indicates that mental disorders impose considerable costs on society and on the sufferer. ...
Technology in cancer research & treatment, 2003
Boron neutron capture therapy (BNCT) is based on the preferential targeting of tumor cells with (... more Boron neutron capture therapy (BNCT) is based on the preferential targeting of tumor cells with (10)B and subsequent activation with thermal neutrons to produce a highly localized radiation. In theory, it is possible to selectively irradiate a tumor and the associated infiltrating tumor cells with large single doses of high-LET radiation while sparing the adjacent normal tissues. The mixture of high- and low-LET dose components created in tissue during neutron irradiation complicates the radiobiology of BNCT. Much of the complexity has been unravelled through a combination of preclinical experimentation and clinical dose escalation experience. Over 350 patients have been treated in a number of different facilities worldwide. The accumulated clinical experience has demonstrated that BNCT can be delivered safely but is still defining the limits of normal brain tolerance. Several independent BNCT clinical protocols have demonstrated that BNCT can produce median survivals in patients wi...
Le traitement cognitivo-comportemental d�une patiente atteinte du trouble d�anxi�t� g�n�ralis�e
Nous présentons ici le cas d’une patiente souffrant du trouble d’anxiété généralisée (TAG) à un d... more Nous présentons ici le cas d’une patiente souffrant du trouble d’anxiété généralisée (TAG) à un degré sévère et bénéficiant d’un traitement cognitivo-comportemental développé par notre équipe. Ce traitement validé empiriquement cible les 4 facteurs de notre modèle identifiés comme étant reliés au TAG: l’intolérance à l’incertitude, la surestimation de l’utilité de s’inquiéter, les difficultés de résolution de problèmes et l’évitement cognitif. Les stratégies thérapeutiques utilisées y sont décrites: modification de l’intolérance à l’incertitude, réévaluation de l’utilité de s’inquiéter, entraînement à la résolution de problèmes et exposition cognitive. Nous soulignons l’importance de l’application flexible du protocole de traitement.In this article, we describe the cognitive-behavioral treatment of a patient with severe generalized anxiety disorder (GAD). The treatment, which was developed by our group, targets the four components of our cognitive model of GAD: intolerance of uncertainty, positive beliefs about worry, ineffective problem solving, and cognitive avoidance. Examples of therapeutic strategies that are described include the modification of intolerance of uncertainty, the reevaluation of positive beliefs about worry, problem solving training, and cognitive exposure. Throughout the manuscript, we stress the importance of applying the treatment package in a flexible fashion.
Journal of Applied Clinical Medical Physics, 2010
The purpose of this study is to assess the temporal and reconstruction accuracy of a surface imag... more The purpose of this study is to assess the temporal and reconstruction accuracy of a surface imaging system, the GateCT under ideal conditions, and compare the device with a commonly used respiratory surrogate: the Varian RPM. A clinical CT scanner, run in cine mode, was used with two optical devices, GateCT and RPM, to detect respiratory motion. A radiation detector, GM-10, triggers the X-ray on/off to GateCT system, while the RPM is directly synchronized with the CT scanner through an electronic connection. Two phantoms were imaged: the first phantom translated on a rigid plate along the anterior-posterior (AP) direction, and was used to assess the temporal synchronization of each optical system with the CT scanner. The second phantom, consisting of five spheres translating 3 cm peak-topeak in the superior-inferior direction, was used to assess the quality of rebinned images created by GateCT and RPM. Calibration assessment showed a nearly perfect synchronization with the scanner for both the RPM and GateCT systems, thus demonstrating the good performance of the radiation detector. Results for the volume rebinning test showed discrepancies in volumes for the 3D reconstruction (compared to ground truth) of up to 36% for GateCT and up to 40% for RPM. No statistical difference was proven between the two systems in volume sorting. Errors are mainly due to phase detection inaccuracies and to the large motion of the phantom. This feasibility study assessed the consistency of two optical systems in synchronizing the respiratory signal with the image acquisition. A new patient protocol based on both RPM and GateCT will be soon started.
International Journal of Radiation OncologyBiologyPhysics
Purpose: External beam accelerated partial breast irradiation requires accurate localization of t... more Purpose: External beam accelerated partial breast irradiation requires accurate localization of the target volume for each treatment fraction. Using the concept of target registration error (TRE), the performance of several methods of target localization was compared. Methods and Materials: Twelve patients who underwent external beam accelerated partial breast irradiation were included in this study. TRE was quantified for four methods of image guidance: standard laser-based setup, kilovoltage imaging of the chest wall, kilovoltage imaging of surgically implanted clips, and three-dimensional surface imaging of the breast. The use of a reference surface created from a free-breathing computed tomography scan and a reference surface directly captured with three-dimensional video imaging were compared. The effects of respiratory motion were also considered, and gating was used for 8 of 12 patients. Results: The median value of the TRE for the laser, chest wall, and clip alignment was 7.1 mm (n = 94), 5.4 mm (n = 81), and 2.4 mm (n = 93), respectively. The median TRE for gated surface imaging based on the first fraction reference surface was 3.2 mm (n = 49), and the TRE for gated surface imaging using the computed tomographybased reference surface was 4.9 mm (n = 56). The TRE for nongated surface imaging using the first fraction reference surface was 6.2 mm (n = 25). Conclusions: The TRE of surface imaging using a reference surface directly captured with three-dimensional video and the TRE for clip-based setup were within 1 mm. Gated capture is important for surface imaging to reduce the effects of respiratory motion in accelerated partial breast irradiation. Ó 2008 Elsevier Inc.
Journal of applied clinical medical physics / American College of Medical Physics, 2011
The purpose of this study is to assess the temporal and reconstruction accuracy of a surface imag... more The purpose of this study is to assess the temporal and reconstruction accuracy of a surface imaging system, the GateCT under ideal conditions, and compare the device with a commonly used respiratory surrogate: the Varian RPM. A clinical CT scanner, run in cine mode, was used with two optical devices, GateCT and RPM, to detect respiratory motion. A radiation detector, GM-10, triggers the X-ray on/off to GateCT system, while the RPM is directly synchronized with the CT scanner through an electronic connection. Two phantoms were imaged: the first phantom translated on a rigid plate along the anterior-posterior (AP) direction, and was used to assess the temporal synchronization of each optical system with the CT scanner. The second phantom, consisting of five spheres translating 3 cm peak-to-peak in the superior-inferior direction, was used to assess the quality of rebinned images created by GateCT and RPM. Calibration assessment showed a nearly perfect synchronization with the scanner...
Practical radiation oncology
Proper positioning of patients with extremity sarcoma tumors can be challenging. A surface imagin... more Proper positioning of patients with extremity sarcoma tumors can be challenging. A surface imaging technique was utilized to quantify the setup uncertainties for sarcoma patients and to assess whether surface imaging could improve the accuracy of patient positioning. Pretreatment and posttreatment 3-dimensional (3D) surface images were obtained for 16 patients and 236 treatments. Offline surface registration was performed to quantify interfraction and intrafraction setup errors, and the required planning target volume (PTV) margins were calculated. Setup differences were also assessed using root mean square (RMS) error analysis. For intrafraction variation, the mean 3D vector shift was 2.1 mm, and the systematic and random errors were 1.3 mm or less. When using a reference surface from the first fraction, the mean interfraction setup variation (3D vector shift) was 7.6 mm. Systematic and random errors were 3-4 mm in each direction. When using a computed tomographic based reference s...
Évaluation D’Un Programme D’Aide Au Succès De Sevrage Des Benzodiazépines
Santé mentale au Québec, 2003
[Evaluation of a program to help discontinuation of benzodiazepines]
Santé mentale au Québec, 2003
The efficacy of a new cognitive-behavioral group program to help discontinuation of benzodiazepin... more The efficacy of a new cognitive-behavioral group program to help discontinuation of benzodiazepines (PASSE) was evaluated by comparison to a group receiving only social support. Both programs lasted 20 weeks commencing with a preparatory period of one month and then tapering continually during 16 subsequent weeks until discontinuation. Forty-eight participants (24 in each condition) with a diagnosis of anxiety disorder took part in the study. These two active conditions were compared with a separate group of 41 people receiving standard tapering with physician counselling only. The results post-treatment supported the hypothesis that those receiving either of the two active treatments succeeded better in discontinuing benzodiazepines than those receiving the standard treatment. Among those completing the two active programs there was no difference in outcome between the social support and the cognitive behavioral (PASSE) group. However, when the rate of dropout was considered, the c...
24 Clinical Implementation of IGRT Techniques
Radiotherapy and Oncology, 2005
Medical Physics, 2007
Interplay between organ (breathing) motion and leaf motion has been shown in the literature to ha... more Interplay between organ (breathing) motion and leaf motion has been shown in the literature to have a small dosimetric impact for clinical conditions (over a 30 fraction treatment). However, previous studies did not consider the case of treatment beams made up of many few-monitor-unit (MU) segments, where the segment delivery time (1-2 s) is of the order of the breathing period (3-5 s). In this study we assess if breathing compromises the radiotherapy treatment with IMRT segments of low number of MUs. We assess (i) how delivered dose varies, from patient to patient, with the number of MU per segment, (ii) if this delivered dose is identical to the average dose calculated without motion over the path of the motion, and (iii) the impact of the daily variation of the delivered dose as a function of MU per segment. The organ motion was studied along two orthogonal directions, representing the left-right and cranial-caudal directions of organ movement for a patient setup in the supine position. Breathing motion was modeled as sin(x), sin 4 (x), and sin 6 (x), based on functions used in the literature to represent organ motion. Measurements were performed with an ionization chamber and films. For a systematic study of motion effects, a MATLAB simulation was written to model organ movement and dose delivery. In the case of a single beam made up of one single segment, the dose delivered to point in a moving target over 30 fractions can vary up to 20% and 10% for segments of 10 MU and 20 MU, respectively. This dose error occurs because the tumor spends most of the time near the edges of the radiation beam. In the case of a single beam made of multiple segments with low MU, we observed 2.4%, 3.3%, and 4.3% differences, respectively, for sin(x), sin 4 (x), and sin 6 (x) motion, between delivered dose and motion-averaged dose for points in the penumbra region of the beam and over 30 fractions. In approximately 5-10% of the cases, differences between the motion-averaged dose and the delivered 30-fraction dose could reach 6%, 8% and 10-12%, respectively for sin(x), sin 4 (x), and sin 6 (x) motion. To analyze a clinical IMRT beam, two patient plans were randomly selected. For one of the patients, the beams showed a likelihood of up to 25.6% that the delivered dose would deviate from the motion-averaged dose by more than 1%. For the second patient, there was a likelihood of up to 62.8% of delivering a dose that differs by more than 1% from the motion-averaged dose and a likelihood of up to ~30% for a 2% dose error. For the entire five-beam IMRT plan, statistical averaging over the beams reduces the overall dose error between the delivered dose and the motion-averaged dose. For both patients there was a likelihood of up to 7.0% and 33.9% that the dose error was greater than 1%, respectively. For one of the patients, there was a 12.6% likelihood of a 2% dose error. Daily intrafraction variation of the delivered dose of more than 10% is non-negligible and can potentially lead to biological effects. We observed [for sin(x), sin 4 (x), and sin 6 (x)] that below 10-15 MU leads to large daily variations of the order of 15-35%. Therefore, for small MU segments, non-negligible biological effects can be incurred. We conclude that for most clinical cases the effects may be small because of the use of many beams, it is desirable to avoid low-MU segments when treating moving targets. In addition, dose averaging may not work well for hypo-fractionation, where fewer fractions are used. For hypo-fractionation, PDF modeling of the tumor motion in IMRT optimization may not be adequate.
SU-FF-J-128: Uncertainties in Target Volume Surrogates in Image Guided External Beam Partial Breast Irradiation
Medical Physics, 2006
SU-FF-J-60: A Video Guided Breath Hold Treatment Technique for Cardiac Sparing Breast Radiotherapy
Medical Physics, 2009
Journal of Radiation Research, 2007
Journal of Anxiety Disorders, 2012
Interpretations of negative, positive, and ambiguous situations were examined in individuals with... more Interpretations of negative, positive, and ambiguous situations were examined in individuals with generalized anxiety disorder (GAD), other anxiety disorders (ANX), and no psychiatric condition (CTRL). Additionally, relationships between specific beliefs about uncertainty (Uncertainty Has Negative Behavioral and Self-Referent Implications [IUS-NI], and Uncertainty Is Unfair and Spoils Everything [IUS-US]) and interpretations were explored. The first hypothesis (that the clinical groups would report more concern for negative, positive, and ambiguous situations than would the CTRL group) was supported. The second hypothesis (that the GAD group would report more concern for ambiguous situations than would the ANX group) was not supported; both groups reported similar levels of concern for ambiguous situations. Exploratory analyses revealed no differences between the GAD and ANX groups in their interpretations of positive and negative situations. Finally, the IUS-US predicted interpretations of negative and ambiguous situations in the full sample, whereas the IUS-NI did not. Clinical implications are discussed.
International Journal of Radiation Oncology*Biology*Physics, 2008
Purpose: External beam accelerated partial breast irradiation requires accurate localization of t... more Purpose: External beam accelerated partial breast irradiation requires accurate localization of the target volume for each treatment fraction. Using the concept of target registration error (TRE), the performance of several methods of target localization was compared. Methods and Materials: Twelve patients who underwent external beam accelerated partial breast irradiation were included in this study. TRE was quantified for four methods of image guidance: standard laser-based setup, kilovoltage imaging of the chest wall, kilovoltage imaging of surgically implanted clips, and three-dimensional surface imaging of the breast. The use of a reference surface created from a free-breathing computed tomography scan and a reference surface directly captured with three-dimensional video imaging were compared. The effects of respiratory motion were also considered, and gating was used for 8 of 12 patients. Results: The median value of the TRE for the laser, chest wall, and clip alignment was 7.1 mm (n = 94), 5.4 mm (n = 81), and 2.4 mm (n = 93), respectively. The median TRE for gated surface imaging based on the first fraction reference surface was 3.2 mm (n = 49), and the TRE for gated surface imaging using the computed tomographybased reference surface was 4.9 mm (n = 56). The TRE for nongated surface imaging using the first fraction reference surface was 6.2 mm (n = 25). Conclusions: The TRE of surface imaging using a reference surface directly captured with three-dimensional video and the TRE for clip-based setup were within 1 mm. Gated capture is important for surface imaging to reduce the effects of respiratory motion in accelerated partial breast irradiation. Ó 2008 Elsevier Inc.
A Voluntary Breath-Hold Treatment Technique for the Left Breast With Unfavorable Cardiac Anatomy Using Surface Imaging
International Journal of Radiation Oncology*Biology*Physics, 2012
Breath-hold (BH) treatments can be used to reduce cardiac dose for patients with left-sided breas... more Breath-hold (BH) treatments can be used to reduce cardiac dose for patients with left-sided breast cancer and unfavorable cardiac anatomy. A surface imaging technique was developed for accurate patient setup and reproducible real-time BH positioning. Three-dimensional surface images were obtained for 20 patients. Surface imaging was used to correct the daily setup for each patient. Initial setup data were recorded for 443 fractions and were analyzed to assess random and systematic errors. Real time monitoring was used to verify surface placement during BH. The radiation beam was not turned on if the BH position difference was greater than 5 mm. Real-time surface data were analyzed for 2398 BHs and 363 treatment fractions. The mean and maximum differences were calculated. The percentage of BHs greater than tolerance was calculated. The mean shifts for initial patient setup were 2.0 mm, 1.2 mm, and 0.3 mm in the vertical, longitudinal, and lateral directions, respectively. The mean 3-dimensional vector shift was 7.8 mm. Random and systematic errors were less than 4 mm. Real-time surface monitoring data indicated that 22% of the BHs were outside the 5-mm tolerance (range, 7%-41%), and there was a correlation with breast volume. The mean difference between the treated and reference BH positions was 2 mm in each direction. For out-of-tolerance BHs, the average difference in the BH position was 6.3 mm, and the average maximum difference was 8.8 mm. Daily real-time surface imaging ensures accurate and reproducible positioning for BH treatment of left-sided breast cancer patients with unfavorable cardiac anatomy.
International Journal of Radiation Oncology*Biology*Physics, 2005
European Neuropsychopharmacology, 2009
This double-blind study compared initial combination therapy against monotherapy using two antide... more This double-blind study compared initial combination therapy against monotherapy using two antidepressant drugs with complementary mechanisms of action on the serotonin (5-HT) and norepinephrine (NE) systems. Sixty one adult patients with a DSM-IV diagnosis of unipolar depression were randomized to receive mirtazapine (30 mg/day), paroxetine (20 mg/day), or the combination of both drugs for 6 weeks. Response at week 4 was defined as a 30% reduction in the Montgomery-Asberg Depression Rating Scale (MADRS), and at week 6 as a 50% reduction in the MADRS. Remission was defined as a reduction in the MADRS score to 10 points or less. After 4 weeks, non-responders in the monotherapy groups had their medication dose increased by 50%. After 6 weeks, non-responders on monotherapy had the second trial drug added to their current regimen. Non-responders on combination therapy had the dosage of both drugs increased by 50%. There was a significantly greater decrease in MADRS scores in the combination group compared to the monotherapy groups at days 28, 35 and 42, with a 10 point difference separating the combination from the monotherapies at day 42. Remission rates at week 6 were 19% on mirtazapine, 26% on paroxetine, and 43% on the combination. Fifteen patients in the mirtazapine arm and 10 in the paroxetine arm who did not respond had the other drug added to their current regimen, and 5 on the combination had an increase in dose of both drugs secondary to nonresponse. Of these 30 patients, approximately 50% went on to achieve remission in the subsequent 2 weeks. These results indicate that the combined use of two antidepressants was well tolerated and produced a greater improvement than monotherapy.
Healthcare Utilization Following Cognitive‐Behavioral Treatment for Panic Disorder with Agoraphobia
Cognitive Behaviour Therapy, 2005
The aim of this study was to examine the overall changes in healthcare services utilization after... more The aim of this study was to examine the overall changes in healthcare services utilization after providing an empirically supported cognitive-behavioral treatment for panic disorder with agoraphobia. Data on healthcare utilization were collected for a total of 84 adults meeting DSM-IV criteria. Participants were completers of a cognitive-behavioral treatment for panic disorder with agoraphobia. Data on utilization of healthcare services and medication were obtained from semi-structured interviews from baseline to 1-year after treatment. Results of the Friedman non-parametric analysis reveal a significant decrease in overall and mental health-related costs following treatment. This study shows a significant reduction in healthcare costs following cognitive behavior therapy for panic disorder with agoraphobia. More studies are needed to examine the potential long-term cost-offset effect of empirically supported treatments for panic disorder.
The Economic Burden of Anxiety Disorders in Canada
Canadian Psychology/Psychologie canadienne, 2004
Abstract 1. Concern over the costs of medical conditions has traditionally overshadowed interest ... more Abstract 1. Concern over the costs of medical conditions has traditionally overshadowed interest in assessing the costs of mental health problems. Recent research, however, indicates that mental disorders impose considerable costs on society and on the sufferer. ...