Image quality and radiation dose in spinal surgery: a comparison of three imaging systems in phantom.

Purpose: Using optimal settings for x-ray scans is crucial for obtaining three-dimensional images of high quality while keeping the patient dose low. Our work compares dose and image quality (IQ) of three intraoperative imaging systems [O-arm cone-beam computed tomography (CBCT), ClarifEye C-arm CBCT, and Airo computed tomography] used for spinal surgery. Approach: Patients of 70, 90, and 110 kg were simulated with an anthropomorphic phantom by adding tissue-equivalent material. Titanium inserts were placed in the phantom spine for reproducing metal artifacts in the images. Organ dose was measured with thermo-luminescent dosimeters for effective dose (E) calculation. Subjective IQ was assessed by ranking the images acquired with the manufacturer-defined imaging protocols. Objective IQ was assessed with a customized Catphan phantom. Results: The ClarifEye protocols resulted in the lowest E ranging from 1.4 to 5.1 mSv according to phantom size and protocol. The highest E was measured for the high-definition protocol of O-arm (E 2.2 to 9 mSv) providing the best subjective IQ for imaging of the spine without titanium inserts. For the images with metal, the best IQ was obtained with ClarifEye. Airo (E 5.5 to 8.4 mSv) was ranked with the lowest IQ for images without metal while the rank improved for images with metal. Airo images had better uniformity, noise, and contrast sensitivity compared with CBCTs but worse high-contrast resolution. The values of these parameters were comparable between the CBCT systems. Conclusions: Both CBCT systems provided better IQ compared with Airo for navigation of lumbar spinal surgery for the original phantom. Metal artifacts particularly affect O-arm images decreasing the subjective IQ. The high spatial resolution of CBCT systems resulted in a relevant parameter for the visibility of anatomical features important for spine navigation. Low dose protocols were enough to obtain a clinically acceptable contrast-to-noise ratio in the bones.

Barriers and facilitators of access and utilization of mental health services among forensic service users along the care pathway.

BACKGROUND: The verdict of Not Criminally Responsible on account of a Mental Disorder (NCRMD) is increasingly used to access specialized mental health services in Canada and elsewhere. This situation highlights the importance of ensuring timely access to services in the community to prevent violence and justice involvement. The objective of the present study is to identify individual and contextual barriers and facilitators of access to mental health services during the period preceding an offense leading to a verdict of NCRMD. METHODS: The sample includes 753 people found NCRMD in Québec, Canada. All episodes of mental health hospitalizations and service use before the index offense were identified using provincial administrative health data, for an average period of 4.5 years. Access was conceptualized as a function of the possibility of seeking, reaching and receiving appropriate health care services, based on Lévesque and colleagues patient-centred model of access to care. Generalized linear models were computed to identify the individual and contextual predictors of: (1) seeking mental healthcare (at least one contact with any type of services for mental health reasons); (2) reaching psychiatric care (at least one contact with a psychiatrist); (3) receiving psychiatric care, operationalized as (3a) continuity and (3b) intensity. Factors associated with volume of emergency mental health services were examined as exploratory analysis. RESULTS: Geographical considerations were highly important in determining who reached, and who received specialized mental health care - above and beyond individual factors related to need. Those who lived outside of major urban centres were 2.6 times as likely to reach psychiatric services as those who lived in major urban centres, and made greater use of emergency mental health services by 2.1 times. Living with family decreased the odds of seeking mental healthcare by half and the intensity of psychiatric care received, even when adjusting for level of need. CONCLUSIONS: Findings support efforts to engage with the family of service users and highlights the importance of providing resources to make family-centred services sustainable for health practitioners. Health policies should also focus on the implementation of outreach programs, such as Forensic Assertive Community Treatment teams as part of prevention initiatives.

COVID-19 et pratiques professionnelles dans les milieux institutionnels fermés.

INTRODUCTION: While governments have focused efforts on implementing health measures such as physical distancing and confinement to protect communities from the spread of COVID-19, some researchers focused on the significant impact of these measures on mental health and well-being. Persons with mental disorders who are both institutionalized and justice-involved in psychiatric and forensic hospitals find themselves more vulnerable to these measures and more limited in their movements and activities. AIMS: The purpose of this paper is to examine the changes in practice in response to the pandemic and their potential impact on individuals in institutional settings. RESULTS: A rapid review including 69 publications identified nine major themes in the literature, which will serve as a framework to analyze the experience of one forensic psychiatry institution in Canada. These themes are: 1) population-specific vulnerability factors; 2) staff management and training; 3) early discharge, parole, and community integration; 4) management of contagion in closed spaces; 5) sanitary measures and personal protective equipment; 6) care and service continuity; 7) use of technology to maintain social ties and services; 8) legal mechanisms and individual rights; and 9) post-pandemic realities. CONCLUSION: Although this is the first pandemic of such international magnitude, experts point to an increase in epidemics over the past decade and continued growth in the coming decades. It is thus essential to learn from this health crisis in order to be prepared and minimize their potential impact on vulnerable populations in the future. The reflections presented here could be contrasted with the lived-experiences of people in institutions in order to nuance the data and propose new strategies.

Strategies for Motion Robust Proton Therapy With Pencil Beam Scanning for Esophageal Cancer.

PURPOSE: Proton therapy of esophageal cancer is superior to photon radiation therapy in terms of normal tissue sparing. However, respiratory motion and anatomical changes may compromise target dose coverage owing to density changes, geometric misses, and interplay effects. Here we investigate the combined effect on clinical target volume (CTV) coverage and compare proton therapy with intensity modulated radiation therapy (IMRT). METHODS AND MATERIALS: This study includes 26 patients with esophageal cancer previously treated with IMRT planned on 4-dimensional computed tomography (4D-CT). For each patient, 7 proton pencil beam scanning (PBS) plans were created with different field configurations and optimization strategies. The effect of respiration was investigated by calculating the phase doses, 4D dose, and 4D dynamic dose (including interplay effects). The effect of anatomical changes was investigated by recalculating all plans on all phases of a 4D-CT surveillance scan. RESULTS: The most robust PBS plans were achieved using 2 posterior beams requiring coverage of planning target volume (PTV) and simultaneously using robust optimization (RO) of CTV (2PAPTVRO), resulting in only 1 patient showing V95%CTV <97% in 1 or more phases of the planning CT. For the least robust PBS plans obtained using lateral + posterior beams and CTV-RO, but not requiring PTV coverage (2LPRO), 10 patients showed underdosage. For IMRT, 2 patients showed underdosage. Interplay effects reduced V95%CTV significantly when delivering only 1 fraction, but the effects generally averaged out after 10 fractions. The effect of interplay was significantly larger for RO-only plans compared with plans optimized with RO combined with PTV coverage. Combining the effect of anatomical changes and respiration on the 4D-CT surveillance scan resulted in V95%CTV <97% for 3 2PAPTVRO, 16 2LPRO, and 8 IMRT patients. CONCLUSIONS: PBS using posterior beam angles was more robust to anatomical changes and respiration than IMRT. The effect of respiration was enhanced when anatomical changes were present. Single fraction interplay effects deteriorated the dose distribution but were averaged out after 10 fractions.

Lessons from Canadian Courts for All Expert Witnesses.

Expert witnesses have a special place in court, bringing their knowledge and skills in the form of opinion evidence to educate the court. This allows the fact-finder to make legal decisions more effectively. Although experts are often allowed a role in civil and criminal matters, this brings certain risks to the court process. Admissibility of expert witness testimony in Canada has generally paralleled American law, including the standards enunciated in Daubert v Merrell Dow Pharmaceutical, Inc. (1993). Recently, there has been a series of decisions in Canadian law that has focused on the role of the expert witness in the court. Although only having precedence in Canada, these cases highlight important legal principles that all expert witnesses must navigate, regardless of their jurisdiction. We review these significant cases to assist forensic psychiatrists in recognizing and professionally navigating potential pitfalls in giving expert opinions.

Canada Should Retain Its Reservation on the United Nation's Convention on the Rights of Persons with Disabilities.

The United Nations adopted the Convention on the Rights of Persons with Disabilities (CRPD) in 2006. When Canada ratified the CRPD, it reserved the right to continue using substitute decision making schemes even if the CRPD was 'interpreted as requiring their elimination'. This was a prescient decision because the CRPD Committee, which is tasked with overseeing the interpretation and implementation of the CRPD, subsequently opined that all legislation supporting substitute decision making schemes contravene the CRPD and must be revoked. The CRPD Committee insists that every person can make decisions with sufficient support and that if a person lacks capacity to make a decision, we must rely on their 'will and preferences'. Many international legal scholars have called this interpretation unrealistic. We agree and, in this article, describe how this unrealistic approach would result in extensive harm and suffering for people with severe cognitive or psychotic disorders. The reader should also be aware that the CRPD Committee also calls for the elimination of all mental health acts and the United Nations Commissioner for Human Rights for the abandonment of the not criminally responsible (NCR) defence.

Sexual sadism in sexual offenders and sexually motivated homicide.

This article gives a clinically oriented overview of forensically relevant forms of sexual sadism disorder and its specific relationship to sexual homicide. In sexual homicide perpetrators, peculiar patterns of sexual sadism may be a motivational pathway to kill. Sexual sadism increases the risk for reoffending in sexual offenders. Through psychotherapy and pharmacological interventions, treatment of sadistic sex offenders has to consider special characteristics that may be different from those of nonsadistic sex offenders. Many of these offenders share a combination of sexual sadistic motives and an intact self-regulation, sometimes combined with a high level of sexual preoccupation.