Cone beam computed tomography in implant dentistry: a systematic review focusing on guidelines, indications, and radiation dose risks.

PURPOSE The aim of the paper is to identify, review, analyze, and summarize available evidence in three areas on the use of cross-sectional imaging, specifically maxillofacial cone beam computed tomography (CBCT) in pre- and postoperative dental implant therapy: (1) Available clinical use guidelines, (2) indications and contraindications for use, and (3) assessment of associated radiation dose risk. MATERIALS AND METHODS Three focused questions were developed to address the aims. A systematic literature review was performed using a PICO-based search strategy based on MeSH key words specific to each focused question of English-language publications indexed in the MEDLINE database retrospectively from October 31, 2012. These results were supplemented by a hand search and gray literature search. RESULTS Twelve publications were identified providing guidelines for the use of cross-sectional radiography, particularly CBCT imaging, for the pre- and/or postoperative assessment of potential dental implant sites. The publications discovered by the PICO strategy (43 articles), hand (12), and gray literature searches (1) for the second focus question regarding indications and contraindications for CBCT use in implant dentistry were either cohort or case-controlled studies. For the third question on the assessment of associated radiation dose risk, a total of 22 articles were included. Publication characteristics and themes were summarized in tabular format. CONCLUSIONS The reported indications for CBCT use in implant dentistry vary from preoperative analysis regarding specific anatomic considerations, site development using grafts, and computer-assisted treatment planning to postoperative evaluation focusing on complications due to damage of neurovascular structures. Effective doses for different CBCT devices exhibit a wide range with the lowest dose being almost 100 times less than the highest dose. Significant dose reduction can be achieved by adjusting operating parameters, including exposure factors and reducing the field of view (FOV) to the actual region of interest.

Ultra-low dose - new approaches in menopausal hormone therapy.

Despite increasing life expectancy, the age of onset of natural menopause has not significantly changed in recent decades. Thus, women spend about one-third of their lives in an estrogen-deficient state if untreated. There is a need for appropriate treatment of acute symptoms and prevention of the sequelae of chronic estrogen deficiency. International guidelines call for the use of the lowest effective hormone dosage for vasomotor symptom relief, the major indication for menopausal hormone therapy (MHT). In 2011, an oral continuous combined ultra-low-dose MHT was approved in Switzerland. This publication was elaborated by eight national menopause specialists and intends to review the advantages and disadvantages of ultra-low-dose MHT after the first years of its general use in Switzerland. It concludes that, for many women, ultra-low-dose MHT may be sufficient to decrease vasomotor symptoms, but not necessarily to guarantee fracture prevention.

High-Dose Benzodiazepine Dependence: A Qualitative Study of Patients' Perceptions on Initiation, Reasons for Use, and Obtainment

BACKGROUND High-dose benzodiazepine (BZD) dependence is associated with a wide variety of negative health consequences. Affected individuals are reported to suffer from severe mental disorders and are often unable to achieve long-term abstinence via recommended discontinuation strategies. Although it is increasingly understood that treatment interventions should take subjective experiences and beliefs into account, the perceptions of this group of individuals remain under-investigated. METHODS We conducted an exploratory qualitative study with 41 adult subjects meeting criteria for (high-dose) BZD-dependence, as defined by ICD-10. One-on-one in-depth interviews allowed for an exploration of this group's views on the reasons behind their initial and then continued use of BZDs, as well as their procurement strategies. Mayring's qualitative content analysis was used to evaluate our data. RESULTS In this sample, all participants had developed explanatory models for why they began using BZDs. We identified a multitude of reasons that we grouped into four broad categories, as explaining continued BZD use: (1) to cope with symptoms of psychological distress or mental disorder other than substance use, (2) to manage symptoms of physical or psychological discomfort associated with somatic disorder, (3) to alleviate symptoms of substance-related disorders, and (4) for recreational purposes, that is, sensation-seeking and other social reasons. Subjects often considered BZDs less dangerous than other substances and associated their use more often with harm reduction than as recreational. Specific obtainment strategies varied widely: the majority of participants oscillated between legal and illegal methods, often relying on the black market when faced with treatment termination. CONCLUSIONS Irrespective of comorbidity, participants expressed a clear preference for medically related explanatory models for their BZD use. We therefore suggest that clinicians consider patients' motives for long-term, high-dose BZD use when formulating treatment plans for this patient group, especially since it is known that individuals are more compliant with approaches they perceive to be manageable, tolerable, and effective.

Azacyclic FTY720 Analogues That Limit Nutrient Transporter Expression but Lack S1P Receptor Activity and Negative Chronotropic Effects Offer a Novel and Effective Strategy to Kill Cancer Cells in Vivo

FTY720 sequesters lymphocytes in secondary lymphoid organs through effects on sphingosine-1-phosphate (S1P) receptors. However, at higher doses than are required for immunosuppression, FTY720 also functions as an anticancer agent in multiple animal models. Our published work indicates that the anticancer effects of FTY720 do not depend on actions at S1P receptors but instead stem from FTY720s ability to restrict access to extracellular nutrients by down-regulating nutrient transporter proteins. This result was significant because S1P receptor activation is responsible for FTY720s dose-limiting toxicity, bradycardia, that prevents its use in cancer patients. Here, we describe diastereomeric and enantiomeric 3- and 4-C-aryl 2-hydroxymethyl pyrrolidines that are more active than the previously known analogues. Of importance is that these compounds fail to activate S1P1 or S1P3 receptors in vivo but retain inhibitory effects on nutrient transporter proteins and anticancer activity in solid tumor xenograft models. Our studies reaffirm that the anticancer activity of FTY720 does not depend upon S1P receptor activation and uphold the promise of using S1P receptor-inactive azacyclic FTY720 analogues in human cancer patients.

Stem cell mobilization chemotherapy with gemcitabine is effective and safe in myeloma patients with bortezomib-induced neurotoxicity.

Vinorelbine chemotherapy with granulocyte-colony stimulating factor (G-CSF) stimulation is a widely applied non-myelosuppressive mobilization regimen in Switzerland for myeloma patients, but its neurotoxic potential limits its use in patients with bortezomib-induced polyneuropathy. In this single-center study, we alternatively evaluated safety and effectiveness of gemcitabine chemotherapy with G-CSF for mobilization of autologous stem cells. Between March 2012 and February 2013, all bortezomib-pretreated myeloma patients planned to undergo first-line high-dose melphalan chemotherapy received a single dose of 1250 mg/m(2) gemcitabine, with G-CSF started on day 4. The 24 patients in this study had received a median of four cycles of bortezomib-dexamethason-based induction. Bortezomib-related polyneuropathy was identified in 21 patients (88%) by clinical evaluation and a standardized questionnaire. Administration of gemcitabine mobilization did not induce new or aggravate pre-existing neuropathy. Stem cell mobilization was successful in all 24 patients, with a single day of apheresis being sufficient in 19 patients (78%). The median yield was 9.51 × 10(6) CD34+ cells/kg. Stem collection could be accomplished at day 8 in 67%. Our data suggest that single-dose gemcitabine together with G-CSF is an effective mobilization regimen in myeloma patients and a safe alternative non-myelosuppressive mobilization chemotherapy for myeloma patients with bortezomib-induced polyneuropathy.

A dose-response analysis of a school-based nutrition intervention in middle school children

Childhood obesity in the US has reached epidemic proportions. Minority children are affected the most by this epidemic. Although there is no clear relationship between obesity and fruits and vegetables consumption, studies suggest that eating fruits and vegetables could be helpful in preventing childhood obesity. A few school-based interventions targeting youth have been effective at increasing fruits and vegetables intake.^ In Austin, Texas, the Sustainable Food Center delivered the Sprouting Healthy Kids (SHK) program that targeted low socio-economic status children in four intervention middle schools. The SHK program delivered six intervention components. This school-based intervention included: a cafeteria component, in-class lessons, an after-school garden program, a field trip to a local farm, food tasting, and farmers' visits to schools. This study aimed to determine the effects of the SHK intervention in middle school students' preferences, motivation, knowledge, and self-efficacy towards fruits and vegetables intake, as well as the actual fruits and vegetables intake. The study also aimed to determine the effects of exposure to different doses of the SHK intervention on participants' fruits and vegetable intake.^ The SHK was delivered during Spring 2009. A total of 214 students completed the pre-and-posttest surveys measuring self-report fruits and vegetables intake as well as intrapersonal factors. The results showed that the school cafeteria, the food tasting, the after school program, and the farmers' visits had a positive effect on the participants' motivation, knowledge, and self-efficacy towards fruits and vegetables intake. The farmers' visits and the food tasting components increased participants' fruits and vegetables intake. Exposure to two or more intervention components increased participants' fruits and vegetables intake. The statistically significant dose-response effect size was .352, which suggests that each intervention component increased participants' fruits and vegetables consumption this amount. Certain intervention components were more effective than others. Food tasting and farmers visits increased participants fruits and vegetables intake, therefore these components should be offered in an ongoing basis. This study suggests that exposure to multiple intervention components increased behaviors and attitudes towards fruits and vegetables consumption. Findings are consistent that SHK can influence behaviors of middle school students.^

Optimal, minimax, and Bayesian two-stage designs in two-dose phase II clinical trials

Background: For most cytotoxic and biologic anti-cancer agents, the response rate of the drug is commonly assumed to be non-decreasing with an increasing dose. However, an increasing dose does not always result in an appreciable increase in the response rate. This may especially be true at high doses for a biologic agent. Therefore, in a phase II trial the investigators may be interested in testing the anti-tumor activity of a drug at more than one (often two) doses, instead of only at the maximum tolerated dose (MTD). This way, when the lower dose appears equally effective, this dose can be recommended for further confirmatory testing in a phase III trial under potential long-term toxicity and cost considerations. A common approach to designing such a phase II trial has been to use an independent (e.g., Simon's two-stage) design at each dose ignoring the prior knowledge about the ordering of the response probabilities at the different doses. However, failure to account for this ordering constraint in estimating the response probabilities may result in an inefficient design. In this dissertation, we developed extensions of Simon's optimal and minimax two-stage designs, including both frequentist and Bayesian methods, for two doses that assume ordered response rates between doses. ^ Methods: Optimal and minimax two-stage designs are proposed for phase II clinical trials in settings where the true response rates at two dose levels are ordered. We borrow strength between doses using isotonic regression and control the joint and/or marginal error probabilities. Bayesian two-stage designs are also proposed under a stochastic ordering constraint. ^ Results: Compared to Simon's designs, when controlling the power and type I error at the same levels, the proposed frequentist and Bayesian designs reduce the maximum and expected sample sizes. Most of the proposed designs also increase the probability of early termination when the true response rates are poor. ^ Conclusion: Proposed frequentist and Bayesian designs are superior to Simon's designs in terms of operating characteristics (expected sample size and probability of early termination, when the response rates are poor) Thus, the proposed designs lead to more cost-efficient and ethical trials, and may consequently improve and expedite the drug discovery process. The proposed designs may be extended to designs of multiple group trials and drug combination trials.^

Chemoradiation therapy is effective for the palliative treatment of malignant dysphagia

Between 1993 and 2001, 106 patients with esophageal cancer were reviewed at a multidisciplinary clinic and treated with palliative intent by chemoradiation therapy. This study assesses the palliative benefit on dysphagia and documents the toxicity of this treatment. The study population comprised 72 men and 34 women with a median age of 69 years. Patients were treated with a median radiation dose of 35 Gy in 15 fractions with a concurrent single course of 5 FU-based chemotherapy. Dysphagia was measured at the beginning and completion of treatment and at monthly intervals until death, using a modified DeMeester (4-point) score. Treatment was well tolerated, with only 5% of patients failing to complete therapy. The treatment-related mortality was 6%. The median survival for the study population was 7 months. The median baseline score at presentation was 2 (difficulty with soft food). Following treatment, 49% of patients were assessed as having a dysphagia score of 0 (no dysphagia). Seventy-eight per cent had an improvement of at least one grade in their dysphagia score after treatment. Only 14% of patients showed no improvement with treatment. Fifty-one per cent maintained improved swallowing until the time of last follow-up or death. This single-institution study shows that chemoradiation therapy administered for the palliation of malignant dysphagia is well tolerated and produces a sustainable normalization in swallowing for almost half of all patients.

Doubling daily inhaled corticosteroid dose is ineffective in mild to moderately severe attacks of asthma in adults

Background: Asthma guidelines recommend increasing or doubling inhaled corticosteroid (ICS) dose to treat mild and moderate exacerbations of asthma in adults. Aim: To: (i) compare the effectiveness of doubling existing daily ICS dose (fluticasone) with maintaining usual ICS dose and usual daily ICS dose accompanied by oral steroids (OS) (dexamethasone) during mild and moderately severe exacerbations of asthma in adults; (ii) examine determinants of success and failure; and (iii) compare side-effect profiles. Methods: A randomized, double-blind, placebo-controlled (double-dummy), triple crossover trial. Participants acted as their own control. Outcome measures included treatment success/failure, peak expiratory flow (PEF) after 7 days therapy or at treatment failure, and side-effects. Results: From 22 participants (nine males and 13 females), 18 pairs of data were available for maintaining usual ICS versus doubling ICS and doubling ICS versus OS, and 19 for maintaining usual ICS versus OS. Median (fifth-95th percentile) age was 46.5 (32-64) years and forced expiratory volume in one second (FEV1) 73% (29-97%) predicted. The outcome after doubling ICS was not superior to maintaining usual ICS, with 11 (61%) failures in both arms (P = 0.66). OS, with only 5 (26%) failures, was superior to maintaining usual ICS with 12 (63%) failures (P = 0.04), and to doubling ICS with 5 (28%) versus 11 (61%) failures (P = 0.07). Median PEF (as percentage of run-in best) at end-points were 90.5% (57.1-177.1) for OS, 78.3% (39.5-103.1) for maintaining usual ICS and 77.9 (27.7-110.3) for doubling ICS. Neither gender nor PEF at exacerbation were predictive of failure. Although doubling ICS was not an effective therapy overall, ICS dose at exacerbation were predictive of success in the doubling ICS arm (P = 0.04). Treatment failures when doubling daily ICS dose were more common if achieved fluticasone dose was less than 2000 mu g (three of 11, 73%) compared to 2000 mu g or greater (eight of eight, 37.5%). Increasing age and the presence of an upper respiratory tract infection (URTI) were predictive of failure with OS. Side-effects were more commonly reported with OS (52.6%) than doubling ICS (42.1%) or maintaining usual ICS (19.1%) with the most common being mood changes (36.8%), sleep disturbance (31.6%) and changes in appetite (26.3%). Conclusions: Doubling daily ICS dose per se is not effective for the treatment of mild to moderately severe exacerbations of asthma in adults. Success may depend on achieved ICS dose. Oral steroids are effective, but side-effects are common. A review of current guidelines may be warranted.

Mini-dose glucagon rescue for mild hypoglycaemia in children with type 1 diabetes: The Brisbane experience

Objectives: To evaluate the use of small doses of glucagon using an insulin syringe in mild or impending hypoglycaemia in children with type 1 diabetes. Methods: Data were collected from patients attending the Paediatric Diabetes Clinic at the Queensland Diabetes Centre at the Mater Hospital, Brisbane in 2002-2004 following the institution of a new protocol for home management of mild or impending hypoglycaemia associated with inability or refusal to take oral carbohydrate. The protocol recommended the use of subcutaneous injections of glucagon using insulin syringes at a dose of two ' units ' (20 mu g) in children 2 years of age or younger, and for older children one unit per year of age up to a maximum of 15 units (150 mu g), with an additional doubled dose given if the blood glucose had not increased in 20 min. Results: Over a 2-year period, 25 children were treated with mini-dose glucagon on a total of 38 occasions. Additional doses were required for recurring hypoglycaemia on 20 (53%) occasions. The child could be managed at home on 32 (84%) of these 38 occasions, with only 6 (16%) children needing hospital treatment. Conclusions: Our study confirmed that small doses of glucagon given subcutaneously with an insulin syringe is a simple, practical and effective home treatment of mild or impending hypoglycaemia due to gastroenteritis or food refusal in children with type 1 diabetes.

Radiation Dose to the Lens of the Eye from Computed Tomography Scans of the Head

While it is well known that exposure to radiation can result in cataract formation, questions still remain about the presence of a dose threshold in radiation cataractogenesis. Since the exposure history from diagnostic CT exams is well documented in a patient’s medical record, the population of patients chronically exposed to radiation from head CT exams may be an interesting area to explore for further research in this area. However, there are some challenges in estimating lens dose from head CT exams. An accurate lens dosimetry model would have to account for differences in imaging protocols, differences in head size, and the use of any dose reduction methods.

The overall objective of this dissertation was to develop a comprehensive method to estimate radiation dose to the lens of the eye for patients receiving CT scans of the head. This research is comprised of a physics component, in which a lens dosimetry model was derived for head CT, and a clinical component, which involved the application of that dosimetry model to patient data.

The physics component includes experiments related to the physical measurement of the radiation dose to the lens by various types of dosimeters placed within anthropomorphic phantoms. These dosimeters include high-sensitivity MOSFETs, TLDs, and radiochromic film. The six anthropomorphic phantoms used in these experiments range in age from newborn to adult.

First, the lens dose from five clinically relevant head CT protocols was measured in the anthropomorphic phantoms with MOSFET dosimeters on two state-of-the-art CT scanners. The volume CT dose index (CTDIvol), which is a standard CT output index, was compared to the measured lens doses. Phantom age-specific CTDIvol-to-lens dose conversion factors were derived using linear regression analysis. Since head size can vary among individuals of the same age, a method was derived to estimate the CTDIvol-to-lens dose conversion factor using the effective head diameter. These conversion factors were derived for each scanner individually, but also were derived with the combined data from the two scanners as a means to investigate the feasibility of a scanner-independent method. Using the scanner-independent method to derive the CTDIvol-to-lens dose conversion factor from the effective head diameter, most of the fitted lens dose values fell within 10-15% of the measured values from the phantom study, suggesting that this is a fairly accurate method of estimating lens dose from the CTDIvol with knowledge of the patient’s head size.

Second, the dose reduction potential of organ-based tube current modulation (OB-TCM) and its effect on the CTDIvol-to-lens dose estimation method was investigated. The lens dose was measured with MOSFET dosimeters placed within the same six anthropomorphic phantoms. The phantoms were scanned with the five clinical head CT protocols with OB-TCM enabled on the one scanner model at our institution equipped with this software. The average decrease in lens dose with OB-TCM ranged from 13.5 to 26.0%. Using the size-specific method to derive the CTDIvol-to-lens dose conversion factor from the effective head diameter for protocols with OB-TCM, the majority of the fitted lens dose values fell within 15-18% of the measured values from the phantom study.

Third, the effect of gantry angulation on lens dose was investigated by measuring the lens dose with TLDs placed within the six anthropomorphic phantoms. The 2-dimensional spatial distribution of dose within the areas of the phantoms containing the orbit was measured with radiochromic film. A method was derived to determine the CTDIvol-to-lens dose conversion factor based upon distance from the primary beam scan range to the lens. The average dose to the lens region decreased substantially for almost all the phantoms (ranging from 67 to 92%) when the orbit was exposed to scattered radiation compared to the primary beam. The effectiveness of this method to reduce lens dose is highly dependent upon the shape and size of the head, which influences whether or not the angled scan range coverage can include the entire brain volume and still avoid the orbit.

The clinical component of this dissertation involved performing retrospective patient studies in the pediatric and adult populations, and reconstructing the lens doses from head CT examinations with the methods derived in the physics component. The cumulative lens doses in the patients selected for the retrospective study ranged from 40 to 1020 mGy in the pediatric group, and 53 to 2900 mGy in the adult group.

This dissertation represents a comprehensive approach to lens of the eye dosimetry in CT imaging of the head. The collected data and derived formulas can be used in future studies on radiation-induced cataracts from repeated CT imaging of the head. Additionally, it can be used in the areas of personalized patient dose management, and protocol optimization and clinician training.

Utilisation de la tomodensitométrie à deux énergies pour le calcul de dose en curiethérapie à bas débit

Dans la pratique actuelle de la curiethérapie à bas débit, l'évaluation de la dose dans la prostate est régie par le protocole défini dans le groupe de travail 43 (TG-43) de l'American Association of Physicists in Medicine. Ce groupe de travail suppose un patient homogène à base d'eau de même densité et néglige les changements dans l'atténuation des photons par les sources de curiethérapie. En considérant ces simplifications, les calculs de dose se font facilement à l'aide d'une équation, indiquée dans le protocole. Bien que ce groupe de travail ait contribué à l'uniformisation des traitements en curiethérapie entre les hôpitaux, il ne décrit pas adéquatement la distribution réelle de la dose dans le patient. La publication actuelle du TG-186 donne des recommandations pour étudier des distributions de dose plus réalistes. Le but de ce mémoire est d'appliquer ces recommandations à partir du TG-186 pour obtenir une description plus réaliste de la dose dans la prostate. Pour ce faire, deux ensembles d'images du patient sont acquis simultanément avec un tomodensitomètre à double énergie (DECT). Les artéfacts métalliques présents dans ces images, causés par les sources d’iode, sont corrigés à l'aide d’un algorithme de réduction d'artefacts métalliques pour DECT qui a été développé dans ce travail. Ensuite, une étude Monte Carlo peut être effectuée correctement lorsque l'image est segmentée selon les différents tissus humains. Cette segmentation est effectuée en évaluant le numéro atomique effectif et la densité électronique de chaque voxel, par étalonnage stoechiométrique propre au DECT, et en y associant le tissu ayant des paramètres physiques similaires. Les résultats montrent des différences dans la distribution de la dose lorsqu'on compare la dose du protocole TG-43 avec celle retrouvée avec les recommandations du TG-186.

(Table 1) Maximal daily erythemally effective UVB radiation and total ozone content at Vernadsky Station, Antarctica

One of the research programs carried out within the Czech-Ukrainian scientific co-operation is the monitoring of global solar and ultraviolet radiation at the Vernadsky Station (formerly the British Faraday Station), Antarctica. Radiation measurements have been made since 2002. Recently, a special attention is devoted to the measurements of the erythemally effective UVB radiation using a broadband Robertson Berger 501 UV-Biometer (Solar Light Co. Inc., USA). This paper brings some results from modelling the daily sums of erythemally effective UVB radiation intensity in relation to the total ozone content (TOC) in atmosphere and surface intensity of the global solar radiation. Differences between the satellite- and ground-based measurements of the TOC at the Vernadsky Station are taken into consideration. The modelled erythemally effective UVB radiation differed slightly depending on the seasons and sources of the TOC. The model relative prediction error for ground- and satellite-based measurements varied between 9.5% and 9.6% in the period of 2002-2003, while it ranged from 7.4% to 8.8% in the period of 2003-2004.

Low-dose salinomycin induces anti-leukemic responses in AML and MLL

Development of anti-cancer drugs towards clinical application is costly and inefficient. Large screens of drugs, efficacious for non-cancer disease, are currently being used to identify candidates for repurposing based on their anti-cancer properties. Here, we show that low-dose salinomycin, a coccidiostat ionophore previously identified in a breast cancer screen, has anti-leukemic efficacy. AML and MLLr cell lines, primary cells and patient samples were sensitive to submicromolar salinomycin. Most strikingly, colony formation of normal hematopoietic cells was unaffected by salinomycin, demonstrating a lack of hemotoxicity at the effective concentrations. Furthermore, salinomycin treatment of primary cells resulted in loss of leukemia repopulation ability following transplantation, as demonstrated by extended recipient survival compared to controls. Bioinformatic analysis of a 17-gene signature identified and validated in primary MLLr cells, uncovered immunomodulatory pathways, hubs and protein interactions as potential transducers of low dose salinomycin treatment. Additionally, increased protein expression of p62/Sqstm1, encoded for by one of the 17 signature genes, demonstrates a role for salinomycin in aggresome/vesicle formation indicative of an autophagic response.
Together, the data support the efficacy of salinomycin as an anti-leukemic at non-hemotoxic concentrations. Further investigation alone or in combination with other therapies is warranted for future clinical trial.

Un poison même à petite dose : étude de la structure latente et des facteurs développementaux du sadisme sexuel

Les délinquants sexuels sadiques sont généralement décrits comme une entité clinique particulière commettant des délits graves. Or, la notion même de sadisme sexuel pose un nombre important de problèmes. Parmi ceux-ci, on retrouve des problèmes de validité et de fidélité. Perçu comme une maladie dont on est atteint ou pas, le sadisme a été étudié comme si les sadiques étaient fondamentalement différents. À l’heure actuelle, plusieurs travaux laissent croire que la majorité des troubles psychologiques se présentent comme une différence d'intensité (dimension) plutôt qu’une différence de nature (taxon). Même si la conception médicale prévaut encore en ce qui concerne le sadisme sexuel, plusieurs évoquent l’idée qu’il pourrait être mieux conceptualisé à l’aide d’une approche dimensionnelle. En parallèle, nos connaissances sur les facteurs contributifs au développement du sadisme sexuel sont limitées et reposent sur de faibles appuis empiriques. Jusqu'à présent, très peu d'études se sont intéressées aux facteurs menant au développement du sadisme sexuel et encore moins ont tenté de valider leurs théories. En outre, nos connaissances proviennent majoritairement d'études de cas portant sur les meurtriers sexuels, un sous-groupe très particulier de délinquants fréquemment motivé par des intérêts sexuels sadiques. À notre connaissance, aucune étude n'a proposé jusqu'à présent de modèle développemental portant spécifiquement sur le sadisme sexuel. Pourtant, l'identification de facteurs liés au développement du sadisme sexuel est essentielle dans notre compréhension ainsi que dans l'élaboration de stratégie d'intervention efficace. La présente thèse s'inscrit dans un contexte visant à clarifier le concept de sadisme sexuel. Plus spécialement, nous nous intéressons à sa structure latente, à sa mesure et à ses origines développementales. À partir d'un échantillon de 514 délinquants sexuels évalué au Massachusetts Treatment Center, la viabilité d’une conception dimensionnelle du sadisme sexuel sera mise à l’épreuve à l'aide d'analyses taxométriques permettant d'étudier la structure latente d'un construit. Dans une seconde étape, à l'aide d'analyses de Rasch et d'analyses appartenant aux théories de la réponse à l'item à deux paramètres, nous développerons la MTC Sadism Scale (MTCSS), une mesure dimensionnelle du sadisme sexuel. Dans une troisième et dernière étape, un modèle développemental sera élaboré à l'aide d'équations structurales. La présente thèse permettra de contribuer à la clarification du concept de sadisme sexuel. Une clarification de la structure latente et des facteurs développementaux permettra de saisir les devis de recherche les plus à même de capturer les aspects essentiels. En outre, ceci permettra d'identifier les facteurs pour lesquels une intervention est la plus appropriée pour réduire la récidive, ou la gravité de celle-ci.