RESUMEN
OBJECTIVE: The scientific literature reports on how social media potentially influences eating disorders, although there is a large gap in the specific case of TikToks influence of adolescent's recovery from anorexia nervosa (AN). Our study uses in-depth interviews with female adolescents primarily suffering from AN to explore how they perceive the social media platform TikTok in relation to their recovery. METHOD: A total of 14 interviews with female adolescents recovering from AN were conducted and analyzed with reflexive thematic analysis. RESULTS: We developed four distinct main themes: social connectivity, algorithmic engagement, regulation and adaptation, and personal agency and recovery pathways. Our findings indicate both potential benefits and harm by TikTok use when in recovery from AN, depending on a complex interplay of individual and contextual factors. DISCUSSION: The study adds nuance to the on-going scientific debate on the role that TikTok plays in recovery from AN in general from the perspective provided by female adolescents. Suggestions are made for clinical implications at adolescent AN outpatient care including parental or professional support in TikTok adaptations and advice on how to discern when use may be triggering or supportive. Future research would benefit from longitudinal designs and inclusion of how individual differences, such as gender and personality, influence the effects on recovery and TikTok use.
RESUMEN
PURPOSE: The purpose of this study was to evaluate our 2 years' experience with single-isocenter, non-coplanar, volumetric modulated arc therapy (VMAT) for brain metastasis (BM) stereotactic radiosurgery (SRS). METHODS: A total of 202 patients treated with the VMAT SRS solution were analyzed retrospectively. Plan quality was assessed for 5â¯mm (120) and 2.5â¯mm (high-definition, HD) central leaf width multileaf collimators (MLCs). For BMs at varying distances from the plan isocenter, the geometric offset from the ideal position for two image-guided radiotherapy workflows was calculated. In the workflow with ExacTrac (BrainLAB, München, Germany; WET), patient positioning errors were corrected at each couch rotation. In the workflow without ExacTrac (W-noET), only the initial patient setup correction was considered. The dose variation due to rotational errors was simulated for multiple-BM plans with the HD-MLC. RESULTS: Plan conformity and quality assurance were equivalent for plans delivered with the two MLCs while the HD-MLC plans provided better healthy brain tissue (BmP) sparing. 95% of the BMs had residual intrafractional setup errors ≤â¯2â¯mm for WET and 68% for WnoET. For small BM (≤1â¯cc) situated >3â¯cm from the plan isocenter, the dose received by 95% of the BM decreased in median (interquartile range) by 6.3% (2.8-8.8%) for a 1-degree rotational error. CONCLUSION: This study indicates that the HD-MLC is advantageous compared to the 120-MLC for sparing healthy brain tissue. When a 2-mm margin is applied, WnoET is sufficient to ensure coverage of BM situated ≤â¯3â¯cm of the plan isocenter, while for BM further away, WET is recommended.
Asunto(s)
Neoplasias Encefálicas , Radioterapia de Intensidad Modulada , Neoplasias Encefálicas/secundario , Humanos , Dosificación Radioterapéutica , Planificación de la Radioterapia Asistida por Computador , Estudios RetrospectivosRESUMEN
BACKGROUND: Besides improving glucose control, sodium-glucose co-transporter 2 inhibition with dapagliflozin reduces blood pressure, body weight and urinary albumin:creatinine ratio (UACR) in patients with type 2 diabetes (T2DM). The parameter response efficacy (PRE) score was developed to predict how short-term drug effects on cardiovascular risk markers translate into long-term changes in clinical outcomes. We applied the PRE score to clinical trials of dapagliflozin to model the effect of the drug on kidney and heart failure (HF) outcomes in patients with T2DM and impaired kidney function. METHODS: The relationships between multiple risk markers and long-term outcome were determined in a background population of patients with T2DM with a multivariable Cox model. These relationships were then applied to short-term changes in risk markers observed in a pooled database of dapagliflozin trials (n = 7) that recruited patients with albuminuria to predict the drug-induced changes to kidney and HF outcomes. RESULTS: A total of 132 and 350 patients had UACR >200 mg/g and >30 mg/g at baseline, respectively, and were selected for analysis. The PRE score predicted a risk change for kidney events of -40.8% [95% confidence interval (CI) -51.7 to -29.4) and -40.4% (95% CI -48.4 to -31.1) with dapagliflozin 10 mg compared with placebo for the UACR >200 mg/g and >30 mg/g subgroups. The predicted change in risk for HF events was -27.3% (95% CI -47.7 to -5.1) and -21.2% (95% CI -35.0 to -7.8), respectively. Simulation analyses showed that even with a smaller albuminuria-lowering effect of dapagliflozin (10% instead of the observed 35% in both groups), the estimated kidney risk reduction was still 26.5 and 26.8%, respectively. CONCLUSIONS: The PRE score predicted clinically meaningful reductions in kidney and HF events associated with dapagliflozin therapy in patients with diabetic kidney disease. These results support a large long-term outcome trial in this population to confirm the benefits of the drug on these endpoints.
Asunto(s)
Albuminuria/prevención & control , Compuestos de Bencidrilo/uso terapéutico , Biomarcadores/sangre , Diabetes Mellitus Tipo 2/tratamiento farmacológico , Nefropatías Diabéticas/prevención & control , Glucósidos/uso terapéutico , Insuficiencia Cardíaca/prevención & control , Inhibidores del Cotransportador de Sodio-Glucosa 2/uso terapéutico , Anciano , Albuminuria/sangre , Albuminuria/epidemiología , Ensayos Clínicos Fase III como Asunto , Diabetes Mellitus Tipo 2/patología , Nefropatías Diabéticas/sangre , Nefropatías Diabéticas/epidemiología , Femenino , Insuficiencia Cardíaca/sangre , Insuficiencia Cardíaca/epidemiología , Humanos , Masculino , Persona de Mediana Edad , Resultado del TratamientoRESUMEN
BACKGROUND: Radiotherapy of lung cancer patients is subject to uncertainties related to heterogeneities, anatomical changes and breathing motion. Use of deep-inspiration breath-hold (DIBH) can reduce the treated volume, potentially enabling dose-escalated (DE) treatments. This study was designed to investigate the need for adaptation due to anatomical changes, for both standard (ST) and DE plans in free-breathing (FB) and DIBH. MATERIAL AND METHODS: The effect of tumor shrinkage (TS), pleural effusion (PE) and atelectasis was investigated for patients and for a CIRS thorax phantom. Sixteen patients were computed tomography (CT) imaged both in FB and DIBH. Anatomical changes were simulated by CT information editing and re-calculations, of both ST and DE plans, in the treatment planning system. PE was systematically simulated by adding fluid in the dorsal region of the lung and TS by reduction of the tumor volume. RESULTS: Phantom simulations resulted in maximum deviations in mean dose to the GTV-T (
Asunto(s)
Carcinoma de Pulmón de Células no Pequeñas/radioterapia , Neoplasias Pulmonares/radioterapia , Derrame Pleural Maligno/etiología , Atelectasia Pulmonar/etiología , Dosificación Radioterapéutica , Contencion de la Respiración , Carcinoma de Pulmón de Células no Pequeñas/complicaciones , Carcinoma de Pulmón de Células no Pequeñas/diagnóstico por imagen , Humanos , Imagenología Tridimensional , Inhalación , Neoplasias Pulmonares/complicaciones , Neoplasias Pulmonares/diagnóstico por imagen , Fantasmas de Imagen , Respiración , Tomografía Computarizada por Rayos XRESUMEN
Interest in psychedelics is increasing due to the potential for improved mental health and quality of life. However, adverse effects on mental health are still a concern. Personality traits have been suggested to both influence the psychedelic experience and mental health, and even be changed by psychedelic use. The present study describes for the first time a national sample of Swedish psychedelic users (n = 400) compared to a sex and age-matched control-group of non-users (n = 400) regarding mental health variables (depression, insomnia, problematic alcohol and drug use, and dissociation) and personality (Big Five). Data was collected in an online survey including individuals from 16 years of age who had at least one psychedelic experience. The main results reported psychedelic users as less depressed (Patient Health Questionnaire-9; PHQ-9) (d = - 0.29) and having more use of drugs (Drug Use Disorders Identification Test; DUDIT) (d = 1.27). In the Big Five personality traits, openness differed notably (d = 1.72), and the between-group effects in PHQ-9 were explained by lower neuroticism. Our findings reveal that psychedelic users report less depression and higher drug use, and this is partly due to personality traits. These results have implications on how we view psychedelic users and the use of psychedelic drugs.
Asunto(s)
Depresión , Alucinógenos , Personalidad , Humanos , Masculino , Femenino , Alucinógenos/efectos adversos , Adulto , Personalidad/efectos de los fármacos , Depresión/tratamiento farmacológico , Depresión/inducido químicamente , Persona de Mediana Edad , Adulto Joven , Adolescente , Suecia , Trastornos Relacionados con Sustancias/psicología , Encuestas y Cuestionarios , Calidad de Vida , Salud MentalRESUMEN
BACKGROUND AND PURPOSE: The purpose of this study was to evaluate the performance of gantry angle optimisation (GAO) compared to equidistant beam geometry for two inverse treatment planning systems (TPSs) by utilising the information obtained from a range of treatment plans. MATERIAL AND METHODS: The comparison was based on treatment plans generated for four different head and neck (H&N) cancer cases using two inverse treatment planning systems (TPSs); Varian Eclipse™ representing dynamic MLC intensity modulated radiotherapy (IMRT) and Oncentra® Masterplan representing segmented MLC-based IMRT. The patient cases were selected on the criterion of representing different degrees of overlap between the planning target volume (PTV) and the investigated organ at risk, the ipsilateral parotid gland. For each case, a number of 'Pareto optimal' plans were generated in order to investigate the trade-off between the under-dosage to the PTV (V(PTV,D < 95%)) or the decrease in dose homogeneity (D(5)-D(95)) to the PTV as a function of the mean absorbed dose to the ipsilateral parotid gland (
Asunto(s)
Algoritmos , Neoplasias de Cabeza y Cuello/radioterapia , Traumatismos por Radiación/prevención & control , Planificación de la Radioterapia Asistida por Computador , Radioterapia de Intensidad Modulada , Relación Dosis-Respuesta en la Radiación , Humanos , PronósticoRESUMEN
Evidence is lacking on how to understand the reasons for variations, both in prevalence of ADHD and ADHD medication prescribing patterns in children and adolescents, within Region Skåne. These variations are not in line with current national clinical guidelines and seem to have increased over time. This qualitative interview study illuminates pediatric psychiatrists' attitudes toward ADHD and their experiences of prescribing ADHD medication. Eleven pediatric psychiatrists described the complex interplay of variables that they experienced while assessing a child, which had influence on their decision to prescribe medication. Being part of a local unit's culture influenced how ADHD medications were prescribed. They wished that the assessment of the child's symptoms was consistent with guidelines in every unit but noted that such alignment was not implemented. They pointed out that an ADHD diagnosis is dependent on the surrounding's motivation and capacity to adapt to the present state of the child. The participants described how they balanced clinical guidelines with demands from the family, as well as from society at large. Their personal attitudes and clinical experiences towards diagnosing and prescribing medications to children with ADHD influenced their decisions. The study adds information about how attitudes may lead to variation in diagnostics and therapy.
Asunto(s)
Trastorno por Déficit de Atención con Hiperactividad , Estimulantes del Sistema Nervioso Central , Psiquiatría , Adolescente , Humanos , Niño , Trastorno por Déficit de Atención con Hiperactividad/epidemiología , Prescripciones de Medicamentos , Estimulantes del Sistema Nervioso Central/uso terapéuticoRESUMEN
BACKGROUND AND PURPOSE: Online adaptive radiotherapy (oART) potentially reduces the dose to organs at risk (OARs) as the planning target volume (PTV) margins are reduced compared to a non-adaptive approach (non-ART). This study evaluates the feasibility and dosimetric impact of cone-beam computed tomography (CBCT)-guided oART of urinary bladder cancer for the first patients treated, using patient-specific margins. MATERIALS AND METHODS: Sixteen consecutive patients with muscle-invasive bladder cancer received two or more (median = 23) fractions as oART, and remaining fractions as non-ART. The non-ART fractions were delivered with standard population-based margins, while reduced patient-specific margins based on intra-fractional variations extracted from 2-4 fractions were applied to the primary PTV (PTV-T) during the oART fractions. Target volume and coverage, and dose to OARs were compared between non-ART and oART plans, and the oART procedure time was recorded. RESULTS: In total, 297/512 fractions were delivered as oART with full re-optimization to the anatomy of the day. The median (interquartile range, IQR) oART procedure time, measured from the end of CBCT generation to completion of plan review, and quality assurance was 13.9 (11.9;16.6) min. The median (IQR) volume reduction in PTV-T volume was 33.9 (24.2;45.0)%, comparing oART and non-ART plans, resulting in median (IQR) reductions in bowel bag V45Gy of 18.8 (12.7;27.9)% and rectum V50Gy of 70.7 (35.9;94.8)%. By re-optimizing the plan to the daily anatomy, full target coverage was achieved at all oART fractions. CONCLUSIONS: oART resulted in large reductions in treatment volumes and doses to OARs, compared to non-ART, while ensuring target coverage. This indicates potential reductions in gastrointestinal toxicity.
Asunto(s)
Radioterapia Guiada por Imagen , Radioterapia de Intensidad Modulada , Neoplasias de la Vejiga Urinaria , Tomografía Computarizada de Haz Cónico/métodos , Humanos , Órganos en Riesgo , Dosificación Radioterapéutica , Planificación de la Radioterapia Asistida por Computador/métodos , Radioterapia Guiada por Imagen/métodos , Radioterapia de Intensidad Modulada/métodos , Neoplasias de la Vejiga Urinaria/radioterapiaRESUMEN
Background and purpose: The Ethos system has enabled online adaptive radiotherapy (oART) by implementing an automated treatment planning system (aTPS) for both intensity-modulated radiotherapy (IMRT) and volumetric modulated arc radiotherapy (VMAT) plan creation. The purpose of this study is to evaluate the quality of aTPS plans in the pelvic region. Material and Methods: Sixty patients with anal (n = 20), rectal (n = 20) or prostate (n = 20) cancer were retrospectively re-planned with the aTPS. Three IMRT (7-, 9- and 12-field) and two VMAT (2 and 3 arc) automatically generated plans (APs) were created per patient. The duration of the automated plan generation was registered. The best IMRT-AP and VMAT-AP for each patient were selected based on target coverage and dose to organs at risk (OARs). The AP quality was analyzed and compared to corresponding clinically accepted and manually generated VMAT plans (MPs) using several clinically relevant dose metrics. Calculation-based pre-treatment plan quality assurance (QA) was performed for all plans. Results: The median total duration to generate the five APs with the aTPS was 55 min, 39 min and 35 min for anal, prostate and rectal plans, respectively. The target coverage and the OAR sparing were equivalent for IMRT-APs and VMAT-MPs, while VMAT-Aps.demonstrated lower target dose homogeneity and higher dose to some OARs. Both conformity and homogeneity index were equivalent (rectal) or better (anal and prostate) for IMRT-APs compared to VMAT-MPs. All plans passed the patient-specific QA tolerance limit. Conclusions: The aTPS generates plans comparable to MPs within a short time-frame which is highly relevant for oART treatments.
RESUMEN
PURPOSE: With the increased commercial availability of intensity modulated arc therapy (IMAT) comes the need for comprehensive QA programs, covering the different aspects of this newly available technology. This manuscript proposes such a program for the RapidArc (RA) (Varian Medical Systems, Palo Alto) IMAT solution. METHODS: The program was developed and tested out for a Millennium120 MLC on iX Clinacs and a HighDefinition MLC on a Novalis TX, using a variety of measurement equipment including Gafchromic film, 2D ion chamber arrays (Seven29 and StarCheck, PTW, Freiburg, Germany) with inclinometer and Octavius phantom, the Delta4 systam (ScandiDos, Uppsala, Sweden) and the portal imager (EPID). First, a number of complementary machine QA tests were developed to monitor the correct interplay between the accelerating/decelerating gantry, the variable dose rate and the MLC position, straining the delivery to the maximum allowed limits. Second, a systematic approach to the validation of the dose calculation for RA was adopted, starting with static gantry and RA specific static MLC shapes and gradually moving to dynamic gantry, dynamic MLC shapes. RA plans were then optimized on a series of artificial structures created within the homogeneous Octavius phantom and within a heterogeneous lung phantom. These served the double purpose of testing the behavior of the optimization algorithm (PRO) as well as the precision of the forward dose calculation. Finally, patient QA on a series of clinical cases was performed with different methods. In addition to the well established in-phantom QA, we evaluated the portal dosimetry solution within the Varian approach. RESULTS: For routine machine QA, the "Snooker Cue" test on the EPID proved to be the most sensitive to overall problem detection. It is also the most practical one. The "Twinkle" and "Sunrise" tests were useful to obtain well differentiated information on the individual treatment delivery components. The AAA8.9 dose calculations showed excellent agreement with all corresponding measurements, except in areas where the 2.5 mm fixed fluence resolution was insufficient to accurately model the tongue and groove effect or the dose through nearly closed opposing leafs. Such cases benefited from the increased fluence resolution in AAA10.0. In the clinical RA fields, these effects were smeared out spatially and the impact of the fluence resolution was considerably less pronounced. The RA plans on the artificial structure sets demonstrated some interesting characteristics of the PRO8.9 optimizer, such as a sometimes unexpected dependence on the collimator rotation and a suboptimal coverage of targets within lung tissue. Although the portal dosimetry was successfully validated, we are reluctant to use it as a sole means of patient QA as long as no gantry angle information is embedded. CONCLUSIONS: The all-in validation program allows a systematic approach in monitoring the different levels of RA treatments. With the systematic approach comes a better understanding of both the capabilities and the limits of the used solution. The program can be useful for implementation, but also for the validation of major upgrades.
Asunto(s)
Radioterapia de Intensidad Modulada/normas , Algoritmos , Humanos , Fantasmas de Imagen , Control de Calidad , Radiometría , Planificación de la Radioterapia Asistida por Computador , Reproducibilidad de los ResultadosRESUMEN
BACKGROUND AND PURPOSE: Studies have demonstrated the potential of online adaptive radiotherapy (oART). However, routine use has been limited due to resource demanding solutions. This study reports on experiences with oART in the pelvic region using a novel cone-beam computed tomography (CBCT)-based, artificial intelligence (AI)-driven solution. MATERIAL AND METHODS: Automated pre-treatment planning for thirty-nine pelvic cases (bladder, rectum, anal, and prostate), and one hundred oART simulations were conducted in a pre-clinical release of Ethos (Varian Medical Systems, Palo Alto, CA). Plan quality, AI-segmentation accuracy, oART feasibility and an integrated calculation-based quality assurance solution were evaluated. Experiences from the first five clinical oART patients (three bladder, one rectum and one sarcoma) are reported. RESULTS: Auto-generated pre-treatment plans demonstrated similar planning target volume (PTV) coverage and organs at risk doses, compared to institution reference. More than 75% of AI-segmentations during simulated oART required none or minor editing and the adapted plan was superior in 88% of cases. Limitations in AI-segmentation correlated to cases where AI model training was lacking. The five first treated patients complied well with the median adaptive procedure duration of 17.6 min (from CBCT acceptance to treatment delivery start). The treated bladder patients demonstrated a 42% median primary PTV reduction, indicating a 24%-30% reduction in V45Gy to the bowel cavity, compared to non-ART. CONCLUSIONS: A novel commercial oART solution was demonstrated feasible for various pelvic sites. Clinically acceptable AI-segmentation and auto-planning enabled adaptation within reasonable timeslots. Possibilities for reduced PTVs observed for bladder cancer indicated potential for toxicity reductions.
RESUMEN
PURPOSE: The aim of this study is to evaluate the patient setup accuracy by investigating the impact of different types of CBCT matches, performed with 3 (translations only) or 6 (including rotations) degrees-of-freedom (DOF). The purpose is also to calculate and compare CTV to PTV margins based on the various CBCT matches, setups using 2D kV planar imaging or setups using skin markers only (non-IGRT). MATERIAL AND METHODS: Setup images from 16 NSCLC patients with weekly CBCT and daily 2D kV planar imaging were analyzed retrospectively. The CBCT matches were based on the columna vertebralis (CV), the whole thorax (WT) and the soft tissue (ST) delineated GTV, where the ST match was chosen as reference. Thus the translational and rotational shifts in three dimensions were assessed. Finally, setup margins were calculated using van Herk's margin recipe. RESULTS: For 80% of the investigated 3 DOF/2D kV CV setups, the translational shifts were within [-3, 2] mm for all three directions. Corresponding values for the 6 DOF/non-IGRT CV and the 6 DOF/non-IGRT ST matches were [-5, 8] mm. Furthermore, 80% of all setups were within ± 2° for pitch-, roll- and yaw-rotations, and none exceeded 5°. The calculated margins for non-IGRT, about 10 mm, were reduced to approximately 4 mm, regardless of using IGRT setup by CBCT or 2D kV imaging on CV. However, if using WT CBCT setup, the margin in LNG direction was slightly larger, approximately 6 mm. CONCLUSION: IGRT for NSCLC is an essential tool for margin reduction, since patient setups based on IGRT leads to approximately half the margin sizes compared to non-IGRT setups. Both CBCT and 2D kV planar imaging yields approximately the same margins for CV/ST matches. The magnitudes of the patient rotations were <5°.
Asunto(s)
Carcinoma de Pulmón de Células no Pequeñas/diagnóstico por imagen , Tomografía Computarizada de Haz Cónico/métodos , Neoplasias Pulmonares/diagnóstico por imagen , Planificación de la Radioterapia Asistida por Computador/métodos , Columna Vertebral/diagnóstico por imagen , Carga Tumoral/fisiología , Carcinoma de Pulmón de Células no Pequeñas/patología , Carcinoma de Pulmón de Células no Pequeñas/radioterapia , Tomografía Computarizada de Haz Cónico/normas , Humanos , Neoplasias Pulmonares/patología , Neoplasias Pulmonares/radioterapia , Análisis por Apareamiento , Fantasmas de Imagen , Interpretación de Imagen Radiográfica Asistida por Computador/métodos , Interpretación de Imagen Radiográfica Asistida por Computador/normas , Radiografía Torácica/métodos , Radiografía Torácica/normas , Planificación de la Radioterapia Asistida por Computador/instrumentación , Planificación de la Radioterapia Asistida por Computador/normas , Valores de Referencia , Reproducibilidad de los Resultados , Estudios Retrospectivos , Tórax/fisiologíaRESUMEN
The flexibility in radiotherapy can be improved if a patient can be moved between any one of the department's medical linear accelerators without the need to change anything in the patient's treatment plan. For this to be possible, the dosimetric characteristics of the various accelerators must be the same, or nearly the same i.e. the accelerators must be beam-matched. During a period of nine months, eight Varian iX accelerators with 6 and 15 MV photon beams and 6-18 MeV electron beams (only four of the eight) were installed at our clinic. All accelerators fulfilled the vendor-defined "fine beam-match" criteria, and a more extensive set of measurements was carried out during commissioning. The measured absorbed dose data for each accelerator were compared with the first accelerator, chosen as reference, and the TPS calculations. Two of the eight accelerators showed a larger discrepancy for the 15 MV beam not revealed by the vendor-defined acceptance criteria, whereas the other six accelerators were satisfactorily matched. The beam-matching acceptance criteria defined by the vendor are not strict enough to guarantee optimal beam-match. Deviations related to dose calculations and to beam-matched accelerators may add up. The safest and most practical way to ensure that all accelerators are within clinical acceptable accuracy is to include TPS calculations in the evaluation. Further, comparisons between measurements and calculations should be done in absolute dose terms.
Asunto(s)
Aceleradores de Partículas/instrumentación , Fenómenos Físicos , Planificación de la Radioterapia Asistida por Computador/métodos , Radioterapia de Intensidad Modulada/instrumentación , Calibración , Formación de Concepto , Eficiencia , Electrones/uso terapéutico , Diseño de Equipo , Humanos , Fotones/uso terapéutico , Dosis de Radiación , Dosificación Radioterapéutica , Planificación de la Radioterapia Asistida por Computador/instrumentación , Radioterapia de Intensidad Modulada/métodos , Sensibilidad y EspecificidadRESUMEN
Pareto optimality is a concept that formalises the trade-off between a given set of mutually contradicting objectives. A solution is said to be Pareto optimal when it is not possible to improve one objective without deteriorating at least one of the other. A set of Pareto optimal solutions constitute the Pareto front. The Pareto concept applies well to the inverse planning process, which involves inherently contradictory objectives, high and uniform target dose on one hand, and sparing of surrounding tissue and nearby organs at risk (OAR) on the other. Due to the specific characteristics of a treatment planning system (TPS), treatment strategy or delivery technique, Pareto fronts for a given case are likely to differ. The aim of this study was to investigate the feasibility of using Pareto fronts as a comparative tool for TPSs, treatment strategies and delivery techniques. In order to sample Pareto fronts, multiple treatment plans with varying target conformity and dose sparing of OAR were created for a number of prostate and head & neck IMRT cases. The DVHs of each plan were evaluated with respect to target coverage and dose to relevant OAR. Pareto fronts were successfully created for all studied cases. The results did indeed follow the definition of the Pareto concept, i.e. dose sparing of the OAR could not be improved without target coverage being impaired or vice versa. Furthermore, various treatment techniques resulted in distinguished and well separated Pareto fronts. Pareto fronts may be used to evaluate a number of parameters within radiotherapy. Examples are TPS optimization algorithms, the variation between accelerators or delivery techniques and the degradation of a plan during the treatment planning process. The issue of designing a model for unbiased comparison of parameters with such large inherent discrepancies, e.g. different TPSs, is problematic and should be carefully considered.
Asunto(s)
Algoritmos , Planificación de la Radioterapia Asistida por Computador/métodos , Calibración , Estudios de Factibilidad , Neoplasias de Cabeza y Cuello/radioterapia , Humanos , Masculino , Fotones/uso terapéutico , Neoplasias de la Próstata/patología , Neoplasias de la Próstata/radioterapia , Dosificación Radioterapéutica , Planificación de la Radioterapia Asistida por Computador/instrumentación , Radioterapia Conformacional/métodos , Recto/patología , Recto/efectos de la radiación , Dispersión de RadiaciónAsunto(s)
Tomografía Computarizada de Haz Cónico , Procesamiento de Imagen Asistido por Computador , Neoplasias Pélvicas/diagnóstico por imagen , Neoplasias Pélvicas/radioterapia , Radioterapia Asistida por Computador , Radioterapia Guiada por Imagen , Humanos , Interpretación de Imagen Asistida por Computador , Fantasmas de Imagen , Intensificación de Imagen Radiográfica , Estudios Retrospectivos , Tomografía Computarizada por Rayos X , Percepción VisualRESUMEN
BACKGROUND AND PURPOSE: Three cone-beam computed tomography (CBCT) registration strategies combined with deep-inspiration breath-hold (DIBH) and free-breathing (FB) were explored, in terms of obtaining the smallest planning target volume (PTV). MATERIAL AND METHODS: CBCT images were acquired pre- and post-treatment in FB and DIBH, for 17 locally advanced lung cancer patients. Bony registration on the spine, and soft-tissue registrations on the primary gross tumor volume (GTV-T) and GTV-Total, including malignant lymph nodes (GTV-N), were retrospectively analyzed. Setup-margins and resulting PTVs were calculated. RESULTS: For the spine, the smallest residual misalignments were observed in FB, independently of registration method. For GTV-T and GTV-N, soft-tissue registrations were superior to bony registration, independently of FB or DIBH. Compared to FB, PTV-Totals were during DIBH reduced by 13% and 8% for the soft-tissue and bony registrations, respectively. If intra-fractional motion was included, the corresponding gain of DIBH was reduced to 9% and 7%, respectively. Superiority of DIBH was mainly due to larger clinical target volumes in FB. CONCLUSIONS: Despite larger setup uncertainties compared to FB, DIBH resulted in smaller PTV-Totals for all registration methods. Soft-tissue registrations were superior to bony registration, independently of FB and DIBH. During DIBH, undesirable arching of the back was identified. Daily CBCT pre-treatment target verification is advised.
Asunto(s)
Contencion de la Respiración , Tomografía Computarizada de Haz Cónico/métodos , Neoplasias Pulmonares/radioterapia , Humanos , Neoplasias Pulmonares/diagnóstico por imagen , Neoplasias Pulmonares/patología , Carga Tumoral , IncertidumbreRESUMEN
PURPOSE: To find the tube voltage that results in the highest image quality per effective dose unit for chest and pelvis radiography, respectively, using image plates. METHODS: Two anthropomorphic phantoms (chest and pelvis) were imaged with several different tube voltages. The mA s settings were chosen so that the effective dose to the phantom was the same, regardless of the tube voltage, for the two examinations, respectively. The quality of the images was evaluated by six experienced radiologists using visual grading analysis. RESULTS: For both the chest and the pelvis examinations, the image quality increased when the tube voltage was reduced compared with the standard settings (125 and 70 kV for chest and pelvis, respectively), which were used for screen-film radiography previously. CONCLUSIONS: The image quality of image plate radiography can be increased by lowering the tube voltage compared with the one that was used for screen-film radiography.
Asunto(s)
Procesamiento de Imagen Asistido por Computador/métodos , Interpretación de Imagen Radiográfica Asistida por Computador/métodos , Radiografía Abdominal/métodos , Radiografía Torácica/métodos , Pantallas Intensificadoras de Rayos X , Humanos , Modelos Estadísticos , Fantasmas de Imagen , Dosis de Radiación , Intensificación de Imagen Radiográfica , Radiografía , Radiografía Abdominal/instrumentación , Radiografía Torácica/instrumentación , Radiometría/métodos , Factores de TiempoRESUMEN
Aims. Evaluation of bariatric surgery as secondary prevention in obese patients with ischemic heart disease (IHD). Methods. Analysis of data from 4047 subjects in the Swedish Obese Subjects (SOSs) study. Thirty-five patients with IHD are treated with bariatric surgery (n = 21) or conventional treatment (n = 14). Mean follow-up is 10.8 years. Results. Bariatric surgery resulted in sustained weight loss during the study period. After 2 years, the surgery group displayed significant reductions in cardiovascular risk factors, relief from cardiorespiratory symptoms, increments in physical activity, and improved quality of life. After 10 years, recovery from hypertension, diabetes, physical inactivity, and depression was still more common in the surgery group. There were no signs of increased cardiovascular morbidity or mortality in the surgery group. Conclusion. Bariatric surgery appears to be a safe and feasible treatment to achieve long-term weight loss and improvement in cardiovascular risk factors, symptoms, and quality of life in obese subjects with IHD.