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Dose/volume-response relations for rectal morbidity using planned and simulated motion-inclusive dose distributions.

ABSTRACT: Many dose-limiting normal tissues in radiotherapy (RT) display considerable internal motion between fractions over a course of treatment, potentially reducing the appropriateness of using planned dose distributions to predict morbidity. Accounting explicitly for rectal motion could improve the predictive power of modelling rectal morbidity. To test this, we simulated the effect of motion in two cohorts.The included patients (232 and 159 cases) received RT for prostate cancer to 70 and 74 Gy. Motion-inclusive dose distributions were introduced as simulations of random or systematic motion to the planned dose distributions. Six rectal morbidity endpoints were analysed. A probit model using the QUANTEC recommended parameters was also applied to the cohorts.The differences in associations using the planned over the motion-inclusive dose distributions were modest. Statistically significant associations were obtained with four of the endpoints, mainly at high doses (55-70 Gy), using both the planned and the motion-inclusive dose distributions, primarily when simulating random motion. The strongest associations were observed for GI toxicity and rectal bleeding (Rs=0.12-0.21; Rs=0.11-0.20). Applying the probit model, significant associations were found for tenesmus and rectal bleeding (Rs=0.13, p=0.02).Equally strong associations with rectal morbidity were observed at high doses (>55 Gy), for the planned and the simulated dose distributions including in particular random rectal motion. Future studies should explore patient-specific descriptions of rectal motion to achieve improved predictive power.

SUBMITTER: Thor M

PROVIDER: S-EPMC4765373 | biostudies-literature | 2013 Dec

REPOSITORIES: biostudies-literature

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Dose/volume-response relations for rectal morbidity using planned and simulated motion-inclusive dose distributions.

Thor Maria M Apte Aditya A Deasy Joseph O JO Karlsdóttir Àsa À Moiseenko Vitali V Liu Mitchell M Muren Ludvig Paul LP

Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology 20131111 3

<h4>Background and purpose</h4>Many dose-limiting normal tissues in radiotherapy (RT) display considerable internal motion between fractions over a course of treatment, potentially reducing the appropriateness of using planned dose distributions to predict morbidity. Accounting explicitly for rectal motion could improve the predictive power of modelling rectal morbidity. To test this, we simulated the effect of motion in two cohorts.<h4>Materials and methods</h4>The included patients (232 and 15 ...[more]

PMID: 24231236

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Project description:Internal organ motion over a course of radiotherapy (RT) leads to uncertainties in the actual delivered dose distributions. In studies predicting RT morbidity, the single estimate of the delivered dose provided by the treatment planning computed tomography (pCT) is typically assumed to be representative of the dose distribution throughout the course of RT. In this paper, a simple model for describing organ motion is introduced, and is associated to late rectal morbidity data, with the aim of improving morbidity prediction.Organ motion was described by normally distributed translational motion, with its magnitude characterised by the standard deviation (SD) of this distribution. Simulations of both isotropic and anisotropic (anterior-posterior only) motion patterns were performed, as were random, systematic or combined random and systematic motion. The associations between late rectal morbidity and motion-inclusive delivered dose-volume histograms (dDVHs) were quantified using Spearman's rank correlation coefficient (Rs) in a series of 232 prostate cancer patients, and were compared to the associations obtained with the static/planned DVH (pDVH).For both isotropic and anisotropic motion, different associations with rectal morbidity were seen with the dDVHs relative to the pDVHs. The differences were most pronounced in the mid-dose region (40-60 Gy). The associations were dependent on the applied motion patterns, with the strongest association with morbidity obtained by applying random motion with an SD in the range 0.2-0.8 cm.In this study we have introduced a simple model for describing organ motion occurring during RT. Differing and, for some cases, stronger dose-volume dependencies were found between the motion-inclusive dose distributions and rectal morbidity as compared to the associations with the planned dose distributions. This indicates that rectal organ motion during RT influences the efforts to model the risk of morbidity using planning distributions alone.

Project description:Delineation of treatment volumes is a major source of uncertainties in radiotherapy (RT). This is also true for rectal cancer patients undergoing neoadjuvant RT, with a potential impact on treatment quality. We investigated the role of the digital platform Anatom-e (Anatom-e Information Sytems Ltd., Houston, Texas) in increasing the compliance to follow a specific treatment protocol in a multicentric setting.Two clinical cases of locally advanced rectal cancer were chosen. Participants were instructed to follow the 2009 Radiation Therapy Oncology Group consensus atlas and asked to manually segment clinical target volumes (CTVs), for both patient 1 and 2, on day 1 with and without the use of Anatom-e. After one week (day 2), the same radiation oncologist contoured again, with and without Anatom-e, the same CT series. Intraobserver (Intra-OV) and interobserver (Inter-OV) variability were evaluated with the Dice similarity coefficient (DSC), the Hausdorff distance (HD) and mean distance to agreement (MDA).For clinical case 1, no significant difference was found for Intra-OV and Inter-OV. For clinical case 2, no significant difference was found for Intra-OV but a statistically significant difference was found for Inter-OV in DSC when using or not the platform. Mean DCS was 0.65 (SD: ±0.64; range: 0.58-0.79) for day 1 vs reference volume without Anatom-e and 0.72 (SD: ±0.39; range: 0.67-0.77) (p?=?0.03) with it. Mean MDA was lower with Anatom-e (3.61; SD: ±1.33; range: 2.85-4.78) than without (4.14; SD: ±2.97; range: 2.18-5.21), with no statistical significance (p?=?0.21) The use of Anatom-e decreased the SD from 2.97 to 1.33. Mean HD was lower with Anatom-e (26.06; SD: ±2.05; range: 24.08-32.62), with no statistical significance (p?=?0.14) compared to that without (31.39; SD: ±1.31; range: 26.14-48.72).The use of Anatom-e decreased the Inter-OV in the CTV delineation process for locally advanced rectal cancer with complex disease presentation planned for neoadjuvant RT. This system may be potentially helpful in increasing the compliance to follow shared guidelines and protocols.

Project description:BackgroundAlthough consensus guidelines on the management of cardiovascular disease in pregnancy reserve cesarean delivery for obstetric indications, there is a paucity of data to support this approach.ObjectiveThe objective of the study was to compare cardiovascular and obstetric morbidity in women with cardiovascular disease according to the plan for vaginal birth or cesarean delivery.Study designWe assembled a prospective cohort of women delivering at an academic tertiary care center with a protocolized multidisciplinary approach to management of cardiovascular disease between September 2011 and December 2016. Our practice is to encourage vaginal birth in women with cardiovascular disease unless there is an obstetric indication for cesarean delivery. We allow women attempting vaginal birth a trial of Valsalva in the second stage with the ability to provide operative vaginal delivery if pushing leads to changes in hemodynamics or symptoms. Women were classified according to planned mode of delivery: either vaginal birth or cesarean delivery. We then used univariate analysis to compare adverse outcomes according to planned mode of delivery. The primary composite cardiac outcome of interest included sustained arrhythmia, heart failure, cardiac arrest, cerebral vascular accident, need for cardiac surgery or intervention, or death. Secondary obstetric and neonatal outcomes were also considered.ResultsWe included 276 consenting women with congenital heart disease (68.5%), arrhythmias (11.2%), connective tissue disease (9.1%), cardiomyopathy (8.0%), valvular disease (1.4%), or vascular heart disease (1.8%) at or beyond 24 weeks' gestation. Seventy-six percent (n = 210) planned vaginal birth and 24% (n = 66) planned cesarean delivery. Women planning vaginal birth had lower rates of left ventricular outflow tract obstruction, multiparity, and preterm delivery. All women attempting vaginal birth were allowed Valsalva. Among planned vaginal deliveries 86.2% (n = 181) were successful, with a 9.5% operative vaginal delivery rate. Five women underwent operative vaginal delivery for the indication of cardiovascular disease without another obstetric indication at the discretion of the delivering provider. Four of these patients tolerated trials of Valsalva ranging from 15 to 75 minutes prior to delivery. Adverse cardiac outcomes were similar between planned vaginal birth and cesarean delivery groups (4.3% vs 3.0%, P = 1.00). Rates of postpartum hemorrhage (1.9% vs 10.6%, P < .01) and transfusion (1.9% vs 9.1%, P = .01) were lower in the planned vaginal birth group. There were no differences in adverse cardiac, obstetric, or neonatal outcomes in the cohort overall or the subset of women with high-risk cardiovascular disease or a high burden of obstetric comorbidity.ConclusionThese findings suggest that cesarean delivery does not reduce adverse cardiovascular outcomes and lend support to a planned vaginal birth for the majority of women with cardiovascular disease including those with high-risk disease.

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Dose/volume-response relations for rectal morbidity using planned and simulated motion-inclusive dose distributions.

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Dose/volume-response relations for rectal morbidity using planned and simulated motion-inclusive dose distributions.

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