Dataset Information

Modeling positioning uncertainties of prostate cancer external beam radiation therapy using pre-treatment data.

ABSTRACT: To investigate the influence of treatment plan data and image guidance (IG) on positioning uncertainty during prostate cancer (PCa) radiotherapy (RT).Body mass index (BMI), planning target volume (PTV), bladder volume (BV), and rectal cross section area (RCS) were collected for 267 consecutive PCa patients undergoing daily IGRT. Radiographic isocenter corrections to intra-prostatic fiducials for 12,490 treatment fractions were used to derive random (RE) and systematic (SE) inter-fraction uncertainties for the cardinal axes. These data were used to simulate RE and SE for weekly IG and Action Level (AL)-IG treatment protocols.SE and RE were 2-5 and 3-4mm in the cardinal axes, respectively, during simulation of no IG. Without IG, positive correlations (p<0.01) were noted for (1) anterior-posterior RE vs. RCS and BV and (2) cranio-caudal RE vs. RCS, BV and BMI. The RE increase was 3mm for the highest quartile of RCS, BV and BMI. Daily IGRT eliminated this relationship. 3D IG corrections of 1cm or more occured in 27% of treatment fractions and in 97% of patients.PCa patients with elevated pre-treatment BV, RCS and BMI have increased inter-fractionation positioning uncertainty and appear the primary candidates for daily IGRT.

SUBMITTER: Munck af Rosenschold P

PROVIDER: S-EPMC4822486 | biostudies-literature | 2014 Feb

REPOSITORIES: biostudies-literature

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Modeling positioning uncertainties of prostate cancer external beam radiation therapy using pre-treatment data.

Munck af Rosenschöld Per P Desai Neil B NB Oh Jung Hun JH Apte Aditya A Hunt Margie M Kalikstein Abraham A Mechalakos James J Happersett Laura L Deasy Joseph O JO Zelefsky Michael J MJ

Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology 20140220 2

<h4>Purpose</h4>To investigate the influence of treatment plan data and image guidance (IG) on positioning uncertainty during prostate cancer (PCa) radiotherapy (RT).<h4>Methods</h4>Body mass index (BMI), planning target volume (PTV), bladder volume (BV), and rectal cross section area (RCS) were collected for 267 consecutive PCa patients undergoing daily IGRT. Radiographic isocenter corrections to intra-prostatic fiducials for 12,490 treatment fractions were used to derive random (RE) and system ...[more]

PMID: 24560753

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Project description:PurposeTo compare patient-reported disease-specific functional outcomes after external beam radiation therapy (EBRT) and EBRT combined with low-dose-rate brachytherapy prostate boost (EB-LDR) among men with localized prostate cancer.Methods and materialsThe prospective, population-based Comparative Effectiveness Analysis of Surgery and Radiation study enrolled men with localized prostate cancer in 2011 to 2012. The 26-item Expanded Prostate Cancer Index Composite measured patient-reported disease-specific function at baseline and at 6, 12, and 36 months. Higher domain scores indicate better function. Minimal clinically important difference was defined as 6 for urinary incontinence, 5 for urinary irritative function, 4 for bowel function, 12 for sexual function, and 4 for hormonal function. Multivariable linear and logistic regression models were fit to estimate the effect of treatment on patient-reported outcomes.ResultsFive-hundred seventy-eight men received EBRT and 109 received EB-LDR. Median patient age was 69 years, and 70% had intermediate- or high-risk disease. Men in the EB-LDR group were younger (P < .001) and less likely to receive androgen deprivation therapy (P < .001). Baseline urinary, bowel, sexual, and hormonal function was similar between treatment groups (P > .05). On multivariable analyses, men receiving EB-LDR reported worse urinary irritative function at 6 months (adjusted mean difference [AMD] -14.4, P < .001), 12 months (AMD -12.9, P < .001), and 36 months (AMD -4.7, P = .034) than men receiving EBRT. At 12 months, men receiving EB-LDR reported worse bowel function (AMD -5.8, P = .002), but these differences were not seen at 36 months. There were no significant differences in sexual or hormone function between treatment groups.ConclusionsMen treated with EB-LDR report worse bowel function at 1 year and worse urinary irritative function through 3 years compared with men treated with EBRT alone. These side effect profiles should be discussed with patients when considering EB-LDR versus EBRT treatment.

Project description:PurposeBeam angle optimization is a critical issue for modern radiotherapy (RT) and is a challenging task, especially for large body sizes and noncoplanar designs. Noncoplanar RT techniques may have dosimetric advantages but increase the risk of mechanical collision. We propose a software solution to accurately predict colliding/noncolliding configurations for coplanar and noncoplanar beams.Materials and methodsIndividualized software models for two different linear accelerators were built to simulate noncolliding gantry orientations for phantom/patient subjects. The sizes and shapes of the accelerators were delineated based on their manuals and on-site measurements. The external surfaces of the subjects were automatically contoured based on computed tomography (CT) simulations. An Alderson Radiation Therapy phantom was used to predict the accuracy of spatial collision prediction by the software. A gantry collision problem encountered by one patient during initial setup was also used to test the validity of the software. Results: In the comparison between the software estimates and on-site measurements, the noncoplanar collision angles were all predicted within a 5-degree difference in gantry position. The confusion matrix was calculated for each of the two empty accelerator models, and the accuracies were 98.7% and 97.3%. The true positive rates were 97.7% and 96.9%, while the true negative rates were 99.8% and 97.9%, respectively. For the phantom study, the collision angles were predicted within a 5-degree difference. The software successfully predicted the collision problem encountered by the breast cancer patient in the initial setup position and generated shifted coordinates that were validated to correspond to a noncolliding geometry.ConclusionThe developed software effectively and accurately predicted collisions for accelerator-only, phantom, and patient setups. This software may help prevent collisions and expand the range of spatially applicable beam angles.

Dataset Information

Modeling positioning uncertainties of prostate cancer external beam radiation therapy using pre-treatment data.

Publications

Modeling positioning uncertainties of prostate cancer external beam radiation therapy using pre-treatment data.

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