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Assessment of the modulation degrees of intensity-modulated radiation therapy plans.

ABSTRACT: BACKGROUND:To evaluate the modulation indices (MIs) for predicting the plan delivery accuracies of intensity-modulated radiation therapy (IMRT) plans. METHODS:A total of 100 dynamic IMRT plans that used TrueBeam STx and 102 dynamic IMRT plans that used Trilogy were selected. For each plan, various MIs were calculated, which included the modulation complexity score (MCS), plan-averaged beam area (PA), plan-averaged beam irregularity (PI), plan-averaged beam modulation (PM), MI quantifying multi-leaf collimator (MLC) speeds (MIs), MI quantifying MLC acceleration (MIa), and MI quantifying MLC acceleration and segment aperture irregularity (MIc,IMRT). To determine plan delivery accuracy, global gamma passing rates, MLC errors of log files, and dose-volumetric parameter differences between original and log file-reconstructed IMRT plans were obtained. To assess the ability of each MI for predicting plan delivery accuracy, Spearman's rank correlation coefficients (rs) between MIs and plan delivery accuracy measures were calculated. RESULTS:PI showed moderately strong correlations with gamma passing rates in MapCHECK2 measurements of both TrueBeam STx and Trilogy (rs?=?-?0.591 with p?

SUBMITTER: Park SY

PROVIDER: S-EPMC6293636 | biostudies-literature | 2018 Dec

REPOSITORIES: biostudies-literature

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Assessment of the modulation degrees of intensity-modulated radiation therapy plans.

Park So-Yeon SY Kim Jung-In JI Chun Minsoo M Ahn Hyunjun H Park Jong Min JM

Radiation oncology (London, England) 20181213 1

<h4>Background</h4>To evaluate the modulation indices (MIs) for predicting the plan delivery accuracies of intensity-modulated radiation therapy (IMRT) plans.<h4>Methods</h4>A total of 100 dynamic IMRT plans that used TrueBeam STx and 102 dynamic IMRT plans that used Trilogy were selected. For each plan, various MIs were calculated, which included the modulation complexity score (MCS), plan-averaged beam area (PA), plan-averaged beam irregularity (PI), plan-averaged beam modulation (PM), MI quan ...[more]

PMID: 30545396

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Project description:Purpose:To evaluate 2 published normal tissue complication probability models for radiation-induced hypothyroidism (RHT) on a large cohort of oropharyngeal carcinoma (OPC) patients who were treated with intensity-modulated radiation therapy (IMRT). Methods and Materials:OPC patients treated with retrievable IMRT Digital Imaging and Communications in Medicine (DICOMs) data and available baseline and follow-up thyroid function tests were included. Mean dose (Dmean) to the thyroid gland (TG) and its volume were calculated. The study outcome was clinical HT at least 6 months after radiation therapy, which was defined as grade ?2 HT per Common Terminology Criteria for Adverse Events grading system (symptomatic hypothyroidism that required thyroid replacement therapy). Regression analyses and Wilcoxon rank-sum test were used. Receiver operating characteristic curves and area under the curve for the fitted model were calculated. Results:In the study, 360 OPC patients were included. The median age was 58 years. Most tumors (51%) originated from the base of tongue. IMRT-split field was used in 95%, and median radiation therapy dose was 69.96 Gy. In the study, 233 patients (65%) developed clinical RHT that required thyroid replacement therapy. On multivariate analysis higher Dmean and smaller TG volume maintained the statistically significant association with the risk of clinical RHT (P < .0001). Dmean was significantly higher in patients with clinical RHT versus those without (50 vs 42 Gy, P < .0001). Patients with RHT had smaller TG volume compared with those without (11.8 compared with 12.8 mL, P < .0001). AUC of 0.72 and 0.66 were identified for fitted model versus for the applied Boomsma et al and Cella et al models, respectively. Conclusions:Volume and Dmean of the TG are important predictors of clinical RHT and shall be integrated into normal tissue complication probability models for RHT. Dmean and thyroid volume should be considered during the IMRT plan optimization in OPC patients.

Project description:PurposeTo compare long-term outcomes and late toxicity between patients treated with 3-dimensional conformal radiation therapy (3D-CRT) and with dose-escalated intensity modulated radiation therapy (IMRT) as salvage radiation therapy (SRT) after prostatectomy.Methods and materialsA total of 110 patients who had been treated at our institution between 2010 and 2018 with SRT for biochemical recurrence after radical prostatectomy were included. The patients were treated either by 3D-CRT with 64 Gy (59 patients) or by IMRT with 70 Gy (51 patients). The irradiation target was the prostate bed only (106 patients) or the prostate bed and pelvic region (4 patients). Twelve patients (11%) received concurrent androgen deprivation therapy. The differences in clinical outcomes and late gastrointestinal (GI) and genitourinary (GU) toxicity between the 3D-CRT and IMRT groups were retrospectively assessed. Toxicities were recorded using the Common Terminology Criteria for Adverse Events, version 5.0. Prostate-specific antigen (PSA) progression after SRT was defined as an increase in the serum PSA level of 0.2 ng/mL from the PSA nadir after SRT and confirmed by a second PSA measurement that was higher than the first.ResultsThe median follow-up time was 7.8 years for 3D-CRT (range:,0.3-9.2 years) and 3.1 years for IMRT (range, 0.4-7.2 years). There was no significant difference in the 4-year biochemical no-evidence-of-disease (bNED) rate between the 3D-CRT and IMRT groups (43.5% vs 52.1%; P = .20). Toxicity analysis showed no significant difference in late GI or GU toxicities of grade 2 or greater between the 3D-CRT and IMRT groups. The respective 4-year cumulative rates of toxicity in the 3D-CRT and IMRT groups were as follows: grade ≥2 GI toxicity, 8.8% and 4.4% (P = .42); grade ≥2 GU toxicity, 19.1% and 20.3% (P = .93); and grade ≥2 hematuria, 5.3% and 8.0% (P = .67). In the 3D-CRT group, the 8-year cumulative rates of GI toxicity, GU toxicity, and hematuria of grade 2 or greater were 8.8%, 28.4%, and 12.6%, respectively.ConclusionsDose-escalated IMRT showed no improvements in bNED or late toxicity compared with 3D-CRT. In addition, the results suggest that GU toxicity can occur after a long period (even after 6 years), whereas GI toxicity is seldom newly observed after 4 years.

Project description:Purpose:Intensity modulated proton beam radiation therapy (IMPT) has a clinically significant dosimetric advantage over intensity modulated photon radiation therapy (IMRT) for the treatment of patients with esophageal cancer, particularly for sparing the heart and lungs. We compared acute radiation therapy-related toxicities and short-term clinical outcomes of patients with esophageal cancer who received treatment with IMPT or IMRT. Methods and Materials:We retrospectively reviewed the electronic health records of consecutive adult patients with esophageal cancer who underwent concurrent chemoradiotherapy with IMPT or IMRT in the definitive or neoadjuvant setting from January 1, 2014, through June 30, 2018, with additional follow-up data collected through January 31, 2019. Treatment-related toxicities were evaluated per the Common Terminology Criteria for Adverse Events, version 4. Survival outcomes were estimated with the Kaplan-Meier method. Results:A total of 64 patients (32 per group) were included (median follow-up time: 10 months for IMPT patients vs 14 months for IMRT patients). The most common radiation therapy regimen was 45 Gy in 25 fractions, and 80% of patients received a simultaneous integrated boost to a median cumulative dose of 50 Gy. Similar numbers of IMPT patients (n = 15; 47%) and IMRT patients (n = 18; 56%) underwent surgery (P = .07), with no difference in pathologic complete response rates (IMPT: n = 5; 33% vs IMRT: n = 7; 39%; P = .14). At 1 year, the clinical outcomes also were similar for IMPT and IMRT patients, respectively. Local control was 92% versus 84% (P = .87), locoregional control 92% versus 80% (P = .76), distant metastasis-free survival 87% versus 65% (P = .08), progression-free survival 71% versus 45% (P = .15), and overall survival 74% versus 71% (P = .62). The rate of acute treatment-related grade 3 toxicity was similar between the groups (P = .71). Conclusions:In our early experience, IMPT is a safe and effective treatment when administered as part of definitive or trimodality therapy. Longer follow-up is required to evaluate the effectiveness of IMPT.

Project description:ImportancePatients with nonmetastatic nasopharyngeal carcinoma (NPC) are primarily treated by radiotherapy with curative intent with or without chemotherapy and often experience substantial treatment-related toxic effects even with modern radiation techniques, such as intensity-modulated radiation therapy (IMRT). Intensity-modulated proton therapy (IMPT) may improve the toxicity profile; however, there is a paucity of data given the limited availability of IMPT in regions with endemic NPC.ObjectiveTo compare toxic effects and oncologic outcomes among patients with newly diagnosed nonmetastatic NPC when treated with IMPT vs IMRT with or without chemotherapy.Design, setting, and participantsThis retrospective cohort study included 77 patients with newly diagnosed nonmetastatic NPC who received curative-intent radiotherapy with IMPT or IMRT at a tertiary academic cancer center from January 1, 2016, to December 31, 2019. Forty-eight patients with Epstein-Barr virus (EBV)-positive tumors were included in a 1:1 propensity score-matched analysis for survival outcomes. The end of the follow-up period was March 31, 2021.ExposuresIMPT vs IMRT with or without chemotherapy.Main outcomes and measuresThe main outcomes were the incidence of acute and chronic treatment-related adverse events (AEs) and oncologic outcomes, including locoregional failure-free survival (LRFS), progression-free survival (PFS), and overall survival (OS).ResultsWe identified 77 patients (25 [32.5%] women; 52 [67.5%] men; median [interquartile range] age, 48.7 [42.2-60.3] years), among whom 28 (36.4%) were treated with IMPT and 49 (63.6%) were treated with IMRT. Median (interquartile range) follow-up was 30.3 (17.9-41.5) months. On multivariable logistic regression analyses, IMPT was associated with lower likelihood of developing grade 2 or higher acute AEs compared with IMRT (odds ratio [OR], 0.15; 95% CI, 0.03-0.60; P = .01). Only 1 case (3.8%) of a chronic grade 3 or higher AE occurred in the IMPT group compared with 8 cases (16.3%) in the IMRT group (OR, 0.21; 95% CI, 0.01-1.21; P = .15). Propensity score matching generated a balanced cohort of 48 patients (24 IMPT vs 24 IMRT) and found similar PFS in the IMPT and IMRT groups (2-year PFS, 95.7% [95% CI, 87.7%-100%] vs 76.7% [95% CI, 60.7%-97.0%]; hazard ratio [HR], 0.31; 95% CI, 0.07-1.47; P = .14). No locoregional recurrence or death was observed in the IMPT group from the matched cohort. Two-year LRFS was 100% (95% CI, 100%-100%) in the IMPT group and 86.2% (95% CI, 72.8%-100%) in the IMRT group (P = .08). Three-year OS was 100% (95% CI, 100%-100%) in the IMPT group and 94.1% (95% CI, 83.6%-100%) in the IMRT group (P = .42). Smoking history was the only clinical factor significantly associated with both poor LRFS (HR, 63.37; 95% CI, 3.25-1236.13; P = .006) and poor PFS (HR, 6.33; 95% CI, 1.16-34.57; P = .03) on multivariable analyses.Conclusions and relevanceIn this study, curative-intent radiotherapy with IMPT for nonmetastatic NPC was associated with significantly reduced acute toxicity burden in comparison with IMRT, with rare late complications and excellent oncologic outcomes, including 100% locoregional control at 2 years. Prospective trials are warranted to direct the optimal patient selection for IMPT as the primary radiotherapy modality for nonmetastatic NPC.

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Assessment of the modulation degrees of intensity-modulated radiation therapy plans.

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Assessment of the modulation degrees of intensity-modulated radiation therapy plans.

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