Youling Gong

The clinical feasibility and effect of online cone beam computer tomography-guided intensity-modulated radiotherapy for nasopharyngeal cancer.

BACKGROUND AND PURPOSE Online adaptive correction in image-guided intensity-modulated radiotherapy appeared to be a promising approach for precision radiation treatment in head and neck tumors. This protocol was designed to evaluate the clinical feasibility and effect of online cone beam computed tomography (CBCT) guidance in IMRT of nasopharyngeal cancer (NPC). METHODS AND MATERIALS The Elekta Synergy system, which integrates an X-ray volumetric imager (XVI), was used to deliver radiation treatment for 22 cases of NPC. The acquired CBCT was registered to the planning CT for online and offline analysis. The systematic and random setup errors, as well as planning target volume (PTV) margin, were calculated at different correction threshold levels. The impact of online setup correction on dosimetry was evaluated by simulation of pre-correction errors. RESULTS The correction-of-setup-errors frequencies for 1, 2 and 3mm thresholds were 41.3-53.9%, 12.7-21.2% and 6.3-10.3%, respectively. Online correction was effective at the 2mm threshold level for all three axes. The pre-correction systematic errors for the whole group ranged 1.1-1.3mm, and the random errors were also 1.1-1.3mm. After online correction, the systematic and random errors ranged 0.4-0.5mm and 0.7-0.8mm, respectively, in the three directions. The PTV margins for the pre-correction, pretreatment and post-treatment positions were 3.5-4.2mm, 1.6-1.8mm and 2.5-3.2mm, respectively, in three directions. Analysis of hypothetical dosimetric change due to a translational isocenter shift of 3mm showed that if no correction was applied, the mean maximum dose to both the brain stem and spinal cord would be increased by 10Gy, the mean dose to the left and right parotids would be increased by 7.8 and 8.5Gy, respectively, and the dose to target volumes would be decreased: 4Gy for 95% GTV and 5.6Gy for 95% CTV(60.) CONCLUSIONS CBCT-based online correction increased the accuracy of IMRT for NPC and reduced irradiated margins, by decreasing both the systematic and random errors. Online CBCT correction reduces the radiation dose to normal tissue and creates room for further dose escalation of tumors.

Planning analysis for locally advanced lung cancer: dosimetric and efficiency comparisons between intensity-modulated radiotherapy (IMRT), single-arc/partial-arc volumetric modulated arc therapy (SA/PA-VMAT)

PurposeTo analyze the differences between the intensity-modulated radiotherapy (IMRT), single/partial-arc volumetric modulated arc therapy (SA/PA-VMAT) techniques in treatment planning for locally advanced lung cancer.Materials and methods12 patients were retrospectively studied. In each patients case, several parameters were analyzed based on the dose-volume histograms (DVH) of the IMRT, SA/PA-VMAT plans respectively. Also, each plan was delivered to a phantom for time comparison.ResultsThe SA-VMAT plans showed the superior target dose coverage, although the minimum/mean/maximum doses to the target were similar. For the total and contralateral lungs, the higher V5/10, lower V20/30 and mean lung dose (MLD) were observed in the SA/PA-VMAT plans (p < 0.05, respectively). The PA-VMAT technique improves the dose sparing (V20, V30 and MLD) of the controlateral lung more notably, comparing to those parameters of the IMRT and SA-VMAT plans respectively. The delivered monitor units (MUs) and treatment times were reduced significantly with VMAT plans, especially PA-VMAT plans (for MUs: mean 458.3 vs. 439.2 vs. 435.7 MUs, p < 0.05 and for treatment time: mean 13.7 vs. 10.6 vs. 6.4 minutes, p < 0.01).ConclusionsThe SA-VMAT technique achieves highly conformal dose distribution to the target. Comparing to the IMRT plans, the higher V5/10, lower V20/30 and MLD were observed in the total and contralateral lungs in the VMAT plans, especially in the PA-VMAT plans. The SA/PA-VMAT plans also reduced treatment time with more efficient dose delivering. But the clinical benefit of the VMAT technique for locally advanced lung cancer needs further investigations.

Salvage concurrent radio-chemotherapy for post-operative local recurrence of squamous-cell esophageal cancer

PurposeTo evaluate the treatment outcome of salvage concurrent radio-chemotherapy for patients with loco-recurrent esophageal cancer after surgery.Methods50 patients with loco-recurrent squamous-cell cancer after curative esophagectomy were retrospectively analyzed. Patients were treated with radiotherapy (median 60 Gy) combined with chemotherapy consisting of either 5-fluorouracil (5-FU) plus cisplatin (DDP) (R-FP group) or paclitaxel plus DDP (R-TP group).ResultsThe median follow-up period was 16.0 months. The 1-year and 3-year survival rates were 56% and 14%, respectively. The median progression-free survival (PFS) and overall survival (OS) time was 9.8 and 13.3 months respectively. There was no statistical significance of the PFS of the two groups. The OS (median 16.3 months) in the R-TP group was superior to that in the R-FP group (median: 9.8 months) (p = 0.012). Among the patients who had received ≥60 Gy irradiation dose, the median PFS (10.6 months) and OS (16.3 months) were significantly superior to the PFS (8.7 months) and OS (11.3 months) among those patients did not (all p < 0.05). Grade 3 treatment-related gastritis were observed in 6 (27.3%) and 7 (25%) patients in the R-FP and R-TP group respectively. By univariate survival analysis, the age (<60 years), TP regimen and higher irradiation dose might improve the OS of such patients in present study.ConclusionsFor those patients with post-operative loco-recurrent squamous-cell esophageal carcinoma, radiotherapy combined with either FP or TP regimen chemotherapy was an effective salvage treatment. Younger age, treatment with the TP regimen and an irradiation dose ≥60 Gy might improve the patients’ treatment outcome.

Conventionally-fractionated image-guided intensity modulated radiotherapy (IG-IMRT): a safe and effective treatment for cancer spinal metastasis

BackgroundTreatments for cancer spinal metastasis were always palliative. This study was conducted to investigate the safety and effectiveness of IG-IMRT for these patients.Methods10 metastatic lesions were treated with conventionally-fractionated IG-IMRT. Daily kilovoltage cone-beam computed tomography (kV-CBCT) scan was applied to ensure accurate positioning. Plans were evaluated by the dose-volume histogram (DVH) analysis.ResultsBefore set-up correction, the positioning errors in the left-right (LR), superior-inferior (SI) and anterior-posterior (AP) axes were 0.3 ± 3.2, 0.4 ± 4.5 and -0.2 ± 3.9 mm, respectively. After repositioning, those errors were 0.1 ± 0.7, 0 ± 0.8 and 0 ± 0.7 mm, respectively. The systematic/random uncertainties ranged 1.4–2.3/3.0–4.1 before and 0.1–0.2/0.7–0.8 mm after online set-up correction. In the original IMRT plans, the average dose of the planning target volume (PTV) was 61.9 Gy, with the spinal cord dose less than 49 Gy. Compared to the simulated PTVs based on the pre-correction CBCT, the average volume reduction of PTVs was 42.3% after online correction. Also, organ at risk (OAR) all benefited from CBCT-based set-up correction and had significant dose reduction with IGRT technique. Clinically, most patients had prompt pain relief within one month of treatment. There was no radiation-induced toxicity detected clinically during a median follow-up of 15.6 months.ConclusionIG-IMRT provides a new approach to treat cancer spinal metastasis. The precise positioning ensures the implementation of optimal IMRT plan, satisfying both the dose escalation of tumor targets and the radiation tolerance of spinal cord. It might benefit the cancer patient with spinal metastasis.

Single-arc volumetric-modulated arc therapy (sVMAT) as adjuvant treatment for gastric cancer: Dosimetric comparisons with three-dimensional conformal radiotherapy (3D-CRT) and intensity-modulated radiotherapy (IMRT)

To compare the dosimetric differences between the single-arc volumetric-modulated arc therapy (sVMAT), 3-dimensional conformal radiotherapy (3D-CRT), and intensity-modulated radiotherapy (IMRT) techniques in treatment planning for gastric cancer as adjuvant radiotherapy. Twelve patients were retrospectively analyzed. In each patients case, the parameters were compared based on the dose-volume histogram (DVH) of the sVMAT, 3D-CRT, and IMRT plans, respectively. Three techniques showed similar target dose coverage. The maximum and mean doses of the target were significantly higher in the sVMAT plans than that in 3D-CRT plans and in the 3D-CRT/IMRT plans, respectively, but these differences were clinically acceptable. The IMRT and sVMAT plans successfully achieved better target dose conformity, reduced the V20/30, and mean dose of the left kidney, as well as the V20/30 of the liver, compared with the 3D-CRT plans. And the sVMAT technique reduced the V20 of the liver much significantly. Although the maximum dose of the spinal cord were much higher in the IMRT and sVMAT plans, respectively (mean 36.4 vs 39.5 and 40.6Gy), these data were still under the constraints. Not much difference was found in the analysis of the parameters of the right kidney, intestine, and heart. The IMRT and sVMAT plans achieved similar dose distribution to the target, but superior to the 3D-CRT plans, in adjuvant radiotherapy for gastric cancer. The sVMAT technique improved the dose sparings of the left kidney and liver, compared with the 3D-CRT technique, but showed few dosimetric advantages over the IMRT technique. Studies are warranted to evaluate the clinical benefits of the VMAT treatment for patients with gastric cancer after surgery in the future.

IMPACTS OF MULTILEAF COLLIMATORS LEAF WIDTH ON INTENSITY-MODULATED RADIOTHERAPY PLANNING FOR NASOPHARYNGEAL CARCINOMA: ANALYSIS OF TWO COMMERCIAL ELEKTA DEVICES

We compared the impacts of multileaf collimator (MLC) widths (standard MLC width of 10 mm [SMLC] and micro-MLC width of 4 mm [MMLC]) on intensity-modulated radiotherapy (IMRT) planning for nasopharyngeal carcinoma (NPC). Ten patients with NPC were recruited in this study. In each patients case, plans were generated with the same machine setup parameter and optimizing methods in a treatment planning system according to 2 commercial Elekta MLC devices. All of the parameters were collected from dose-volume histograms of paired plans and evaluated. The average conformity index (CI) and homogeneous index (HI) for the planning gross target volume in IMRT plans with MMLC were 0.790 ± 0.036 and 1.062 ± 0.011, respectively. Data in plans with SMLC were 0.754 ± 0.038 and 1.070 ± 0.010, respectively. The differences were statistically significant (p < 0.05). Compared with CI and HI for planning target volume in paired plans, data with MMLC obviously were better than those with SMLC (CI: 0.858 ± 0.026 vs. 0.850 ± 0.021, p < 0.05; and HI: 1.185 ± 0.011 vs. 1.195 ± 0.011, p < 0.05). However, there was no statistical significance between evaluated parameters (Dmean, Dmax, D₅, gEUD, or NTCP) for organs at risk (OARs) in the 2 paired IMRT plans. According to these two kinds of Elekta MLC devices, IMRT plans with the MMLC have significant advantages in dose coverage for the targets, with more efficiency in treatment for NPC but fail to improve dose sparing of the OARs.

Feasibility of using intravenous contrast-enhanced computed tomography (CT) scans in lung cancer treatment planning

BACKGROUND AND PURPOSE To investigate the feasibility of using intravenous contrast-enhanced computed tomography (CT) scans in 3-dimensional conformal radiotherapy (3D-CRT), stereotactic body radiation therapy (SBRT) and intensity-modulated radiotherapy (IMRT) treatment planning for lung cancers, respectively. MATERIALS AND METHODS Twelve patients with bulky lung tumors and 14 patients with small lung tumors were retrospectively analyzed. Each patient took two sets of CT in the same position with active breathing control (ABC) technique before and after intravenous contrast agent (CA) injections. Bulky tumors were planned with 3D-CRT, while SBRT plans were generated for patients with small tumors based on CT scans with intravenous CA. In addition, IMRT plans were generated for patients with bulky tumors to continue on a planning study. All plans were copied and replaced on the scans without intravenous CA. The radiation doses calculated from the two sets of CTs were compared with regard to planning volumes (PTV), the organ at-risk (OAR) and the lungs using Wilcoxons signed rank test. RESULTS In comparisons for 3D-CRT plans, CT scans with intravenous CA reduced the mean dose and the maximum dose of PTV with significant differences (p<0.05) that were within 1.0%. Comparing IMRT and SBRT plans, CT scans with intravenous CA obviously increased the minimum irradiation dose and dose of 95% volume of target received (D(95)) for targets, respectively (p<0.05). There was no statistical significance for lung parameters between two sets of scans in SBRT plans and IMRT plans. CONCLUSIONS The enhanced CT scans can be used for both target delineation and treatment planning in 3D-CRT. The dose difference caused by intravenous CA is small. But for SBRT and IMRT, the minimum irradiation dose in targets may be estimated to be increased up to 2.71% while the maximum dose may be estimated to be decreased up to 1.36%. However, the difference in dose distribution in most cases were found to be clinical tolerable.

Dosimetric comparison using different multileaf collimeters in intensity-modulated radiotherapy for upper thoracic esophageal cancer

PurposeTo study the impacts of multileaf collimators (MLC) width [standard MLC width of 10 mm (sMLC) and micro-MLC width of 4 mm (mMLC)] in the intensity-modulated radiotherapy (IMRT) planning for the upper thoracic esophageal cancer (UTEC).Methods and materials10 patients with UTEC were retrospectively planned with the sMLC and the mMLC. The monitor unites (MUs) and dose volume histogram-based parameters [conformity index (CI) and homogeneous index (HI)] were compared between the IMRT plans with sMLC and with mMLC.ResultsThe IMRT plans with the mMLC were more efficient (average MUs: 703.1 ± 68.3) than plans with the sMLC (average MUs: 833.4 ± 73.8) (p < 0.05). Also, compared to plans with the sMLC, the plans with the mMLC showed advantages in dose coverage of the planning gross tumor volume (Pgtv) (CI 0.706 ± 0.056/HI 1.093 ± 0.021) and the planning target volume (PTV) (CI 0.707 ± 0.029/HI 1.315 ± 0.013) (p < 0.05). In addition, the significant dose sparing in the D5 (3260.3 ± 374.0 vs 3404.5 ± 374.4)/gEUD (1815.1 ± 281.7 vs 1849.2 ± 297.6) of the spinal cord, the V10 (33.2 ± 6.5 vs 34.0 ± 6.7), V20 (16.0 ± 4.6 vs 16.6 ± 4.7), MLD (866.2 ± 174.1 vs 887.9 ± 172.1) and gEUD (938.6 ± 175.2 vs 956.8 ± 171.0) of the lungs were observed in the plans with the mMLC, respectively (p < 0.05).ConclusionsComparing to the sMLC, the mMLC not only demonstrated higher efficiencies and more optimal target coverage, but also considerably improved the dose sparing of OARs in the IMRT planning for UTEC.

Adjuvant Therapeutic Modalities in Primary Small Cell Carcinoma of Esophagus Patients: A Retrospective Cohort Study of Multicenter Clinical Outcomes.

AbstractTo evaluate the treatment pattern and survival of patients receiving radical resection for primary small cell carcinoma of the esophagus (PSCCE).This retrospective study included 150 patients who received radical resection of PSCCE. Data were retrieved from 4 centers in Western China. Thirty-nine of 150 patients received postoperative chemo-radiotherapy, 62 received postoperative chemotherapy, and 49 received radical resection only. The median radiation dosage was 50 Gy. The chemotherapeutic regimen was platinum-based and lasted for 2 to 6 cycles (median, 3).Median disease-free survival (mDFS) and overall survival (mOS) were 12.0 and 18.3 months, respectively. Subgroup analysis revealed that postoperative therapy did not improve survival in limited stage I (LSI) disease, whereas postoperative chemotherapy improved survival in limited stage II (LSII) disease. Relative to chemotherapy alone, chemoradiotherapy did not improve survival in patients with completely resected LSII disease. A multivariate analysis indicated an association of no postoperative chemotherapy with shorter DFS (P = 0.050) and OS (P = 0.010). Higher lymph node stage and length of disease longer than 3 cm were poor prognostic factors for both DFS and OS.Adjuvant chemotherapy improves survival in PSCCE patients with completely resected LSII disease. Adjuvant treatment with postoperative chemotherapy alone or postoperative chemo-radiotherapy does not increase survival in completely resected LSI disease.

Efficacy of epidermal growth factor receptor–tyrosine kinase inhibitors for lung squamous carcinomas harboring EGFR mutation: A multicenter study and pooled analysis of published reports

Epidermal growth factor receptor (EGFR) mutations are common in lung adenocarcinoma (ADC) but rare in squamous cell carcinoma (SQC). The efficacy of EGFR-tyrosine kinase inhibitors (EGFR-TKIs) for SQC with EGFR mutations is unclear. The aim of this study was to evaluate the efficacy of EGFR-TKIs for these patients. We performed a retrospective matched-pair case-control study from 3 cancer centers, including 44 SQC and 44 ADC patients with EGFR mutation who were treated with EGFR-TKI. Subsequently, we performed a pooled analysis on the efficacy of EGFR-TKIs for EGFR-mutant SQC in 115 patients, including 71 patients selected from 25 published reports. In our multicenter study, EGFR-mutant SQC and ADC patients had similar objective response rate (ORR) (43.2% vs. 54.5%, p = 0.290), but SQC patients had lower disease control rate (DCR) (71.3% vs. 100%, p = 0.001), significant shorter median progression free survival (PFS) (5.1 vs. 13.0 months, p = 0.000) and median overall survival (OS) (17.2 vs. 23.6 months, p = 0.027). In pooled analysis, the ORR, DCR, PFS and OS of SQC patients were 39.1%, 71.3%, 5.6 months and 15.0 months, respectively. Performance status was the only independent predictor of PFS and erlotinib treatment was associated with a better survival. In conclusion, EGFR-TKI was less effective in EGFR-mutant SQC than in ADC but still has clinical benefit for SQC patients. Further study is need to evaluate the using of EGFR-TKIs in these SQC patients.