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1.  Laparoscopic vs open D2 gastrectomy for locally advanced gastric cancer: A meta-analysis 
World Journal of Gastroenterology : WJG  2014;20(44):16750-16764.
AIM: To conduct a meta-analysis comparing laparoscopic (LGD2) and open D2 gastrectomies (OGD2) for the treatment of advanced gastric cancer (AGC).
METHODS: Randomized controlled trials (RCTs) and non-RCTs comparing LGD2 with OGD2 for AGC treatment, published between 1 January 2000 and 12 January 2013, were identified in the PubMed, Embase, and Cochrane Library databases. Primary endpoints included operative outcomes (operative time, intraoperative blood loss, and conversion rate), postoperative outcomes (postoperative analgesic consumption, time to first ambulation, time to first flatus, time to first oral intake, postoperative hospital stay length, postoperative morbidity, incidence of reoperation, and postoperative mortality), and oncologic outcomes (the number of lymph nodes harvested, tumor recurrence and metastasis, disease-free rates, and overall survival rates). The Cochrane Collaboration tools and the modified Newcastle-Ottawa scale were used to assess the quality and risk of bias of RCTs and non-RCTs in the study. Subgroup analyses were conducted to explore the incidence rate of various postoperative morbidities as well as recurrence and metastasis patterns. A Begg’s test was used to evaluate the publication bias.
RESULTS: One RCT and 13 non-RCTs totaling 2596 patients were included in the meta-analysis. LGD2 in comparison to OGD2 showed lower intraoperative blood loss [weighted mean difference (WMD) = -137.87 mL, 95%CI: -164.41--111.33; P < 0.01], lower analgesic consumption (WMD = -1.94, 95%CI: -2.50--1.38; P < 0.01), shorter times to first ambulation (WMD = -1.03 d, 95%CI: -1.90--0.16; P < 0.05), flatus (WMD = -0.98 d, 95%CI: -1.30--0.66; P < 0.01), and oral intake (WMD = -0.85 d, 95%CI: -1.67--0.03; P < 0.05), shorter hospitalization (WMD = -3.08 d, 95%CI: -4.38--1.78; P < 0.01), and lower postoperative morbidity (odds ratio = 0.78, 95%CI: 0.61-0.99; P < 0.05). No significant differences were observed between LGD2 and OGD2 for the following criteria: reoperation incidence, postoperative mortality, number of harvested lymph nodes, tumor recurrence/metastasis, or three- or five-year disease-free and overall survival rates. However, LGD2 had longer operative times (WMD = 57.06 min, 95%CI: 41.87-72.25; P < 0.01).
CONCLUSION: Although a technically demanding and time-consuming procedure, LGD2 may be safe and effective, and offer some advantages over OGD2 for treatment of locally AGC.
PMCID: PMC4248223  PMID: 25469048
D2 lymph node dissection; Gastrectomy; Gastric cancer; Laparoscopy; Meta-analysis
2.  Use Dose Bricks Concept to Implement Nasopharyngeal Carcinoma Treatment Planning 
BioMed Research International  2014;2014:720876.
Purpose. A “dose bricks” concept has been used to implement nasopharyngeal carcinoma treatment plan; this method specializes particularly in the case with bell shape nasopharyngeal carcinoma case. Materials and Methods. Five noncoplanar fields were used to accomplish the dose bricks technique treatment plan. These five fields include (a) right superior anterior oblique (RSAO), (b) left superior anterior oblique (LSAO), (c) right anterior oblique (RAO), (d) left anterior oblique (LAO), and (e) superior inferior vertex (SIV). Nondivergence collimator central axis planes were used to create different abutting field edge while normal organs were blocked by multileaf collimators in this technique. Results. The resulting 92% isodose curves encompassed the CTV, while maximum dose was about 115%. Approximately 50% volume of parotid glands obtained 10–15% of total dose and 50% volume of brain obtained less than 20% of total dose. Spinal cord receives only 5% from the scatter dose. Conclusions. Compared with IMRT, the expenditure of planning time and costing, “dose bricks” may after all be accepted as an optional implementation in nasopharyngeal carcinoma conformal treatment plan; furthermore, this method also fits the need of other nonhead and neck lesions if organ sparing and noncoplanar technique can be executed.
PMCID: PMC4055401  PMID: 24967395
3.  A Light-Field-Based Method to Adjust On-Axis Rounded Leaf End MLC Position to Predict Off-Axis MLC Penumbra Region Dosimetric Performance in a Radiation Therapy Planning System 
BioMed Research International  2013;2013:461801.
Purpose. An analytical and experimental study of split shape dose calculation correction by adjusting the position of the on-axis round leaf end position is presented. We use on-axis corrected results to predict off-axis penumbra region dosimetric performance in an intensity-modulated radiation therapy treatment planning system. Materials and Methods. The precise light-field edge position (X tang.p) was derived from the on-axis 50% dose position created by using the nominal light field for geometric and mathematical manipulation. Leaf position (X mlc.p) could be derived from X tang.p by defining in the treatment planning system for monitor unit calculation. On-axis offset (correction) could be obtained from the position corresponding to 50% of the central axis dose minus the Xmlc.p position. The off-axis 50% dose position can then be derived from the on-axis 50% dose position. Results. The monitor unit calculation of the split shape using the on-axis rounded leaf end MLC penumbra region could provide an under-or overdose of 7.5% per millimeter without an offset correction. When using the on-axis rounded leaf end offset correction to predict the off-axis dose, the difference between the off- and on-axis 50% dose position is within ±1.5 mm. Conclusions. It is possible to achieve a dose calculation within 0.5% error for an adjusted MLC leaf edge location in the treatment planning system with careful measurement and an accurate on-axis offset correction. Dose calculations located at an off-axis spilt shape region should be used carefully due to noncorrectable errors which were found to be up to 10%.
PMCID: PMC3821896  PMID: 24288680
4.  Dose Verification in Intensity Modulation Radiation Therapy: A Fractal Dimension Characteristics Study 
BioMed Research International  2013;2013:349437.
Purpose. This study describes how to identify the coincidence of desired planning isodose curves with film experimental results by using a mathematical fractal dimension characteristic method to avoid the errors caused by visual inspection in the intensity modulation radiation therapy (IMRT). Methods and Materials. The isodose curves of the films delivered by linear accelerator according to Plato treatment planning system were acquired using Osiris software to aim directly at a single interested dose curve for fractal characteristic analysis. The results were compared with the corresponding planning desired isodose curves for fractal dimension analysis in order to determine the acceptable confidence level between the planning and the measurement. Results. The film measured isodose curves and computer planning curves were deemed identical in dose distribution if their fractal dimensions are within some criteria which suggested that the fractal dimension is a unique fingerprint of a curve in checking the planning and film measurement results. The dose measured results of the film were presumed to be the same if their fractal dimension was within 1%. Conclusions. This quantitative rather than qualitative comparison done by fractal dimension numerical analysis helps to decrease the quality assurance errors in IMRT dosimetry verification.
PMCID: PMC3722795  PMID: 23956976
5.  Using Multivariate Regression Model with Least Absolute Shrinkage and Selection Operator (LASSO) to Predict the Incidence of Xerostomia after Intensity-Modulated Radiotherapy for Head and Neck Cancer 
PLoS ONE  2014;9(2):e89700.
The aim of this study was to develop a multivariate logistic regression model with least absolute shrinkage and selection operator (LASSO) to make valid predictions about the incidence of moderate-to-severe patient-rated xerostomia among head and neck cancer (HNC) patients treated with IMRT.
Methods and Materials
Quality of life questionnaire datasets from 206 patients with HNC were analyzed. The European Organization for Research and Treatment of Cancer QLQ-H&N35 and QLQ-C30 questionnaires were used as the endpoint evaluation. The primary endpoint (grade 3+ xerostomia) was defined as moderate-to-severe xerostomia at 3 (XER3m) and 12 months (XER12m) after the completion of IMRT. Normal tissue complication probability (NTCP) models were developed. The optimal and suboptimal numbers of prognostic factors for a multivariate logistic regression model were determined using the LASSO with bootstrapping technique. Statistical analysis was performed using the scaled Brier score, Nagelkerke R2, chi-squared test, Omnibus, Hosmer-Lemeshow test, and the AUC.
Eight prognostic factors were selected by LASSO for the 3-month time point: Dmean-c, Dmean-i, age, financial status, T stage, AJCC stage, smoking, and education. Nine prognostic factors were selected for the 12-month time point: Dmean-i, education, Dmean-c, smoking, T stage, baseline xerostomia, alcohol abuse, family history, and node classification. In the selection of the suboptimal number of prognostic factors by LASSO, three suboptimal prognostic factors were fine-tuned by Hosmer-Lemeshow test and AUC, i.e., Dmean-c, Dmean-i, and age for the 3-month time point. Five suboptimal prognostic factors were also selected for the 12-month time point, i.e., Dmean-i, education, Dmean-c, smoking, and T stage. The overall performance for both time points of the NTCP model in terms of scaled Brier score, Omnibus, and Nagelkerke R2 was satisfactory and corresponded well with the expected values.
Multivariate NTCP models with LASSO can be used to predict patient-rated xerostomia after IMRT.
PMCID: PMC3938504  PMID: 24586971
6.  A Novel Medical Image Quality Index 
Journal of Digital Imaging  2010;24(5):874-882.
A novel medical image quality index using grey relational coefficient calculation is proposed in this study. Three medical modalities, DR, CT and MRI, using 30 or 60 images with a total of 120 images used for experimentation. These images were first compressed at ten different compression ratios (10 ∼ 100) using a medical image compression algorithm named JJ2000. Following that, the quality of the reconstructed images was evaluated using the grey relational coefficient calculation. The results were shown consistent with popular objective quality metrics. The impact of different image aspects on four grey relational coefficient methods were further tested. The results showed that these grey relational coefficients have different slopes but very high consistency for various image areas. Nagai’s grey relational coefficient was chosen in this study because of higher calculation speed and sensitivity. A comparison was also made between this method and other windows-based objective metrics for various window sizes. Studies found that the grey relational coefficient results are less sensitive to window size changes. The performance of this index is better than some windows-based objective metrics and can be used as an image quality index.
PMCID: PMC3180531  PMID: 21104000
Image compression; Image quality analysis; JPEG2000

Results 1-6 (6)