Predicting passing rate for VMAT validation using machine learning based on plan complexity parameters / 中华放射医学与防护杂志

Objective:To establish a prediction model using the random forest (RF) and support vector machine (SVM) algorithms to achieve the numerical and classification predictions of the gamma passing rate (GPR) for volumetric arc intensity modulation (VMAT) validation.Methods:A total of 258 patients who received VMAT radiotherapy in the 1 st Affiliated Hospital of Wenzhou Medical University from April 2019 to August 2020 were retrospectively selected for patient-specific QA measurements, including 38 patients who received VMAT radiotherapy for head and neck, and 220 patients who received VMAT radiotherapy for chest and abdomen. Thirteen complexity parameters were extracted from the patient′s VMAT plans and the GPRs for VMAT validation under the analysis criteria of 3%/3 mm and 2%/2 mm were collected. The patients were randomly divided into a training cohort (70%) and a validation cohort (30%) , and the complexity parameters for the numerical and classification predictions were screened using the RF and minimum redundancy maximum correlation (mRMR) method, respectively. Complexity models and mixed models were established using PTV volume, subfield width, and smoothness factors based on the RF and SVM algorithms individually. The prediction performance of the established models was analyzed and compared. Results:For the validation cohort, the GPR numerical prediction errors of the complexity models based on RF and SVM under the two analysis criteria are as follows. The root-mean-square errors (RMSEs) under the analysis criterion of 3%/3 mm were 1.788% and 1.753%, respectively; the RMSEs under the analysis criterion of 2%/2 mm were 5.895% and 5.444%, respectively; the mean absolute errors (MAEs) under the analysis criterion of 3%/3 mm were 1.415% and 1.334%, respectively, and the MAEs under the analysis criteria of 2%/2 mm were 4.644% and 4.255%, respectively. For the validation cohort, the GPR numerical prediction errors of the mixed models based on RF and SVM under the two analysis criteria were as follows. The RMSEs under the analysis criterion of 3%/3 mm were 1.760% and 1.815%, respectively; the RMSEs under the analysis criterion of 2%/2 mm were 5.693% and 5.590%, respectively; the MAEs under the analysis criterion of 3%/3 mm were 1.386% and 1.319%, respectively, and the MAEs under the analysis criteria of 2%/2 mm were 4.523% and 4.310, respectively. For the validation cohort, the AUC result of the GPR classification prediction of the complexity models based on RF and SVM were 0.790 and 0.793, respectively under the analysis criterion of 3%/3 mm and were 0.763 and 0.754, respectively under the analysis criterion of 2%/2 mm. For the validation cohort, the AUC result of the GPR classification prediction of the mixed models based on RF and SVM were 0.806 and 0.859, respectively under the analysis criterion of 3%/3 mm and were 0.796 and 0.796, respectively under the analysis criterion of 2%/2 mm cohort.Conclusions:Complexity models and mixed models were developed based on the RF and SVM method. Both types of models allow for the numerical and classification predictions of the GPRs of VMAT radiotherapy plans under analysis criteria of 3%/3 mm and 2%/2 mm. The mixed models have higher prediction accuracy than the complexity models.

Determination of minimal persistent pigment dose of normal skin to long-wave ultraviolet among healthy volunteers / 中华医学美学美容杂志

Objective To investigate the minimal persistent pigment dose (MPPD)of normal skin to UVA in Guangzhou city,and to observe its relationship to sex,age,skin type,seasons,ITA,and the years lived in Guangzhou.Methods 316 healthy subjects were exposed to Solar 601-300,and the MPPD was measured and observed by two professional technicians after 2-3 hours.Results The average MPPD value of all subjects was (9.61±2.57) J/cm2.In male and female,the average MPPD values were (11.09 ± 2.82) J/cm2 and (9.01 ± 2.20) J/cm2 respectively,and male was significantly higher than female (P＜0.01).There was significant difference of the MPPD value in different seasons (P＜0.01).The MPPD value in winter (10.66± 2.71) J/cm2) was significantly higher than spring (9.37±2.39) J/cm2,summer (9.53±2.66) J/cm2 and autumn (8.98±2.25) J/cm2.There was significant difference of the MPPD value between different ITA groups (P＜0.01).ITA grade-3 (10.72± 2.84) J/cm2 was significantly higher than grade-1 (8.50±1.45) J/cm2 and grade-2 (9.12±2.31) J/cm2 (P＜0.01),but there was no significant difference from grade-4 (11.87±2.73) J/cm2 (P =0.93).The MPPD value in subjects lived in Guangzhou over 10 years (8.97± 1.88) J/cm2 was significantly lower than those whose residence was less than 1 year and from 1 to 5 years,respectively (P＜0.01),but there was no significant difference from those lived from 5 to 10 years (P =0.47).Conclusions The MPPD value of the subjects in Guangzhou is related to gender,seasons,ITA grade and the years lived in Guangzhou city,while there is no correlation with age and skin types.

Performance of transfection with a complex plasmid encoding green fluorescent protein tagged cathepsin D in researches on chronic photodamaged fibroblasts / 中华皮肤科杂志

Objective To evaluate the performance of transfection with a complex plasmid encoding green fluorescent protein tagged CatD (GFP-CatD)in researches on chronic photodamaged fibroblasts. Methods Human dermal fibroblasts (HSFs)were irradiated with ultraviolet A (UVA)at 25 J/cm2 once a day for 21 consecutive days to establish a chronic photodamaged cell model. A plasmid encoding GFP-CatD was constructed and transfected into some chronic photodamaged fibroblasts (experimental group). The photodamaged HSFs receiving no treatment served as the blank control group, and those transfected with the negative plasmid encoding GFP only as the negative control group. After additional culture, fluorescence microscopy and Western-blot analysis were performed to observe and measure the expression of GFP-CatD in HSFs respectively, flow cytometry and methyl thiazolyl tetrazolium (MTT)assay to evaluate the apoptosis and proliferation of chronic photodamaged fibroblasts respectively. Results Fluorescence microscopy showed the expression of GFP-CatD in cytoplasm of chronic photodamaged fibroblasts at 96 hours after transfection with the GFP-CatD-encoding plasmid. Western-blot analysis revealed that the expression of CatD in the experimental group was 1.28 times that in the blank control group. There were no significant differences in the apoptosis rate(4.29% ± 1.30%vs. 3.03% ± 1.70% , P > 0.05)or proliferative rate (45.20% ± 4.70% vs. 43.60 ± 3.90% , P > 0.05)between the experimental group and blank control group. Conclusion CatD could be traced in chronic photodamaged fibroblasts with no changes in biological activity or cell cycle after transfection with the GFP-CatD-encoding complex plasmid.

Comparison of ArcCheck and film verification for VMAT in the treatment of nasopharyngeal carcinoma / 中国医疗器械杂志

To compare the performance of ArcCheck and film verification for volumetric intensity modulated arc therapy (VMAT) in the treatment of nasopharyngeal carcinoma, and to study the feasibility of ArcCheck in VMAT dosimetric verification. Five patients of nasopharyngeal carcinoma treated with VMAT were enrolled in this study. Dose verification was carried out by ArcCheck and film respectively. The result showed that there were no significant differences between ArcCheck and film verification. ArcCheck software can obtain three dimensional dose distribution directly with simple operation. It is convenient for ArcCheck to be used for VMAT dosimetric verification.

Determination of minimal erythema dose of normal skin to ultraviolet rays / 中华医学美学美容杂志

Objective To investigate the minimal erythema does (MED) of normal skin to UV in Guangzhou city,and to observe its relationship to sex,age,skin type,seasons and the years lived in Guangzhou.Methods 621 healthy subjects were exposed to Solar Simulator (GS2004) and the MED was measured and observed by two professional technicians after (24±2) hours.Results The average MED value of all subjects was (1170.2±333.2) mJ/cm2.In male and female group,the average MED values were (1132.8-339.4) mJ/cm2 and (1182.1 ± 330.7) mJ/cm2,respectively,and there was no significant difference between male and female (P=0.20).The MED value in subjects aged from 30 to 50 (1014.7 ± 359.7) mJ/cm2 was significantly lower than those aged from 20 to 29 (1222.9±304.3) mJ/cm2 and over 50 years (1179.0±374.3) mJ/cm2 (P＜0.01).The MED value in skin type Ⅱ (673.53±228.3) mJ/cm2 was significantly lower than those in type Ⅲ (1224.3±254.2) mJ/cm2 and Ⅳ(1363.1±278.5) mJ/cm2(P＜0.01).There was significant difference of the MED value between different seasons (P＜0.01).The MED value in spring (969.2±355.8) mJ/cm2 was lowest,and followed by summer (969.2± 355.8) mJ/cm2.However,there was no significant difference between autumn and winter (P＞0.05).The MED value in subjects lived in Guangzhou from 5 to 10 years was significantly lower than those whose residence time was from 1 to 4 years and over 10 years,respectively.Conclusions The MED value of the subjects in Guangzhou is quite different from other cities of China,and related to age,skin types,seasons and the years lived in Guangzhou city,while there is no correlation between MED value and gender difference.

Comparison between three detective methods of sun protection factor for sunscreen in vivo / 中华医学美学美容杂志

Objective To investigate the three methods for sun protection factor determination in vivo in Chinese under the same condition, and to evaluate the feasibility and reliability of the three methods. Methods There were 45 healthy volunteers in Guangzhou area were involved in the study. All of them were randomly divided into three groups. Among them 15 volunteers were in the current method group, 5 volunteers in the simplified method group, and 25 volunteers were in the single-exposure method group. Two standard sunscreens of SPF 4 and SPF 15 and one sunscreen labeled as SPF 20 were tested by all the three methods in the study. Two experienced observers read results, respectively, under the same conditions. Results The volunteers in the current method group received the largest dose of UV light.The simple method was next to it and the single-exposure reduced 4-5 folds of UV dose received. The results of the two observers in the current method group and the single-exposure group were very close. But the test results of P3 were not completely coincident between the two observers in the simplified method group. SPFs value of the three sunscreens were 4. 12, 16.09, and 22.60 obtained by the observer 1 and 4. 18, 15.92, and 21.97 obtained by the observer 2, respectively. In the simplified method group, SPFs values of ＜4, ＞15, ＞20 and ＜4, ＜15, ＞20 were obtained by the two observers. In the single-exposure method group, SPFs values of the three sunscreens were 4.04, 15.34, 21.33 by the observer 1 and 3. 96, 15.82, 21.33 by the observer 2, respectively. Conclusion The single-exposure method is convenient and easily to operate and may replace the current method some day. The simple method is not valuable in determination of SPF labeled on the packages of sunscreens, but may be useful in supervision of the market sunscreen products.

Expressions of aspartic proteinase and cysteine proteinase in photoaged fibroblasts / 中华皮肤科杂志

Objective To investigate the expression changes of aspartic proteinase (cathepsin D) and cysteine proteinase (cathepsin K) in photoaged fibroblasts. Methods The senescence of human fibroblasts was induced via culture in the presence of 8-methoxypsralen (MOP) of 50 mg/L in darkness for 24 hours followed by irradiation with UVA of 80 kJ/m~2. Then, aged fibroblasts were confirmed by senescence-associated β-galactosidase (SA-β-gal) staining. Real-time RT-PCR and Western blot were carried out to detect the mRNA and protein expressions of cathepsin D and cathepsin K in photoaged and normal control fibroblasts, respectively. Results Western blot showed a significant difference between photoaged and control fibroblasts in the grey scale of cathepsin D and cathepsin K (3.25 ± 0.33 vs 14.18 ± 2.25, f = 30.61, P < 0.01; 2.39 ± 0.66 vs 29.38 ± 4.62, t = 12.63, P< 0.01). The △Ct values for cathepsin D and cathepsin K mRNA were 2.79 ± 0.17 and -0.92 ± 0.06, respectively, in photoaged fibroblasts, significantly lower than those in the control fibroblasts (4.54 ± 0.34, 2.57 ± 0.13, t = 20.78, 28.50, respectively, both P < 0.01). According to the value of 2~(-△△Ct), the expression of cathepsin D and cathepsin K mRNA decreased 0.24 ± 0.021 and 0.09 ± 0.005 folds, respectively, in photoaged fibroblasts compared with the control fibroblasts. Conclusion The expression of cathepsin D and cathepsin K is decreased in photoaged fibroblasts.

Expression of cathepsin G in photoaged fibroblasts / 中华医学美学美容杂志

Objective To investigate the role of cathepsin G in photoaged fibroblasts. Methods Human fibroblasts were cultured and induced to premature senescence using UVA + MOP methods. Senescence-associated-β-galactosidase (SA-β-gal) stain was used to evaluate the positive rate of aged cells. The mRNA and protein expression of cathepsin G in photoaged fibroblasts were detected by real-time RT-PCR and Western blot techniques. Results Over 98 % induced cells presented a positive SA-β-gal straining. The expression of cathepsin G, detected by Western blot, was increased to (1. 70±0. 028) times of the control. And RT-PCR revealed that the synthesis of cathepsin G mRNA was also up-regulated to 1. 42±0. 09. Conclusion The results of our study demonstrates a significant correlation between photoaged fibroblasts and cathepsin G. The up-regulation of cathepsin G may play an important role in the damages of extracellular matrix and activation of MMPS in photoaged human skin.