Clinical application of radiotherapy based on UIH linear accelerators to in vivo dose verification / 中华放射医学与防护杂志

Objective:To explore the clinical application of the electronic portal imaging device (EPID) based on the linear accelerator produced by Shanghai United Imaging Healthcare Co., Ltd. (UIH) to in vivo dose verification. Methods:A total of 68 patients (32 cases with head and neck tumors, 16 cases with chest tumors, and 20 cases with abdomen and pelvis tumors) who were treated with volumetric modulated arc therapy (VMAT) in the Henan Provincial People′s Hospital were selected in this study. Each patient underwent the pre-treatment dose verification using an Arccheck device (Pre Arccheck), the pre-treatment dose verification using an EPID (Pre EPID), and the in vivo dose verification using an EPID (In vivo EPID). Moreover, the position verification based on fan beam computed tomography (FBCT) was also performed for each patient in the first three treatments and then once a week. The patients were treated when the setup error in any direction ( x: left-right, y: head-foot, z: vertical) was less than 3 mm; otherwise, position correction would be conducted. The three-dimensional setup deviation d was calculated according to setup errors x, y, and z. Results:The γ passing rates of dose verifications Pre EPID and In vivo EPID of 68 patients were (99.97±0.1)% and (94.15±3.84)%, respectively, significantly different from that (98.86±1.48)% of the Pre Arccheck dose verification ( t = -6.12, 9.43; P < 0.05). The γ passing rates of the chest, abdomen and pelvis, and head and neck in the In vivo EPID dose verification showed no significant differences ( P > 0.05). The difference in the γ passing rates (5.56±3.72)% between dose verifications Pre EPID and first In vivo EPID was unrelated to the three-dimensional setup deviation d (1.46±1.51 mm) ( P > 0.05). As the treatment proceeded, the γ passing rate of In vivo EPID gradually decreased from (94.15±3.84)% in the first week to (92.15±3.24)% in the fifth week. From the third week to the fifth week, the γ passing rates of In vivo EPID were significantly different from those in the first week ( t = 2.48, 2.75, 3.09, P < 0.05). Conclusions:The setup errors within 3 mm do not affect the γ passing rate of in vivo dose verification. The clinically acceptable threshold for the γ passing rate of in vivo EPID needs to be further determined. In addition, in vivo dose verification can support the clinical application of adaptive radiotherapy to a certain extent.

Estratégica metodológica a través del juego para la enseñanza del pase-recepción en baloncesto

El proceso de enseñanza-aprendizaje requiere de estrategias didácticas que contribuyan a la adquisición de hábitos motrices específicos de una forma eficaz; el método del juego puede contribuir considerablemente a dicho propósito. En tal sentido, se plantea como objetivo de la investigación perfeccionar el proceso de enseñanza del pase-recepción en baloncesto a través de una estrategia metodológica, utilizando el método de juego. Se conforman dos grupos independientes con 20 basquetbolistas masculinos, cada uno de la Unidad Educativa del Milenio Nela Martínez Espinosa; se implementa un entrenamiento tradicional al Grupo Control y una estrategia metodológica con seis juegos al Grupo Experimental durante un semestre y se prioriza el proceso de enseñanza del pase-recepción. El Grupo Control no mejoró significativamente la técnica del pase-recepción (p=0.180), a diferencia del Grupo Experimental (p=0.000), mientras que, al comparar los resultados en el postest entre grupos independientes, el Grupo Experimental presentó un mejor rango promedio (24.50) que el Grupo Control (16.50), con una diferencia significativa a su favor (p=0.030). Para la presente investigación, se logra una mejora significativa en la técnica del pase-recepción en los basquetbolistas del Grupo Experimental. Se deduce que el uso de una estrategia metodológica que priorice el método de juego, contribuye notablemente al proceso de enseñanza-aprendizaje en la adquisición de hábitos motrices específicos del baloncesto como parte de la etapa de iniciación deportiva.

O processo de ensino-aprendizagem requer estratégias didáticas que contribuam para a aquisição de hábitos motores específicos de forma eficaz; o método do jogo pode contribuir consideravelmente para este propósito. Neste sentido, o objetivo da pesquisa é melhorar o processo de ensino da recepção de passes no basquetebol através de uma estratégia metodológica, usando o método de jogo. Dois grupos independentes foram formados com 20 jogadores masculinos de basquete, cada um da Unidade Educacional Nela Martínez Espinosa Millennium; um treinamento tradicional foi implementado para o Grupo de Controle e uma estratégia metodológica com seis jogos para o Grupo Experimental durante um semestre e o processo de ensino da recepção de passes foi priorizado. O Grupo de Controle não melhorou significativamente a técnica de recepção de passagem (p=0,180), ao contrário do Grupo Experimental (p=0,000), enquanto que, ao comparar os resultados no pós-teste entre grupos independentes, o Grupo Experimental apresentou uma faixa média melhor (24,50) do que o Grupo de Controle (16,50), com uma diferença significativa a seu favor (p=0,030). Para a presente investigação, uma melhoria significativa na técnica de recepção de passes é alcançada nos jogadores de basquete do Grupo Experimental. Deduz-se que o uso de uma estratégia metodológica que prioriza o método de jogo, contribui significativamente para o processo de ensino-aprendizagem na aquisição de hábitos motores específicos no basquetebol como parte da fase de iniciação esportiva.

The teaching-learning process requires didactic strategies that contribute to the acquisition of specific motor habits in an effective way; the game method can contribute considerably to this purpose. In this sense, the objective of the research is to improve the teaching process of pass-reception in basketball through a methodological strategy, using the game method. Two independent groups were formed with 20 male basketball players, each one from the Millennium Educational Unit Nela Martínez Espinosa; a traditional training was implemented to the Control Group and a methodological strategy with six games to the Experimental Group during one semester and the teaching process of the pass-reception was prioritized. The Control Group did not significantly improve the pass-reception technique (p=0.180), unlike the Experimental Group (p=0.000), while, when comparing the results in the post-test between independent groups, the Experimental Group presented a better average range (24.50) than the Control Group (16.50), with a significant difference in its favor (p=0.030). For the present research, a significant improvement in the pass reception technique is achieved in the basketball players of the Experimental Group. It is deduced that the use of a methodological strategy that prioritizes the game method, contributes significantly to the teaching-learning process in the acquisition of specific motor habits of basketball as part of the sports initiation stage.

Transport mechanism of bergenin aross MDCK-MDRl cell monolayer model / 中国药理学通报

Aim To study the transport mechanism of bergenin passing through blood-brain barrier ( BBB ) . Methods MTT assay was used to investigate the tox-icity of bergenin on MDCK-MDRl cells. Molecular docking was used to predict the binding mode and effect ability of bergenin with P-gp. In vitro MDCK-MDRl cell monolayer model was used to analyze trans¬port characteristics of bergenin and the effect of con¬centration, time and verapamil (a P-gp inhibitor) on the transport of bergenin. Results Bergenin was non-toxic to MDCK-MDRl cells within the concentration of 5 to 40 jjunol • L . There was hydrogen-bond and hy-drophobic interaction between P-gp and bergenin, and P-gp-bergenin was more stable than P-gp-verapamil. The P value of bergenin transported from AP to BL (PappAP

Preliminary study of tolerance limits and action limits of IMRT plan dose verification based on AAPM-TG218 report / 中华放射肿瘤学杂志

Objective:Based on the AAPM-TG218 report, the dose verification of intensity-modulated radiotherapy (IMRT) plans were classified to understand the current status, establish the process and determine the limits of dose verification in our hospital.Methods:Different combinations of tumor locations, accelerators, treatment planning systems and verification devices in our hospital were verified and compared to determine the tolerance limits and action limits of each combination. The measurement requirement was adopted according to the AAPM-TG218 report, and 80 cases were selected for each measurement. The measurement procedures were implemented based upon the AAPM-TG218 report and clinical experience of our hospital.Results:The clinical action limits of IMRT plans in our hospital could meet the recommended range of the AAPM-TG218 report, and the tolerance limits were slightly lower than the AAPM-TG218 report′s recommendation (93.94% for 3%/2 mm). The measurement of verification devices was related to the sensitivity. The tolerance limits measured by EPID were higher than ArcCHECK, especially when the dose/distance requirements were more stringent (94.12% and 92.03% for 3%/2 mm, P=0.074; 86.82% and 74.61% for 2%/2 mm, P=0.017). Conclusion:Through the AAPM-TG218 report, the work flow of IMRT dose verification and the limit range are established in our hospital, providing guidance for subsequent clinical dosimetric measurement.

Effects of gantry acceleration limitations on VMAT plans / 中华放射医学与防护杂志

Objective:To study the effects of gantry acceleration limitations of a linear accelerator (linac) on the dosimetry of volumetric modulated arc therapy (VMAT) plans, machine efficiency, and dose verification result of VMAT plans and to explore the optimal selection of gantry motion models in the Pinnacle treatment planning system.Methods:Ten cases of nasopharyngeal carcinoma, non-small cell lung cancer, sigmoid adenocarcinoma with retroperitoneal lymph node metastasis, and invasive ductal carcinoma of the breast were each selected for this study. Then two models were set up in the Pinnacle v9.10 treatment planning system, namely the one allowing gantry acceleration and the one limiting gantry acceleration. The same field arrangement, optimized target parameters, and optimized weights of VMAT plans were adopted in the two models, in order to analyze the dosimetric variations in targets and organs at risk (OARs) and compare the differences in treatment time and gamma passing rates.Results:The treatment time of the enrolled patients under the model allowing gantry acceleration was significantly lower than that of the patients under the model limiting gantry acceleration was adopted ( t=-6.751, -0.209, -19.523, -28.999; P< 0.05) and decreased by 15.27%, 18.07%, 19.71%, and 28.75%, respectively. Meanwhile, the conformity and uniformity of target areas were affected, while there was no statistical significance in the gamma passing rates in the validation of VMAT plans ( P>0.05). For the cases of nasopharyngeal carcinoma (NPC), the maximum dose to brainstem PRV increased by 1.25%. For the cases of lung cancer, the maximum dose to the spinal cord and lung V20 increased by 1.19% and 1.21%, respectively, while lung V5 decreased by 1.21%. For the cases of sigmoid adenocarcinoma with retroperitoneal lymph node metastasis, the mean doses to bilateral kidneys, livers, small intestine, and colon all increased. For the cases of breast cancer, lung V10 on the opposite side of cancer increased by 1.66% and the mean dose to the lungs on the same side of cancer decreased by 7.45%. Conclusions:The model allowing gantry acceleration allows the treatment time to be significantly shortened and the treatment efficiency improved. Although this model had the shortcomings such as affecting the conformity and uniformity of target areas to a certain extent and increasing the doses to some OARs, clinical requirements for dosimetry were still met. Therefore, it is recommended to use the model allowing gantry acceleration in the Pinnacle planning system.

Agnes e Garfinkel: pensando gênero através de um clássico da sociologia / Agnes and Garfinkel: thinking about gender through a classic of sociology / Agnes y Garfinkel: Pensando género a través de un clásico de la sociología

Resumo Neste artigo buscamos apontar como a relação entre Agnes e o sociólogo estadunidense Harold Garfinkel produziu uma análise de gênero que se diferenciava das teorias biologizantes do seu tempo. Através do conceito de passing e da noção de rotineirização da Etnometodologia, o autor antecipa, em certa medida, certos pressupostos que viriam a nortear a noção de gênero que se desenvolveria na década de 1990. Na primeira parte do texto, o nosso enfoque será nos impactos da experiência de Agnes para a etnometodologia; em um segundo momento, provocaremos um diálogo entre Garfinkel e a teoria da performatividade de Judith Butler.

Abstract In this article we intend to show how the relationship between Agnes and the American sociologist Harold Garfinkel produced a gender analysis that differed from the biological theories of its time. Through the concept of passing and the ethnomethodology's notion of routine the author anticipates certain assumptions that would guide the notion of gender that would develop in the 1990s. In the first part of the text, our focus will be on impacts of Agnes' experience for ethnomethodology; in a second step, we will provoke a dialogue between Garfinkel and Judith Butler's theory of performativity.

Resumen En este artículo buscamos señalar como la relación entre Agnes y el sociólogo estadounidense Harold Garfinkel ha producido un análisis de género que se distinguía de las teorías biologizantes de su época. A través de la concepción de passing y de la idea de rotinerización de la Etnometodología, el autor adelanta, hasta cierto punto, determinados presupuestos que vendrían a guiar la idea de género que se desarrollaría en la década de 1990. En la primera parte del texto, nuestro énfasis será en los impactos de la experiencia de Agnes para la Etnometodología; en segundo momento, provocaremos un diálogo entre Garfinkel y la teoría de la performatividad de Judith Butler.

Speed and heart rate variation during marathon running in a hot environment / Variación de la velocidad y la frecuencia cardiaca durante un maratón en un ambiente caluroso

Abstract The purpose of the study was to analyze the variation of running speed and heart rate in amateur runners during a marathon in a hot environment. Eighteen runners (weight: 65.2 ± 12.21 kg, height: 168.4 ± 10.6 cm, VO2max: 52.9 ± 7.1 ml/kg/min) took part of a beach-side marathon (42195 m) under a temperature of 27.8 ± 3.52 ºC and at 0-80 m altitude. Pearson's correlation showed a significant linear relationship between the increase in thermal stress index (WGBT) and the speed variation (r= 0.168, p= 0.049). In this respect, the total duration of the race revealed a direct relationship with speed (r= 0.675, p= 0.003) and heart rate (r= 0.631, p= 0.007) variation. Multiple regressions analysis showed that 61.6% of the final race time was explained by the speed variation in the 26 to 30 km course section (r 2 = 0.61; F= 26.17; p< 0.001) and 37% by the heart rate variation in the 31 to 35 km section (r 2 = 0.37; F= 10.38; p< 0.001). In conclusion, an increase in the environmental temperature provoked a decrease in running pacing, with a stronger effect in the second half of the race. Therefore, coaches should take these aspects into account in training and strategies to mitigate the impact of these conditions on the physical and physiological performance of amateur runners.

Resumo O presente estudo teve como objetivo analisar a variação da velocidade da corrida e a frequência cardíaca em corredores amadores durante uma maratona em um ambiente de alto índice térmico. Dezoito corredores amadores (peso: 65,2 ± 12,21 kg, altura: 168,4 ± 10,6 cm, VO2max: 52,9 ± 7,1 ml/kg/min) correram uma maratona (42195 m) em proximidade ao mar, sob um índice térmico de 27,8 ± 3,52 ºC e com percurso de 0-80 metros acima do nível do mar. O teste de Pearson apresentou uma correlação significativa entre o aumento do índice de estresse térmico (IBUTG) e a variação da velocidade (r= 0,168, p= 0,049). Neste sentido, a duração total da corrida apresentou uma relação direta com a velocidade (r= 0,675, p= 0,003) e a variação da frequência cardíaca (r= 0,631, p= 0,007). O tempo final da corrida se interpretou em 61,6% e 37% pela variação da velocidade de 26 a 30 km (r 2 = 0,61; F= 26,17; p< 0,001) e pela variabilidade da frequência cardíaca no lapso de 31 a 35 km (r 2 = 0,37; F= 10,38; p< 0,001), respectivamente. Em suma, o índice térmico provoca uma diminuição no ritmo da velocidade, sendo esse efeito maior na segunda metade da corrida. Devido a isso, os preparadores devem planejar treinamentos e estratégias para mitigar o impacto dessas condições no desempenho físico e fisiológico dos corredores amadores.

Resumen El objetivo del presente estudio fue analizar la variación de la velocidad de carrera y la frecuencia cardíaca en corredores aficionados durante un maratón en un entorno de alto índice térmico. Dieciocho corredores aficionados (peso: 65.2 ± 12.21 kg, altura: 168.4 ± 10.6 cm, VO2max: 52.9 ± 7.1 ml/kg/min) corrieron un maratón (42 195 m) en cercanía al mar bajo un índice térmico de 27.8 ± 3.52ºC y con recorrido de 0-80 m.s.n.m. La prueba de Pearson mostró una correlación significativa entre el aumento del índice de estrés termal (TGBH) y la variación de la velocidad (r = 0.168, p = 0.049). En este sentido, la duración total de la carrera presentó una relación directa con la velocidad (r = 0.675, p = 0.003) y la variación de la frecuencia cardíaca (r= 0.631, p = 0.007). El tiempo final de carrera se explicó en un 61.6% y 37% por la variación de la velocidad de 26 a 30 km (r 2 = 0.61; F = 26.17; p < 0.001) y por la variabilidad de la frecuencia cardíaca en el lapso de 31 a 35 km (r 2 = 0.37; F= 10.38; p < 0.001) respectivamente. En conclusión, el índice térmico provoca una disminución en el ritmo de la velocidad, este efecto mayor en la segunda mitad de la carrera. Por lo anterior, entrenadores deben planificar entrenamientos y estrategias para mitigar el impacto de estas condiciones en el desempeño físico y fisiológico de los corredores amateur.

Establishment of antioxidative activity determination for Achnatherum inebrians by graphene nanoenzyme / 中草药

Objective: To develop a new method for the determination of anti-oxidant activity of drugs by using the peroxidase activity of graphene nanoenzyme, and apply it for the determination of the anti-oxidant activity of the national medicine Achnatherum inebrians. Methods: The anti-oxidant activity of 18 batches of samples was measured after optimizing H2O2 concentration and reaction time. At the same time, the anti-oxidative activity was measured again using the DPPH method. The Bland-Altman and Passing-Bablok regression methods were used to compare the detection data of the two methods. Results: Using the nanoenzyme method, the inhibition rates of 18 batches of A. inebrians were between 37.28% and 71.58%, with an average of 50.87% and a median of 47.09%. Free radical scavenging rates of 18 batches of A. inebrians measured by the DPPH method were between 36.06% and 83.11%, with an average of 54.89% and a median of 50.83%. The statistical results showed that the measured values of nanoenzyme method and DPPH method were similar; There was a linear relationship between the two methods, and different methods can be transformed by Passing-Bablok regression method. Conclusion: The graphene nanoenzyme was successfully applied to the detection of anti-oxidant activity, and the anti-oxidant activity of A. inebrians was also found. The nanoenzyme method can avoid the problem of light sensitivity of the reagent, shorten the reaction time, reduce the amount of medicinal solution, and the results are consistent with the DPPH method, which is suitable for the determination of antioxidant activity.

Lessons Learned From Performance Of Students Of Pharmacology In Self Coded Surprise Test With Negative Marking

Introduction: The present study aims to find the effect of instruction of negative marking in a self-coded MCQ examination on the performance of students in the subject of Pharmacology concerning the raw score, correct score and negative score. Methodology: This longitudinal study was conducted in the Department of Pharmacology. The Second MBBS students were exposed to a self-coded MCQ test twice by surprise. The first test (T1) was given without instructions of negative marking, while during the second test (T2) instructions for negative marking were given. The parameters of the raw score, negative score, corrected score and number of students who did not attempt respective MCQs was calculated. The number of students passing with modified Minimum Passing Level was calculated was compared with conventional Minimum Passing Level. Results:Sixty-seven students participated in the study. There was a statistically significant decrease in the raw score in the T2, while an increase in the negative score when compared with T1. The number of non-attempted questions was increased in T2. There was a statistically significant difference in the number of students passed concerning raw score in T1 and T2, while no such difference was seen concerning Negative score and Corrected score. Conclusion:The Corrected score and Negative score are not affected by the minimum passing level, indicating a better parameter of scoring than the raw score. Hence, the use of Negative score or Corrected score should be encouraged rather than the use of conventional Raw score.

The effect of respiratory motion states on dynamic IMRT dose distribution / 中华放射医学与防护杂志

Objective To investigate the effect of respiratory movement of different amplitude,period and direction on the dose distribution of target area in dynamic intensity modulated radiation therapy.Methods A total of 30 cases of lung cancer were selected and divided into three groups according to the volume size of the target area,including groups A (72.0-200.2 cm3),B (271.7-380.0 cm3) and C (498.9-684.9 cm3).The average volume was 151.5,327.1 and 583.3 cm3,respectively.Breathing motion simulation platform was used to drive the mode body with two-dimensional ionization chamber matrix along the Gun-Target direction,then turn the collimator to 0° and 90°,respectively.The doses were collected at the central level in different amplitudes of 0,4,8,12 and 15 mm,periodic respiratory movement at the intervals of 3,4 and 5 s and respiratory motion measurement with a cycle of 4 s 5 times.The difference of dose distribution between the collected dose and TPS output was analyzed by taking the absolute dose and γ-passing rate (3 mm/3％) as indicators.Results In the two-sided upward,respiratory movement reduced the dose at the medial edge of the target area and increased the dose at the lateral edge of the target area.The difference of γ-passing rate between respiration cycle was up to 3.54％ (t=2.301,P＜0.05),and when the respiration movement was more than 8 mm,the γ-passing rate was less than 90％ and decreased with the increase of amplitude.The difference of γ-passing rate between static and respiratory motion was negatively correlated with the volume of target area,and the average γ-passing rate of A,B and C three groups increased gradually.The γ-passing rate of 5 composited dose was higher than that of single dose,and the difference was statistically sigificant(t=-9.36--5.95,P＜0.05).Conclusions The dose distribution of dynamic IMRT target area is mainly influenced by respiration range and its own volume,and the respiration cycle has an effect on dose distribution under partial amplitude.After implementing the multiple doses,some single dose implementation errors can be eliminated.Physicians need to expand the target area reasonably according to the range of respiratory movement,and optimize the amount of marginal tissue in the target area in the direction of respiratory movement.For patients with small target volume and large respiratory movement,respiratory management technology should be adopted to improve the accuracy of target dose implementation.

Application of EPID-based 3D dose reconstruction in cancer patients / 中华放射肿瘤学杂志

Objective To perform 3D dose reconstruction based on electronic portal imaging device ( EPID) of linear accelerator for the static intensity-modulated using Edose, a dose verification system, Aiming to assist the radiotherapy professionals to better understand the radiotherapy organs at risk and target dose changes. Methods CBCT image was acquired for patients with head and neck cancer and thoracic cancer once a week for a total of six times. Subsequently,CBCT images and planning CT images were subject to rigid registration and exported to the Edose software. According to the setup error, EPID-based three-dimensional dose reconstruction was performed by using Edose software. The gamma passing rate and dose of different organs at risk ( OARs ) were analyzed and statistically compared. Results For patients with nasopharyngeal carcinoma,the intra-fractional Dmax of the spinal cord was more significantly fluctuated and higher compared with the planning dose, whereas the intra-fractional Dmax of the brainstem did not significantly fluctuate. The V30 of the parotid gland significantly changed with a maximum increase of 28. 69％ per fraction. For patients with thoracic tumors,the Dmax of the spinal cord was slightly changed,and the actual doses in the lung and heart were higher than the planning doses. The average deviation of the pulmonary V5 was up to 16. 99％ between the actual and planning doses with statistical significance ( P<0. 05).According to the analysis of gamma passing rate,significant dose changes occurring in the OARs were detected in the 16th fraction for the head and neck cancer and the 24th fraction for the thoracic neoplasms. Conclusions The dose changes in the OARs can be obtained by reconstructing the EPID-based 3D dose distribution using the Edose software for each fraction, which can better protect the OAR, enhance the coverage of target dose and provide certain reference for dose-guided and self-adaptive radiotherapy.

Development of methodology for dose quality audit of multi-leaf collimator in intensity modulated radiotherapy / 中华放射医学与防护杂志

Objective To develop the methodology for using TLDs and films to measure absorbed dose and 2D dose distribution produced by the multi-leaf collimator (MLC) in intensity modulated radiotherapy (IMRT),in order to provide the guidance on dose quality audit in IMRT.Methods A total of 30 different-typed accelerators were selected from 27 hospitals in Jiangsu,Sichuan,Hubei and Henan provinces,including 17 Varian accelerators,10 Elektas and 3 Simens.The same batch of films and TLDs were put in a 2 cm-thick solid plate for fixation and then loaded in a 15 cm × 15 cm × 15 cm polysyrene solid phantom supplied by International Atomic Energy Agency(IAEA) in terms of 90 cm SSD,19 cm depth,10 cm × 10 cm field at different doses.The standard dose curves wcrc established for film and TLD,respectively.The irradiated film was measured and then sent to the External Audit Group (EAG) in China.The TLD-and film-absorbed doses were compared with TPS-calculated doses.The 2D dose distribution on the IRMT MLC field was measured using films.The homogeneous phanton of 30 cn × 30 cm was scanned by CT and the image was transferred to the TPS.The IMRT was implemented with 6 Gy fractionated irradiation by placing a 25 cm × 25 cm film on the phantom surface at 95 cm SSD and at 5 cm depth.The irradiated film was sent to the IAEA dosimetry laboratory for measurement and calculation.2D dose distribution verification was conducted in thc same way consistent with the procedure of international multi-radiotherapy center.The 3 mm/3％ passing rate was calculated for 2D dose distribution and compared with the film-measured and TPS calculated result.Results IAEA requires the relative deviation of TLD and film measured absorbed dose are with in ± 5％.The relative deviation of TLD-and filmmeasured to TPS-calculated absorbed dose was within the range of ±0.7％-± 8.5％ and within ±0.3％ ±7.8％ in Jiangsu,Sichuan,Hubei and Henan provinces,respectively.IAEA requires the 3 mm/3％ passing rate of film-measured 2D distribution to be 90％.The result of the present study were up to 94.0％.The verification result of 2D dose distribution were within 70.0％-99.9％ in Sichuan,Jiangsu,Hubei and Henan provinces.Conclusions The adsorbed dose and 2D distribution can be audited using TLDs and films for MLC in IRMT.The method is scientific and applicable,economical and convenient for development of dose quality audit for a wide range of IRMT.

The primary research for the influence of immobilization baseplate of carbon fiber on dose distribution of radiation field of radiotherapy / 中国医学装备

Objective:To analyze the attenuation of immobilization baseplate of carbon fiber for ray and the change of dose verification results for enhanced radiation field of MatriXX. And to primarily research the influence of this immobilization baseplate for the dose distribution of radiation field of radiotherapy.Methods: 20 patients with cervical cancer were enrolled in the research. The angle of gantry was 180°in the enhanced plan of immobilization field, and the corresponding verification plans were designed. When the verification plan was implemented on the Varian Clinac iX of accelerator, the two-dimensional ionization chamber array (MatriXX) was used to measure dose distributions of the plan. The immobilization baseplate of carbon fiber (ORFIT AIO) was used in the research. The situations of no baseplate (A group), one baseplate (B group), two baseplates (C group)and three baseplates (D group)between the handpiece of accelerator and Matri XX were researched, respectively. The data of the 4 groups were obtained by using software (OminiPro I'mRT), and the largest dose point and passing rate of Gamma in plane of radiation field were counted and analyzed.Results: Compared with A group, the average attenuation factors for ray on the largest dose point of B, C and D group in the plane of radiation field were (1.73±0.11)％, (3.44±0.36)％, and (5.48±0.44)％, respectively. The passing rates of Gamma in the 4 groups were (94.87±2.31)％, (99.18±0.61)％, (99.79±0.27)％ and (96.24±1.99)％, respectively. And the differences of passing rate between each group and A group were statistical significance (t=9.788,t=9.261,t=2.256,P<0.05).Conclusion:The immobilization baseplate of carbon fiber has influence for the attenuation of high-energy X-rays and it can affect the dose distribution of radiation field which has passed baseplate in some degrees. And when physicists calculates the dose, they should consider the effect of immobilization baseplate of carbon fiber for dose distribution of radiation field.

Analysis of VMAT dosimetric verifications with different techniques / 中华放射肿瘤学杂志

Objective To investigate the gamma (γ) passing rates for volumetric-modulated arc therapy (VMAT) dosimetric verification with different techniques.Methods A total of 12 VMAT plans for the treatment of different anatomical sites in cancer patients were chosen.The Octavius 4D system was used to measure the dose distributions in two different settings:the gantry was rotating (three-dimensional (3D) and 2D γ-analysis) and the gantry was fixed at 0°(2D γ-analysis).The γ passing rates were analyzed with 3%/3 mm and 2%/2 mm criteria, using the paired t test or Wilcoxon signed-rank test.The 2D γ passing rates for different irradiation methods were calculated.Results For the 3D and 2D dose distributions obtained at a rotating gantry angle as well as the 2D dose distribution obtained at zero gantry angle, the average γ passing rates were 96.03%, 96.98%, and 98.90% for 3%/3 mm (P=0.227, P=0.000, P=0.003);82.08%, 84.04%, and 90.90% for 2%/2 mm (P=0.379, P=0.000, P=0.000).For the 2D dose distributions obtained with different irradiation methods, the average γ passing rate was 98.99% for 3%/3 mm and 93.68% for 2%/2 mm.Conclusions The VMAT dosimetric verification based on a 3D volumetric dosimeter at a rotating gantry position can be clinically useful for delivery quality assurance (QA), and can achieve the most reliable dose calculation for VMAT, which has more referential values.

Study of dose variations induced by MLC weight effect for IMRT delivery / 医疗卫生装备

Objective To evaluate dose variations induced by gravity of multi-leaf collimator to provide references for clinical intensity-modulated radiotherapy.Methods Two-dimensional dose distributions in the central plane of IMRT fields were measured by use of a 2D ion chamber array.All measurements were repeated at two collimator angles (C=0 and 90°),for each of the following gantry angles:G=0 and 270°.Comparisons were made to dose distributions generated at G=0°and their differences were analyzed using gamma index analysis (3％/3 mm and 1％/1 mm).Results Under the radiation field of 10 cm×10 cm,the gamma passing rate was higher than 99％ for 3％ 3 mm anch close to 95％ for 1％/1mm Under a 3％/3mm error standard,the average matching rate for step & shoot fields was (96.46±0.33)％ and for DMLC fields was (94.67±0.54)％ at C=0°;The average matching rate for step & shoot fields was (94.59±0.47)％ and for DMLC fields was (92.60±0.52)％ at C=90°.Under a 1％/1mm error standard,the average matching rate for step & shoot fields was (89.83 ±1.06)％ and for DMLC fields was (85.84±0.57)％ at C=0°;The average matching rate for step & shoot fields was (86.91 ±1.71)％ and for DMLC fields was (83.89±0.69)％ at C=90°.Concusion MLC weight effect affects IMRT delivery dose,and DMLC fields are more sensitive to gravity than step & shoot fields.

The Theme of “Passing” in the Novels of James Weldon Johnson and Nella Larsen.

The depiction of the experience of a very fair-skinned person of some ―coloured‖ background who successfully passes into white society was a recurrent theme in early African American writings. In this paper an attempt is made to look at, and compare and contrast, two African American novels, The Autobiography of an Ex-Coloured Man (l912) and Passing (1929) which deal with the theme of passing, written by James Weldon Johnson and Nella Larsen, a Black man and a Black woman writer. This paper analyses how the two novels reject the rules of colour division, rules which demand that one accepts a position within a predetermined hierarchy.

The study of angular dependence of gamma index for Delta4 phantom / 中华放射肿瘤学杂志

Objective To study the effect of the uncertain deflection of the Delta4 phantom (ScandiDos AB,Sweden) in setting up on the Gamma index passing rate during the VMAT plan verification.Methods Two patients with head and neck cancer,two with lung cancers and one with pelvic cancer receiving VMAT radiotherapy were randomly chosen.By means of Eclipse8.6 TPS the treatment plans elaborated for the five patients were picked up to make the verification plans and Delta4 was used to perform dose verification On VARIAN Clinac Ⅸ.The Delta4 phantom was precisely set up first,and then it was deflected in a given angle towards the horizontal direction in relation to the center of the linear accelerator isocenter to perform the dose verification for 11 times successively.To figure out the relationship between the deflection angle of the Delta4 phantom and the Gamma index passing rate.Results As the Delta4 phantom was deflected by 0.0°,0.2°,0.4°,0.6°,0.8°,1.0°,1.2°,1.4°,1.6°,1.8° and 2.0° in sequence,the measured Gamma index passing rates presented a slight decline,but all greater than 90％ (DD 3％,DTA 3 mm).Conclusions In the VMAT plan verification,the Gamma index passing rate of Delta4 has no dependence on the uncertain deflection of the Delta4 phantom provided that the uncertain deflection of the Delta4 phantom is no greater than 2°,but the passing rates of DD and DTA vary significantly with the uncertain deflection of the Delta4 phantom.

A primary research of intensity-modulated dose verification based on anatomic structure of three-dimensional images / 中华放射肿瘤学杂志

Objective To verify IMRT plans in point,planar and 3D dose,and to concretely analyze the dose differences of 3D anatomic structure based on Gamma passing rate.Methods Thimble ion-chamber,Matrixx and ArcCheck were separately used to measure six nasopharyngeal carcinoma treatment plans and six lung cancer treatment plans.The dose measurement deviation of the center point was compared as well as the Gamma passing rate of dose verification under the criteria of both 3％/3 mm and 2％/2 mm,the group t-test and one-way ANOVA were also proceeded.3DVH system was used to analyze the dose measurement deviation of target volume (TV) and organ at risk (OAR) through DVH.Results For IMRT and VMAT treatment plans,the mean deviation of point dose was (0.59 ± 1.31) ％ and (-1.00 ± 1.03)％ respectively,and the maximum deviation was less than 3％.Under the criterion of 3％/3 mm,the Gamma passing rate measured by Matrixx,ArcCheck and 3DVH for IMRT plans was 96.28％,97.55％ and 99.02％ respectively,and for VMAT plans,the corresponding results of three different detectors were 97.24％,99.67％ and 98.48％.The results analyzed and compared by 3DVH showed that even under the condition of high Gamma pass rate (more than 95％ for a Gamma criterion of 3％/3 mm),the DVH metrics of both TV and OAR in two cases (account for 16.7％ of the total plan) were significantly different on the clinical parameters,including GTV,spinal cord and brain stem etc.Conclusions The analysis of dose difference of the measurement results based on Gamma pass rate and on anatomic structure of 3D images can more effectively evaluate the influence of dose error to the implementing of clinical plan and the impact to the clinical treatment.

The effect of carbon fiber couch on dose distribution of conformal intensity modulated plan / 中华放射肿瘤学杂志

Objective To evaluate the effect of carbon fiber couch on dose distribution of radiotherapy planning and verification pass rate.Methods Establishing the carbon fiber treatment couch model in Pinnacle8.0m Treatment Planning system (TPS),and then this model was used to correct dose calculations of oblique fields in the treatment plans of 10 cases of nasopharyngeal carcinoma,10 cases of breast cancer and 10 cases of lung cancer and evaluate the effect of carbon fiber couch on the whole dose distribution of the plans.Then these plans were measured by three-dimensional dose verification equipment Delta4 to confirm the improvement extent of Gamma pass rate after considering the carbon fiber treatment couch.Results For the majority of plans,when the carbon fiber couch was taken into consideration,the target doses was significantly reduced (4772 cGy-7266 cGy vs.4859 cGy-7347 cGy,P=0.000-0.002) and the relative deviation of D95 was 1％ to 3％.Measurement results of Delta4 showed that Gamma pass rate (3 mm/3％ criteria) increased in all plans (96.4％-98.8％ vs.93.4％-97.3％,P =0.000),some of that were up to 5 percentage when the couch model was applied.Conclusions Target doses will be overestimated if the treatment couch is ignored in TPS measurement.,However it should arouse enough attention when the disease with smaller doses corresponding gradient.

The research on the factors of effecting with γ passing rate of delivery quality assurance for helical tomotherapy / 中华放射肿瘤学杂志

Objective To investigate the factors of effecting with yindex analysis of delivery for helical tomotherapy (HT).Methods Measuring γindex with the ArcCheck device for introduced errors in HT.The errors include setup errors in three-dimensional,the gantry angle error,calculating the dose in the phantom,low dose rate.All the results were compared with the 3％/3 mm and 2％/2 mm criteria.The effect of the accuracy in the application of kilovoltage computed tomography (KVCT) and mega-voltage computed tomography (MVCT) images in HT was also analyzed.Paired-t test method was used for difference compared.Results When the errors were introduced to the HT,theγpassing rate of left-right,superior-inferior,anterior-posterior direction dropped 2.7％,7.2％,3.6％ under the 3％/3 mm criteria (P =0.002,0.022,0.007),with 4.6％,15.7 ％,7.6％ under the 2％/2 mm criteria (P =0.001,0.003,0.002) respectively.There was no statistical significance for theγpassing between scanning the ArcCheek phantom with the KVCT and MVCT under the 3％/3 mm and 2％/2 mm criteria (98.6％ vs 98.7％,P =0.859 and 92.7％ vs 92.8％,P =0.984).Conclusions The errors of the setup position and machine paraments can lead to the dose delivery errors in HT,the quality accurance of machine and plan should be enhanced to minimize the dose errors.The results also showed that there is no difference of KVCT and MVCT image on the delivery of HT.