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Purpose: To describe the acoustic characteristics of a classroom, voice quality, fatigue, and vocal load of university professors. Methods: Exploratory, observational, longitudinal, and descriptive study with a single group of participants, including vocal monitoring data over two weeks. Acoustic characterization of the classroom, perceptual-auditory evaluation, and acoustic analysis of voice samples were conducted before and after classes. Vocal dosimetry was performed during classes, and the Vocal Fatigue Index (VFI) was assessed at the beginning of each week. Descriptive analysis of the findings was conducted, and randomization test was performed to verify the internal reliability of the judge. Results: All participants reported speaking loudly in the classroom, with the majority reporting vocal changes in the past six months, and only one participant reported a current vocal change. The classroom had acoustical measures and estimations that deviated from established standards. The professors used high vocal intensities during classes. After the classes, an increase in the absolute values of the aggregated data for CAPE-V, jitter, and fundamental frequency was found, varying within the range of normality. Furthermore, there was an observed increase in both post-lesson intensity and VFI when comparing the two-week period. Conclusions: Vocal intensities and VFI were possibly impacted by the acoustics of the classroom. The increase in average VFI between the weeks may be attributed to a cumulative fatigue sensation. Further research with a larger number of participants and in acoustically conditioned classrooms is suggested in order to evaluate collective intervention proposals aimed at reducing the vocal load on teachers.
Objetivo: Describir las características acústicas, calidad vocal, fatiga y carga vocal de profesores universitarios. Métodos: Estudio exploratorio, observacional, longitudinal, descriptivo con un solo grupo de participantes y datos de monitoreo vocal durante dos semanas. Se realizó caracterización acústica de la sala, evaluación auditiva-perceptiva y acústica de muestras de voz antes y después de las clases. Se realizó dosimetría vocal durante las clases y se verificó el Índice de Fatiga Vocal (IFV) en dos semanas. Se realizó un análisis descriptivo de los hallazgos y una prueba de aleatorización para verificar la confiabilidad interna del juez. Resultados: Todos los participantes informaron hablar en voz alta en clase, la mayoría informó cambios vocales en los últimos seis meses y solo uno informó cambios vocales actuales. La sala presentó mediciones y estimaciones acústicas fuera de las normas establecidas. Los profesores utilizaron intensidades vocales altas durante las clases. Hubo un aumento en los valores absolutos de los datos agrupados para CAPE-V, jitter y frecuencia fundamental, variando dentro de los límites normales, después de las clases. La intensidad después de las clases y el IFV, en la comparación entre las dos semanas, mostraron un aumento. Conclusiones: La dosis vocal y el IFV posiblemente se vieron afectados por la acústica del aula. El aumento del IFV medio entre semanas pudo deberse a la sensación de cansancio acumulada. Se sugieren nuevas investigaciones con un mayor número de participantes y que se realicen en la sala acondicionada acústicamente para evaluar propuestas de intervención colectiva, con el objetivo de reducir la carga vocal de los docentes.
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Objective The present situation and hotspots of KM mouse research were visualized by CiteSpace software,which provided a reference for breaking through the bottleneck of KM mouse research and finding new ideas in China.Methods A total of 3981 articles were retrieved from CNKI and Web of Science databases from January 1,2004 to June 10,2023,of which the number of publications,countries(regions),institutions,author cooperation network,keyword co-occurrence,clustering,burst words,and cited English literature for analysis.Results The number of documents published in Chinese was decreased and the number of documents published in English was increased gradually in KM mouse research.The three countries with the most published articles were China,the United States,and Japan,where the leading research institutions were the China Agricultural University,Chinese Academy of Sciences,and Nanjing University of Chinese Medicine.The main authors at home and abroad were Liu Weihui,Li Guangwu,and Zhao Xin.The domestic research focused on the toxicology,immunology,and reproduction of KM mouse,and the foreign research focused on the cell biology and physiology of KM mouse.Conclusions KM mouse have been used and popularized in our country for more than 70 years,mainly focusing on toxicology,immunology,and reproduction.Although the use of KM mouse has led tove made allowed some achievements in experiments,certain it is necessary to solve their problems in the future,such as the standardization of population breeding,the discovery of the dominant research fields,and the further promotion of animal ethics,should be resolved.
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Objective To identify the exact locations of the brain being irradiated in advanced nasopharyngeal carcinoma(NPC)patients during radiotherapy,and to analyze the differences in brain dose distribution between advanced NPC patients treated with intensity-modulated radiotherapy(IMRT)and volumetric modulated arc therapy(VMAT).Methods Based on the CT brain template provided by the Montreal Neurological Institute,the brain dose distribution was analyzed with voxel-based method.Results For advanced NPC patients,VMAT plans did not demonstrate superiority in normal brain tissue sparing,while IMRT performed better,with advantages observed in regions such as the brainstem,the posterior lobe of the cerebellum,the anterior lobe of the cerebellum,temporal lobes,occipital lobes,limbic lobes,and certain areas of the subcortical regions.Conclusion IMRT is advantageous over VMAT in protecting the normal brain tissues in advanced NPC patients.
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Objective To evaluate the dosimetric effect of three-dimensional(3D)printed headrests made of different materials in radiotherapy for head and neck tumor,and to evaluate whether the existence of customized 3D-printed headrest can be neglected during planning phase by comparing differences in target area doses,homogeneity index(HI),conformity index(CI),monitor units(MU),and organ-at-risk(OAR)dose.Methods Ten patients with head and neck tumors,including 5 cases with nasopharyngeal carcinoma and 5 with other head and neck tumors,were enrolled.The headrest contours were outlined using Monaco treatment planning system,and with the same calculation parameters,treatment plans were generated for scenarios without a headrest,with a standard headrest,and with 3D-printed headrests made of 10%filled polylactic acid and thermoplastic polyurethane.The target area doses,OAR dose,MU,and other results were recorded and subjected to statistical analysis.Results No significant differences were observed among the 4 groups(ignoring headrest,standard headrest,3D-printed headrests with 10%filled polylactic acid and thermoplastic polyurethane)in parameters such as D95,D5,Dmean,HI,CI,MU,and OAR dose(the maximum dose to the spinal cord)(P>0.05).Considering the presence of the headrest,significant differences were found in CI for nasopharyngeal carcinoma and other head and neck tumors(P<0.05).Conclusion During the planning phase,the existence of customized 3D-printed headrest can be ignored,but it should be noted that the presence of a headrest may reduce the MU in radiotherapy plans.When considering the headrest,the average CI of patients with other head and neck tumors is significantly higher than that with nasopharyngeal carcinoma.
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Objective:To design and evaluate the application value of intracavitary-interstitial brachytherapy (IC-ISBT) applicator template for locally advanced cervical cancer.Methods:MRI data of 100 patients with ⅡB-ⅣA stage cervical cancer (International Federation of Gynecology and Obstetrics 2018 staging system) before and after external beam radiation therapy (EBRT) admitted to Sun Yat-sen University Cancer Center from March 2019 to September 2020 were collected. The range of primary cervical lesions was retrospectively analyzed and compared. Based on the residual mass of patients, the corresponding high-risk clinical target volume (HR-CTV) was delineated, and the IC-ISBT applicator template was designed and initially applied to cervical cancer patients. Dosimetry analysis and efficacy evaluation were compared between the applicator template-guided ( n=37) and free-hand implantation groups ( n=63). Chi-square test or Fisher exact test was performed for categorical variables, and t-test or U-test for continuous variables. Results:The median distance between the residual tumor margin (clockwise 3, 6, 9, 12 o'clock) and the center of 100 patients with ⅡB-ⅣA stage cervical cancer after EBRT was 16.5, 14.0, 17.0 and 13.0 mm, respectively. The corresponding HR-CTV was superimposed to reconstruct the three-dimensional diagram, and the cylindrical IC-ISBT applicator template with mushroom-like head was designed and manufactured: the longest and shortest diameter of the head was 35 and 20 mm, respectively; the central channel was adapted to the uterine tube, the C1-C12 channels was arranged in inner circle, and the peripheral B1-B5 and A1-A4 pin channels were expanded bilaterally. In terms of dose coverage, there was no significant difference between the HR-CTV D 90% [(635.12±22.65) vs. (635.80±25.84) cGy], bladder D 2 cm3 [(473.79±44.78) vs. (463.55±66.43) cGy)], rectum D 2 cm3 [(396.99±73.54) vs. (408.00±73.94) cGy] and sigmoid colon D 2 cm3 [(293.07±152.72) vs. (311.31±135.77) cGy] between the template-guided and free-hand implantation groups (all P>0.05), but the HR-CTV D 98% was significantly higher [(544.78±32.07) vs. (536.78±32.04) cGy, P=0.007] and the rectum D 1 cm3 and D 0.1 cm3 were significantly lower [(438.62±69.65) vs. (453.97±67.89) cGy, P=0.016; (519.46±70.67) vs. (543.82±81.24) cGy, P=0.001] in the template-guided implantation group. In addition, there was no significant difference in the complete response rate between two groups (86% vs. 83%, P>0.05). Conclusions:This IC-ISBT applicator template is reasonably designed, and the therapeutic efficacy of the template-guided implantation is equivalent to that of free-hand implantation. The dose coverage of the target area meets the clinical demand with a better protection of the organs at risk. The applicator template has the potential to be widely used as a conventional template in clinical practice as the applicator-guided implantation is convenient to operate and repeat.
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Objective:To investigate the necessity of adaptive re-planning during radiotherapy for nasopharyngeal carcinoma (NPC) and its impact on dose improvement.Methods:Clinical data of 89 NPC patients admitted to Sun Yat-sen University Cancer Center from July 2014 to December 2017 were retrospectively analyzed. All patients received 25+7 rounds of adaptive re-planning during radiotherapy. Plan-A was defined as the initial CT scan-based 25-fraction radiotherapy plan, while plan-B was defined as the re-planned 7-fraction radiotherapy plan based on a subsequent CT scan. The changes in the target and parotid gland volumes were compared between plan-A and plan-B. Plan-I was a one-time simulation of plan-A extended to 32 fraction radiotherapy plan, and plan-II was generated through registration and fusion of the plan-A and plan-B for adaptive re-planning. The differences in dose metrics, homogeneity index (HI), conformity index (CI), and dose to organs at risk (OAR) were compared between plan-I and plan-II. Statistical analysis was performed by using paired t-test. Results:Compared with plan-A, the gross tumor volume of massive bleeding lesions (GTV nx) and parotid gland volume of plan-B were decreased by 13.14% and 11.12%, respectively (both P<0.001). While planning clinical target volume of metastatic lymph nodes (PCTV nd) of plan-B was increased by 7.75%( P<0.001). There were significant changes in the lymph nodes of plan-A and plan-B. The D mean, D 5%, D 95% of massive bleeding lesions planning target volume (PTV nx) and D 5% of high risk planning target volume (PTV1) in plan-II were all significantly higher than those in plan-I (all P<0.05). The CI of PTV nx and PTV1 in plan-II was closer to 1 than that in plan-I. In all assessed OAR, the D mean, D 50%, and D max of plan-II were significantly lower than those of plan-I (all P<0.05). Conclusions:During radiotherapy, NPC patients may experience varying degrees of primary tumor shrinkage, parotid gland atrophy, and lymph node changes. It is necessary to deliver re-planning and significantly improve the dose of target areas and OAR.
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Objective To evaluate the characteristics of dose distribution of neuronal networks in vitro on microelectrode arrays(MEAs)under 2.6 GHz radiofrequency(RF)exposure.Methods The MEAs were coupled with a real-time RF exposure setup,and electromagnetic simulation software was used to calculate the RF dose absorbed in cultured neuronal networks.A fiber-optic temperature probe was used for experimental validation and monitoring of the cell temperature during RF exposure.The MEAs were used to record the electrical activity of neurons.Results For an input power of 1 W,a specific absorption rate(SAR)level of(15.51±2.48)W/kg was calculated,and the variability of the SAR distribution was 16%.In our experimental system,the temperature elevation of neurons was up to 0.15℃for an SAR of 4 W/kg RF exposure.Conclusion The exposure device can provide high SAR efficiency and uniformity in the 2.6 GHz band,which is suitable for studying the real-time effects of RF fields on the electrical activity of neuronal networks in the 5G network band.
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Objective To explore the feasibility of automatic segmentation of clinical target volume(CTV)and organs at risk(OARs)for cervical cancer using AccuLearning(AL)based on geometric and dosimetric indices.Methods Seventy-five CT localization images with manual contouring data of postoperative cervical cancer were enrolled in this study.Sixty cases were randomly selected to trained to generate automatic segmentation model by AL,and the CTV and OARs of the remaining 15 cases were automatically contoured.Radiotherapy plans on the automatic segmentation contours were imported on the CT images of manual contours.The efficiency,Dice similarity coefficient(DSC),Hausdorff distance(HD)and dosimetric parameters were compared between the two methods.Results The time of automatic segmentation was significantly shorter than that of the manual contour(P<0.05).The DSC of all structures were≥0.87.The HD of bowel bag and rectum were about 10 mm,and that of the rest of OARs were less than 5 mm.CTV(D98,V90% ,V95% ,Dmean,HI),bowel bag(V50)and bladder(V50)had significant differences in dosimetric comparison(P<0.05).Conclusion The automatic segmentation model based on AL can improve the efficiency of radiotherapy.Automatic segmentation of OARs has the potential of clinical application,while that of CTV still needs to be further modified.
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Objective To sort out and summarize the research hotspots and trends of Chinese medicine nursing technolo-gy at the present stage.Methods We searched the research literature on TCM nursing technology included in China Knowledge,Wanfang,and Wipu build-up to November 30,2023,and used CiteSpace 6.1.R6 software to perform co-occurrence analysis of research institutions and keyword clustering,timeline,and emergence analysis.Results A total of 5 771 documents were in-cluded,with a general upward trend in the number of publications,peaking at 692 publications in 2021.5 206 documents from 673 journals were included in the research literature,of which 19 journals had ≥50 publications(35.47％).2 087 research or-ganizations were involved,of which 27 had ≥20 publications(13.24％).Involving 9 484 authors,there were a total of 8 au-thors ≥5 in the cluster,indicating the existence of stable teamwork in the cluster.The keyword co-occurrence analysis yielded the research hotspots of TCM nursing technology as TCM nursing,training,nursing management,clinical efficacy,complica-tions,and quality of life.Conclusion Based on the econometrics and visualization analysis of the literature on TCM nursing technology,we explored the research hotspots and trends in this field,and provided two theoretical paths for medical institution managers to construct and optimize the management system of TCM nursing technology:to standardize the TCM nursing technology in hospitals and establish a clinical access management system;and based on the multidimensional management method,to inno-vate the training system of TCM nursing technology.
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Objectives: This was a single-subject study, aimed to demonstrate different vocal demand situations that are typical for primary school and teacher's vocal demand response under two acoustical conditions, with and without voice amplification, during five working days. Methods: The long-term voice dosimetry with Vocal Holter Med (PR.O. Voice Srl) was carried out on a 49-year-old female teacher with voice disorders during daily teaching activities. A sound field amplification system (SFAS) PentaClass Runa was installed in the classroom. Voice dosimetry was provided under two different acoustical conditions: without SFAS (2 days) and with SFAS (3 days). Results: Phonation time percentage, sound pressure level (SPL), SPL SD, fundamental frequency (F0), F0 SD, cycle, and distance doses were investigated in seven communication scenarios (lessons, group/individual classes, sports lessons in the gym and schoolyard, breaks, lunch breaks, and other activities). The median scores of all voice parameters differed significantly between different vocal demand contexts. The significant statistical difference in the vocal demand response was in the communication situations with and without SFAS. In addition, the number of children, reverberation time, and ambient air relative humidity impacted voice SPL and the cycle dose. Conclusions: Lessons, sports lessons held in the gym or schoolyard, breaks, and lunch breaks were considered as high vocal demand communication situations requiring higher voice intensity and fundamental frequency, higher phonation time percentage, cycle, and distance doses. Group/individual work and other teacher activities during the day, unrelated to direct work with students, were categorized as low vocal demand communication scenarios.
Objetivos: Este fue un estudio de sujeto único, cuyo objetivo fue demostrar diferentes situaciones de demanda vocal típicas de la escuela primaria y la respuesta vocal de los docentes bajo dos condiciones acústicas, con y sin amplificación de voz, durante cinco días laborables. Métodos: Se llevó a cabo dosimetría vocal a largo plazo con Vocal Holter Med (PR.O. Voice Srl) durante las actividades diarias de enseñanza en una docente de 49 años con trastornos de la voz. Se instaló un sistema de amplificación de campo sonoro (SFAS) PentaClass Runa en el aula. La dosimetría vocal se realizó bajo dos condiciones acústicas diferentes: sin SFAS (2 días) y con SFAS (3 días). Resultados: Se investigaron el porcentaje de tiempo de fonación, el nivel de presión sonora (SPL), SPL SD, la frecuencia fundamental (F0), F0 SD, ciclos y dosis de distancia en siete escenarios de comunicación diferentes (clases, clases grupales/individuales, clases de educación física en el gimnasio y el patio de la escuela, recreos, almuerzos y otras actividades). Las puntuaciones medias de todos los parámetros vocales diferían significativamente entre los diferentes contextos de demanda vocal. La diferencia estadísticamente significativa en la respuesta a la demanda vocal se observó en las situaciones de comunicación con y sin SFAS. Además, el número de niños, el tiempo de reverberación y la humedad relativa del aire ambiente afectaron al SPL de la voz y la dosis de ciclo. Conclusiones: Las lecciones, las clases de educación física en el gimnasio o el patio de la escuela, los recreos y los almuerzos se consideraron situaciones de comunicación de alta demanda vocal, que requerían una mayor intensidad y frecuencia fundamental de la voz, un mayor porcentaje de tiempo de fonación y dosis de ciclo y distancia más altas. El trabajo grupal/individual y otras actividades del profesor durante el día no relacionadas con el trabajo directo con los estudiantes se categorizaron como escenarios de comunicación de baja demanda vocal.
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ABSTRACT: The aim of this work is to provide a methodology for evaluating the committed effective dose E(50) due to the incorporation of [18F] FDG in the occupationally exposed worker (OEW) of the Cyclotron-PET/CT Laboratory of the Centro de Investigación en Ciencias Atómicas, Nucleares y Moleculares (CICANUM) at Universidad de Costa Rica using in vivo measurements. The measurement system was calibrated to perform in vivo measurements and defined as the corresponding bioassay function for the radiopharmaceutical used. The conversion factor was assessed with a known activity of 18F in the geometry and measurement time established. Among the most relevant results, the measurement parameters and the calibration procedure were defined. A value of 1.73 x 103 Bq/cps for in vivo brain measurements was obtained as a conversion factor. This study provides a methodology, to evaluate the committed effective dose due to the incorporation of 18F-FDG in a radionuclide production and diagnostic center
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Radiation Protection , Occupational Exposure/adverse effects , Cyclotrons/instrumentation , Radiation DosageABSTRACT
Abstract Objective: To develop an automated co-registration system and test its performance, with and without a fiducial marker, on single-photon emission computed tomography (SPECT) images. Materials and Methods: Three SPECT/CT scans were acquired for each rotation of a Jaszczak phantom (to 0°, 5°, and 10° in relation to the bed axis), with and without a fiducial marker. Two rigid co-registration software packages-SPM12 and NMDose-coreg-were employed, and the percent root mean square error (%RMSE) was calculated in order to assess the quality of the co-registrations. Uniformity, contrast, and resolution were measured before and after co-registration. The NMDose-coreg software was employed to calculate the renal doses in 12 patients treated with 177Lu-DOTATATE, and we compared those with the values obtained with the Organ Level INternal Dose Assessment for EXponential Modeling (OLINDA/EXM) software. Results: The use of a fiducial marker had no significant effect on the quality of co-registration on SPECT images, as measured by %RMSE (p = 0.40). After co-registration, uniformity, contrast, and resolution did not differ between the images acquired with fiducial markers and those acquired without. Preliminary clinical application showed mean total processing times of 9 ± 3 min/patient for NMDose-coreg and 64 ± 10 min/patient for OLINDA/EXM, with a strong correlation between the two, despite the lower renal doses obtained with NMDose-coreg. Conclusion: The use of NMDose-coreg allows fast co-registration of SPECT images, with no loss of uniformity, contrast, or resolution. The use of a fiducial marker does not appear to increase the accuracy of co-registration on phantoms.
Resumo Objetivo: Desenvolver corregistro automático e testar seu desempenho com ou sem marcador fiducial em imagens de tomografia computadorizada de emissão de fóton único (SPECT). Materiais e Métodos: Três SPECT/CTs foram adquiridas para cada rotação de um simulador de Jaszczak em relação ao eixo da maca (0°, 5° e 10°), com e sem fiducial. Dois métodos de corregistro inelástico foram aplicados - SPM12 e NMDose-coreg -, e a porcentagem do erro quadrático médio (%RMSE) foi usada para analisar a qualidade do corregistro. Uniformidade, contraste e resolução foram medidos antes e após o corregistro. NMDose com corregistro automático foi usado para calcular a dose renal de 12 pacientes tratados com 177Lu-DOTATATE e comparado com OLINDA/EXM. Resultados: A marcação fiducial não modificou a qualidade do corregistro das imagens SPECT, medida pela %RMSE (p = 0,40). Não houve impacto na uniformidade, contraste e resolução após o corregistro de imagens adquiridas com ou sem fiduciais. Aplicação clínica preliminar mostrou tempo total de processamento de 9 ± 3 min/paciente para NMDose e 64 ± 10 min/paciente para OLINDA/EXM, com alta correlação entre ambos, apesar de menor dose renal em NMDose. Conclusão: NMDose-coreg permite o corregistro rápido de imagens SPECT, sem perda de uniformidade, contraste ou resolução. O uso da marcação fiducial não aumentou a precisão do corregistro em fantomas.
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The purpose of this study is to establish and apply a correction method for titanium alloy implant in spinal IMRT plan, a corrected CT-density table was revised from normal CT-density table to include the density of titanium alloy implant. Dose distribution after and before correction were calculated and compared to evaluate the dose deviation. Plans were also copied to a spinal cancer simulation phantom. A titanium alloy fixation system for spine was implanted in this phantom. Plans were recalculated and compared with the measurement result. The result of this study shows that the max dose of spinal cord showed significant difference after correction, and the deviation between calculation results and measurement results was reduced after correction. The method for expanding the range CT-density table, which means that the density of titanium alloy was included, can reduce the error in calculation.
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Radiotherapy, Intensity-Modulated/methods , Titanium , Radiotherapy Dosage , Alloys , Radiometry/methods , Radiotherapy Planning, Computer-Assisted/methodsABSTRACT
Objective To explore the feasibility of quartz glass for radiotherapy dosimetry through the experimental study of the thermoluminescence characteristics of synthetic quartz glass. Methods The thermoluminescence glow curves of quartz glass under different annealing conditions were analyzed, the thermoluminescence characteristics of quartz glass were studied, and the measurement parameters were optimized. Using the Co-60 reference radiation field in the National Secondary Standard Dosimetry Laboratory, the quartz glass samples under different annealing conditions were irradiated following the dose levels of radiotherapy, i.e., 0.5, 1.0, 2.0, 4.0, 6.0, 8.0, and 10.0 Gy, respectively. According to the relationship between the absorbed dose of quartz glass and the relative thermoluminescence signal intensity, the linearity and dispersion of the dose response of quartz glass were obtained, and the feasibility of quartz glass for radiotherapy dosimetry was analyzed. Results The linear correlation coefficient of dose response of quartz glass under annealing condition of 430℃ for 10 min was 0.9984, and the dose response dispersion was 0.97% at the absorbed dose of 2 Gy. The linear correlation coefficient of dose response of quartz glass under annealing condition of 600℃ for 1 h was 0.9911, and the dose response dispersion was 1.4% at the absorbed dose of 2 Gy. Conclusion Preliminary results suggest that quartz glass with annealing condition of 430℃ for 10 min has the potential to be used for radiotherapy dosimetry.
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Objective To analyze the individualized CTV-to-PTV margin dose and positioning errors in radiotherapy for esophageal cancer for improving the treatment accuracy while meeting dose requirements.Methods Fifty-four esophageal cancer patients admitted to Sun Yat-sen University Cancer Center at Huangpu District from June 2021 to June 2022 were enrolled.All of the patients underwent CBCT scans in each fraction,and a total of 1283 CBCT images were collected.The image registration between CBCT image before radiotherapy and planning CT image was carried out to obtain errors in vertical(VRT),longitudinal(LNG),lateral(LAT),Roll,Pitch,and YAW directions.The mean values of six-dimensional positioning errors in the first 5 fractions were calculated,and the results were compared with the total fractional errors using the single sample t-test method for determining the differences.The CTV-to-PTV margin was calculated with the formula(margin=2.5∑+0.7δ),and the calculated margins were divided into 5 groups:Group A(5 mm expansion in all directions),Group B(7.9 mm expansion in LAT direction,and 5 mm expansion in other directions),Group C(11.03 mm expansion in LNG direction,and 5 mm expansion in the other directions),Group D(6.36 mm expansion in VRT direction,and 5 mm expansion in the other directions),and Group E(7.9 mm expansion in LAT direction,11.03 mm expansion in LNG direction,and 6.36 mm expansion in VRT direction).Simulation planning was conducted for 10 patients.Results The proportions of differences between the mean values of six-dimensional errors in the first 5 fractions and the total fractional errors in 54 patients were analyzed.There was no significant difference in 192 out of the 324 directions in 54 patients,accounting for 59.26%(P>0.05).Among them,the LAT,LNG,VRT,Pitch,Roll and YAW directions accounted for 64.81%,57.41%,51.85%,64.81%,57.41%and 59.26%of the total cases.The calculated CTV-to-PTV margin was 7.90,11.03 and 6.36 mm in LAT,LNG and VRT directions.The statistical analysis showed that the differences in the coverage rates of organs-at-risk and target areas among the 5 groups of CTV-to-PTV margins were trivial(P>0.05).Conclusion Using the positioning errors in the first 5 fractions of radiotherapy for esophageal cancer to predict subsequent positioning errors is feasible.The reasonable individualized margin in radiotherapy for esophageal cancer can reduce the inter-fractional off-target rate without increasing the dose delivered to organs-at-risk.The study provides a reference for the target volume margin of esophageal cancer and an important basis for precision treatment.
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Objective:To assess the feasibility of the designed dual-isocenter IMRT plans based on Halcyon 3.0 linear accelerator in postoperative radiotherapy of radical mastectomy for left side of breast cancer.Methods:A total of sixteen patients received the postoperative radiotherapy of radical mastectomy for left side of breast cancer at Shuguang Hospital Affiliated to Shanghai University of Traditional Chinese Medicine from December 2022 to June 2023 were retrospectively selected.The dual-isocenter plans based respectively on Halcyon 3.0 linear accelerator and Truebeam linear accelerator were designed,and the dosimetric parameters included conformity index(CI)values of target region,homogeneity index(HI)values and doses to organs at risk(OAR)of the two plans were calculated as statistic method.And then,the dosimetric performance of Halcyon 3.0 dual-isocenter plan was compared and analyzed.Utilizing two dose verification tools,ArcCHECK and Portal Dosimetry,to assess the precision of beam delivery of Halcyon 3.0 dual-isocenter plan.Results:The Halcyon dual-isocenter plan and the Truebeam single-isocenter plan had similar plan quality.There were not statistically significant differences(P>0.05)in dosimetric parameters such as CI,HI,exposure dose to 2%of the target volume(D2%)and exposure dose to 98%of the target volume(D98%).Compared to the average monitor unit(MU)of Truebeam single-isocenter plan,the MU values of Halcyon 3.0 dual-isocenter plan increased by 366 MU,while the difference was not statistically significant(P>0.05).The Halcyon 3.0 dual-isocenter plan provided comprehensive protection for OAR,which was better than that of the Truebeam single-isocenter plan.The values of the left side of lung volume(V20)that were covered by 20 Gy dose of the Halcyon 3.0 dual-isocenter plan and the Truebeam single-isocenter plan were respectively 20.41%±1.56%and 24.88%±2.95%,and the difference was statistically significant(t=6.413,P<0.05).There were not significant differences in other OAR dosimetric parameters between the two kinds of plans(P>0.05).The verification pass rates of the Halcyon 3.0 dual-isocenter plans on the ArcCHECK and Portal Dosimetry platforms were respectively 97.6%-98.9%and 98.1%-100%when the ratio of dose tolerance(DT)to distance to agreement(DTA)was set at 2%/2 mm.The verification pass rates of the Halcyon 3.0 dual-isocenter plans on the ArcCHECK and Portal Dosimetry platforms were respectively 99.1%-100%and 99.7%-100%when DT/DTA was set at 3%/3 mm.The beam delivery precision of the Halcyon 3.0 dual-isocenter plan could meet verification standards of clinical treatments.Conclusion:The Halcyon 3.0 dual-isocenter IMRT plan demonstrates a higher feasibility in the postoperative radiotherapy of radical mastectomy for left side of breast cancer.The precision of dose delivery of plan is high,and the dose of target area is sufficient,uniform and favorable conformability.It can effectively limit the OAR exposure dose at the same time.
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Objective:To assess the accuracy of dose reconstruction of the in-vivo dose verification EPIgray system in intensity-modulated radiation therapy(IMRT)and volumetric-modulated arc therapy(VMAT)through acceptance testing,and to explore the preliminarily clinical application of that.Methods:A total of 37 patients with cancer at various parts were selected for clinical testing.Referring to the suggestions of the acceptance manual of manufacturer and the American Association of Physicists in Medicine(AAPM)TG-119 report,the square field,strip field and intensity-modulated plan were adopted to test the precision of dose reconstruction of EPIgray system on phantom.The recognition ability of the system for error was researched through changed the thickness of homogeneous phantom and the skin distance of exposure source.A total of 37 patients with cancer at different parts who underwent VMAT were selected to conduct clinical test,and then,the consistence between the dose reconstruction of EPIgray system and the counted dose of treatment plan system were further analyzed.Results:In the tests of square field,EPIgray dose reconstruction demonstrated excellent linearity and higher accuracy.On the phantoms with different thicknesses of fields with different sizes,the highest precision of dose reconstruction of central axis of field was(0.10±0.39)%.The all precisions of dose reconstruction were within 3.0%besides the built region of dose and field edges.In the tests of IMRT and VMAT plan,the deviation of dose reconstruction was<5.0%.With the increasing of the complexity of plan and the heterogeneity of phantom,there was a slight decrease in the reconstruction precision,but all deviations of dose reconstruction were within the range of allowable deviations.In clinical testing of 37 patients,the average reconstruction deviation of the prescription dose point was(-0.6±4.8)%,and the average deviation of sampling points within the range of target area was(-2.1±2.7)%.The reconstruction deviations outside of field and that with large dose gradient were larger.Conclusion:The dose reconstructions of in-vivo dose verification system EPIgray has better consistency with treatment planning system in calculating dose,and the precision of dose reconstruction can meet the requirement of clinical application.
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Objective:To evaluate the dosimetric effects of different aperture shape controller (ASC) parameters based on the Halcyon 3.0 accelerator in the hippocampal avoidance-whole brain radiotherapy (HA-WBRT) plans.Methods:This study enrolled 13 patients treated with WBRT using a Halcyon 3.0 accelerator at the Department of Radiotherapy of the Shuguang Hospital Affiliated to Shanghai University of Traditional Chinese Medicine. According to different aperture shape controller (ASC) parameters, the HA-WBRT plans were divided into six groups, namely non, very low, low, moderate, high, and very high ASC settings, marked by AO, AVL, AL, AM, AH, and AVH, respectively. This study presented a statistical evaluation of the effects of different ASC parameters on conformity index (CI), homogeneity index (HI), radiation doses to the hippocampus and other organs at risk, and the plans’ execution efficiency. Furthermore, using two dose verification tools, namely ArcCHECK and Portal Dosimetry, this study delivered a comprehensive analysis of the differences in beam delivery precision of the plans with different ASC parameters.Results:The six groups all met the requirements for clinical treatment. They had similar CI and HI values, with no statistically significant differences ( P > 0.05). The AVH group showed better protection effects on organs at risk. Compared to the control group, the AVL group showed lower Dmax of brainstems but higher Dmax of chiasma opticum ( F = 6.26, 8.04, P < 0.05). Compared to the control group, the AH group showed lower Dmax of eyeballs but higher Dmax of optic nerves ( F = 2.04, 1.37, P < 0.05). In contrast, the AVH group exhibited lower Dmax of brainstems, eyeballs, and lens than the control group ( F = 6.26, 2.04, 2.02, P < 0.05). No statistically significant differences were observed in dosimetric indices of other organs at risk ( P > 0.05). As verified using ArcCHECK and Portal Dosimetry, the γ passing rates of the six groups were over 98% at 2%/2 mm and 100% at 3%/3 mm. The overall γ passing rates verified using ArcCHECK were lower than those verified using Portal Dosimetry. The maximum difference in the monitor unit among the six groups was less than 15, and these groups did not show significant differences in terms of execution efficiency. Conclusions:The HA-WBRT plans based on the Halcyon 3.0 accelerator can meet the requirements for clinical treatment. Different ASC parameters can significantly optimize the dosimetric parameters. Among them, the AVH parameters can highly reduce the radiation dose to organs at risk. Furthermore, different ASC parameters show insignificant effects on beam delivery precision and plan execution efficiency, meeting the verification standards for clinical therapeutic doses.
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Objective:To perform dosimetric audits on medical accelerators in radiotherapy institutions in Jiangsu province by using a radiophoto luminescent glass dosimeter (RPLGD) and to evaluate both the accuracy of radiotherapy doses and the effectiveness of RPLGD as an auditing tool.Methods:Firstly, the purposive sampling method was used to select three prefecture-level cities in Jiangsu province with good cooperation between radiotherapy institutions and a large number of patients treated by medical accelerators. Secondly, a simple random sampling method was used to select 31 radiotherapy institutions from all radiotherapy institutions in the selected three cities. Finally, one medical accelerator was selected from each institution for dose audit. A dose audit was performed by using RPLGD combined with a 30 cm × 30 cm × 30 cm standard phantom. The dosimeter was placed 10 cm underwater in the center of a 10 cm × 10 cm field with a 100 cm source skin distance. The dosimeter was irradiated with absorbed dose of 2 Gy. After the completion of irradiation, the dosimeter was read by the reader and the deviation was calculated. The acceptance level of the present research was ±5%. A non-parametric test was used to test the significance of differences between different manufacturers, installation years, and geographic distribution.Results:The dose deviation of 31 accelerators was from -16.9% to 2.0%. Of these, 28 accelerators pass the audit with pass rate of 90.3%. A follow-up audit was conducted on the only accelerator whose dose deviation exceeds±10%, also with discrepancy within ±5%. Two accelerators with a dose deviation larger than ±5% were re-measured using ionization chambers, both with dose deviation within ±3%. The non-parametric test result showed that there were no significant statistical differences in dose deviation for accelerators with different manufacturers, installation years, and geographic distribution( P>0.05). Conclusions:The levels of dose deviation for accelerators in Jiangsu province are consistent with those in the previous studies. However, there is still a difference with developed countries. RPLGD is feasible as a dose audit tool. The coverage of the RPLGD audit should be expanded to promote the quality of the radiotherapy through dose aduit.
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Objective:To design a method to introduce random six-dimensional setup error (6D-SE) into the intensity-modulated radiotherapy (IMRT) planning for rectal cancer and evaluate its dosimetric effect.Methods:A total of 21 IMRT plans for patients with rectal cancer were randomly selected as reference plans [2 Gy per fraction for a total of 50 Gy; a 5 mm uniform margin around the clinical target volume (CTV) was taken as the planning target volume (PTV)]. For each fraction of the reference plan, a randomly generated 6D-SE was introduced by adjusting the geometrical parameters of the radiation field, and the dose was recalculated. The overall dose distribution with 6D-SE was obtained by adding up the dose of each fraction. A treatment simulation program that could complete the above workflow was developed using the Varian Eclipse scripting API (ESAPI). 6D-SEs that obey two preset distributions [distribution 1: translational error obey N(0, 4 2), and rotational error obey N(0, 2 2); distribution 2: translational error obey N(0, 2 2), and rotational error obey N(0, 1 2)] were introduced into the reference plans, and the dosimetric effects were assessed. Results:When the reference plans, error distribution 1, and error distribution 2 were applied, the Dmin values of the CTV were (49.4±0.41), (47.56±0.76), and (49.17±0.64) Gy, respectively; the D98% values of the CTV were (50.23±0.07), (49.98±0.10), and (50.27±0.09) Gy, respectively; the D98% values of the primary target area (the kernel part of the target area, excluding the margins) were (50.25±0.08), (50.42±0.13), and (50.33±0.10) Gy, respectively; the D98% values of the marginal area were (50.22±0.10), (49.88±0.11), and (50.26±0.10) Gy, respectively. In addition, compared with the result of the reference plans, the result of errors 1 and 2 showed no significant changes in the mean dose of the bladder and femoral heads ( P>0.05), despite slight decreases in the conformity index of the dose distribution with limited clinical significance. Conclusion:The proposed method and the treatment simulation program developed thereupon can introduce the 6D-SE obeying different distributions into the IMRT plans for rectal cancer on demand and provide overall dosimetric changes.