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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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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 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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Objective:To compare dosimetric and radiobiological parameters between automatic and manual uARC plans in the treatment of esophageal cancer patients, aiming to provide reference for clinical application.Methods:High-quality uARC plans of 100 patients with esophageal cancer were selected, and the mean values of the dosimetric parameters in the target area and organs at risk (OAR) were counted, and the goal table of uRT-TPOIS intelligent plan was established. Automatic and manual uARC plans were generated with UIH (United Imaging) treatment planning system (TPS) for 21 esophageal cancer patients. The differences in mean dose (D mean), approximate minimum (D 98%) and maximum (D 2%) dose of planning target volume (PTV), homogeneity index (HI) and conformity index (CI), dose of OAR, mean planning time, monitor unit (MU), tumor control probability (TCP) and normal tissue complication probability (NTCP) were compared between automatic and manual uARC plans. Normally distributed data between two groups were compared by paired t-test, and non-normally distributed data were assessed by nonparametric Wilcoxon test. Results:The D 98% (PTV 60 Gy: P<0.001, PTV 54 Gy: P=0.001) , CI (PTV 60 Gy: P<0.001, PTV 54 Gy: P=0.002) and target volume of area covered by prescription dose (V 54 Gy: P<0.001) of the automatic uARC plans were better than those of manual uARC plans (all P<0.05). There was no significant difference in D mean or HI between the two plans [PTV 54 Gy (59.32±1.87) Gy vs. (59.13±1.64) Gy, (0.19±0.02) vs. (0.18±0.02), all P>0.05]. The D mean and D max of spinal cord of the automatic plan were better than those of the manual plan [(13.22±4.27) Gy vs. (13.75±4.44) Gy, P=0.020 and (36.99±1.67) Gy vs. (38.14±1.31) Gy, P=0.011]. There was no significant difference in the mean dose of V 20 Gy of the lung between two plans ( P>0.05), whereas the mean doses of V 5 Gy and V 10 Gy of the lung of the manual plan were less than those of the automatic plan ( both P<0. 001). Automatic uARC plan had a significantly shorter mean planning time than manual uARC plan [(11.79±1.71) min vs. (53.36±8.23) min, P<0.001]. MU did not significantly differ between two plans [(762.84±74.83) MU vs. (767.41±80.63) MU, P>0.05]. The TCP of the automatic plan was higher than that of the manual plan (PTV 60 Gy 89.15%±0.49% vs. 86.75%±6.46%, P=0.004 and PTV 54 Gy 79.79%±3.48% vs. 77.51%±5.04%, P=0.006). However, manual plan had a lower NTCP of the lung than automatic uARC plan (0.46%±0.40% vs. 0.35%±0.32%, P<0.001). There was no significant difference in NTCP of heart and spinal cord between two plans (all P>0.05). Conclusion:It is feasible to generate automatic uARC plan with uRT-TPOIS TPS for esophageal cancer patients, which can increase the target CI and shorten the plan design time.
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In recent years, the issue of "reproducibility" of scientific research results has become more and more prominent. Radiobiology is a medical science that studies the biological effect of radiation on living organisms, and there is also a serious problem of "reproducibility of findings". Inaccuracy of physical dose or incomplete dosimetric reports is one of the main causes. Use of guidelines, specifications and recommendations for dosimetric measurement, such as the standardized scoring system for dosimetric reports, will help improving the standardization and accuracy of physical dose measurement in radiobiological research. In this article, multiple guidelines and recommends for improving collaboration between radiobiology and radiation physics, as well as for dose standardization of radiobiological research were evaluated, aiming to provide reference for improving the reproducibility of radiobiological research.
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Objective:To compare the dosimetric differences between the VenusX accelerator with an orthogonal dual-layer multi-leaf collimator (MLC) and the Varian′s CLINAC IX and EDGE accelerators with a single-layer MLC for hippocampus protection in the whole-brain radiotherapy (WBRT).Methods:Forty patients with multiple brain metastases admitted to the Radiotherapy Department of the Shanghai General Hospital from June 2021 to February 2023 were selected in this study. Three whole-brain treatment plans were designed based on the above three accelerators for each patient. Under the same prescription dose, radiation field, and plan constraints, the three plans were compared in terms of the dosimetric differences in target volumes, hippocampi, and adjacent organs at risk (OARs), as well as the execution efficiency.Results:For the planning target volume (PTV), there were statistically significant differences in approximate maximum dose ( D2) between the VenusX and IX plans ( t = 4.94, P < 0.05), in approximate minimum dose ( D98) between the VenusX and EDGE plans ( t = 5.98, P < 0.05), in the target conformity indices (CIs) between VenusX plan and EDGE plans, and between the VenusX and IX plans ( t = -6.84, -14.30; P < 0.05), and dose homogeneity indices (HIs) between the VenusX and IX plans ( t = 3.48, P < 0.05). For OARs, the maximum doses ( Dmax) and average doses ( Dmean) to bilateral hippocampi of the VenusX plan were lower than those of the EDGE and IX plans ( t = 8.59-17.11, P < 0.05); the maximum doses ( Dmax) to bilateral lenses, bilateral optic nerves, and optic chiasma of the VenusX plan were lower than those of the other two plans ( t = 2.10-20.80, P < 0.05); and the differences between the maximum doses ( Dmax) to the brain stem of the VenusX and EDGE plans were statistically significant ( t = 3.86, P < 0.05). In terms of plan execution efficiency, the number of machine jumps (MU) and the treatment time of the VenusX plan were higher than those of the EDGE and IX plans, with statistically significant differences ( t = -56.48, -56.90, P < 0.05). Conclusions:The doses to target volumes of the three treatment plans all meet the prescription requirements, and the VenusX plan outperforms the EDGE and IX plans in the protection of OARs. Despite the reduced execution efficiency, the VenusX plan shortens the actual treatment time by improving the dosage rate, thus meeting the clinical requirements.
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Objective:To investigate the level of radiation doses to adults caused by CT examination in Huai′an, and explore the local CT diagnostic reference levels (DRLs).Methods:Totally 45 CT scaners were selected to investigate the information on hospitals, equipment, scanning parameters, and radiation doses. Empirical formula were used to estimate the effective dose to adults. Nonparametric rank sum tests were used to analyze differences in radiation dose level between CT service age and hospital grade.Results:A total of 3 483 patients were collected, including 890 for head examinations, 890 for chest, 846 for abdomen, and 857 for lumbar spine. The 75% percentile values of CTDI vol to adult patients from CT scanning for head, chest, abdomen, lumbar spine examinations were 63.0, 12.4, 20.0 and 24.0 mGy, respectively. The 75% percentile values of DLP were 858.6, 416.0, 620.7 and 559.2 mGy·cm, respectively. The 75% percentile values of DLP for males was higher than those for females. There were significant statistical differences in radiation doses dependent on equipment service (head: U =10 326.00, P<0.05; chest: U=36 094.50, P<0.05; abdomen: U= 7 859.00, P<0.05; lumbar spine: U=42 408.00, P<0.05), and hospital grade (head: H=14.280, P<0.05; chest: H=17.85, P<0.05; abdomen: H=97.18, P<0.05; lumbar spine: H=138.94, P<0.05). Conclusions:The CT radiation dose levels in Huai′an city is basically consistent with standard-reommended values, which is in line with the current status of CT equipment dose levels in the country. It is necessary to strengthen the quality control and maintenance of CT equipment.
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Objective:To comprehensively evaluate the effects of different bolus usages in postmastectomy intensity-modulated radiotherapy (PM-IMRT) on doses.Methods:Fifty patients receiving PM-IMRT at Fudan University Shanghai Cancer Center from April to October 2021 were retrospectively studied. The planning target volume (PTV) was divided into four parts, namely chest wall (CW), internal mammary node, retained axillary lymph node, and supraclavicular node. The prescription dose was 50 Gy/25 fractions. Three PM-IMRT plans applying boluses with different thicknesses (3, 5 and 10 mm) were designed for each patient. The effects of different thicknesses and usage frequencies of boluses on PTV coverage, high dose volume of the CW skin, and dose to surrounding normal tissues were comprehensively evaluated.Results:When boluses were applied throughout the PM-IMRT, the PTV V95% of plans applying 10 mm-thick boluses was lower than that of plans applying 3 and 5 mm-thick boluses ( F=3.340, P < 0.05), the CI of plans applying 3 mm-thick boluses was higher than that of plans applying 5 and 10 mm-thick boluses ( F = 50.05, P < 0.05), and there was no statistically significant differences in the skin V105% and V110% of three plans( P > 0.05). Both PTV V95% and skin V105% were reduced with a decrease in the usage frequency of boluses. At a frequency of 20, PTV V95% decreased slightly (< 1%), while skin V105% decreased sharply to nearly half of the original values. At a frequency of 15, the PTV V95%, CI, and HI in the three plans showed no statistically significant dosimetric differences ( P > 0.05). The PTV Dmax of plans applying 3 mm-thick boluses was lower than that of plans applying 5 and 10 mm-thick boluses ( F = 9.21, P < 0.05). As for the dose to surrounding normal tissues, different bolus thicknesses and frequencies had negligible effects on doses to heart and lung, causing little different biological effects. Conclusions:For PM-IMRT, different bolus thicknesses have similar effects on doses to the PTV, skin, heart, and lung. Bolus usage frequency, rather than thickness, was the major factor determining the PTV coverage and the dose to CW skin.
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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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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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Radioterapia de Intensidad Modulada/métodos , Titanio , Dosificación Radioterapéutica , Aleaciones , Radiometría/métodos , Planificación de la Radioterapia Asistida por Computador/métodosRESUMEN
Objective:To analyze the cardiac dosimetry of lymph node irradiation in the internal breast region after left-sided breast cancer surgery and to assess its impact on patients' quality of life.Methods:The clinical data of 108 patients who underwent inverse intensity modulated radiotherapy (IMRT) after left-sided breast cancer surgery in Cancer Hospital of Nantong University from May 2019 to May 2021 were collected and retrospectively analyzed, and divided into a study group (with internal breast, 55 cases) and a control group (without internal breast, 53 cases) according to whether the postoperative radiotherapy included lymph node irradiation in the internal breast region. The dosimetric indexes of planned target area (PTV) , cardiac tolerance, serum myocardial injury markers and quality of life before and after radiotherapy were compared between the two groups.Results:In terms of PTV dosimetry, the conformality index (CI) of the study group and the control group were 0.73±0.07 and 0.75±0.08, the homogeneity index (HI) were 0.17±0.03 and 0.17±0.02, the D max were (55.69±1.02) Gy and (55.46±1.13) Gy, the D mean were (50.54±0.23) Gy and (50.48±0.21) Gy respectively, there were no statistically significant differences ( t=1.38, P=0.169; t<0.01, P>0.999; t=1.11, P=0.269; t=1.41, P=0.160) . In terms of cardiac receptivity, the D mean of the two groups were (5.93 ± 0.32) Gy, (5.64 ± 0.30) Gy, V 40 were (0.47 ± 0.10) %, (0.41 ± 0.11) %, and V 30 were (2.48 ± 0.51) %, (2.06 ± 0.49) % respectively, and there were statistically significant differences ( t=4.86, P<0.001; t=2.97, P=0.004; t=4.36, P<0.001) . The levels of serum troponin Ⅰ (cTnⅠ) before radiotherapy in the study group and the control group were (0.09±0.02) ng/ml and (0.09±0.01) ng/ml, creatine kinase isoenzyme MB (CK-MB) were (0.27±0.08) U/L and (0.25±0.08) U/L, myoglobin (MYo) were (3.84±1.02) μg/L and (3.69±0.97) μg/L, and brain natriuretic peptide (BNP) were (172.35±16.24) pg/ml and (169.81±15.93) pg/ml respectively, there were no statistically significant differences ( t<0.01, P>0.999; t=1.30, P=0.197; t=0.78, P=0.436; t=0.82, P=0.414) . One month after radiotherapy, the levels of serum cTnⅠ in the two groups were (0.09±0.03) ng/ml and (0.09±0.02) ng/ml, CK-MB were (0.29±0.09) U/L and (0.28±0.08) U/L, MYo were (4.06±1.08) μg/L and (4.01±1.03) μg/L, and BNP were (175.13±17.09) pg/ml, (172.47±16.28) pg/ml respectively, there were no statistically significant differences ( t<0.01, P>0.999; t=0.61, P=0.544; t=0.25, P=0.806; t=0.83, P=0.410) . The European Organization for Research and Treatment of Cancer Quality of Life Questionnaire Core 30 (EORTC QLQ-C30) scores before radiotherapy in the study and the control groups were (60.24±5.13) points and (61.19±5.46) points, (74.12±7.20) points and (75.35±7.88) points at 1 month after radiotherapy, (77.53±7.14) points and (78.95±7.08) points at 6 months after radiotherapy, and (75.02±6.93) points and (76.68±6.74) points at 1 year after radiotherapy respectively, there were no statistically significant differences ( t=0.93, P=0.353; t=0.85, P=0.399; t=1.04, P=0.302; t=1.26, P=0.210) . The EORTC QLQ-C30 scores at 1 month, 6 months, and 1 year after radiotherapy were higher than those before radiotherapy in the two groups, and there were statistically significant differences (all P<0.001) . Conclusion:IMRT containing lymph node irradiation in the internal breast region after left breast cancer surgery brings a certain degree of increased cardiac dose, but it is feasible to control it within a certain range and does not affect the patients' cardiac function or quality of life in the short term.
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Abstract This study evaluated the centralization of the region of interest (ROI) in acquisition of the CBCT images, when the freely positionable scout-view (SV) function is applied. Additionally, the dosimetry of the acquired images was assessed in the SV function alone as well as in complete tomographic image in two different fields of view (FOV) (50x50 and 78x150mm). A three-location device was created to accommodate the dosimeters and the specimens, in the right, middle and left location during image acquisition. For dose assessment, thermoluminescent dosimeters were irradiated within the FOV and analyzed in a portable reader. For ROI evaluation, three specimens of gutta-percha stick were placed on the same device and the CT scans were acquired (CBCT OP 300 Maxio device, 90kV, 13mA, 85 µm voxel size, FOV of 50X50mm), with and without the SV, in three positions (3-9, 1-7 and 5-11 o'clock), simulating different regions of the mouth. Two image evaluations were performed, an objective and subjective. There was a slight percentage increase (1.36% to 1.40%) of the radiation dose with the use of SV. The distances were significantly greater in the images acquired without SV (p < 0.05). Every image obtained with SV was classified as being at the FOV's center. In conclusion, the results demonstrated that SVs function is effective to centralize the ROI in the FOV, increasing the scan precision and avoiding repetitions due to positioning errors.
Resumo Este estudo avaliou a centralização da região de interesse (ROI) na aquisição das imagens de TCFC, quando a função scout-view (SV) posicionável livremente é aplicada. Adicionalmente, a dosimetria das imagens adquiridas foi avaliada isoladamente na presença da função SV, bem como após aquisição de imagem tomográfica completa em dois diferentes campos de visão (FOV) (50x50 e 78x150mm). Um dispositivo de três localizações foi criado para acomodar os dosímetros e os espécimes, na localização direita, central e esquerda, durante a aquisição das imagens. Para avaliação da dose, dosímetros termoluminescentes foram irradiados dentro dos campos de visão e analisados em leitor portátil. Para avaliação da ROI, três espécimes de guta percha foram colocados no mesmo aparelho e as tomografias foram adquiridas (CBCT OP 300 Maxio, 90kV, 13mA, 85 μm tamanho de voxel, FOV de 50X50mm), com e sem a SV, em três posições (3-9, 1-7 e 5-11 horas), simulando diferentes regiões da boca. Foram realizadas duas avaliações de imagem, uma objetiva e outra subjetiva. Houve um leve aumento percentual (1,36% para 1,40%) da dose de radiação com o uso de SV. As distâncias foram significativamente maiores nas imagens adquiridas sem SV (p < 0,05). Todas as imagens obtidas com SV foram classificadas como sendo do centro do FOV. Em conclusão, os resultados do presente estudo demonstraram que a função scout view é eficaz para centralizar a ROI no FOV, aumentando a precisão do escaneamento e evitando repetições devido a erros de posicionamento.
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Resumen Introducción: el laboratorio de citogenética del Instituto de Investigaciones en Salud (INISA) de la Universidad de Costa Rica estableció un Servicio de Dosimetría Biológica en enero del 2020 utilizando biomarcadores citogenéticos de exposición a radiaciones ionizantes. Es el primero de su tipo en la región centroamericana. Objetivo: establecer un servicio de dosimetría biológica para Costa Rica, elaborando una curva de calibración dosis-efecto para rayos gamma. Metodología: para la realización de la curva de calibración se irradiaron muestras de sangre periférica in vitro con rayos gamma de dos voluntarios, uno femenino y otro masculino, en 11 puntos de dosis en el rango de 0 a 5 Gy. Se cultivó la sangre acorde a los protocolos internacionales durante 48 horas y se registraron las aberraciones inducidas. Los programas Dose Estimate V5.2 y R versión 4.03 se utilizaron para el cálculo de los coeficientes de la curva de calibración que correlaciona la frecuencia de cromosomas dicéntricos con la dosis. Resultados: los coeficientes de la curva son α: 0.02737±0.00658, ß: 0,05938±0,00450 y C: 0.00129±0.00084. Estos coeficientes tienen valores similares a los reportados internacionalmente. La curva se validó calculando dos dosis incógnitas, en la primera incógnita la dosis suministrada fue de 1,5 Gy y la dosis estimada fue 1,47 Gy y en la segunda la dosis suministrada fue de 4 Gy y la dosis estimada fue 3,616 Gy, para ambos casos no existen diferencias estadísticamente significativas entre las dosis suministradas y las estimadas. Conclusiones: actualmente El Servicio de Dosimetría Biológica del INISA puede estimar dosis absorbida en personas que se sospecha de una sobre exposición a rayos gamma en personal ocupacionalmente expuesto o personas involucradas en un accidente radiológico.
Abstract Introduction. The cytogenetics laboratory of the Health Research Institute (INISA) of the University of Costa Rica established a Biological Dosimetry Service in January 2020 using cytogenetic biomarkers of exposure to ionizing radiation. It is the first of its kind in the Central American region. Objective: establish a biological dosimetry service for Costa Rica, developing a dose-effect calibration curve for gamma rays. Methodology: to carry out the calibration curve, peripheral blood samples from two volunteers, one female and the other male, were irradiated in vitro with gamma rays, at 11 dose points in the range of 0 to 5 Gy. Blood was cultured according to international protocols for 48 hours and induced aberrations were recorded. The Dose Estimate V5.2 and R version 4.03 programs were used to calculate the coefficients of the calibration curve that correlates the frequency of dicentric chromosomes with the dose. Results: the coefficients of the curve are α: 0.02737 ± 0.00658, ß: 0.05938 ± 0.00450 and C: 0.00129 ± 0.00084. These coefficients have values similar to those reported internationally. The curve was validated by calculating two unknown doses, in the first unknown case the delivered dose was 1.5 Gy and the estimated dose was 1.47 Gy and in the second case the delivered dose was 4 Gy and the estimated dose was 3.616 Gy. for both cases there are no statistically significant differences between the delivered and estimated doses. Conclusions: the Biological Dosimetry Service of the INISA can estimate absorbed dose in persons suspected of overexposure to gamma rays in occupationally exposed personnel or persons involved in a radiological accident.Health is loaded with symbolisms and practical manifestations that differ according to social groups and sociocultural contexts. In order to make everyday life and needs visible, the Theoretical Paradigm of Social Representations provides the theoretical-methodological bases necessary to understand the common sense knowledge associated with health among the Nicaraguan migrant population in Costa Rica. Methodology: Qualitative study with ethnographic approach that aimed to identify the social representation of health, through the process of objectification, present among Nicaraguan migrants living in Costa Rica. Data collected through semi-structured interviews, participant observation, and field diaries. Processing according to Content Analysis. Results: The social representation of health found behaves analogously to a formula; where, the search for peaceful environments is added to the achievement of financial stability to result in two interdependent representations: 1) Health as physical-mental strength; and 2) Health as a future and abstract sensation of well-being, happiness and transcendence. The socio-political antecedents in Nicaragua, the migratory process, and the adaptation to Costa Rica play a preponderant role in shaping the representation on health. Conclusion: Social representations about health have direct practical implications on the ways of life and needs of migrant groups. Understanding their common sense knowledge allows to move towards more contextualized public policies. More integration of the thoughts, opinions and feelings of migrants in decision-making platforms is recommended.
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Humanos , Masculino , Femenino , Radiación Ionizante , Dosimetría , Costa Rica , Rayos gammaRESUMEN
Objective:To compare three fixed-field intensity-modulated radiotherapy (IMRT) plans for nasal cavity and paranasal sinus tumors, including the coplanar IMRT (C-IMRT) plan and the non-coplanar IMRT(NC-IMRT) plan which were based on a conventional C-arm LINAC (Trilogy), and the coplanar IMRT (H-IMRT) plan based on an O-ring LINAC (Halcyon).Methods:Based on the data of 10 patients in the Ningbo First Hospital from December 2018 to December 2021 with nasal cavity and paranasal sinus tumors who underwent postoperative radiotherapy, this study redesigned three IMRT plans with the same prescribed doses and optimization objectives. Then, this study compared the doses of target volumes and organ at risks(OARs), the validation pass rates, and the execution time of these plans. Friedman test was employed in this study, and multiple comparisons were further made in cases of different results.Results:The differences in the conformal index (CI) of PTV and PTV boost of the three plans were statistically significant ( χ2 = 7.51, 9.69, P < 0.05). The multiple comparisons showed that the median CI of the H-IMRT plan was higher than that of the NC-IMRT plan ( Z = 2.53, 2.68, P < 0.05). The differences in other parameters of target volumes were not statistically significant. Compared with the C-IMRT plan, the H-IMRT plan reduced the Dmax of bilateral lenses, bilateral corneas, ipsilateral optic nerve, and ipsilateral eyeball ( Z = 2.80, 2.80, 2.80, 2.80, 2.81, 2.09, P < 0.05). Compared with the C-IMRT plan, the NC-IMRT reduced the Dmax of bilateral lenses, corneas, and eyeballs and contralateral optic nerve ( Z = 2.80, 2.66, 2.80, 2.70, 2.29, 2.29, 2.65, P < 0.05) and reduced the Dmean of bilateral eyeballs ( Z = 2.80, 2.80, P < 0.05). Compared with the NC-IMRT plan, the H-IMRT plan reduced the Dmax of the ipsilateral lens and cornea ( Z = 2.50, 2.08, P < 0.05), but increased the Dmax of the contralateral optic nerve and the Dmean of bilateral eyeballs ( Z = 2.80, 2.80, 2.80, P < 0.05). The validation pass rate of the three plans met the institutional standards, and the differences were not statistically significant. Moreover, the H-IMRT plan had the shortest median execution time (172.00 s), followed by the C-IMRT plan (337.50 s), and the NC-IMRT plan (388.00 s). Conclusions:The verification pass rate of the three plans can achieve the requirements of treatment implementation. The three plans had similar dosimetric differences in target volumes. However, the H-IMRT and NC-IMRT plans can protect the normal tissues (especially optical organs) more effectively than the C-IMRT plan, which is conducive to reducing the toxicity after radiotherapy and provides space for local dose increase or the radiotherapy for the treatment of tumor recurrence. The execution efficiency of the three plans is in the order of H-IMRT > C-IMRT > NC-IMRT. It is necessary to select appropriate radiotherapy equipment and technology according to actual situations.
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Objective:To study the differences in the dosimetry and delivery time between helical tomotherapy (HT) and volumetric modulated arc therapy (VMAT) in postoperative radiotherapy of synchronous bilateral breast cancer (SBBC) and to explore the feasibility of clinical application of the HT technology.Methods:A retrospective analysis was conducted for nine SBBC patients who underwent modified radical postoperative radiotherapy in the Fourth Affiliated Hospital of Guangxi Medical University from February 2017 to May 2022. For each patient, the Precision planning system was used to formulate the HT plan, and the RayStation planning system was employed to develop the VMAT plan. All plans obtained were divided into HT group and VMAT group according to plan type. The paired sample t-test was used to compare the dosimetric parameters of the target volume and organ at risk (OAR) and delivery time between the two radiotherapy technologies. Results:The plans of both groups could meet the clinical treatment requirements. The coverage ( D95% and V100%), conformity index (CI), average dose ( Dmean), and median dose ( D50%) of the target volumes in the HT group were better than those in the VMAT group, and the differences were statistically significant ( t=-3.21, -3.39, -5.03, 3.76, 4.97, P < 0.05). The differences in the maximum dose ( D2%), minimum dose ( D98%), high dose volumes ( V107% and V110%), and homogeneity index (HI) of the target volumes between the two groups were not statistically significant ( P > 0.05). Regarding the OAR, the V20 and Dmean of both lungs in the HT group were significantly lower than those in the VMAT group, but the irradiation volume V5 of both lungs in the HT group was significantly higher than that in the VMAT group ( t=-3.01, 3.83, -2.81, P < 0.05). Moreover, V20, V30, V40, and Dmean of heart and the V20 and Dmean of liver in the HT group were significantly lower than those in the VMAT group, with statistically significant differences ( t=3.76, -2.83, -2.74, 5.93, 4.57, 4.48, P < 0.05). There was no significant difference in the radiation doses to other OARs (spinal cord, thyroid gland, and humerus head, P > 0.05). The delivery time of the HT group was significantly higher than that of the VMAT group ( t = 11.32, P < 0.05). Conclusions:Compared with VMAT, HT has greater dosimetric advantages, and can provide higher target coverage, conformability and average dose, and significantly reduce the overall radiation doses to both lungs, heart, and liver in OARs. However, the irradiation volume V5 at low-dose areas of both lungs and the delivery time in the HT group are higher than those in the VMAT group, but still meet the clinical treatment requirements. Therefore, it is feasible to apply the HT technology to the modified radical postoperative radiotherapy of SBBC.
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Objective:To evaluate the effects of orthogonal magnetic fields on the dose distribution of 6 MeV X-ray in a uniform water and heterogeneous phantoms.Methods:The Monte Carlo simulation software Gate v8.2 was used to investigate the dose distribution of X-ray beams of different field sizes in a uniform water phantom, water-air/bone-water layer phantom and" custom lung model" in the magnetic field strength of 0.0, 0.5, 1.0, 1.5, 3.0 T, respectively. The relationship between the intensity of magnetic field and the dose distribution of X-rays in the phantoms was analyzed.Results:The existence of a magnetic field would cause the X-ray to shorten the built-up area in the water phantom; when the field was 10 cm×10 cm, the maximum dose on the central axis could change by up to 56.22%(3.0 T). The transverse dose distribution of the radiation field in the direction of the vertical magnetic field shifted to one side by up to 43.64%(-44.55%). The average dose of the air layer in the water-air-water phantom could be reduced by 57.4%(3.0 T). In the water-bone-water phantom, the dose at the proximal end of the bone layer was decreased by 16.5%, whereas the dose at the distal end was increased by 22.6%(1.5 T). The dose change in each layer in the customed lung model was positively correlated with the magnetic field strength.Conclusion:The existence of the orthogonal magnetic field will cause the change of X-ray dose distribution on the built-up area and both sides of the radiation field in the phantoms, which is more obvious adjacent to the interface of heterogeneous phantom.
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Objective:To compare the dosimetry and efficacy of intracavitary brachytherapy (ICBT) and intracavitary/interstitial brachytherapy (IC+ ISBT) based on CT image guidance in the treatment of stage Ⅲ B cervical cancer. Methods:Clinical data of 93 patients with stage Ⅲ B cervical cancer treated in Department of Radiotherapy of Jilin Cancer Hospital from June 2014 to February 2017 were analyzed retrospectively. According to the results of Gynecological examination and pelvic MRI before brachytherapy, confirming the size of residual tumor and the degree of parauterine infiltration, all patients were divided into the ICBT and IC+ ISBT groups. The D 90%, D 100%, V 100% and D 2cm 3 of bladder and rectum were compared, and the short-term and long-term efficacy was observed between two groups. Results:The median follow-up time was 60 months. The 5-year local control rate, distant metastasis-free survival rate and overall survival rate of all patients were 83%, 71% and 68%, respectively. Compared with the ICBT group, HR-CTV D 90% in the IC+ ISBT group was all more than 85 Gy, while there was no significant difference between two groups ( P=0.188). The D 2cm 3 of bladder and rectum in the IC+ ISBT group was significantly decreased by 7 Gy and 8 Gy (both P<0.01), and the distant metastasis-free survival rate was significantly improved ( P=0.009). The 5-year local control rate in the HR-CTV volume>60 cm 3 in the IC+ ISBT group was significantly higher than that in the IC group ( P=0.029). Conclusion:For patients with Ⅲ B cervical cancer, IC+ ISBT can not only ensure target coverage, but also significantly reduce the incidence of distant metastasis and the dose of organs at risk, and significantly improve the local control rate of large tumors.
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Objective:To perform testing and clinical application of a volumetric-modulated arc therapy (VMAT) dosimetry verification system based on three-dimensional dose reconstruction of patient anatomical structures.Methods:ArcCheck array calibration was performed. Then, 200 MU was delivered with a 10 cm×10 cm field when the source to center of ArcCheck was 100 cm to calibrate the absolute dose and the dose was simultaneously measured by a FC65-G detector in the center of the ArcCheck. The absolute dose calibration value or the CT value of ArcCheck was adjusted to minimize the differences between the planning and measurement values of FC65-G, reconstructed value by 3DVH and reconstructed percent depth dose by 3DVH. 10 lung and 10 cervical cancer VMAT cases were selected and measured by ArcCheck and FC65-G under the delivery of a TrueBeam LINAC. The three-dimensional doses of all cases were reconstructed by 3DVH and compared with the planning and measurement values.Results:Different array calibration files of ArcCheck exerted different effect upon the two-dimensional dose measured by ArcCheck and three-dimensional dose reconstructed by 3DVH. The optimal reconstructed dose was obtained when self-calibration file was adopted and 249.96 cGy was regarded as the absolute dose calibration value. The deviations of the mean dose (D mean) and D 95% of the target were within ±4.2% and parameters of some organs at risk significantly differed compared with the reconstructed and planning dose for all cases. A negative mean point dose difference was obtained and the reconstructed dose was closer to the measured value. The γ-passing rate of the target for some cases was low, the proportion of regions irradiated by 50% prescription dose was slightly higher and the proportion of other organs was relatively high. Conclusion:The 3DVH model can be accurately established and tested with the acceptance test method in the present study, which can provide detailed information for dose verification.
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Objective:To investigate the safety and dose of 4D template (real-time adjustable angle template) in the treatment of advanced malignant tumors with 125I seeds. Methods:98 patients with advanced malignant tumors admitted to Department of Thoracic Surgery of Shaanxi Provincial Tumor Hospital were treated with 4D template-navigated radioactive 125I seed implantation from June 2018 to December 2019. Preoperative TPS plan, intraoperative optimization, postoperative verification of immediate dose and postoperative evaluation of implantation dose were performed. The treatment results were observed. Results:All 98 patients completed the seed implantation. The implantation dose of GTV of implantation site receiving external irradiation was (12 489±414) cGy and the dose of no external irradiation was (15 036±514) cGy. V 100% was 84.7%-94.1%, and 88.2%-93.7%. The implantation dose of CTV was (7 450±621) cGy, and (9 080±761) cGy. The quality of dose implantation was evaluated as: excellent in 89 cases (91%, 89/98), good in 7 cases (7%, 7/98), fair in 2 cases (2%, 2/98), and poor in 0 case, respectively. The symptom relief rate of patients with pain was 92%(36/39). The 1-and 2-year local control rates were 61%, 36% and 82%, 54% in patients treated with and without external irradiation, respectively. The difference was statistically significant ( P=0.02). The incidence rates of pneumothorax and hemoptysis were 19%(9/48) and 10%(5/48). No corresponding complications were observed in other parts of the patients. Conclusion:4D template-assisted 125I seed therapy is safe and effective for malignant tumors, and intraoperative adjustment of needle angle and dose optimization can realize the precise control of implantation dose.
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Objective:To introduce the clinical dosimetry commissioning methods and results of the 1.5 T MR-linac.Methods:In May, 2019, an Elekta Unity 1.5 T MR-linac was installed in Cancer Hospital, Chinese Academy of Medical Sciences and dosimetry commissioning was performed with magnetic field compatible measuring instruments. Commissioning items include absolute dose calibration, data acquisition and planning system model verification.Results:Absolute dose calibration in magnetic field should be corrected by magnetic field correction factor. The standard output dose of Unity was 87 cGy. Gamma analysis (3%/2 mm) was performed on the beam collection data and the planning system calculation data. The average pass rate of dose verification of standard field test cases was 96.41%, and the TG119 test case was 98.24%. The IROC end to end test case was 97.5%(7%/4 mm).Conclusions:The planning system model and the beam collection data have good consistency. The dose verification results of the standard field and TG119 test cases meet the general tolerance limit requirements of the AAPM TG218 report, and the verification results of the IROC end-to-end test cases meet the IROC center standards.