The accuracy of the position measurements obtained by the radiation positioning system (RADPOS) was evaluated under static and dynamic conditions. In the static verifications, the RADPOS was fixed to the treatment cou...The accuracy of the position measurements obtained by the radiation positioning system (RADPOS) was evaluated under static and dynamic conditions. In the static verifications, the RADPOS was fixed to the treatment couch in a photon treatment room and a proton treatment room, and was translocated with the treatment couch in x, y and z directions. Because the presence of magnetic and/or electrically conductive materials can cause a systematic shift in the measured position by distorting the RADPOS transmitted field, the effect of metals on the performance of the positioning system was also investigated. Dynamic verification was performed using the couch drive and a dynamic anthropomorphic thorax phantom. We thus confirmed the utility of RADPOS as a position sensor to perform in vivo dosimetry.展开更多
Purpose: During computed tomography (CT) helical scanning mode the patient surface dose distribution is assumed to be non-uniform, therefore point dose measurement methods may lead to imprecise estimation of the radia...Purpose: During computed tomography (CT) helical scanning mode the patient surface dose distribution is assumed to be non-uniform, therefore point dose measurement methods may lead to imprecise estimation of the radiation dose received by the patient skin in particular. We have used XRQA2 films as in-vivo dosimeters to measure the entrance skin dose during sinus exams. Methods: The films were placed under the patient head rest in order to sample the entrance surface dose in-vivo. We have performed in-vivo film irradiation on 23 patients in this study to verify the clinical suitability of the method and were found adequate. Results: The measured average ESD in the sinus exam was 11.7 ± 1.0 mGy, the PSD was 15.7 ± 1.7 mGy and the CTDI(vol) was 13.3 ± 0.1 mGy. The ratio of ESD/CTDI(vol) and PSD/CTDI(vol) was 0.88 and 1.18 respectively. The results indicate that the scanner registered CTDI(vol) underestimates the PSD and in the same time it overestimates the ESD by 18% and 13.6% respectively. Conclusion: The observed differences between the ESD, PSD and CTDI(vol) although seem small for the radiation dose range measured during CT of the sinus [13.2 - 13.4] mGy, but important for the medical physicist to know, since monitoring of patients’ doses from CT examinations is becoming more mandatory. The use of radiochromic film as in-vivo dosimeter does not interfere with the clinical radiological exam and does not produce any image artifacts. The method can be used to study other CT examinations specially the ones with large beam width, high pitch factor and high dose exams. The method allows measurement of the peak skin dose, examination of the CT dose profile and the 2D dose distribution in the XZ plan.展开更多
This study reports the dosimetric response of a(ZnO)_(0.2)(TeO_(2))_(0.8)thin film sensor irradiated with high-energy X-ray radiation at various doses.The spray pyrolysis method was used for the film deposition on sod...This study reports the dosimetric response of a(ZnO)_(0.2)(TeO_(2))_(0.8)thin film sensor irradiated with high-energy X-ray radiation at various doses.The spray pyrolysis method was used for the film deposition on soda-lime glass substrate using zinc acetate dehydrate and tellurium dioxide powder as the starting precursors.The structural and morphological properties of the film were determined.The I-V characteristics measurements were performed during irradiation with a 6 MV X-ray beam from a Linac.The results revealed that the XRD pattern of the AS-deposited thin film is non-crystalline(amorphous)in nature.The FESEM image shows the non-uniform shape of nanoparticles agglomerated separately,and the EDX spectrum shows the presence of Te,Zn,and O in the film.The I-V characteristics measurements indicate that the current density increases linearly with X-ray doses(0-250 cGy)for all applied voltages(1-6 V).The sensitivity of the thin film sensor has been found to be in the range of 0.37-0.94 mA/cm^(2)/Gy.The current-voltage measurement test for fading normalised in percentage to day 0 was found in the order of day 0>day 15>day 30>day 1>day 2.These results are expected to be beneficial for fabricating cheap and practical X-ray sensors.展开更多
Purpose: To present a protocol of a dual-field rotational (DFR) total skin electron therapy (TSET) and to provide an assessment of clinical implementation, dosimetry properties, and skin dose evaluation. Methods and M...Purpose: To present a protocol of a dual-field rotational (DFR) total skin electron therapy (TSET) and to provide an assessment of clinical implementation, dosimetry properties, and skin dose evaluation. Methods and Materials: The DFR-TSET combined the Stanford 6-field and McGill rotational methods. Dual 6 MeV electron beams in high dose total skin electron mode were used for DFR-TSET on a commercial linac. Beam profiles and dosimetric properties were measured using solid phantoms. The dose rate at expanded source-to-surface distance (SSD) was a combination of static rate and rotational rate. In vivo dosimetry of patient skin was performed on patients’ skin using film, metal oxide semiconductor field-effect transistors (MOSFET), and optically stimulated luminescent dosimeters (OSLD). Results: Dual field rotational total skin electron therapy exhibited good (≤±10%) uniformity in the beam profiles in the vertical direction at an extended SSD of 332 cm with a gantry angulation of ±20˚ deviated from the horizontal direction. In-vivo measurements confirmed acceptable uniformity of the patients’ total body surfaces and revealed anatomically self-blocked or shielded areas where underdosing occurred. Conclusions: The clinical implementation of DFR-TSET effectively utilizes the special mode on a linac. This technique provides short beam-on times, uniform dose distribution, large treatment field, and reduced dose of x-ray contamination to the patients. In-vivo measurements indicate satisfactory delivery and dose uniformity of the prescribed dose. Electron boost fields are recommended at normal SSDs to address underdosed areas.展开更多
目的利用CiteSpace文献计量学软件,本文对KM小鼠的研究现状和热点进行了可视化分析,旨在为国内KM小鼠研究的突破和创新提供依据。方法本文基于中国知网和Web of Science两个数据库,纳入了2004年1月1日~2023年6月10日的3981篇KM小鼠相关...目的利用CiteSpace文献计量学软件,本文对KM小鼠的研究现状和热点进行了可视化分析,旨在为国内KM小鼠研究的突破和创新提供依据。方法本文基于中国知网和Web of Science两个数据库,纳入了2004年1月1日~2023年6月10日的3981篇KM小鼠相关文献,分析了其发文量、国家(地区)、机构、作者合作网络、关键词共现、聚类、突现词和英文文献被引情况。结果KM小鼠研究中文文献发文量波动下降,英文文献发文量逐渐上升,国内外对于KM小鼠的研究热度不同。发文最多的3个国家是中国、美国和日本,国内的主要研究机构有中国农业大学、南京中医药大学以及中国科学院等,发文量较多的作者主要是刘慧雯、李光武和赵欣等。国内期刊研究内容主要集中于KM小鼠毒理学、免疫学和生殖学方面,国外期刊研究主要集中于KM小鼠细胞生物学、生理学方面。结论目前,KM小鼠在我国已有80余年的应用与推广历史,主要集中在毒理学、免疫学和生殖学方面研究。KM小鼠虽在实验方面有一定成果,但规范化种群培育、优势研究领域发掘以及动物伦理的进一步推进是未来需要继续解决的问题。展开更多
文摘The accuracy of the position measurements obtained by the radiation positioning system (RADPOS) was evaluated under static and dynamic conditions. In the static verifications, the RADPOS was fixed to the treatment couch in a photon treatment room and a proton treatment room, and was translocated with the treatment couch in x, y and z directions. Because the presence of magnetic and/or electrically conductive materials can cause a systematic shift in the measured position by distorting the RADPOS transmitted field, the effect of metals on the performance of the positioning system was also investigated. Dynamic verification was performed using the couch drive and a dynamic anthropomorphic thorax phantom. We thus confirmed the utility of RADPOS as a position sensor to perform in vivo dosimetry.
文摘Purpose: During computed tomography (CT) helical scanning mode the patient surface dose distribution is assumed to be non-uniform, therefore point dose measurement methods may lead to imprecise estimation of the radiation dose received by the patient skin in particular. We have used XRQA2 films as in-vivo dosimeters to measure the entrance skin dose during sinus exams. Methods: The films were placed under the patient head rest in order to sample the entrance surface dose in-vivo. We have performed in-vivo film irradiation on 23 patients in this study to verify the clinical suitability of the method and were found adequate. Results: The measured average ESD in the sinus exam was 11.7 ± 1.0 mGy, the PSD was 15.7 ± 1.7 mGy and the CTDI(vol) was 13.3 ± 0.1 mGy. The ratio of ESD/CTDI(vol) and PSD/CTDI(vol) was 0.88 and 1.18 respectively. The results indicate that the scanner registered CTDI(vol) underestimates the PSD and in the same time it overestimates the ESD by 18% and 13.6% respectively. Conclusion: The observed differences between the ESD, PSD and CTDI(vol) although seem small for the radiation dose range measured during CT of the sinus [13.2 - 13.4] mGy, but important for the medical physicist to know, since monitoring of patients’ doses from CT examinations is becoming more mandatory. The use of radiochromic film as in-vivo dosimeter does not interfere with the clinical radiological exam and does not produce any image artifacts. The method can be used to study other CT examinations specially the ones with large beam width, high pitch factor and high dose exams. The method allows measurement of the peak skin dose, examination of the CT dose profile and the 2D dose distribution in the XZ plan.
文摘This study reports the dosimetric response of a(ZnO)_(0.2)(TeO_(2))_(0.8)thin film sensor irradiated with high-energy X-ray radiation at various doses.The spray pyrolysis method was used for the film deposition on soda-lime glass substrate using zinc acetate dehydrate and tellurium dioxide powder as the starting precursors.The structural and morphological properties of the film were determined.The I-V characteristics measurements were performed during irradiation with a 6 MV X-ray beam from a Linac.The results revealed that the XRD pattern of the AS-deposited thin film is non-crystalline(amorphous)in nature.The FESEM image shows the non-uniform shape of nanoparticles agglomerated separately,and the EDX spectrum shows the presence of Te,Zn,and O in the film.The I-V characteristics measurements indicate that the current density increases linearly with X-ray doses(0-250 cGy)for all applied voltages(1-6 V).The sensitivity of the thin film sensor has been found to be in the range of 0.37-0.94 mA/cm^(2)/Gy.The current-voltage measurement test for fading normalised in percentage to day 0 was found in the order of day 0>day 15>day 30>day 1>day 2.These results are expected to be beneficial for fabricating cheap and practical X-ray sensors.
文摘Purpose: To present a protocol of a dual-field rotational (DFR) total skin electron therapy (TSET) and to provide an assessment of clinical implementation, dosimetry properties, and skin dose evaluation. Methods and Materials: The DFR-TSET combined the Stanford 6-field and McGill rotational methods. Dual 6 MeV electron beams in high dose total skin electron mode were used for DFR-TSET on a commercial linac. Beam profiles and dosimetric properties were measured using solid phantoms. The dose rate at expanded source-to-surface distance (SSD) was a combination of static rate and rotational rate. In vivo dosimetry of patient skin was performed on patients’ skin using film, metal oxide semiconductor field-effect transistors (MOSFET), and optically stimulated luminescent dosimeters (OSLD). Results: Dual field rotational total skin electron therapy exhibited good (≤±10%) uniformity in the beam profiles in the vertical direction at an extended SSD of 332 cm with a gantry angulation of ±20˚ deviated from the horizontal direction. In-vivo measurements confirmed acceptable uniformity of the patients’ total body surfaces and revealed anatomically self-blocked or shielded areas where underdosing occurred. Conclusions: The clinical implementation of DFR-TSET effectively utilizes the special mode on a linac. This technique provides short beam-on times, uniform dose distribution, large treatment field, and reduced dose of x-ray contamination to the patients. In-vivo measurements indicate satisfactory delivery and dose uniformity of the prescribed dose. Electron boost fields are recommended at normal SSDs to address underdosed areas.
文摘目的利用CiteSpace文献计量学软件,本文对KM小鼠的研究现状和热点进行了可视化分析,旨在为国内KM小鼠研究的突破和创新提供依据。方法本文基于中国知网和Web of Science两个数据库,纳入了2004年1月1日~2023年6月10日的3981篇KM小鼠相关文献,分析了其发文量、国家(地区)、机构、作者合作网络、关键词共现、聚类、突现词和英文文献被引情况。结果KM小鼠研究中文文献发文量波动下降,英文文献发文量逐渐上升,国内外对于KM小鼠的研究热度不同。发文最多的3个国家是中国、美国和日本,国内的主要研究机构有中国农业大学、南京中医药大学以及中国科学院等,发文量较多的作者主要是刘慧雯、李光武和赵欣等。国内期刊研究内容主要集中于KM小鼠毒理学、免疫学和生殖学方面,国外期刊研究主要集中于KM小鼠细胞生物学、生理学方面。结论目前,KM小鼠在我国已有80余年的应用与推广历史,主要集中在毒理学、免疫学和生殖学方面研究。KM小鼠虽在实验方面有一定成果,但规范化种群培育、优势研究领域发掘以及动物伦理的进一步推进是未来需要继续解决的问题。
文摘目的:探究左侧乳腺癌保乳术后基于内缘切线拉弧的容积调强放疗(volumetric modulated arc therapy,VMAT)与常规切线拉弧的VMAT的剂量学差异,挖掘VMAT技术在乳腺癌保乳术后更大的获益,为乳腺癌保乳术后VMAT计划设计提供更多的参考和数据支持。方法:回顾性选取30例左侧乳腺癌保乳术后行调强放疗的患者,为每位患者分别设计常规切线拉弧(conventional tangential arc,CTA)和内缘切线拉弧(inner edge tangentialarc,IETA)两组VMAT计划。统计两组计划的靶区适形度指数(conformity index,CI)、均匀性指数(homogeneity index,HI)、机器跳数、危及器官受照剂量等数据,并进行数据分析。结果:靶区适形性指数(CI)CTA组和IETA组分别为0.86±0.02和0.87±0.02(P<0.05),D_(98)、D_(50)、D_(2)、均匀性指数(HI)和机器跳数均无明显差异(P>0.05);IETA组危及器官左肺V_(5)、V_(10)、V_(20)、V_(30)、V_(40)、D_(mean),右肺V_(5)、D_(mean),心脏V_(5)、V_(10)、V_(20)、D_(mean)均低于CTA组(P<0.05),其中左肺V_(5)和V_(20)CTA组和IETA组分别为37.18±7.18 vs 34.32±6.43、11.00±2.40 vs 9.65±2.17;右肺D_(mean)和心脏D_(mean)CTA组和IETA组分别为302.26±42.78 vs 273.50±26.62,479.30±60.08 vs 442.39±140.92,IETA组均低于CTA组;两组右侧乳腺D_(mean)相差甚微(P>0.05)。结论:两种计划均能满足临床要求,但IETA的VMAT靶区适形度明显提高,同时还显著降低了左肺、右肺、心脏和脊髓的受量。因此,左侧乳腺癌保乳术后基于内缘切线拉弧VMAT可实现靶区和危及器官更大的获益,值得推荐。
