A few CT-based voxel phantoms were produced to investigate the sensitivity of Monte Carlo simulations of X-ray beam and electron beam to the proportions of elements and the mass densities of the materials used to expr...A few CT-based voxel phantoms were produced to investigate the sensitivity of Monte Carlo simulations of X-ray beam and electron beam to the proportions of elements and the mass densities of the materials used to express the patient’s anatomical structure. The human body can be well outlined by air, lung, adipose, muscle, soft bone and hard bone to calculate the dose distribution with Monte Carlo method. The effects of the calibration curves established by using various CT scanners are not clinically significant based on our investigation. The deviation from the values of cumulative dose volume histogram derived from CT-based voxel phantoms is less than 1% for the given target.展开更多
目的:通过使用不同的扫描剂量,扫描模拟标准肝脏密度体模,比较深度学习重建技术(DLIR)与自适应统计迭代重建技术(ASIR-V)重建图像的质量。方法:使用Gammex标准CT体模模拟标准肝脏密度的插入物(ρ^(w)_(e)=1.06),在6种不同辐射剂量水平(...目的:通过使用不同的扫描剂量,扫描模拟标准肝脏密度体模,比较深度学习重建技术(DLIR)与自适应统计迭代重建技术(ASIR-V)重建图像的质量。方法:使用Gammex标准CT体模模拟标准肝脏密度的插入物(ρ^(w)_(e)=1.06),在6种不同辐射剂量水平(容积CT剂量指数(CTDIvol):30、20、15、10、7.5和4.5 m Gy)下进行CT扫描。随后,使用DLIR技术和ASIR-V算法,对每种剂量下获得的图像进行重建。通过im Quest软件对图像进行质量分析,使用Bland-Altman方法比较DLIR算法在4.5 m Gy(本实验采用的最低辐射剂量)和ASIR-V在15 m Gy(肝脏扫描推荐剂量)下的图像质量。结果:在6种剂量水平下,DLIR在噪声、信噪比、对比噪声比和可检测度等关键指标上,均显著优于ASIR-V。Bland-Altman分析结果表明,在4.5 m Gy的剂量水平下,DLIR的图像质量显著优于ASIR-V在15 m Gy剂量水平下的表现;在4.5 m Gy下DLIR图像的噪声为(17.41±0.32),显著低于ASIR-V在15 m Gy的(21.17±0.67);在4.5 m Gy下DLIR的信噪比、对比噪声比和可检测度分别为(3.21±0.24),(3.42±0.35)和(8.81±0.63),显著高于ASIR-V在15 m Gy剂量下的(2.69±0.14);(2.87±0.11)和(5.61±1.28)。结论:在模拟标准肝脏密度的局灶性病变体模CT扫描实验中,DLIR相较于ASIR-V,不仅显著提升信噪比,对比噪声比和可检测度值,而且大幅度降低图像噪声。DLIR技术能够在4.5 m Gy的较低辐射剂量下,实现优于常规15 m Gy剂量下ASIR-V重建图像的质量效果。展开更多
In this paper,we have addressed the problem of the radiation transport with the Monte Carlo N-particle(MCNP) code.This is a general-purpose Monte Carlo tool designed to transport neutron,photon and electron in three d...In this paper,we have addressed the problem of the radiation transport with the Monte Carlo N-particle(MCNP) code.This is a general-purpose Monte Carlo tool designed to transport neutron,photon and electron in three dimensional geometries.To examine the performance of MCNP5 code in the field of external radiotherapy,we performed the modeling of an Electron Density phantom(EDP) irradiated by photons from 60Co source.The model was used to calculate the Percent Depth Dose(PDD) at different depths in an EDP.One field size for PDD has been examined.A 60Co photons source placed at 80 cm source to surface distance(SSD).The results of calculations were compared to TPS data obtained at National Institute of Oncology of Rabat.展开更多
The proposed phantom is designed for the quality control of micro-SPECT/CT and micro-PET/CT systems. However, it is an assembly of six patterns stored in a cylindrical box enabling to control both micro-SPECT unit in ...The proposed phantom is designed for the quality control of micro-SPECT/CT and micro-PET/CT systems. However, it is an assembly of six patterns stored in a cylindrical box enabling to control both micro-SPECT unit in terms of uniformity, spatial linearity and spatial resolution and micro-CT unit in terms of uniformity, spatial linearity, spatial resolution, diffusion rate, low contrast detectability, Hounsfield unit linearity and slice thickness. The construction material is Plexiglas. As for the implementation, it was made on a micro-SPECT/CT machine of the type “speCZT eXplore CT 120”. Compared to the NEMA NU 4-2008 image quality phantom, this phantom offers micro-CT quality control and is more efficient in control of spatial resolution for micro-SPECT and micro- PET systems.展开更多
Dose estimation and quality control in computed tomography (CT) scanners are useful in controlling the dose of radiation given to patients while tests are carried out. The study was performed in a 16-slice Computed To...Dose estimation and quality control in computed tomography (CT) scanners are useful in controlling the dose of radiation given to patients while tests are carried out. The study was performed in a 16-slice Computed Tomography (CT) system of LightSpeed RT16 Xtra CT scanner. Quality control was done using a vendor-provided QA Phantom, and the six aspects of image quality were measured. For CT dosimetry, Computed Tomography Dose index volume (CTDIvol) was performed using Computed Tomography Dose Index (CTDI) Phantom. CTDI Phantom consists of three parts: Pediatric Head, Adult Head, and Adult Body Phantom. A 10 cm long pencil ion chamber DCT-10 was used to measure the dose at different positions inside the CTDI Phantom. Data were collected using MagicMax Universal software. For dose estimation of the CTDIvol Report of AAPM Task Group, 96 and 111 formalisms were used. For Pediatric Head, Adult Head, and Adult Body Phantom the measured CIDIvol was 61.04 mGy, 48.11 mGy, and 18.08 mGy respectively. The study has shown deviations of 7%, 15%, and 19% between estimated and console-displayed doses for Pediatric Head, Adult Head, and Adult Body scan techniques respectively. The six aspects of image quality measured by QA Phantom were found to be compatible with the specifications of the machine and CTDIvol measured by CTDI Phantom were found within a tolerance limit of ±20%. Hence, the QC and dosimetry of the mentioned machine are within the limit.展开更多
目的通过仿真人体模型实验,针对现在所使用的腹部扫描条件,对患者的受照情况进行全面了解。方法选择常规扫描参数和低剂量扫描参数,利用仿真人体模型,在相应体表位置和预定孔中插入剂量计,测量体表剂量和器官或组织的吸收剂量,并计算有...目的通过仿真人体模型实验,针对现在所使用的腹部扫描条件,对患者的受照情况进行全面了解。方法选择常规扫描参数和低剂量扫描参数,利用仿真人体模型,在相应体表位置和预定孔中插入剂量计,测量体表剂量和器官或组织的吸收剂量,并计算有效剂量。结果常规剂量组和低剂量组的器官或组织的受照剂量范围分别为0.014-96.7 m Gy,0.00148-5.56 m Gy,有效剂量结果分别为14.5 m Sv和1.52 m Sv。结论合理减少CT检查所致受检者剂量,需要建立科学实用的放射诊断的医疗照射参考（指导）水平。展开更多
基金The project supported by the An Hui Natural Science Foundation (No. 01043601)
文摘A few CT-based voxel phantoms were produced to investigate the sensitivity of Monte Carlo simulations of X-ray beam and electron beam to the proportions of elements and the mass densities of the materials used to express the patient’s anatomical structure. The human body can be well outlined by air, lung, adipose, muscle, soft bone and hard bone to calculate the dose distribution with Monte Carlo method. The effects of the calibration curves established by using various CT scanners are not clinically significant based on our investigation. The deviation from the values of cumulative dose volume histogram derived from CT-based voxel phantoms is less than 1% for the given target.
文摘目的:通过使用不同的扫描剂量,扫描模拟标准肝脏密度体模,比较深度学习重建技术(DLIR)与自适应统计迭代重建技术(ASIR-V)重建图像的质量。方法:使用Gammex标准CT体模模拟标准肝脏密度的插入物(ρ^(w)_(e)=1.06),在6种不同辐射剂量水平(容积CT剂量指数(CTDIvol):30、20、15、10、7.5和4.5 m Gy)下进行CT扫描。随后,使用DLIR技术和ASIR-V算法,对每种剂量下获得的图像进行重建。通过im Quest软件对图像进行质量分析,使用Bland-Altman方法比较DLIR算法在4.5 m Gy(本实验采用的最低辐射剂量)和ASIR-V在15 m Gy(肝脏扫描推荐剂量)下的图像质量。结果:在6种剂量水平下,DLIR在噪声、信噪比、对比噪声比和可检测度等关键指标上,均显著优于ASIR-V。Bland-Altman分析结果表明,在4.5 m Gy的剂量水平下,DLIR的图像质量显著优于ASIR-V在15 m Gy剂量水平下的表现;在4.5 m Gy下DLIR图像的噪声为(17.41±0.32),显著低于ASIR-V在15 m Gy的(21.17±0.67);在4.5 m Gy下DLIR的信噪比、对比噪声比和可检测度分别为(3.21±0.24),(3.42±0.35)和(8.81±0.63),显著高于ASIR-V在15 m Gy剂量下的(2.69±0.14);(2.87±0.11)和(5.61±1.28)。结论:在模拟标准肝脏密度的局灶性病变体模CT扫描实验中,DLIR相较于ASIR-V,不仅显著提升信噪比,对比噪声比和可检测度值,而且大幅度降低图像噪声。DLIR技术能够在4.5 m Gy的较低辐射剂量下,实现优于常规15 m Gy剂量下ASIR-V重建图像的质量效果。
基金Laboratory of Radiation and Nuclear Systems (LRSN)
文摘In this paper,we have addressed the problem of the radiation transport with the Monte Carlo N-particle(MCNP) code.This is a general-purpose Monte Carlo tool designed to transport neutron,photon and electron in three dimensional geometries.To examine the performance of MCNP5 code in the field of external radiotherapy,we performed the modeling of an Electron Density phantom(EDP) irradiated by photons from 60Co source.The model was used to calculate the Percent Depth Dose(PDD) at different depths in an EDP.One field size for PDD has been examined.A 60Co photons source placed at 80 cm source to surface distance(SSD).The results of calculations were compared to TPS data obtained at National Institute of Oncology of Rabat.
文摘The proposed phantom is designed for the quality control of micro-SPECT/CT and micro-PET/CT systems. However, it is an assembly of six patterns stored in a cylindrical box enabling to control both micro-SPECT unit in terms of uniformity, spatial linearity and spatial resolution and micro-CT unit in terms of uniformity, spatial linearity, spatial resolution, diffusion rate, low contrast detectability, Hounsfield unit linearity and slice thickness. The construction material is Plexiglas. As for the implementation, it was made on a micro-SPECT/CT machine of the type “speCZT eXplore CT 120”. Compared to the NEMA NU 4-2008 image quality phantom, this phantom offers micro-CT quality control and is more efficient in control of spatial resolution for micro-SPECT and micro- PET systems.
文摘Dose estimation and quality control in computed tomography (CT) scanners are useful in controlling the dose of radiation given to patients while tests are carried out. The study was performed in a 16-slice Computed Tomography (CT) system of LightSpeed RT16 Xtra CT scanner. Quality control was done using a vendor-provided QA Phantom, and the six aspects of image quality were measured. For CT dosimetry, Computed Tomography Dose index volume (CTDIvol) was performed using Computed Tomography Dose Index (CTDI) Phantom. CTDI Phantom consists of three parts: Pediatric Head, Adult Head, and Adult Body Phantom. A 10 cm long pencil ion chamber DCT-10 was used to measure the dose at different positions inside the CTDI Phantom. Data were collected using MagicMax Universal software. For dose estimation of the CTDIvol Report of AAPM Task Group, 96 and 111 formalisms were used. For Pediatric Head, Adult Head, and Adult Body Phantom the measured CIDIvol was 61.04 mGy, 48.11 mGy, and 18.08 mGy respectively. The study has shown deviations of 7%, 15%, and 19% between estimated and console-displayed doses for Pediatric Head, Adult Head, and Adult Body scan techniques respectively. The six aspects of image quality measured by QA Phantom were found to be compatible with the specifications of the machine and CTDIvol measured by CTDI Phantom were found within a tolerance limit of ±20%. Hence, the QC and dosimetry of the mentioned machine are within the limit.
文摘目的通过仿真人体模型实验,针对现在所使用的腹部扫描条件,对患者的受照情况进行全面了解。方法选择常规扫描参数和低剂量扫描参数,利用仿真人体模型,在相应体表位置和预定孔中插入剂量计,测量体表剂量和器官或组织的吸收剂量,并计算有效剂量。结果常规剂量组和低剂量组的器官或组织的受照剂量范围分别为0.014-96.7 m Gy,0.00148-5.56 m Gy,有效剂量结果分别为14.5 m Sv和1.52 m Sv。结论合理减少CT检查所致受检者剂量,需要建立科学实用的放射诊断的医疗照射参考（指导）水平。
