扫描及重建参数对肺磨玻璃结节体积测量影响的体模研究

目的探讨MSCT扫描与重建参数对仿真人体体模肺磨玻璃结节容积测量的影响。方法采用GE VCT对8个肺磨玻璃结节进行不同管电压(80 kV、100 kV、120 kV)、管电流(100 mA、150 mA、200 mA)扫描,并对80 kV、150 mA组原始数据行不同层厚(0.625 mm、1.250 mm)、不同重建算法(soft、standard、lung、bone)、不同重建野(36 cm、18 cm)重建。由2名胸部放射诊断医师分别用软件对磨玻璃结节进行容积测量,并对绝对错误率(APE)=(|V_(测量)-V_(实际)|)/V_(实际)×100%进行统计学分析。采用组内相关系数(ICC)评估2名医师体积测量结果的一致性。结果 2名医师对肺磨玻璃结节体积测量的ICC=0.98。不同管电压条件下各结节的APE值差异无统计学意义(P0.05),而管电流为150 mA,APE值最小(P0.05)。结节的APE值在2种层厚之间差异无统计学意义(P0.05)。随着重建野缩小,APE值减小(P0.05)。不同重建算法对结节的APE值影响不同,差异有统计学意义(P0.05),lung算法时APE值较小。低密度小结节(CT值为-800 HU,直径5 mm)在各种条件下的APE值均大于10。结论 MSCT采用80 kV、150 mA扫描结合靶重建、肺算法可一定程度减小辐射剂量并且提高磨玻璃结节容积测量的准确性。低密度小结节不适合用肺结节分析软件分析。     

Evaluation of the Accuracy of 3‐Dimensional Ultrasonography of the Kidney Using an In Vitro Renal Model

Objective. Three‐dimensional ultrasonography (3DUS) has recently become a reality because of advances in ultrasound probes and machine processing ability. We have developed an anthropomorphic phantom of the human loin to assess both the accuracy of 3DUS of the kidney and its potential usefulness for training in ultrasonographically guided percutaneous renal intervention. Methods. The model was built with easily available and inexpensive materials such as agar and latex with known ultrasonographic properties. The accuracy of 2‐dimensional ultrasonography (2DUS) and 3DUS was assessed by measuring the dimensions of the pelvicalyceal system (PCS) ultrasonographically (pelvis width and calyx diameters) and then comparing these with measurements obtained at the time of construction. Radiology interventional trainees then punctured the PCS with 2DUS and 4‐dimensional ultrasonographic (real‐time/time‐resolved 3DUS) guidance and reported the phantom's performance. Results. The 3‐dimensional nature of the model's PCS could be clearly visualized on 2DUS and 3DUS, and the scan characteristics were very similar to those in real life. Measurements using 3DUS proved to be closer to the true dimensions of the model's PCS than those using 2DUS. The mean error percentage for 2DUS measurements was ?10.2%, and that for 3DUS was ?2.2% (P < 0.0001). Interventional trainees were satisfied with the “tissue feel” and level of difficulty posed on puncturing the phantom. Conclusions. Three‐dimensional ultrasonography proved to be more accurate than 2DUS for intrarenal measurements using this in vitro renal model. Three‐dimensional ultrasonography has the potential to ease diagnostic renal scanning with the ability to further scrutinize and postprocess the scanned volumes. The model was realistic in its anthropomorphic properties and simulated human tissue during puncture.     

Risk of developing second cancer from neutron dose in proton therapy as function of field characteristics, organ, and patient age

PURPOSE: To estimate the risk of a second malignancy after treatment of a primary brain cancer using passive scattered proton beam therapy. The focus was on the cancer risk caused by neutrons outside the treatment volume and the dependency on the patient's age. METHODS AND MATERIALS: Organ-specific neutron-equivalent doses previously calculated for eight different proton therapy brain fields were considered. Organ-specific models were applied to assess the risk of developing solid cancers and leukemia. RESULTS: The main contributors (>80%) to the neutron-induced risk are neutrons generated in the treatment head. Treatment volume can influence the risk by up to a factor of approximately 2. Young patients are subject to significantly greater risks than are adult patients because of the geometric differences and age dependency of the risk models. Breast cancer should be the main concern for females. For males, the risks of lung cancer, leukemia, and thyroid cancer were significant for pediatric patients. In contrast, leukemia was the leading risk for an adult. Most lifetime risks were <1% (70-Gy treatment). The only exceptions were breast, thyroid, and lung cancer for females. For female thyroid cancer, the treatment risk can exceed the baseline risk. CONCLUSION: The risk of developing a second malignancy from neutrons from proton beam therapy of a brain lesion is small (i.e., presumably outweighed by the therapeutic benefit) but not negligible (i.e., potentially greater than the baseline risk). The patient's age at treatment plays a major role.     

3-D Cell Culture Systems in Bone Marrow Tissue and Organoid Engineering,and BM Phantoms as In Vitro Models of Hematological Cancer Therapeutics—A Review

We review the state-of-the-art in bone and marrow tissue engineering (BMTE) and hematological cancer tissue engineering (HCTE) in light of the recent interest in bone marrow environment and pathophysiology of hematological cancers. This review focuses on engineered BM tissue and organoids as in vitro models of hematological cancer therapeutics, along with identification of BM components and their integration as synthetically engineered BM mimetic scaffolds. In addition, the review details interaction dynamics of various BM and hematologic cancer (HC) cell types in co-culture systems of engineered BM tissues/phantoms as well as their relation to drug resistance and cytotoxicity. Interaction between hematological cancer cells and their niche, and the difference with respect to the healthy niche microenvironment narrated. Future perspectives of BMTE for in vitro disease models, BM regeneration and large scale ex vivo expansion of hematopoietic and mesenchymal stem cells for transplantation and therapy are explained. We conclude by overviewing the clinical application of biomaterials in BM and HC pathophysiology and its challenges and opportunities.     

Experimental validation of a radiographic simulation code using breast phantom for X-ray imaging

Computer models and simulations of X-ray imaging systems are becoming a very precious tool during the development and evaluation of new X-ray imaging techniques. To provide, however, a faithful simulation of a system, all components must be accurately modelled and tested, followed by verification through experimental measurements. This paper presents a validation study of the XRayImagingSimulator, an in-house developed X-ray imaging simulator, which is extensively used as a basic tool in carrying out complex breast imaging simulations. The approach followed compares results obtained via an experimental setup for breast phantom (CIRS 011A) imaging, using synchrotron radiation (SYRMEP beamline at ELETTRA), with those from its simulated setup under the same conditions. The study demonstrated a very good agreement between experimental and simulated images compared both in terms of subjective and objective criteria. The combination of the XRayImagingSimulator with our BreastSimulator provides a powerful tool for in silico testing of new X-ray breast imaging approaches.     

X线管电压对图像质量和放射剂量影响的研究

目的:探讨X线管电压(kVp)与体模管图像质量和放射剂量之间的相关性。方法:在丙烯酸模板内制作25组直径为1.2mm的圆柱形平行排列的体模管,其间距为11mm。体模管内造影剂碘浓度为4.0~50mg/ml。获取X线图像后,采用曲线拟合的方法,研究不同X线管电压对体模管图像质量和表面剂量的影响。结果:当X线管电压从54kVp增加到85kVp时,体模表面剂量的变化较图像质量变化大;当超过85kVp后,体模表面剂量的变化不明显而图像质量却出现较大幅度下降。结论:在特定体模厚度下,通过建立并分析管电压与图像质量及体模表面剂量间的关系曲线,可以确定最优kVp值,既保证了图像质量又能使体模表面剂量最低。     

Measuring absorbed dose for i-CAT CBCT examinations in child,adolescent and adult phantoms

Objectives:

Design and construct child and adolescent head phantoms to measure the absorbed doses imparted during dental CBCT and compare with the absorbed dose measured in an adult phantom.

Methods:

A child phantom was developed to represent the smallest patients receiving CBCT, usually for craniofacial developmental concerns, and an adolescent phantom was developed to represent healthy orthodontic patients. Absorbed doses were measured using a thimble ionization chamber for the custom-built child and adolescent phantoms and compared with measurements using a commercially available adult phantom. Imaging was performed with an i-CAT Next Generation (Imaging Sciences International, Hatfield, PA) CBCT using two different fields of view covering the craniofacial complex (130 mm high) or maxilla/mandible (60 mm high).

Results:

Measured absorbed doses varied depending on the location of the ionization chamber within the phantoms. For CBCT images obtained using the same protocol for all phantoms, the highest absorbed dose was measured in all locations of the small child phantom. The lowest absorbed dose was measured in the adult phantom.

Conclusions:

Images were obtained with the same protocol for the adult, adolescent and child phantoms. A consistent trend was observed with the highest absorbed dose being measured in the smallest phantom (child), while the lowest absorbed dose was measured in the largest phantom (adult). This study demonstrates the importance of child-sizing the dose by using dedicated paediatric protocols optimized for the imaging task, which is critical as children are more sensitive to harmful effects of radiation and have a longer life-span post-irradiation for radiation-induced symptoms to develop than do adults.