Temperature-controlled power modulation compensates for heterogeneous nanoparticle distributions: a computational optimization analysis for magnetic hyperthermia

Purpose: To study, with computational models, the utility of power modulation to reduce tissue temperature heterogeneity for variable nanoparticle distributions in magnetic nanoparticle hyperthermia.

Methods: Tumour and surrounding tissue were modeled by elliptical two- and three-dimensional computational phantoms having six different nanoparticle distributions. Nanoparticles were modeled as point heat sources having amplitude-dependent loss power. The total number of nanoparticles was fixed, and their spatial distribution and heat output were varied. Heat transfer was computed by solving the Pennes’ bioheat equation using finite element methods (FEM) with temperature-dependent blood perfusion. Local temperature was regulated using a proportional-integral-derivative (PID) controller. Tissue temperature, thermal dose and tissue damage were calculated. The required minimum thermal dose delivered to the tumor was kept constant, and heating power was adjusted for comparison of both the heating methods.

Results: Modulated power heating produced lower and more homogeneous temperature distributions than did constant power heating for all studied nanoparticle distributions. For a concentrated nanoparticle distribution, located off-center within the tumor, the maximum temperatures inside the tumor were 16% lower for modulated power heating when compared to constant power heating. This resulted in less damage to surrounding normal tissue. Modulated power heating reached target thermal doses up to nine-fold more rapidly when compared to constant power heating.

Conclusions: Controlling the temperature at the tumor-healthy tissue boundary by modulating the heating power of magnetic nanoparticles demonstrably compensates for a variable nanoparticle distribution to deliver effective treatment.     

生理影像信息技术及其临床应用

生理影像是功能性医学影像的一个重要分支,也是临床医学工程的一个极其重要的研究和应用领域。多年来,作者及其研究生与临床医务人员相结合,在电生理影像和热生理影像的信息获取和数字化处理技术方面进行了大量及深入的研究,提出了一种体内热估计(ITE)新技术。本文重点介绍热生理影像信息在妇女乳腺癌诊断中的应用。通过对约五千例妇女乳腺病筛选的结果,表明了生理影像信息处理及ITE技术在临床医学上的应用价值。     

援外针灸临床综述(二)

介绍我国援外医疗队在 3 6个国家以 17种治疗方法为主治疗 40多种病的概况。     

Demonstration of synergistic effects of hyperthermia and photodynamic therapy using the chick chorioallantoic membrane model.

The chick chorioallantoic membrane (CAM) model was used to study vascular effects of photodynamic therapy (PDT) and hyperthermia (HPT) and the synergism of these modalities. The CAM is a convenient medium for monitoring the modifications of the vasculature. It is possible to view the CAM and to examine structural changes of individual blood vessels in real time. Moreover, the CAM is a closed system which lends itself to mathematical modeling of the temporal and spatial temperature profile and in which HPT can be performed quantitatively and to a selected depth, using different lasers. A porphyrin-type photosensitizer solution was applied to areas of the CAM, defined by teflon O-rings placed on the surface. Uptake dynamics of the sensitizer into the CAM was determined by analyzing its fluorescence in vivo. The CAM area was irradiated with a dual-wavelength laser system composed of a dye laser at 644 nm (to induce PDT) and a CO2 laser at 10.6 microns (to bring about HPT). Damage to the CAM vasculature, due to combined PDT+HPT, was compared to the outcome of the separate modalities, and a synergistic effect of about 40% was observed.     

Development and experimental in vivo validation of mathematical modeling of laser coagulation

Most clinical procedures using the laser are based on thermal laser-tissue interactions. The treatment often consists of inducing damage of given degree and extent by heating the tissue. The aim of this study was to develop a model called HELIOS. The ability of HELIOS to predict thermal coagulation was evaluated by comparison with in vivo experimental results. Conversion of laser light in tissue was studied using the beam-broadening model. Temperature was described by the heat conduction equation solved using the finite difference method. The tissue dena-turation was modeled by the Henriques equation leading to the determination of the damage coefficient ω. For a given set of laser and tissue parameters, HELIOS makes a graphic representation of coagulation necrosis and temperature evolution in tissue. HELIOS was validated by experimental studies in vivo on rat liver using a CW Nd:YAG laser, a CO₂ laser, and an argon laser. For given sets of laser parameters, temperature measurements were performed using an infrared camera. Histological examinations were carried out on samples to quantify the depth of coagulation necrosis. Experimental data obtained in vivo were compared with those calculated using HELIOS and similar sets of parameters. The difference between the predicted temperature evolution on tissue surface and that measured by the infrared camera was < 5°C in all cases. The difference between the predicted coagulation necrosis depth and the corresponding experimental one was < 10%. In conclusion, HELIOS allows good prediction of tissue temperature and coagulation necrosis. © 1994 Wiley-Liss, inc.     

中西药物保留灌肠合并针灸治疗溃疡性结肠炎的临床研究

目的 观察中西药物保留灌肠合并针灸治疗溃疡性结肠炎(UC)的疗效.方法 对确诊的63例UC患者随机分为两组,治疗组(32例)用中西药物150 mL睡前保留灌肠合并针灸治疗,每日1次,疗程4周;对照组(31例)用强的松龙100 mg、庆大霉素16万u加生理盐水150 mL睡前保留灌肠,每日1次,疗程4周.然后比较疗效.结果 治疗组疗效明显高于对照组,总有效率分别为96.9%和77.4%,1年复发率分别为9.37%和25.8% (P<0.05).两组差异有统计学意义.结论 中西药物保留灌肠合并针灸治疗UC疗效显著,复发率低,有临床应用价值.     

肿瘤物理治疗技术及设备

简要介绍了肿瘤的放射治疗和热治疗的技术及设备，介绍了各种技术及设备的特点。     

Early bronchoscopic and morphological diagnostics and prognosis in thermal inhalation trauma

Thermal injury is diagnosed by fibrobronchoscopy within the first 5 days after inhalation burn trauma in 73 patients (34% of the total number of patients hospitalized during the last 2 years). Pathological changes of the mucosa with predominant multiple ulceration at different levels of the tracheobronchial tree are detected in 44% patients and in more than 70% patients with acute respiratory deficiency. These changes determine variation and severity of thermal inhalation injury in the patients, and, together with morphofunctional characteristics, provide objective basis for the early diagnostics and prognosis. Translated fromByullelen' Eksperimental'noi Biologii i Meditsiny, Vol. 124, No. 8, pp. 221–225, August, 1997     

热分析方法对几种不同产地山药的鉴别

目的：考察热分析方法对不同种质、地域山药鉴别的可行性。方法：对5个产地的山药分别在氮气与空气气氛下的DTA和DTG曲线进行分析，根据其图谱的特征差异进行鉴别。结果：不同种山药的DTA，DTG图谱，不同种、不同地域山药的DTG图谱均有差异。结论：此方法可用于不同种、不同地域山药的鉴别。     

大型Tokamak装置中环向场超导线圈的传热研究

分析了HT-7U超导Tokamak核聚变装置中环向场超导线圈上的涡流损耗热产生的机理和迫流式超临界氦对流换热等过程，特别针对等离子体快速破裂时，极短时间内在环向场磁体中所产生的较大的涡流损耗而引起的焦耳热，对环向场线圈盒与超导磁体之间的热传递过程加以研究。本文采用国际上通用的有限元分析软件ANSYS5.7进行计算，计算所得的结果较为乐观。