Calculation of Electromagnetic Field and SAR Dis- tributions of Two Antenna Structures for Bone Tu- mors Microwave Hyperthermia

Objective: To investigate the electromagnetic field and specific absorptionrate (SAR) distribution of different structure applicators with different depths for treating bonetumors using microwave hyperthermia. Methods: The finite element method (FEM) was used to calculate,electromagnetic field and SAR distribution. Two different structure applicators were simulated. Theone is simple coaxial antenna, which has been successfully used in clinic treating bone tumors inTangdu hospital of the Forth Military Medical University several years. It was formed by a coaxialcable peeled off the out copper at end. The other applicator was coaxial- slot antenna, which waswidely used in microwave hyperthermia. The applicator inserted into the cylindrical bone withdifferent depths, and worked at the frequency of 2 450 MHz. Results: The electric field and SARgenerated by the simple coaxial applicator were mainly concentrated out the tissues, and were notuniform in the tissues, while the coaxial- slot applicator well transmits the electric field and SARinto the tissues, and can easily treat different position by adjusting the slat position.Conclusion: The results calculated by EFM, were well accordant with the experimental and clinicalresulls, and will be important for improving the clinical effects of microwave hyperthermia.

Application of the condenser lens in microwave hyperthermia

According to the aplanatism theory, lens can be used to focus the electromagnetic wave. A piano-convex hyperboloid of revo- lution lens made of low loss material is designed for combinatorial applications with the rectangle microstrip applicator in microwave hyperthermia. Results of the extensive simulations and experiments show that the introduction of the lens to the clinical used antenna can significantly improve the directivity and hence increase the microwave power density in near field. In microwave hyperthermia applications, the lens antenna will exhibit superior directivity, high gain and well thermal efficiency for tumor in superficial layer. Besides, it has small treatment area that is helpful for reducing the injury of the normal tissue around the tumor.

A CLINICAL STUDY ONINTRALUMINAL HYPERTHERMIA COMBINED WITH EXTERNAL IRRADIATION FOR ESOPHAGEAL CARCINOMA

A randomized trial of intracavitary microwave hyperthermia combined with external irradiation (R+H) versus radiation (R) alone in the treatment of esophageal cancer was performed form February 1986 to February 1988. In the R group, radiation was given by 8 MV X-ray with 2 Gy/fraction, 5 fractions per week with a total dose of 60 Gy/6 weeks. In the R+H group, the radiation was given as R group but with a total dose of 40 Gy/4 weeks. Intracavitary 915 Mhz microwave hyperthermia was given with a nominal temperature of 43.5℃ at the margin of the tumor surface, 45 minutes/session, 1-2 sessions/week for 4-8 session. The 1-, 3-, and 5-year survival rates in R+H group were 81.2% (48/59 cases), 42.4% (25/59) and 23.7% (14/59), while in the R group 59.0% (39/66 cases), 24.2% (16/66) and 16.7% (11/66) respectively. The differences in 1- and 3-year survival rates were statistically significant (P<0.05) between the 2 groups. Using the thermal dose T90 analysis, after the cases with T90<43℃ (insufficient thermal dose) were eliminated, 52 cases with T90 equal to or higher than 43 ℃ had 1, 3, and 5 year survival rates of 84.6%, 44.2% and 26.9%, respectively. Statistically significant differences in the 2 groups were also limited only to 1- and 3-year survivals. Higher 5-year survivals is anticipated if more cases are studied.

医用介质部分加载波导辐射器

本文报导一种带有抗流槽的介质加载波导辐射器的研制结果。这种辐射器有相对均匀的加热图形,泄漏辐射较其它波导辐射器小,能满足临床治疗需要。用小探针法测试了这种辐射器在模拟肌肉内近场分布,结果与用温度计测出的辐射器加热后的温度分布基本一致。实验还表明波导辐射器的抗流槽对宽边的泄漏辐射有明显抑制,但对窄边的泄漏抑制作用不很明显。

Fabrication of microwave-sensitized nanospheres of covalent organic framework with apatinib for tumor therapy

A new nanocomposite of hollow covalent organic framework(COF)conjugated with the apatinib(AP)and loading microwave-sensitizer(ionic liquid,IL)was prepared by layer by layer(LBL)method and hyaluronic acid(HA)coating,named as COF-AP-IL@HA.AP loading rate in COF hollow-spheres(~30 nm shell thickness)was~40.3%,due to the interactions of hydrogen andπ-πbonds between AP and COF shell,and acidic environment destroyed COF structure,promoting AP release.Microwave sensitization of loaded IL in COF hollow-spheres could enhance the microwave heat-effect,and combined AP therapeutic ability,leading to their higher inhibitation on tumor,due to targeting ability of HA and the local release of apatinib.88.9%of inhibition rate of COF-AP-IL@HA under microwave on the in vivo tumor was significantly higher than those without microwave(12.3%)and COF-IL@HA with microwave(37.5%),indicating a synergism of sensitized microwave hyperthermia and AP therapy on the reduced expression of VEGF via the downregulation pathway of hypoxia inducible factor.These results indicated that COF-AP-IL@HA was potential to the application in the combination therapy of tumor of the sensitized microwave hyperthermia and apatinib.

MoS_(2)-based nanocomposites for cancer diagnosis and therapy

Molybdenum is a trace dietary element necessary for the survival of humans.Some molybdenum-bearing enzymes are involved in key metabolic activities in the human body(such as xanthine oxidase,aldehyde oxidase and sulfite oxidase).Many molybdenum-based compounds have been widely used in biomedical research.Especially,MoS_(2)-nanomaterials have attracted more attention in cancer diagnosis and treatment recently because of their unique physical and chemical properties.MoS_(2)can adsorb various biomolecules and drug molecules via covalent or non-covalent interactions because it is easy to modify and possess a high specific surface area,improving its tumor targeting and colloidal stability,as well as accuracy and sensitivity for detecting specific biomarkers.At the same time,in the near-infrared(NIR)window,MoS_(2)has excellent optical absorption and prominent photothermal conversion efficiency,which can achieve NIR-based phototherapy and NIR-responsive controlled drug-release.Significantly,the modified MoS_(2)-nanocomposite can specifically respond to the tumor microenvironment,leading to drug accumulation in the tumor site increased,reducing its side effects on non-cancerous tissues,and improved therapeutic effect.In this review,we introduced the latest developments of MoS_(2)-nanocomposites in cancer diagnosis and therapy,mainly focusing on biosensors,bioimaging,chemotherapy,phototherapy,microwave hyperthermia,and combination therapy.Furthermore,we also discuss the current challenges and prospects of MoS_(2)-nanocomposites in cancer treatment.