Purpose: This study was aimed to evaluate the utility based on imaging quality of the fast non-local means (FNLM) filter in diagnosing lung nodules in pediatric chest computed tomography (CT).

Methods: We retrospectively reviewed the chest CT reconstructed with both filtered back projection (FBP) and iterative reconstruction (IR) in pediatric patients with metastatic lung nodules. After applying FNLM filter with six h values (0.0001, 0.001, 0.01, 0.1, 1, and 10) to the FBP images, eight sets of images including FBP, IR, and FNLM were analyzed. The image quality of the lung nodules was evaluated objectively for coefficient of variation (COV), contrast to noise ratio (CNR), and point spread function (PSF), and subjectively for noise, sharpness, artifacts, and diagnostic acceptability.

Results: The COV was lowest in IR images and decreased according to increasing h values and highest with FBP images (P < 0.001). The CNR was highest with IR images, increased according to increasing h values and lowest with FBP images (P < 0.001). The PSF was lower only in FNLM filter with h value of 0.0001 or 0.001 than in IR images (P < 0.001). In subjective analysis, only images of FNLM filter with h value of 0.0001 or 0.001 rarely showed unacceptable quality and had comparable results with IR images. There were less artifacts in FNLM images with h value of 0.0001 compared with IR images (p < 0.001).

Conclusion: FNLM filter with h values of 0.0001 allows comparable image quality with less artifacts compared

Jina Shim, Myonggeun Yoon*

Department of Bio-Convergence Engineering, Korea University, Seoul, Republic of Korea

Department of Diagnostic Radiology, Severance Hospital, Seoul, Republic of Korea

Mi-Jung Lee* 

Department of Radiology and Research Institute of Radiological Science, Severance Children’s Hospital, Yonsei University, College of Medicine, Seoul, Republic of Korea

Youngjin Lee

Department of Radiological Science, Gachon University, Incheon, Republic of Korea

Physica Medica 81 (2021) 52-89

Glioblastoma multiforme (GBM), the most common type of brain tumor, is a very aggressive and treatment-refractory cancer, with a 5-year survival rate of approximately 5%. Hyperthermia (HT) and tumor treating fields (TTF) therapy have been used to treat cancer, either alone or in combination with other treatment methods. Both treatments have been reported to increase the efficacy of other treatment techniques and to improve patient prognosis. The present study evaluated the therapeutic effects of combining HT and TTF on GBM cell lines. Cells were subjected to HT, TTF, HT+TTF, or neither treatment, followed by comparisons of cell proliferation, apoptosis, migration and invasiveness. Clonogenic assays showed that the two treatments had a synergistic effect. The levels of cleaved PARP and cleaved caspase-3 were higher and apoptosis was increased in cells treated with HT+TTF than in cells treated with HT or TTF alone. In addition, HT+TTF showed greater inhibition of GBM cell migration and invasiveness and greater downregulation of STAT3 than either HT or TTF alone. The stronger anticancer effect of HT+TTF suggested that this combination treatment can increase the survival rate of patients with difficult-to-treat cancers such as GBM.

Yunhui Jo, Young In Han

Institute of Global Health Technology (IGHT), Korea University, Seoul, Republic of Korea

Eunjun Lee, Geon Oh, Heehun Sung, Yongha Gi, Hyunwoo Kim, Sangmin Park

Department of Biomedical Engineering, Korea University, Seoul, Republic of Korea

Jaehyeon Seo

Department of Bioconvergence Engineering, Korea University, Seoul, Republic of Korea 

Myonggeun Yoon

Department of Biomedical Engineering, Korea University, Seoul, Republic of Korea

Department of Bioconvergence Engineering, Korea University, Seoul, Republic of Korea

Am J Cancer Res. 2022; 12(3): 1423–1432.

Background: Tumor-treating fields (TTFields) therapy is increasingly utilized clinically because of its demonstrated efficacy in cancer treatment. However, the risk of skin burns must still be reduced to improve patient safety and posttreatment quality of life.

Purpose: The purpose of this study was to evaluate the methods of constructing electrode arrays that reduce current density exceeding threshold values, which can cause skin burns during TTFields therapy.

Methods: Electrode and body models were generated using COMSOL software. The body model had the dielectric properties of the scalp. The average current density beneath the central region of the electrode was maintained at ∼31 mA/cm2 RMS. The deviations in current density at the edges of the electrode were reduced by three methods:adjustment of the ceramic thickness ratio of the center to the edge from 1/5 to 4/5, adjustment of the radius of the metal plate from 5.0 to 8.0 mm, and insertion of an insulator of width 0.5 to 2 mm at the edge.

Results: While using a single circular electrode, adjustment of the ceramic thickness ratio, adjustment of the metal plate radius, and insertion of an insulator near the edge reduced the deviations of current density by 14.6%, 67.7%, and 75.3%, respectively. Similarly, while using circular electrode arrays, inserting an insulator at the edge of each electrode reduced the deviations of current density significantly, from 8.62 to 2.40 mA/cm2.

Conclusions: Insertion of an insulator at the edge of each electrode was found to be the most effective method of attaining uniform current density distribution beneath the electrode, thereby lowering the risk of adverse effects of TTFields therapy.

Heehun Sung Geon Oh, Yongha Gi, Jaehyeon Seo

Department of Bioengineering, Korea University, Seoul,Republic of Korea

Yunhui Jo 

Institute of Global Health Technology (IGHT), Korea University, Seoul,Republic of Korea

Hyunwoo Kim, Sangmin Park, Myonggeun Yoon

Department of Bioengineering, Korea University, Seoul,Republic of Korea

FieldCure Ltd, Seoul,Republic of Korea

Med Phys. 2022;49:4837–4844.