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In this work, three-dimensional (3D) film-based proton beam measurements were used for the first time to verify the patient-specific radiation dose distribution, beam range and compensator shape. Three passively scattered proton beams and one uniform scanning proton beam were directed onto an acrylic phantom with inserted Gafchromic EBT films. The average gamma index for a comparison of the dose distributions was less than one for 97.2 % of all pixels from the passively scattered proton beams and 98.1 % of all pixels for the uniform scanning proton beams, with a 3 % dose and a 3 mm distance-to-dose agreement tolerance limit. The results also showed that the average percentage of points within the acceptance criteria for proton beam ranges was 94.6 % for the passively scattered proton beams. Both the dose distribution and the proton beam range determined by the 3D EBT film measurement agreed well with the planning system values. [ABSTRACT FROM AUTHOR]

This study examined the dose response of an optically stimulated luminescence dosemeter (OSLD) to megavoltage photon and electron beams. A nanoDot™ dosemeter was used to measure the dose response of the OSLD. Photons of 6–15 MV and electrons of 9–20 MeV were delivered by a Varian 21iX machine (Varian Medical System, Inc. Milpitas, CA, USA). The energy dependency was <1 %. For the 6-MV photons, the dose was linear until 200 cGy. The superficial dose measurements revealed photon irradiation to have an angular dependency. The nanoDot™ dosemeter has potential use as an in vivo dosimetric tool that is independent of the energy, has dose linearity and a rapid response compared with normal in vivo dosimetric tools, such as thermoluminescence detectors. However, the OSLD must be treated very carefully due to the high angular dependency of the photon beam. [ABSTRACT FROM PUBLISHER]

Background Purpose Method Result Conclusion Although generalized‐dataset‐based auto‐segmentation models that consider various computed tomography (CT) scanners have shown great clinical potential, their application to medical images from unseen scanners remains challenging because of device‐dependent image features.This study aims to investigate the performance of a device‐dependent auto‐segmentation model based on a combined dataset of a generalized dataset and single CT scanner dataset.We constructed two training datasets for 21 chest and abdominal organs. The generalized dataset comprised 1203 publicly available multi‐scanner data. The device‐dependent dataset comprised 1253 data, including the 1203 multi‐CT scanner data and 50 single CT scanner data. Using these datasets, the generalized‐dataset‐based model (GDSM) and the device‐dependent‐dataset‐based model (DDSM) were trained. The models were trained using nnU‐Net and tested on ten data samples from a single CT scanner. The evaluation metrics included the Dice similarity coefficient (DSC), the Hausdorff distance (HD), and the average symmetric surface distance (ASSD), which were used to assess the overall performance of the models. In addition, DSCdiff, HDratio, and ASSDratio, which are variations of the three existing metrics, were used to compare the performance of the models across different organs.For the average DSC, the GDSM and DDSM had values of 0.9251 and 0.9323, respectively. For the average HD, the GDSM and DDSM had values of 10.66 and 9.139 mm, respectively; for the average ASSD, the GDSM and DDSM had values of 0.8318 and 0.6656 mm, respectively. Compared with the GDSM, the DDSM showed consistent performance improvements of 0.78%, 14%, and 20% for the DSC, HD, and ASSD metrics, respectively. In addition, compared with the GDSM, the DDSM had better DSCdiff values in 14 of 21 tested organs, better HDratio values in 13 of 21 tested organs, and better ASSDratio values in 14 of 21 tested organs. The three averages of the variant metrics were all better for the DDSM than for the GDSM.The results suggest that combining the generalized dataset with a single scanner dataset resulted in an overall improvement in model performance for that device image. [ABSTRACT FROM AUTHOR]

The present study aimed to determine a method for estimating a potential prognostic factor in alternating electric fields for the treatment of solid tumors based on cell survival curves that evaluate cell proliferation capability. In AGS, B16F10, U373, and HPAF-II cancer cell lines, the proportional relationships of the electric field magnitude and the duration of application with the proliferation of cancer cell lines was identified by in vitro alternating current electric field experiments performed under various conditions. A prognostic factor applicable to alternating electric field therapy was developed by identifying proportional relationships of the electric field magnitude and the duration of application with the proliferation of the four cancer cell lines. Through the experimental results, the absorbed energy in tissue has been suggested as a potential prognostic factor in alternating electric field therapy. The absorbed energy in tissue can be used as a reference to quantify the inhibition of cell proliferation related to control, enabling systematic assessment of alternating electric field therapy which, to date, has not been possible. [ABSTRACT FROM AUTHOR]

Introduction: This study describes a simple method of inter-fractional photon beam monitoring to measure the entrance dose of radiation treatment using Gafchromic EBT3 film.Materials and Methods: The film was placed at the center of a 1-cm thick phantom shaped like a block tray and fixed on the accessory tray of the gantry. The entrance dose was measured following the placement of the film in the accessory tray. The dose distribution calculated with the treatment planning system was compared with the dose distribution on the irradiated EBT3 films. The effectiveness of this methodology, as determined by gamma passing rates, was evaluated for the 22 fields of eight three-dimensional conformal radiotherapy (3D-CRT) plans and the 41 fields of nine intensity-modulated radiotherapy (RT) plans. The plans for three-dimensional conformal RT included treatments of the rectum, liver, breast, and head and neck, whereas the plans for intensity-modulated RT included treatments of the liver, brain, and lung.Results: The gamma passing rates for 3D-CRT ranged from 96.4% to 99.5%, with the mean gamma passing rate for 22 fields being 98.0%. The gamma passing rate for intensity-modulated RT ranged from 96.1% to 98.9%, with the mean gamma passing rate for 41 fields being 97.7%. All gamma indices were over the 95% tolerance level.Conclusions: The methodology described in this study, based on Gafchromic EBT3 film, can be utilized for inter-fractional entrance dose monitoring as quality assurance during RT. Clinical application of this method to patients can verify the accuracy of beam delivery in the treatment room. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the dosimetric characteristics and applications of a dosimetry system composed of a flexible amorphous silicon thin‐film solar cell and scintillator screen (STFSC‐SS) for therapeutic X‐rays. Methods: The real‐time dosimetry system was composed of a flexible a‐Si thin‐film solar cell (0.2‐mm thick), a scintillator screen to increase its efficiency, and an electrometer to measure the generated charge. The dosimetric characteristics of the developed system were evaluated including its energy dependence, dose linearity, and angular dependence. Calibration factors for the signal measured by the system and absorbed dose‐to‐water were obtained by setting reference conditions. The application and correction accuracy of the developed system were evaluated by comparing the absorbed dose‐to‐water measured using a patient treatment beam with that measured using the ion chamber. Results: The responses of STFSC‐SS to energy, field size, depth, and source‐to‐surface distance (SSD) were more dependent on measurement conditions than were the responses of the ion chamber, although the former dependence was due to the scintillator screen, not the solar cell. The signals of STFSC‐SS were also dependent on dose rate, while the responses of solar cell alone and scintillator screen were not dependent on dose rate. The scintillator screen reduced the output of solar cell at 6 and 15 MV by 0.60 and 0.55%, respectively. The different absorbed dose‐to‐water measured using STFSC‐SS for patient treatment beam differed by 0.4% compared to those measured using the ionization chamber. The uncertainties of the developed system for 6 and 15 MV photon beams were 1.8 and 1.7%, respectively, confirming the accuracy and applicability of this system. Conclusions: The thin‐film solar cell‐based detector developed in this study can accurately measure absorbed dose‐to‐water. The increased signal resulting from the use of the scintillator screen is advantageous for measuring low doses and stable signal output. In addition, this system is flexible, making it applicable to curved surfaces, such as a patient's body, and is cost‐effective. [ABSTRACT FROM AUTHOR]

Abstract: Purpose: To compare the secondary radiation doses following intensity-modulated radiotherapy (IMRT) and proton beam therapy (PBT) in patients with lung and liver cancer. Methods and materials: IMRT and PBT were planned for three lung cancer and three liver cancer patients. The treatment beams were delivered to phantoms and the corresponding secondary doses during irradiation were measured at various points 20–50cm from the beam isocenter using ion chamber and CR-39 detectors for IMRT and PBT, respectively. Results: The secondary dose per Gy (i.e., a treatment dose of 1Gy) from PBT for lung and liver cancer, measured 20–50cm from the isocenter, ranged from 0.17 to 0.086mGy. The secondary dose per Gy from IMRT, however, ranged between 5.8 and 1.0mGy, indicating that PBT is associated with a smaller dose of secondary radiation than IMRT. The internal neutron dose per Gy from PBT for lung and liver cancer, 20–50cm from the isocenter, ranged from 0.03 to 0.008mGy. Conclusions: The secondary dose from PBT is less than or compatible to the secondary dose from conventional IMRT. The internal neutron dose generated by the interaction between protons and body material is generally much less than the external neutron dose from the treatment head. [Copyright &y& Elsevier]

Abstract: We wanted to evaluate the influence of bone cement on the proton range and to derive a conversion factor predicting the range shift by correcting distorted computed tomography (CT) data as a reference to determine whether the correction is needed. Two CT datasets were obtained with and without a bone cement disk placed in a water phantom. Treatment planning was performed on a set of uncorrected CT images with the bone cement disk, and the verification plan was applied to the same set of CT images with an effective CT number for the bone cement disk. The effective CT number was determined by measuring the actual proton range with the bone cement disk. The effects of CT number, thicknesses, and position of bone cement on the proton range were evaluated in the treatment planning system (TPS) to draw a conversion factor predicting the range shift by correcting the CT number of bone cement. The effective CT number of bone cement was 260 Hounsfield units (HU). The calculated proton range for native CT data was significantly shorter than the measured proton range. However, the calculated range for the corrected CT data with the effective CT number coincided exactly with the measured range. The conversion factor was 209.6 [HU·cm/mm] for bone cement and predicted the range shift by approximately correcting the CT number. We found that the heterogeneity of bone cement could cause incorrect proton ranges in treatment plans using CT images. With an effective CT number of bone cement derived from the proton range and relative stopping power, a more actual proton range could be calculated in the TPS. The conversion factor could predict the necessity for CT data correction with sufficient accuracy. [Copyright &y& Elsevier]

Abstract: The commercially available glass dosimeter (model GD-301) was investigated for its dosimetric characteristics, in order to evaluate its use for in vivo dosimetry. We specifically assessed overall precision of dosimetric dose data in patients who received treatment with the total body irradiation (TBI). Uniformity obtained in this study was within 1.2% (1 SD). The dose–response was linear in the range of 0.5–10Gy with R of 0.999. Dose rate, SSD, field size, angular and energy dependence were found to be within 3.0%. In vivo skin dosimetry for TBI was performed for 3 patients. For all patients, the glass dosimeter was exposed and measured dose recorded for one fraction in addition to conventional used TLD and MOSFET. Overall uncertainty of the glass dosimeter for in vivo dose measurement was estimated at 2.4% (68.3% confidence level). The measured doses of the glass dosimeter were well within ±5.0% of the prescription dose at all sites expect mediastinum of one patient, for which it is within ±5.7%. Agreement of measured doses between glass dosimeter and TLD, MOSFET was within ±6.3% and ±6.6%, respectively. Results show that the glass dosimeter can be used as an accurate and reproducible dosimeter for TBI treatment skin dose measurements. The glass dosimeter is a practical alternative to TLD or MOSFET as an in vivo dosimeter. [ABSTRACT FROM AUTHOR]

Abstract: Background and purpose: As an alternative to whole breast irradiation in early breast cancer, a variety of accelerated partial breast irradiation (APBI) techniques have been investigated. The purpose of our study is to compare the dosimetry of four different external beam APBI (EB-APBI) plans: three-dimensional conformal radiation therapy (3D-CRT), intensity-modulated radiation therapy (IMRT), helical tomotherapy (TOMO), and proton beam therapy (PBT). Methods and materials: Thirty patients were included in the study, and plans for four techniques were developed for each patient. A total dose of 30Gy in 6Gy fractions once daily was prescribed in all treatment plans. Results: In the analysis of the non-PTV breast volume that was delivered 50% of the prescribed dose (PD), PBT (mean: 16.5%) was superior to TOMO (mean: 22.8%), IMRT (mean: 33.3%), and 3D-CRT (mean: 40.9%) (p <0.001). The average ipsilateral lung volume percentage receiving 20% of the PD was significantly lower in PBT (0.4%) and IMRT (2.3%) compared with 3D-CRT (6.0%) and TOMO (14.2%) (p <0.001). The average heart volume percentage receiving 20% and 10% of the PD in left-sided breast cancer (N =19) was significantly larger with TOMO (8.0%, 19.4%) compared to 3D-CRT (1.5%, 3.1%), IMRT (1.2%, 4.0%), and PBT (0%, 0%) (p <0.001). Conclusions: All four EB-APBI techniques showed acceptable coverage of the PTV. However, effective non-PTV breast sparing was achieved at the cost of considerable dose exposure to the lung and heart in TOMO. [Copyright &y& Elsevier]

Purpose: Lung cancer remains a leading cause of cancer-related mortality, with non-small cell lung cancer (NSCLC) being particularly challenging due to poor survival rates, emphasizing the need for new treatments. This study examined the therapeutic effects of combining hyperthermia (HT) with tumor-treating electric fields (TTF) in NSCLC., Methods: Cells were exposed to four different conditions: hyperthermia at 42 °C for 30 min, electric fields at 150 kHz and 0.8 V/cm for 24 h, a combination of both treatments, or no treatment (control). Cell proliferation was measured using WST and colony-formation assays, while apoptosis, DNA damage, and repair protein levels were analyzed via Western blotting. Metastatic potential was evaluated with a transwell assay, and cell migration was assessed using the wound-healing assay., Results: The combination therapy significantly inhibited colony formation and reduced cell migration and invasion more effectively than individual treatments. The combined treatment also enhanced apoptosis, as indicated by increased cleaved-PARP and Annexin V levels. In addition, the DNA-damage marker γ-H2AX was elevated, while BRCA1, a protein involved in DNA repair, was significantly downregulated compared to the individual treatments., Conclusions: These results suggest that the enhanced anticancer effects of HT and TTF are due to increased DNA damage and suppression of DNA-repair mechanisms, highlighting the potential of this combination therapy for NSCLC treatment., (© 2024. The Author(s), under exclusive licence to Federación de Sociedades Españolas de Oncología (FESEO).)

Introduction: The aim of this study was to demonstrate the potential of an in vivo four-dimensional (4D) tracking system to accurately localize the radiation source, Iridium-192 (Ir-192) in high-dose rate brachytherapy. Methods: To achieve time-dependent 3D positioning of the Ir-192 source, we devised a 4D tracking system employing multiple compact detectors. During the system's design phase, we conducted comprehensive optimization and analytical evaluations of the diverging collimator employed for detection purposes. Subsequently, we executed 3D reconstruction and positioning procedures based on the 2D images obtained by six detectors, each equipped with an optimized diverging collimator. All simulations for designing and evaluating the 4D tracking system were performed using the open-source GATE (v9.1) Monte Carlo platform based on the GEANT4 (v10.7) toolkit. In addition, to evaluate the accuracy of the proposed 4D tracking system, we conducted simulations and 3D positioning using a solid phantom and patient data. Finally, the error between the reconstructed position coordinates determined by the tracking system and the original coordinates of the Ir-192 radiation source was analyzed. Results: The parameters for the optimized diverging collimator were a septal thickness of 0.3 mm and a collimator height of 30 mm. A tracking system comprising 6 compact detectors was designed and implemented utilizing this collimator. Analysis of the accuracy of the proposed Ir-192 source tracking system found that the average of the absolute values of the error between the 3D reconstructed and original positions for the simulation with the solid phantom were 0.440 mm for the x coordinate, 0.423 mm for the y coordinate, and 0.764 mm for the z coordinate, and the average Euclidean distance was 1.146 mm. Finally, in a simulation based on data from a patient who underwent brachytherapy, the average Euclidean distance between the original and reconstructed source position was 0.586 mm. Discussion: These results indicated that the newly designed in vivo 4D tracking system for monitoring the Ir-192 source during brachytherapy could determine the 3D position of the radiation source in real time during treatment. We conclude that the proposed positioning system has the potential to make brachytherapy more accurate and reliable., Competing Interests: Author HL was employed by ARALE Laboratory Co., Ltd. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Oh, Lee, Kim, Kim, Kang, Chung, Jeong, Lee, Yoon and Lee.)

Background: Despite extensive efforts to obtain accurate segmentation of magnetic resonance imaging (MRI) scans of a head, it remains challenging primarily due to variations in intensity distribution, which depend on the equipment and parameters used., Purpose: The goal of this study is to evaluate the effectiveness of an automatic segmentation method for head MRI scans using a multistep Dense U-Net (MDU-Net) architecture., Methods: The MDU-Net-based method comprises two steps. The first step is to segment the scalp, skull, and whole brain from head MRI scans using a convolutional neural network (CNN). In the first step, a hybrid network is used to combine 2.5D Dense U-Net and 3D Dense U-Net structure. This hybrid network acquires logits in three orthogonal planes (axial, coronal, and sagittal) using 2.5D Dense U-Nets and fuses them by averaging. The resultant fused probability map with head MRI scans then serves as the input to a 3D Dense U-Net. In this process, different ratios of active contour loss and focal loss are applied. The second step is to segment the cerebrospinal fluid (CSF), white matter, and gray matter from extracted brain MRI scans using CNNs. In the second step, the histogram of the extracted brain MRI scans is standardized and then a 2.5D Dense U-Net is used to further segment the brain's specific tissues using the focal loss. A dataset of 100 head MRI scans from an OASIS-3 dataset was used for training, internal validation, and testing, with ratios of 80%, 10%, and 10%, respectively. Using the proposed approach, we segmented the head MRI scans into five areas (scalp, skull, CSF, white matter, and gray matter) and evaluated the segmentation results using the Dice similarity coefficient (DSC) score, Hausdorff distance (HD), and the average symmetric surface distance (ASSD) as evaluation metrics. We compared these results with those obtained using the Res-U-Net, Dense U-Net, U-Net++, Swin-Unet, and H-Dense U-Net models., Results: The MDU-Net model showed DSC values of 0.933, 0.830, 0.833, 0.953, and 0.917 in the scalp, skull, CSF, white matter, and gray matter, respectively. The corresponding HD values were 2.37, 2.89, 2.13, 1.52, and 1.53 mm, respectively. The ASSD values were 0.50, 1.63, 1.28, 0.26, and 0.27 mm, respectively. Comparing these results with other models revealed that the MDU-Net model demonstrated the best performance in terms of the DSC values for the scalp, CSF, white matter, and gray matter. When compared with the H-Dense U-Net model, which showed the highest performance among the other models, the MDU-Net model showed substantial improvements in the HD view, particularly in the gray matter region, with a difference of approximately 9%. In addition, in terms of the ASSD, the MDU-Net model outperformed the H-Dense U-Net model, showing an approximately 7% improvements in the white matter and approximately 9% improvements in the gray matter., Conclusion: Compared with existing models in terms of DSC, HD, and ASSD, the proposed MDU-Net model demonstrated the best performance on average and showed its potential to enhance the accuracy of automatic segmentation for head MRI scans., (© 2023 American Association of Physicists in Medicine.)

Introduction: The purpose of this study was to evaluate a plastic scintillating plate-based beam monitoring system to perform quality assurance (QA) measurements in pencil beam scanning proton beam., Methods: Single spots and scanned fields were measured with the high-resolution dosimetry system, consisting of a plastic scintillation plate coupled to a camera in a dark box at the isocenter. The measurements were taken at 110-190 MeV beam energies with 30° gantry angle intervals at each energy. Spot positions were determined using the plastic scintillating plate-based dosimetry system at the isocenter for 70-230 MeV beam energies with 30° gantry angle intervals. The effect of gantry angle on dose distribution was also assessed by determining the scanning pattern for daily QA and 25 fields treated with intensity-modulated proton therapy., Results: Spot size, field flatness, and field symmetry of plastic scintillating plate-based dosimetry system were consistent with EBT3 at all investigated energies and angles. In all investigated energies and angles, the spot size measured was ±10% of the average size of each energy, the spot position measured was within ±2 mm, field flatness was within ±2%, and field symmetry was within ±1%. The mean gamma passing rates with the 3%/3 mm gamma criterion of the scanning pattern and 25 fields were 99.2% and 99.8%, respectively., Conclusions: This system can be effective for QA determinations of spot size, spot position, field flatness, and field symmetry over 360° of gantry rotation in a time- and cost-effective manner, with spatial resolution comparable to that of EBT3 film., (Copyright © 2023 Copyright: © 2023 Journal of Cancer Research and Therapeutics.)

The present study investigated the therapeutic potential of combining tumor-treating fields (TTF), a novel cancer treatment modality that employs low-intensity, alternating electric fields, with 5-fluorouracil (5-FU), a standard chemotherapy drug used for treating pancreatic cancer. The HPAF-II and Mia-Paca II pancreatic cancer cell lines were treated with TTF, 5-FU, or their combination. Combination treatment produced a significantly greater inhibitory effect on cancer cell proliferation than each single modality. Furthermore, combination therapy induced a substantially higher rate of pancreatic cancer cell apoptosis and exhibited a synergistic effect in clonogenic assays. Additionally, combination treatment showed a greater inhibition of cancer cell migration and invasion than either TTF or 5-FU alone. In conclusion, these findings suggest that the synergistic properties of TTF and 5-FU result in greater therapeutic efficacy against pancreatic cancer cells than either modality alone and may improve survival rates in patients with pancreatic cancer., Competing Interests: None., (AJCR Copyright © 2023.)

Purpose: This study evaluated the properties of a scintillation sheet-based dosimetry system for beam monitoring with high spatial resolution, including the effects of this system on the treatment beam. The dosimetric characteristics and feasibility of this system for clinical use were also evaluated., Methods: The effects of the dosimetry system on the beam were evaluated by measuring the percentage depth doses, dose profiles, and transmission factors. Fifteen treatment plans were created, and the influence of the dosimetry system on these clinical treatment plans was evaluated. The performance of the system was assessed by determining signal linearity, dose rate dependence, and reproducibility. The feasibility of the system for clinical use was evaluated by comparing intensity distributions with reference intensity distributions verified by quality assurance., Results: The spatial resolution of the dosimetry system was found to be 0.43 mm/pixel when projected to the isocenter plane. The dosimetry system attenuated the intensity of 6 MV beams by about 1.1%, without affecting the percentage depth doses and dose profiles. The response of the dosimetry system was linear, independent of the dose rate used in the clinic, and reproducible. Comparison of intensity distributions of evaluation treatment fields with reference intensity distributions showed that the 1%/1 mm average gamma passing rate was 99.6%., Conclusions: The dosimetry system did not significantly alter the beam characteristics, indicating that the system could be implemented by using only a transmission factor. The dosimetry system is clinically suitable for monitoring treatment beam delivery with higher spatial resolution than other transmission detectors., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Associazione Italiana di Fisica Medica e Sanitaria. Published by Elsevier Ltd. All rights reserved.)

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., Competing Interests: None., (AJCR Copyright © 2022.)

Background: Tumor-treating fields (TTFields) is an emerging non-invasive cancer-treatment modality using alternating electric fields with low intensities and an intermediate range of frequency. TTFields affects an extensive range of charged and polarizable cellular factors known to be involved in cell division. However, it causes side-effects, such as DNA damage and apoptosis, in healthy cells., Objective: To investigate whether thymidine can have an effect on the DNA damage and apoptosis, we arrested the cell cycle of human glioblastoma cells (U373) at G1/S phase by using thymidine and then exposed these cells to TTFields., Methods: Cancer cell lines and normal cell (HaCaT) were arrested by thymidine double block method. Cells were seeded into the gap of between the insulated wires. The exposed in alternative electric fields at 120 kHz, 1.2 V/cm. They were counted the cell numbers and analyzed for cancer malignant such as colony formation, Annexin V/PI staining, γH2AX and RT-PCR., Results: The colony-forming ability and DNA damage of the control cells without thymidine treatment were significantly decreased, and the expression levels of BRCA1, PCNA, CDC25C, and MAD2 were distinctly increased. Interestingly, however, cells treated with thymidine did not change the colony formation, apoptosis, DNA damage, or gene expression pattern., Conclusions: These results demonstrated that thymidine can inhibit the TTFields-caused DNA damage and apoptosis, suggesting that combining TTFields and conventional treatments, such as chemotherapy, may enhance prognosis and decrease side effects compared with those of TTFields or conventional treatments alone., (© 2021. The Genetics Society of Korea.)

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 with IR in diagnosing metastatic lung nodules in pediatric chest CT., (Copyright © 2020. Published by Elsevier Ltd.)

Purpose: The entrance beam fluence of therapeutic proton scanning beams can be monitored using a gantry-attachable plastic scintillating plate (GAPSP). This study evaluated the clinical application of the GAPSP using a method that measures intensity modulated proton therapy (IMPT) beams for patient treatment., Methods: IMPT beams for the treatment of nine patients, at sites that included the spine, head and neck, pelvis, and lung, were measured using the GAPSP, composed of an EJ-212 plastic scintillator and a CMOS camera. All energy layers distinguished by the GAPSP were accumulated to determine the dose distribution of the treatment field. The evaluated fields were compared with reference dose maps verified by quality assurance., Results: Comparison of dose distributions of evaluation treatment fields with reference dose distributions showed that the 3%/1 mm average gamma passing rate was 96.4%, independent of the treatment site, energy range and field size. When dose distributions were evaluated using the same criteria for each energy layer, the average gamma passing rate was 91.7%., Conclusions: The GAPSP is a suitable, low-cost method for monitoring pencil beam scanning proton therapy, especially for non-spot scanning or additional collimation. The GAPSP can also estimate the treatment beam by the energy layer, a feature not common to other proton dosimetry tools., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.)

Tumor treating fields (TTFs) are a newly developed cancer therapy technology using an alternating electric field that may be a possible candidate for overcoming the limitations of conventional treatment methods currently used in cancer treatment. Although clinical results using TTFs appear promising, concerns regarding side effects must be clarified to demonstrate the effectiveness of this treatment method. To investigate the side effects of TTF treatment, the damage to normal cell lines and normal tissue of a mouse model was compared with the damage to tumor cells and tumors in a mouse model after TTF treatment. No serious damage was found in the normal cells and normal tissues of the mouse model, suggesting that the side effects of TTF treatment may not be serious. Our evidence based on in vitro and in vivo experiments suggests that TTF may cause selective damage to cancer cells, further demonstrating the potential of TTF as an attractive alternative to conventional cancer treatment modalities., Competing Interests: The authors declare that they have no conflict of interest.

In this paper, we report the results of our investigation into whole brain radiotherapy (WBRT) using linear accelerator-based intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) in lung cancer patients with a high risk of metastasis to the brain. Specifically, we assessed the absorbed dose and the rate of adverse effects for several organs at risk (OAR), including the hippocampus, according to the tilt of a patient's head. We arbitrarily selected five cases where measurements were made with the patients' heads tilted forward and five cases without such tilt. We set the entire brain as the planning target volume (PTV), and the hippocampi, the lenses, the eyes, and the cochleae as the main OAR, and formulated new plans for IMRT (coplanar, non-coplanar) and VMAT (coplanar, non-coplanar). Using the dose-volume histogram (DVH), we calculated and compared the effective uniform dose (EUD), normal tissue complication probability (NTCP) of the OAR and the mean and the maximum doses of hippocampus. As a result, if the patient tilted the head forward when receiving the Linac-based treatment, for the same treatment effect in the PTV, we confirmed that a lower dose entered the OAR, such as the hippocampus, eye, lens, and cochlea. Moreover, the damage to the hippocampus was expected to be the least when receiving coplanar VMAT with the head tilted forward. Accordingly, if patients tilt their heads forward when undergoing Linac-based WBRT, we anticipate that a smaller dose would be transmitted to the OAR, resulting in better quality of life following treatment., (Copyright © 2016 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.)

Background: This study was designed to compare the quality assurance (QA) results of four dosimetric tools used for intensity modulated radiation therapy (IMRT) and to suggest universal criteria for the passing rate in QA, irrespective of the dosimetric tool used., Materials and Methods: Thirty fields of IMRT plans from five patients were selected, followed by irradiation onto radiochromic film, a diode array (Mapcheck), an ion chamber array (MatriXX) and an electronic portal imaging device (EPID) for patient-specific QA. The measured doses from the four dosimetric tools were compared with the dose calculated by the treatment planning system. The passing rates of the four dosimetric tools were calculated using the gamma index method, using as criteria a dose difference of 3% and a distance-to-agreement of 3 mm., Results: The QA results based on Mapcheck, MatriXX and EPID showed good agreement, with average passing rates of 99.61%, 99.04% and 99.29%, respectively. However, the average passing rate based on film measurement was significantly lower, 95.88%. The average uncertainty (1 standard deviation) of passing rates for 6 intensity modulated fields was around 0.31 for film measurement, larger than those of the other three dosimetric tools., Conclusions: QA results and consistencies depend on the choice of dosimetric tool. Universal passing rates should depend on the normalization or inter-comparisons of dosimetric tools if more than one dosimetric tool is used for patient specific QA.

To evaluate the feasibility of tumor-tracking radiotherapy that does not consider tumor deformation during respiration. Four-dimensional computed tomography (4D-CT) data, which considers 10 phases of the respiration cycle, were acquired in 4 patients with lung cancer and 4 patients with liver cancer. Initial treatment plans were established at the end of the inhalation phase (phase 1). As a simulation of deformation-free tumor-tracking radiotherapy, the beam center of the initial plan was moved to the tumor center for all other phases, and the tumor shape acquired from phase 1 was used for all 10 phases. The feasibility of this method was analyzed based on assessment of equivalent uniform dose (EUD), homogeneity index (HI) and coverage index (COV). In photon radiation treatment, movement-induced dose reduction was not particularly significant, with 0.5%, 17.3% and 2.8% average variation in EUD, HI and COV, respectively. In proton radiation treatment, movement-induced dose reduction was more significant, with 0.3%, 40.5% and 2.2% average variation in EUD, HI and COV, respectively. Proton treatment is more sensitive to tumor movement than is photon treatment, and that it is reasonable to disregard tumor deformation during photon therapy employing tumor-tracking radiotherapy.

We compared the main characteristics of movement-induced dose reduction during photon and proton beam treatment, based on an analysis of dose-volume histograms. To simulate target movement, a target contour was delineated in a scanned phantom and displaced by 3 to 20 mm. Although the dose reductions to the target in the 2 treatment systems were similar for transverse (perpendicular to beam direction) target motion, they were completely different for longitudinal (parallel to beam direction) target motion. While both modalities showed a relationship between the degree of target shift and the reduction in dose coverage, dose reduction showed a strong directional dependence in proton beam treatment. Clinical simulation of target movement for a prostate cancer patient showed that, although coverage and conformity indices for a 6-mm lateral movement of the prostate were reduced by 9% and 16%, respectively, for proton beam treatment, they were reduced by only 1% and 7%, respectively, for photon treatment. This difference was greater for a 15-mm target movement in the lateral direction, which lowered the coverage and conformity indices by 34% and 54%, respectively, for proton beam treatment, but changed little during photon treatment. In addition, we found that the equivalent uniform dose (EUD) and homogeneity index show similar characteristics during target movement. These results suggest that movement-induced dose reduction differs significantly between photon and proton beam treatment. Attention should be paid to the target margin in proton beam treatment due to the distinct characteristics of heavy ion beams.