Radiation Therapy Applications Research Articles

Synchrotron x-ray spectra characterisation for radiation therapy applications at the ESRF - ID17 biomedical beamline

Objective. Radiation therapy requires reliable dosimetry protocols to deliver successful treatments with high accuracy and precision. In this context, accurate knowledge of the beam’s energy spectra is mandatory. The goal of this study was to validate the synchrotron x-ray spectrum of the ID17 beamline at the European Synchrotron Radiation Facility (ESRF). The modification of the synchrotron storage ring and beamline in recent years necessitates a new characterisation of the radiation spectra of the ID17 beamline. The validated spectra will be a starting point for possible future clinical applications. Approach. The half value layer method was used to measure the attenuation of the x-ray spectrum in Al and Cu. Experimental data was validated against theoretical data produced using OASYS; an in-house developed software for calculating beamline spectra. Two different spectral configurations, ‘conventional’ and ‘clinical’, were investigated. The characterised spectra were used to perform dosimetric validation of depth dose profiles measured in a water-equivalent phantom. The dose profile was measured using two different detectors and compared with calculations generated using two different Monte Carlo algorithms. Main results. The results showed good agreement between measured and predicted half value layers, with differences of less than 1% in most cases. Excellent dosimetric agreement to within 3% was obtained, an agreement that satisfies the requirements in conventional radiotherapy for approvable treatment planning. Significance. Accurate spectra have been defined and validated for the ESRF—ID17 Biomedical beamline. The validated spectra can be used as input for future dosimetric studies and treatment planning systems in the context of preclinical studies and possible future clinical trials.

Radiation therapy in mycosis fungoides

Radiation therapy (RT) is administered with varying intentions, sometimes even several times in the same or in different body areas, to over 50% of patients with neoplastic conditions. Numerous techniques are available to patients in the clinical evolution of mycosis fungoides (MF), and there are several indications for radiation therapy (RT). RT as a skin-directed therapy is very widely used in these patients, either alone or in conjunction with other therapies. The application of RT, a tried-and-true therapy that improves MF patients’ quality of life and treatment, can be encouraged by a multidisciplinary approach and an understanding of current methods and action mechanisms.

Developing simulation-based learning application for radiation therapy students at pre-clinical stage

Simulation-based education has been particularly valuable as a preclinical training method that adequately prepares students for clinical practice, including simulation in educational programs enhances the quality of learning outcomes. However, relevant previous research has exhibited several crucial limitations, with most of them having focused solely on the setup procedures. This study aimed to outline the development of an educational application in radiationtherapy and emphasizes the essential factors that radiation therapist technologists(RTTs) must consider in the treatment room from the perspective of experienced RTTs. We connected the virtual pendants to the linear accelerator components using C# programming and Unity. Customized scripts were assigned to specific linear accelerator (LINAC) functions, and the patient and RTT avatars were developed. We also included audio feedback for the realistic gantry movement sounds. This study outlines various aspects of radiotherapy procedures duringtreatment, such as the simulation of patient positioning, treatment fields, and pendantfunctions, aimed toward enabling the effective use of virtual reality technology inradiation therapy. This study explores the potential of an avatar-based app for radiotherapy education, providing foundational data for future trials. Simulation learning is the most advantageous pre-clinical instrument for equipping students with the skills necessary for clinical practice. This study's resultsare expected to facilitate radiotherapy students' adoption of clinical replacement applications and improve collaborative partnerships and knowledge sharing. Notably, this application complements traditional learning methods, further enhancing the overall educational experience.

A model that predicts a real-time tumour surface using intra-treatment skin surface and end-of-expiration and end-of-inhalation planning CT images.

To develop a mapping model between skin surface motion and internal tumour motion and deformation using end-of-exhalation (EOE) and end-of-inhalation (EOI) 3D CT images for tracking lung tumours during respiration. Before treatment, skin and tumour surfaces were segmented and reconstructed from the EOE and the EOI 3D CT images. A non-rigid registration algorithm was used to register the EOE skin and tumour surfaces to the EOI, resulting in a displacement vector field that was then used to construct a mapping model. During treatment, the EOE skin surface was registered to the real-time, yielding a real-time skin surface displacement vector field. Using the mapping model generated, the input of a real-time skin surface can be used to calculate the real-time tumour surface. The proposed method was validated with and without simulated noise on 4D CT images from 15 patients at Léon Bérard Cancer Center and the 4D-lung dataset. The average centre position error, dice similarity coefficient (DSC), 95%-Hausdorff distance and mean distance to agreement of the tumour surfaces were 1.29 mm, 0.924, 2.76 mm, and 1.13 mm without simulated noise, respectively. With simulated noise, these values were 1.33 mm, 0.920, 2.79 mm, and 1.15 mm, respectively. A patient-specific model was proposed and validated that was constructed using only EOE and EOI 3D CT images and real-time skin surface images to predict internal tumour motion and deformation during respiratory motion. The proposed method achieves comparable accuracy to state-of-the-art methods with fewer pre-treatment planning CT images, which holds potential for application in precise image-guided radiation therapy.

Abstract 1129: A multifaceted study of X-Ray radiation therapy across diverse mouse tumor models

Abstract In this study, we showcase the application of X-ray radiation therapy of tumor-bearing mice across 13 syngeneic tumors, one intracranial tumor, and in combination with radiosensitizing drugs, aiming to develop potent cancer treatment strategies. 1.We examined the effects of different radiation levels on multiple tumor models using a therapeutic device delivering targeted radiation to the tumor site. 2.We investigated the combined benefits of radiation with the radiosensitizer Gemcitabine on the H22 liver tumor model. 3.We assessed the impact of radiation sensitization on the HCC1975-luc intracranial tumor model in combination with AZD0156, a drug that cannot cross the blood-brain barrier. The integrity of the blood-brain barrier and the presence of the pharmacodynamic marker pRAD50 of AZD0156 were evaluated. The results show that X-ray radiation has anti-tumor effects across diverse models, with combination drug treatment with both Gemcitabine and AZD0156 showing enhanced therapeutic effects. Furthermore, pRAD50 showed decreasing trend in the single dose PD study in HCC1975-luc intracranial model. We conclude that our platform provides robust methods for evaluating the therapeutic effects of X-Ray radiation, offering invaluable insights for the creation of new cancer therapies. Citation Format: Jingqi Huang, Wentao Li, Xiaoyan He, Weiwei Cheng, Lingyun Zhang, Guannan Li, Qiuliang Li, Yongfei Wang, Xuesong Ren, Zhi Wei, Long Shi, Yiran Wei, Jing Jin, Linfeng Li, Wei Yun. A multifaceted study of X-Ray radiation therapy across diverse mouse tumor models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1129.

PET/SPECT/Spectral-CT/CBCT imaging in a small-animal radiation therapy platform: A Monte Carlo study-Part II: Biologically guided radiotherapy.

This study addresses the technical gap between clinical radiation therapy (RT) and preclinical small-animal RT, hindering the comprehensive validation of innovative clinical RT approaches in small-animal models of cancer and the translation of preclinical RT studies into clinical practices. The main aim was to explore the feasibility of biologically guided RT implemented within a small-animal radiation therapy (SART) platform, with integrated quad-modal on-board positron emission tomography (PET), single-photon emission computed tomography, photon-counting spectral CT, and cone-beam CT (CBCT) imaging, in a Monte Carlo model as a proof-of-concept. We developed a SART workflow employing quad-modal imaging guidance, integrating multimodal image-guided RT and emission-guided RT (EGRT). The EGRT algorithm was outlined using positron signals from a PET radiotracer, enabling near real-time adjustments to radiation treatment beams for precise targeting in the presence of a 2-mm setup error. Molecular image-guided RT, incorporating a dose escalation/de-escalation scheme, was demonstrated using a simulated phantom with a dose painting plan. The plan involved delivering a low dose to the CBCT-delineated planning target volume (PTV) and a high dose boosted to the highly active biological target volume (hBTV) identified by the 18F-PET image. Additionally, the Bayesian eigentissue decomposition method illustrated the quantitative decomposition of radiotherapy-related parameters, specifically iodine uptake fraction and virtual noncontrast (VNC) electron density, using a simulated phantom with Kidney1 and Liver2 inserts mixed with an iodine contrast agent at electron fractions of 0.01-0.02. EGRT simulations generated over 4,000 beamlet responses in dose slice deliveries and illustrated superior dose coverage and distribution with significantly lower doses delivered to normal tissues, even with a 2-mm setup error introduced, demonstrating the robustness of the novel EGRT scheme compared to conventional image-guided RT. In the dose-painting plan, doubling the dose to the hBTV while maintaining a low dose for the PTV resulted in an organ-at-risk (OAR) dose comparable to the low-dose treatment for the PTV alone. Furthermore, the decomposition of radiotherapy-related parameters in Kidney1 and Liver2 inserts, including iodine uptake fractions and VNC electron densities, exhibited average relative errors of less than 1.0% and 2.5%, respectively. The results demonstrated the successful implementation of biologically guided RT within the proposed quad-model image-guided SART platform, with potential applications in preclinical RT and adaptive RT studies.

Dosimetric Impact of Voluntary Deep Inspiration Breath Hold (DIBH) in Mediastinal Hodgkin Lymphomas: A Comparative Evaluation of Three Different Intensity Modulated Radiation Therapy (IMRT) Delivery Methods Using Voluntary DIBH and Free Breathing Techniques.

Hodgkin lymphomas are radiosensitive and curable tumors that often involve the mediastinum. However, the application of radiation therapy to the mediastinum is associated with late effects including cardiac and pulmonary toxicities and secondary cancers. The adoption of conformal IMRT and deep inspiration breath- hold (DIBH) can reduce the dose to healthy normal tissues (lungs, heart and breast). We compared the dosimetry of organs at risk (OARs) using different IMRT techniques for two breathing conditions, i.e., deep inspiration breath hold (DIBH) and free breathing. Twenty-three patients with early-stage mediastinal Hodgkin lymphomas were accrued in the prospective study. The patients were given treatment plans which utilized full arc volumetric modulated arc therapy (F-VMAT), Butterfly VMAT (B-VMAT), and fixed field IMRT (FF-IMRT) techniques for both DIBH and free breathing methods, respectively. All the plans were optimized to deliver 95% of the prescription dose which was 25.2 Gy to 95% of the PTV volume. The mean dose and standard error of the mean for each OAR, conformity index (CI), and homogeneity index (HI) for the target using the three planning techniques were calculated and compared using Student's t-test for parametric data and Wilcoxon signed-rank test for non-parametric data. The HI and CI of the target was not compromised using the DIBH technique for mediastinal lymphomas. The mean values of CI and HI for both DIBH and FB were comparable. The mean heart doses were reduced by 2.1 Gy, 2.54 Gy, and 2.38 Gy in DIBH compared to FB for the F-VMAT, B-VMAT, and IMRT techniques, respectively. There was a significant reduction in V5Gy, V10Gy, and V15Gy to the heart (p < 0.005) with DIBH. DIBH reduced the mean dose to the total lung by 1.19 Gy, 1.47 Gy, and 1.3 Gy, respectively. Among the 14 female patients, there was a reduction in the mean right breast dose with DIBH compared to FB (4.47 Gy vs. 3.63 Gy, p = 0.004). DIBH results in lower heart, lung, and breast doses than free breathing in mediastinal Hodgkin Lymphoma. Among the different IMRT techniques, FF-IMRT, B-VMAT, and F-VMAT showed similar PTV coverage, with similar conformity and homogeneity indices. However, the time taken for FF-IMRT was much longer than for the F-VMAT and B-VMAT techniques for both breathing methods. B-VMAT and F-VMAT emerged as the optimal planning techniques able to achieve the best target coverage and lower doses to the OARs, with less time required to deliver the prescribed dose.

Использование интраоперационной лучевой терапии при комбинированном лечении операбельного рака лёгкого. Обзор

The treatment of non-small-cell lung cancer (NSCLC) continues to be a pressing issue. It is therefore necessary to advance and to put into practice the methods that will improve patients survival. The aim of the study was to estimate available information on application of intraoperative radiation therapy (IORT) in combined treatment of patients with NSCLC. The treatment plans, safety and tolerability of the treatment method were evaluated. From data analysis it became clear that IORT is a topical treatment for operable non-small cell lung cancer (NSCLC). The new technology has proved its effectiveness due to the reliable local control and significant improve the late survival of patients. During the IORT high one-off dose is selectively delivered to the tumor or tumor bed with maximum preservation of the adjacent normal tissues. The key point in planning radiation exposure during the IORT is to calculate accurately the single radiation dose. The reduction of local relapses and the improvement in overall survival are most likely due to the IORT damaging effect on possible tumor microfoci located in the bronchus cult, its surrounding tissues and lymphatic outflow pathways. To date, further study of the IORT effectiveness and feasibility will remain relevant. However, intraoperative irradiation has already proved to be an effective component of a multimodal approach to cancer treatment.

INVESTIGATION OF LINEAR AND MASS ATTENUATION COEFFICIENT OF OZANOGOGO KAOLIN, AGBOR, DELTA STATE

This study investigates the linear and mass attenuation coefficients of Ozanogogo Kaolin, a material with unique physical and chemical properties, across varying radiation energies. The study aims to contribute to understanding how Ozanogogo Kaolin interacts with radiation, particularly in fields such as medical imaging, radiation therapy, and industrial applications. The research thoroughly explores the material's characteristics, including density, thermal stability, corrosion resistance, and mechanical strength. The linear attenuation coefficient (μ) and mass attenuation coefficient (μ/ρ) are fundamental parameters measured experimentally through a transmission-based technique. The experimental setup includes a radiation source, Ozanogogo Kaolin samples, a radiation detector, and appropriate shielding. The values of attenuation coefficients obtained at different radiation energies are presented, indicating a linear decrease in attenuation with increasing energy. The research discusses the implications of the findings for practical applications, emphasizing Ozanogogo Kaolin's potential in radiation shielding materials and protective equipment. Possible sources of error in the experimental procedure are identified, and recommendations for future research are proposed, including investigations into sample characteristics, comparative studies with other shielding materials, and examinations of material behaviour at higher energies. In conclusion, this study enhances the understanding of Ozanogogo Kaolin's attenuation properties and highlights its potential in diverse applications related to radiation attenuation. The research findings contribute valuable insights for developing improved radiation shielding materials and equipment.

Palmitoyl ascorbic acid glucoside enhanced cell survival with post irradiation treatment

Radiation exposure poses a significant threat to cellular integrity by inducing DNA damage through the generation of free radicals and reactive oxygen species. Ascorbic acid, particularly its derivative Palmitoyl Ascorbic Acid 2-Glucoside (PA2G), has demonstrated remarkable radioprotective properties. While previous research focused on its pre-irradiation application, this study explores the post-irradiation radiomitigation potential of PA2G. Our findings reveal that post-irradiation treatment with PA2G enhances cell survival and accelerates DNA repair processes, particularly the non-homologous end-joining (NHEJ) repair pathway. Notably, PA2G treatment reduces the frequency of lethal chromosomal aberrations and micronuclei formation, indicating its ability to enhance the repair of complex DNA lesions. Furthermore, PA2G is shown to play a role in potentially lethal damage repair (PLDR). These radioprotective effects are specific to NHEJ and ATM pathways, as cells deficient in these mechanisms do not benefit from PA2G treatment. This study highlights PA2G as a versatile radioprotector, both pre- and post-irradiation, with significant potential for applications in radiation therapy and protection, offering new insights into its mechanism of action. Further research is required to elucidate the precise molecular mechanisms underlying PA2G's radiomitigation effects and its potential clinical applications.

Comprehensive Study of Lung Cancer Proton Therapy with Injection of GNPs

The application of radiation therapy (RT) in lung cancer has shown some exciting and sometimes disappointing advances in recent years. Protons compared with photons interact differently with human tissues, and can be used to improve patient care for suffering from lung cancer. A new strategy is the simultaneous injection of nanoparticles with proton radiation into the tumor which has been given over a decade to improve conventional RT. In this work, proton beam therapy (PBT) with gold nanoparticles (GNPs) is used as a part of a combination program to treat advanced localized lung cancers. This paper aims to develop the complex Geant4 model on the human lung and predict the distribution of absorbed dose in lung tumors during proton therapy without and with a high-Z injection of GNPs. Thus, the absorbed dose distribution in lung tumors for four modes such as (i) Bethe-Bloch’s relativistic quantum theory, (ii) GEANT4/ GATE7 simulation model, (iii) Hartree-Fock-Roothaan(HFR) wave functions, and the (vi) Bortfeld theoretical model without and with the injection of GNPs in predicted lung phantom are compared.

The multiple-set split feasibility problem and its application in intensity-modulated radiation therapy

In this paper, we apply a parallel iterative method for solving the split common fixed point problem in Hilbert spaces, without prior knowledge of the transfer operator norm, to the multiple-set split feasibility problem, which plays an important role in medical image reconstruction and signal processing. By formulating a model of the intensity-modulated radiation therapy treatment in a mathematical framework based on the multiple-set split feasibility problem, we also offer an effective approach for solving the intensity-modulated radiation therapy treatment planning.

Treatment of high-risk Hodgkin lymphoma with a modified Stanford V regimen in the AHOPCA: Substituting chemotherapy agents and hampered outcomes.

High-risk Hodgkin lymphoma (HRHL) in children is curable with combined modality therapy. The Association of Pediatric Hematology-Oncology of Central America (AHOPCA) is a consortium of cancer centers from Central America. In 2004, AHOPCA implemented a guideline with a short course of chemotherapy (mStanfordV), strict diagnostics, and radiation guidelines, aimed at reducing abandonment and improving outcomes. Newly diagnosed children less than 18years of age with high-risk HL (Ann Arbor stages: IIB, IIIB, IV) from AHOPCA centers were staged with chest radiography and ultrasound or computed tomography. Therapy was a modified Stanford V (mStanfordV), substituting cyclophosphamide for mechlorethamine and involved field radiation. Of 219 patients with HRHL, 181 patients were eligible and evaluable; 146 (81%) were boys, 22% being less than 6years; 43 were stage IIB, 84 IIIB, and 54 IV. Thirty-one (17%) abandoned therapy, 28 (15%) progressed, 30 (17%) relapsed, and eight (4%) died of toxicity. Radiation guidelines were not followed. Five-year abandonment-sensitive event-free survival and overall survival (AS-EFS, AS-OS±SE) for the cohort were 46%±4% and 56%±4%; 5-year AS-OS for stages IIB, IIIB, and IV was 76%±7%, 59%±7%, and 35%±7% (p=.0006). Despite instituting a short treatment guideline, it did not improve the abandonment rate (17%) and did not achieve the reported outcomes of Stanford V. The cyclophosphamide dose used to replace merchlorethamine was inadequate. Despite strict guidelines, the radiation therapy application was inaccurate. Weekly chemotherapy may have adversely affected abandonment of therapy by increasing the burden of travel time. Based on these results, AHOPCA established a new abandonment strategy and a new guideline.

Polyoxometalates as next-generation of theragnostic gadgets in cancer

Abstract Polyoxometalates (POMS) are a class of mineral clusters of transition metals or rare-earth elements linked together by Oxo ligands. POMs have been identified as antibacterial, antiviral, and anticancer agents after decades of research since the onset of the 20th century. Furthermore, in recent years POMs have been studied for their applications in diagnosis, photodynamic therapy, photothermal therapy, and theragnostic. However, these last-mentioned POM applications have rarely been reviewed. Considering the potential characteristic features of POMs, comprising their easy, inexpensive, and scalable synthesis, and with special attention to the challenges of their application, POMs would be great alternatives to many conventional medical tools in the field of cancer treatment and diagnosis. In this review, we report recent updated research around utilizing POMs in cancer diagnosis and theragnostic. Publications are on basic topics including POMs in magnetic resonance imaging (MRI), POMs in computed tomography (CT), POMs in cancer photoluminescence (PL) imaging, POMs in multimodality, POMs in radiation therapy applications, POMs as radiosensitizer and promotor of drug release, and POMs in theragnostic applications. It is hoped that this review paper will be useful for those researchers who are interested in expanding the applications of polyoxometalates in the field of cancer treatment and diagnosis.

2023 Radiation oncology highlights.

Radiation oncology plays an important role in the local treatment of cancers. Understanding recent advances in the application of radiation therapy to solid tumors is important for all disciplines. The radiation oncology section editors for this journal have selected the following articles for their overall significance, relevance to surgical oncologists, and to illustrate important concepts within the practice of radiation oncology.

Dosimetric characterization of double network Fricke hydrogel based on PVA-GTA and phenylalanine peptide derivative

A double network hydrogel based on Poly(vinyl-alcohol) (PVA) cross-linked with Glutaraldehyde (GTA) was recently developed by using self-assembling phenylalanine (Phe) peptide derivative (Fmoc-Phe-Phe-OMe), with the aim to improve the mechanical-elastic properties of PVA-GTA hydrogels. In this study, a characterization of the properties of Xylenol Orange based Fricke gel dosimeters obtained by infusing a Fricke solution into the double network hydrogel was performed. The gel dosimeters were irradiated with 6 MV and 15 MV X-rays produced by a medical linear accelerator and investigated by means optical absorbance measurements. The double network hydrogel formulation maintained a satisfactory level of radiological water-equivalence within the investigated radiotherapy range. Fricke gel dosimeters prepared with such network kept the desired properties of independence of the response of the dose rate and energy in the investigated intervals. Furthermore, the addition of self-assembling Phe peptide derivative proved not avoid the motion of radio-inducted ferric ions into the hydrogel, probably maintaining the main characteristics of the standard, no Phe peptide infused, formulation. The time course of formation of the optical response after the irradiation was observed to be similar to what previously measured in traditional PVA-GTA Fricke gel dosimeters, while a decrease of the sensitivity to radiation dose of the order of 30% was found. The extent of the decrease does not seem such as to impair the use of these dosimeters for evaluation of doses typical of radiation therapy applications. The overall dosimetric properties, coupled with the mechanical-elastic characteristics of the double network hydrogel, pave theway to the development of phantoms able both to mimic the deformation of organs possibly occurring during radiotherapy treatments and at the same time to assess the 3D dose distribution within such volumes.

High Dose‐Rate MeV Electron Beam from a Tightly‐Focused Femtosecond IR Laser in Ambient Air

AbstractUltrashort electron beams with femtosecond to picosecond bunch durations offer unique opportunities to explore active research areas ranging from ultrafast structural dynamics to ultra‐high dose‐rate radiobiological studies. It presents a straightforward method to generate relativistic electron beams in ambient air via the tight focusing of a few‐cycle, mJ‐class femtosecond infrared laser. It demonstrates experimentally that electrons can reach up to 1.4 MeV at a dose‐rate of 0.15 Gy/s, providing enough dose rate for radiation therapy applications. 3D Particle‐In‐Cell simulations confirm that the acceleration mechanism is based on the relativistic ponderomotive force and show theoretical agreement with the measured electron energies and divergence. Relativistic peak intensities up to 1019 Wcm−2 are reached in ambient air due to a very low B‐integral accumulation during focusing, which prevents intensity clamping. Furthermore, it discusses the scalability of this method with the continuing development of mJ‐class high average power lasers, and providing a promising approach for FLASH radiation therapy.

First clinical application of image-guided intraoperative electron radiation therapy with real time intraoperative dose calculation in recurrent rectal cancer: technical procedure

Intraoperative radiation therapy (IORT) is a radiation technique applying a single fraction with a high dose during surgery. We report the first abdomino-pelvic application of an image-guided intraoperative electron radiation therapy with intraoperative real time dose calculation based on the individual intraoperative patient anatomy. A patient suffering from locoregionally recurrent rectal cancer after treatment with neoadjuvant re-chemoradiation was chosen for this approach. After surgical removal of the recurrence, an adequate IORT applicator was placed as usual. A novel mobile imaging device (ImagingRing, MedPhoton) was positioned around the patient covering the region to be treated with the IORT-applicator in place. It allowed the acquisition of three-dimensional intraoperative cone-beam computed tomography images suitable for dose calculation using an automated scaling (heuristic object and head scatter as well as hardening corrections) of Hounsfield units. After image acquisition confirmed the correct applicator position, the images were transferred to our treatment planning system for intraoperative dose calculation. Treatment could be accomplished using the calculated dose distribution. We herein describe the details of the procedure including necessary adjustments in the typically used IORT equipment and work flow. We further discuss the pros and cons of this new approach generally overcoming a decade long limitation of IORT procedures as well as future perspectives regarding IORT treatments.

Toward a Transportable Cell Culture Platform for Evaluating Radiotherapy Dose Modifying Factors

The current tools for validating dose delivery and optimizing new radiotherapy technologies in radiation therapy do not account for important dose modifying factors (DMFs), such as variations in cellular repair capability, tumor oxygenation, ultra-high dose rates and the type of ionizing radiation used. These factors play a crucial role in tumor control and normal tissue complications. To address this need, we explored the feasibility of developing a transportable cell culture platform (TCCP) to assess the relative biological effectiveness (RBE) of ionizing radiation. We measured cell recovery, clonogenic viability and metabolic viability of MDA-MB-231 cells over several days at room temperature in a range of concentrations of fetal bovine serum (FBS) in medium-supplemented gelatin, under both normoxic and hypoxic oxygen environments. Additionally, we measured the clonogenic viability of the cells to characterize how the duration of the TCCP at room temperature affected their radiosensitivity at doses up to 16 Gy. We found that (78±2)% of MDA-MB-231 cells were successfully recovered after being kept at room temperature for three days in 50% FBS in medium-supplemented gelatin at hypoxia (0.4±0.1)% pO2, while metabolic and clonogenic viabilities as measured by ATP luminescence and colony formation were found to be (58±5)% and (57±4)%, respectively. Additionally, irradiating a TCCP under normoxic and hypoxic conditions yielded a clonogenic oxygen enhancement ratio (OER) of 1.4±0.6 and a metabolic OER of 1.9±0.4. Our results demonstrate that the TCCP can be used to assess the RBE of a DMF and provides a feasible platform for assessing DMFs in radiation therapy applications.

One approach for selection of materials available for 3D printing of a dosimetry pelvic phantom: numerical simulation

Pelvic organ tumors are a serious problem in the field of oncology and account for one-third of the total number of the most common locations of neoplasms. Radiation therapy is often used to treat these types of cancer. A necessary procedure in the application of radiation therapy is the verification of the dosimetric plan to ensure maximum accuracy of radiation and minimize the negative effects of overexposure. To achieve these goals, dosimetry phantoms are used to mimic the structure and properties of biological tissues. Additive technologies can be an effective method for manufacturing such phantoms due to their high-precision ability to replicate both body geometry and anatomical structures. Today, the search and development of materials suitable for both additive technologies and assessing the interaction of ionizing radiation with matter is a relevant task. In this study, models of biological tissues and organs, as well as materials for 3D printing, were created. The features of Co-60 photon beam interaction with these materials were analyzed by numerical simulation. The calculated results demonstrated the suitability of plastic materials based on polylactide for simulating individual biological tissues and human organs from the point of view of interaction with ionizing radiation.