Radiotherapy Techniques Research Articles

Reirradiation of metastases of the central nervous system: part 2-metastatic epidural spinal cord compression.

An increasing number of patients irradiated for metastatic epidural spinal cord compression (MESCC) experience an in-field recurrence and require a second course of radiotherapy. Reirradiation can be performed with conventional radiotherapy or highly-conformal techniques such as intensity-modulated radiation therapy (IMRT), volumetric modulated arc therapy (VMAT), and stereotactic body radiation therapy (SBRT). When using conventional radiotherapy, a cumulative biologically effective dose (BED) ≤120 calculated with an α/β value of 2 Gy (Gy2) was not associated with radiation myelopathy in a retrospective study of 124 patients and is considered safe. In that study, conventional reirradiation led to improvements of motor deficits in 36% of patients and stopped further symptomatic progression in another 50% (overall response 86%). In four other studies, overall response rates were 82-89%. In addition to the cumulative BED or equivalent dose in 2 Gy fractions (EQD2), the interval between both radiotherapy courses <6 months and a BED per course ≥102 Gy2 (corresponding to an EQD2 ≥51 Gy2) were identified as risk factors for radiation myelopathy. Without these risk factors, a BED >120 Gy2 may be possible. Scoring tools have been developed that can assist physicians in estimating the risk of radiation myelopathy and selecting the appropriate dose-fractionation regimen of re-treatment. Reirradiation of MESCC may also be performed with highly-conformal radiotherapy. With IMRT or VMAT, rates of pain relief and improvement of neurologic symptoms of 60-93.5% and 42-73%, respectively, were achieved. One-year local control rates ranged between 55% and 88%. Rates of myelopathy or radiculopathy and vertebral compression fractures were 0% and 0-9.3%, respectively. With SBRT, rates of pain relief were 65-86%. Two studies reported improvements in neurologic symptoms of 0% and 82%, respectively. One-year local control rates were 74-83%. Rates of myelopathy or radiculopathy and vertebral compression fractures were 0-4.5% and 4.5-13.8%, respectively. For SBRT, a cumulative maximum EQD2 to thecal sac ≤70 Gy2, a maximum EQD2 of SBRT ≤25 Gy2, a ratio ≤0.5 of thecal sac maximum EQD2 of SBRT to maximum cumulative EQD2, and an interval between both courses ≥5 months were associated with a lower risk of myelopathy. Additional prospective trials are required to better define the options of reirradiation of MESCC.

Unbalanced core detector (UCD): a novel direct-reading dosimeter for FLASH radiotherapy

FLASH radiotherapy (FRT) is a novel radiotherapy technique based on dose rates that are several orders of magnitude greater than those used in conventional radiotherapy (40 Gy/s vs. 0.5–5 Gy/min). FRT is still in its preclinical and early clinical stage of development. However these studies indicate that FRT is more effective in sparing normal tissues from radiation-related side effects, as compared to conventional radiotherapy. This is the so-called "FLASH effect" and was observed with multi-MeV electron beams. Before FRT is made available to humans, more basic research is needed to fully understand its radiobiology fundamentals. Meanwhile, suitable radiation sources and dosimetric tools are gradually becoming available. Within this framework, INFN-LNF developed the Unbalanced Core Detector (UCD), a novel type of electron dosimeter designed to operate in the FRT domain. UCD main characteristics are the nearly isotropic response, the independence from the electron energy, the very high radiation resistance, the linearity up to dose rates of MGy/s and the possibility to record the time evolution of a single radiation pulse. UCD was tested using 7 and 9 MeV electron beams produced with the ElectronFlash accelerator from Sordina IORT Technologies (SIT S.p.A.) in Aprilia, Italy. UCD was used to measure dose distributions in a water phantom. The results well compare to those obtained with a flashDiamond detector from PTW.

A New hybrid radiotherapy technique for non-small cell lung cancer: Is more effective for functional lung sparing

A New hybrid radiotherapy technique for non-small cell lung cancer: Is more effective for functional lung sparing

Randomized prospective trial comparing two schedules of hypofractionated adjuvant radiotherapy 3 weeks against 1 week fractionation regimen in females with breast cancer

Purpose Acceleration of radiotherapy in five fractions for breast cancer can improve treatment accessibility, especially in low, middle-income countries and during pandemics. We report on acute toxicity after whole breast irradiation/chest wall irradiation±nodal irradiation, radiotherapy interruption and reported acute pneumonitis with an ultra-hypofractionation schedule compared to modest hypofractionation protocol during the coronavirus disease pandemic. Patients and methods Acute toxicity assessment using the RTOG acute toxicity scoring system. One of two specified doses was administered to the breast: 15 × 2.67 Gy (40.05 Gy) or 5 × 5.2 Gy (26 Gy), tumor boost when indicated prescribed dose 5 × 200 Gy with three-dimensional conformal radiotherapy technique. Inclusion criteria were: T1–T3 invasive breast cancer, N0–N1 and N2 after breast conserving or modified radical surgery. Results A total of 101 patients were included in the study. Median age was 53 ± 10.29 years, with median follow-up time 14 months (12–20 months). A significant difference was observed for acute skin toxicity after radiotherapy in favor of better tolerability for the ultrafractionation schedule (P&lt;0.0001). None of the cases in ultra-hypofractionation had interrupted radiotherapy course for more than 2 days, on the other hand, 45.8% of the cases in modest hypofractionation had interrupted course with chest infection as the second most common cause. Regarding acute radiation pneumonitis none of the cases in both arms reported grades 3–4 acute radiation pneumonitis within the first 90 days postradiotherapy. Conclusion Regarding initial toxicity and patient adherence to the radiation course, this single institute study suggests that hypofractionated breast irradiation in 15 fractions compares favorably to accelerated breast radiotherapy in five fractions over 5 days. However, a longer time for follow-up and larger enrolled numbers are needed to confirm noninferiority of this approach.

The impact of advancing the standard of care in radiotherapy on operational treatment resources.

To demonstrate the impact of implementing hypofractionated prescription regimens and advanced treatment techniques on institutional operational hours and radiotherapy personnel resources in a multi-institutional setting. The study may be used to describe the impact of advancing the standard of care with modern radiotherapy techniques on patient and staff resources. This study uses radiation therapy data extracted from the radiotherapy information system from two tertiary care, university-affiliated cancer centers from 2012 to 2021. Across all patients in the analysis, the average fraction number for curative and palliative patients was reported each year in the decade. Also, the institutional operational treatment hours are reported for both centers. A sub-analysis for curative intent breast and lung radiotherapy patients was performed to contextualize the impact of changes to imaging, motion management, and treatment technique. From 2012 to 2021, Center 1 had 42214 patient plans and Center 2 had 43252 patient plans included in the analysis. Averaged over both centers across the decade, the average fraction number per patient decreased from 6.9 to 5.2 (25%) and 21.8 to 17.2 (21%) for palliative and curative patients, respectively. The operational treatment hours for both institutions increased from 8h 15 min to 9h 45 min (18%), despite a patient population increase of 45%. The clinical implementation of hypofractionated treatment regimens has successfully reduced the radiotherapy workload and operational treatment hours required to treat patients. This analysis describes the impact of changes to the standard of care on institutional resources.

Dosimetric evaluation of intensity modulated photon versus proton reirradiation of head and neck cancer

BackgroundReirradiation of head and neck cancer (HNC) became more accessible in the last decade, owing to modern irradiation techniques which offer a reduction in treatment related toxicities. The aim of this paper was to comparatively evaluate the dosimetric aspects derived from intensity modulated photon vs. proton treatment planning in reirradiated HNC patients. MethodsSix recurrent HNC patients were enrolled in this retrospective study. For each patient two treatment plans were created: one IMRT/VMAT and one IMPT plan. The prescribed dose for the second irradiation was between 50 and 70 Gy RBE. The study comparatively analyzed the CTV coverage, doses to organs at risk (OARs) and low doses received by the healthy tissue (other than OAR). ResultsSimilar CTV coverage was achieved for photon vs proton plans, with the latter presenting better homogeneity in four cases. Maximum dose to CTV was generally higher for photon plans, with differences ranging from 0.3 to 1.9%. For parotid glands and body, the mean dose was lower for proton plans. A notable reduction of low dose to healthy tissue (other than OARs) could be achieved with protons, with an average of 60% and 64% for D10% and Dmean, respectively. ConclusionThe dosimetric comparison between photon and proton reirradiation of HNC showed a great need for treatment individualization, concluding that protons should be considered for reirradiation on an individual basis.

Re-re-irradiation for palliation: knowns, unknowns, and next steps.

With improving rates of survival among patients with metastatic malignancies, the request for palliative re-irradiation and re-re-irradiation continues to grow despite an absence of standardized guidelines. With only limited data regarding extra-cranial third-course palliative radiation, many radiation oncologists may feel uncomfortable proceeding with third-course irradiation of the same site. The review explores the available modern data regarding re-re-irradiation. A literature review identified four modern peer-reviewed studies investigating palliative, extra-cranial third-course irradiation with external beam radiation. These studies were retrospective, small, and heterogenous. While they reported comparable rates of pain palliation to first course irradiation and low rates of acute toxicity, interpretation is complicated by heterogeneous treatment parameters and insufficient reporting of cumulative dose equivalents and time intervals. With limited data available, it is critical to prioritize patient safety and quality of life in palliative radiotherapy. Patient selection should be meticulous, considering factors such as initial treatment response and predicted life expectancy. Conformal radiation techniques, strict immobilization, and daily image guidance should be employed to minimize toxicity to organs at risk (OARs). Long-term follow-up is essential for identifying and managing late toxicities effectively. Despite the scarcity of data, retrospective series suggest that extra-cranial third course irradiation can provide effective pain palliation comparable to first-course irradiation with tolerable rates of toxicity. However, careful consideration of patient prognosis and adherence to established principles of palliative radiotherapy are essential in decision-making. Further research and long-term follow-up are needed to refine treatment strategies and ensure safe and efficacious care delivery in this complex clinical scenario.

Stereotactic Body Radiation Therapy for Locally Advanced Pancreatic Cancer.

For patients with locally advanced pancreatic cancer (LAPC), who are candidates for radiation therapy, dose-escalated radiation therapy (RT) offers unique benefits over traditional radiation techniques. In this review, we present a historical perspective of dose-escalated RT for LAPC. We also outline advances in SBRT delivery, one form of dose escalation and a framework for selecting patients for treatment with SBRT. Techniques for delivering SBRT to patients with LAPC have evolved considerably, now allowing for dose-escalation and superior respiratory motion management. At the same time, advancements in systemic therapy, particularly the use of induction multiagent chemotherapy, have called into question which patients would benefit most from radiation therapy. Multidisciplinary assessment of patients with LAPC is critical to guide management and select patients for local therapy. Results from ongoing trials will establish if there is a role of dose-escalated SBRT after induction chemotherapy for carefully selected patients. Patients with LAPC have more therapeutic options than ever before. Careful selection for SBRT may enhance patient outcomes, pending the maturation of pivotal clinical trials.

Total Neoadjuvant Therapy in Localized Pancreatic Cancer: Is More Better?

Pancreatic ductal adenocarcinoma (PDAC) poses a significant challenge in oncology due to its advanced stage upon diagnosis and limited treatment options. Surgical resection, the primary curative approach, often results in poor long-term survival rates, leading to the exploration of alternative strategies like neoadjuvant therapy (NAT) and total neoadjuvant therapy (TNT). While NAT aims to enhance resectability and overall survival, there appears to be potential for improvement, prompting consideration of alternative neoadjuvant strategies integrating full-dose chemotherapy (CT) and radiotherapy (RT) in TNT approaches. TNT integrates chemotherapy and radiotherapy prior to surgery, potentially improving margin-negative resection rates and enabling curative resection for locally advanced cases. The lingering question: is more always better? This article categorizes TNT strategies into six main groups based on radiotherapy (RT) techniques: (1) conventional chemoradiotherapy (CRT), (2) the Dutch PREOPANC approach, (3) hypofractionated ablative intensity-modulated radiotherapy (HFA-IMRT), and stereotactic body radiotherapy (SBRT) techniques, which further divide into (4) non-ablative SBRT, (5) nearly ablative SBRT, and (6) adaptive ablative SBRT. A comprehensive analysis of the literature on TNT is provided for both borderline resectable pancreatic cancer (BRPC) and locally advanced pancreatic cancer (LAPC), with detailed sections for each.

Cellulose fiber derived from sugarcane bagasse and polyethylene glycol/acrylic acid/ branched polyethylenimine-based hydrogel composite prepared by gamma irradiation: A platform for mercury (II) ions adsorption

In this study, cellulose was successfully purified from sugarcane bagasse by alkali treatment and bleaching process. Then, 2-10 wt% of purified cellulose was added into polyethylene glycol and acrylic acid-based hydrogel composite. 25 kGy of gamma irradiation dose was employed to form the gel. With the presence of various cellulose contents, no significant change of functional group was therefore observed. The hydrogel composite was thermally resisted up to 250°C. The microstructure of composite exhibited as an interconnected porosity throughout hydrogel network. Cellulose was located inside hydrogel composite. The gel fraction and porosity for all of composites were reported to be 92-97% and 73-81%, respectively. The swelling behavior was very rapid within initial stage (5 hours) and then, it presented as a plateau region. The presence of purified cellulose significantly offered high dimensional stability. After that, in order to enhance the ability for Hg2+ adsorption, bPEI was coated onto the surface of hydrogel composite. FTIR was employed to evaluate the presence of N-H stretching. At the neutral pH, it defined as an optimal region for adsorption. The efficiency and capacity for Hg2+ adsorption were reported to be 55.17% and 82.94 mg/g in 24 hours, respectively. This was related to the pseudo-second-order kinetic model due to R2 of 0.9941 indicating the chemical adsorption process. Furthermore, EDX analysis confirmed that the existence of Hg was presented onto hydrogel composite surface. It was remarkably noted that purified cellulose from sugarcane bagasse was successfully inserted into hydrogel composite by gamma irradiation technique. It provided a great promise as a platform for mercury ion adsorption.

Technologies of modern radiotherapy and development prospects. Quality assurance concept

At the clinic of the N.N. Blokhin National Medical Research Center of Oncology has been using the following conformal irradiation technologies for cancer patients that meet international standards for more than 13 years: 3D conformal radio therapy (3DCRT); intensity modulated radiotherapy (IMRT); volume modulated arc therapy (VMAT); stereotactic radiation technique (SRT); radiotherapy technique with breathing control, total therapeutic irradiation (TRT) technique followed by bone marrow transplantation. The technological complex with which these technologies are implemented has demonstrated an increase in the quality of radiation treatment for cancer patients. However, despite the “advancement” of technology, there are limitations in the ability to reduce dose loads on critical organs for a number of nosologies. Therefore, the prospects for the development of radiotherapy in Russia lie in the creation of several clinical centers for the use of heavy charged particles that have different physical and dosimetric characteristics and, from this point of view, carry other opportunities and prospects. There is great interest in flash therapy.

Pseudoprogression After Adaptive Radiation Therapy For Early-Stage Non-Small Cell Lung Cancer: Case Report

Background: Differentiating local recurrence from pseudoprogression after radiotherapy for early-stage non-small cell lung cancer (NSCLC) can be challenging. Adaptive radiation therapy (ART) is an innovative radiotherapy technique that adjusts the radiation dose and treatment plan to ensure the tumor receives the optimal radiation while minimizing exposure to the surrounding healthy tissue. To our knowledge, there is no report of pseudoprogression in a patient with NSCLC who received ART. Objectives: The purpose of this article is to present the CT and 18-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) imaging findings of pseudoprogression after ART and discuss the imaging findings important for diagnosis and management. Case summaries: An 87-year-old woman with early-stage NSCLC underwent ART, receiving a total dose of 74 Gy administered in 37 fractions. The maximum standard uptake value (SUVmax) of 18F-FDG in the tumor increased from 2.5 before ART to 3.7 six months after ART on PET, suggesting local recurrence. However, the SUVmax decreased to 2.2 one year after ART, and on CT, the tumor size decreased consistently after ART. Based on serial CT and PET imaging findings, the temporal uptake of 18F-FDG at 6 months after ART was diagnosed as pseudoprogression. Conclusion: Serial CT and PET imaging findings may help differentiate local recurrence from pseudoprogression when tumor size decreases on CT but 18F-FDG uptake increases on PET. Keywords: Differential Diagnosis; Lung Neoplasms; Adaptive Radiation Therapy, Positron-emission Tomography

Comparison of setup errors between two immobilization techniques for image-guided pelvic radiotherapy: Can an ankle fixator be used as an alternative to a thermoplastic mask for immobilization without compromising treatment?

Comparison of setup errors between two immobilization techniques for image-guided pelvic radiotherapy: Can an ankle fixator be used as an alternative to a thermoplastic mask for immobilization without compromising treatment?

Using ANN for thermal neutron shield designing for BNCT treatment room

Occupational radiation protection should be applied to the design of treatment rooms for various radiation therapy techniques, including BNCT, where escaping particles from the beam port of the beam shaping assembly (BSA) may reach the walls or penetrate through the entrance door. The focus of the present study is to design an alternative shielding material, other than the conventional material of lead, that can be considered as the material used in the door and be able to effectively absorb the BSA neutrons which have slowed down to the thermal energy range of <1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$< 1$$\\end{document} eV after passing through the walls and the maze of the room. To this aim, a thermal neutron shield, composed of polymer composite and polyethylene, has been simulated using the Geant4 Monte Carlo code. The neutron flux and dose values were predicted using an artificial neural network (ANN), eliminating the need for time-consuming Monte Carlo simulations in all possible suggestions. Additionally, this technique enables simultaneous optimization of the parameters involved, which is more effective than the traditional sequential and separate optimization process. The results indicated that the optimized shielding material, chosen through ANN calculations that determined the appropriate thickness and weight percent of its compositions, can decrease the dose behind the door to lower than the allowable limit for occupational exposure. The stability of ANN was tested by considering uncertainties with the Gaussian distributions of random numbers to the testing data. The results are promising as they indicate that ANNs could be used as a reliable tool for accurately predicting the dosimetric results, providing a drastically powerful alternative approach to the time-consuming Monte Carlo simulations.

High Rates of Organ Preservation in Rectal Cancer with Papillon Contact X-ray Radiotherapy: Results from a Swiss Cohort.

Rectal cancer typically necessitates a combination of radiotherapy (RT), chemotherapy, and surgery. The associated functional disorders and reduction in quality of life have led to an increasing interest in organ preservation strategies. Response strongly correlates with RT dose, but dose escalation with external beam remains limited even with modern external beam RT techniques because of toxicity of the surrounding tissues. This study reports on the use of Papillon, an endocavitary Radiotherapy device, in the treatment of rectal cancer. The device delivers low energy X-rays, allowing for safe dose escalation and better complete response rate. Between January 2015 and February 2024, 24 rectal cancer patients were treated with the addition of a boost delivered by Papillon to standard RT, with or without chemotherapy, in an upfront organ preservation strategy. After a median follow-up (FU) of 43 months, the organ preservation rate was 96% (23/24), and the local relapse rate was 8% (2/24). None of our patients developed grade 3 or more toxicities. Our results demonstrate that the addition of Papillon contact RT provides a high rate of local remission with sustained long-term organ preservation, offering a promising alternative to traditional surgical approaches in patients with rectal cancer.

Advances in research on organ-at-risk protection in pelvic tumor external beam radiotherapy

The simultaneous objectives of destroying tumor cells while protecting normal pelvic organs present a dual clinical and technical challenge within the realm of pelvic tumor radiotherapy. This article reviews the latest literatures, focusing on technological innovations in key aspects of radiotherapy such as positioning, planning, and delivery. These include positioning fixation techniques, organ-at-risk avoidance irradiation, non-coplanar irradiation techniques, as well as organ displacement protection and image-guided adaptive techniques. It summarizes and discusses the research progress made in the protection of critical organs during pelvic tumor radiotherapy. The paper emphasizes technological advancements in the protection of critical organs throughout the processes of radiotherapy positioning, planning, and implementation, aiming to provide references for further research on the protection of critical organs in the external irradiation treatment of pelvic tumors.

Radiation Techniques for Tracking the Progress of the Hydrometallurgical Leaching Process: A Case Study of Mn and Zn

With advancements in hardware and software, non-destructive radiometric analytical methods have become popular in a wide range of applications. A typical case is the study of the leaching process of metals from mineral ores and mine tailings. The objective of the current study was to develop a radiometric method based on neutron activation analysis (NAA), in particular, delayed gamma neutron activation analysis (DGNAA), to monitor the process of Mn and Zn leaching from Ti ore, Cu mine tailings, and Zn-Pb mine tailings. The DGNAA method was performed using a neutron source: a deuterium-tritium (D-T) neutron generator for Mn and a MARIA research nuclear reactor for Zn. Laboratory-scale Mn leaching from Ti ores, Cu tailings, and Zn-Pb tailings was investigated using delayed gamma-rays of 56Mn (half-life of 2.6 h). The dissolution efficiencies of Mn were found to increase with interaction time and HCl concentration (1 to 5 M) and to vary with the leaching temperature (22.5 to 110 °C). Such results were found to agree with those obtained by total reflection X-ray fluorescence (TXRF) spectrometry for the same samples. 65Zn (half-life of 244 days) was chosen to investigate real-time/online leaching of Zn in Ti ore, Cu tailings, and Zn-Pb tailings. During online monitoring, Zn recovery was also reported to increase with increased leaching time. After approximately 300 min of leaching, 80%, 79%, and 53% recovery of Zn in Zn-Pb tailings, Ti ore, and Cu tailings, respectively, were reported. Theoretically, developed mathematical prediction models for 65Zn radiotracer analysis showed that the spherical diffusion model requires much less time to attain saturation compared to the linear diffusion model. The results of NAA for Zn were compared with those obtained by handheld X-ray fluorescence (handheld-XRF) and TXRF analysis. The analyzed samples encompassed leached Ti ore, Cu tailings, and Zn-Pb tailings which were subjected to different conditions of leaching time, temperature, and HCl concentrations. The XRF analysis confirmed that the leaching efficiencies of Zn rise with the increase in leaching time and HCl concentration and fluctuate with leaching temperature. The developed approach is important and can be applied in laboratories and industrial setups for online monitoring of the recovery of any element whose isotopes can be activated using neutrons. The efficiency of the metal-recovery process has a direct impact on the normal operation and economic advantages of hydrometallurgy.

Efficacy and Toxicity of (Chemo)Radiation Therapy in HIV+ Patients with Squamous Cell Anal Cancer, a Subgroup Analysis of the National Multicenter Cohort FFCD-ANABASE

The influence of human immunodeficiency virus (HIV) infection on clinical outcomes in patients receiving (chemo)radiation therapy (RT) for squamous cell carcinoma of the anus (SCCA) is debated. The objective of this study was to compare efficacy and safety according to HIV status in patients with SCCA treated with C/RT. Between January 2015 and April 2020, 488 patients with a known HIV status (17.6% HIV+) were treated with radiation therapy for SCCA and included in the FFCD-ANABASE multicentric prospective cohort. Clinical outcomes including overall survival (OS), locoregional recurrence-free survival, colostomy-free survival, response rate at 4 to 6 months, cancer-specific survival, relapse-free survival, and severe acute and late toxicity were compared between HIV+ and HIV- patients. The median follow-up was 35.8 months. HIV+ patients were younger (P < .01) and predominantly male (P < .01). Intensity modulated radiation therapy was performed in 80.7% of patients, and 80.9% received concurrent chemotherapy. A higher proportion of HIV+ patients received induction chemotherapy compared with HIV- patients. No statistically significant difference in overall treatment time or severe acute and late toxicities was found between HIV+ and HIV- patients. In univariate analyses, OS (HR = 2.1 [CI 95% 1.2;3.5], P = .007), locoregional recurrence-free survival (HR = 1.7 [1.1;2.7], P = .02), and colostomy-free survival (HR = 1.7 [1.1;2.6], P = .01) were significantly shorter in HIV+ patients than in HIV- patients. Response rate, cancer-specific survival, and relapse-free survival were not significantly different. The recurrence site was significantly different according to HIV status. In the multivariate analysis, prognostic factors for OS were a World Health Organization performance status of ≥1 for the whole population, as well as HIV+ status for the subgroup of women. HIV+ patients treated with chemo-RT for SCCA have poorer clinical outcomes, especially women. No difference was found in toxicity according to HIV status with intensity modulated radiation therapy technique.

Dosimetric analysis of six whole-breast irradiation techniques in supine and prone positions

In breast cancer radiation therapy, minimizing radiation-related risks and toxicity is vital for improving life expectancy. Tailoring radiotherapy techniques and treatment positions can reduce radiation doses to normal organs and mitigate treatment-related toxicity. This study entailed a dosimetric comparison of six different external beam whole-breast irradiation techniques in both supine and prone positions. We selected fourteen breast cancer patients, generating six treatment plans in both positions per patient. We assessed target coverage and organs at risk (OAR) doses to evaluate the impact of treatment techniques and positions. Excess absolute risk was calculated to estimate potential secondary cancer risk in the contralateral breast, ipsilateral lung, and contralateral lung. Additionally, we analyzed the distance between the target volume and OARs (heart and ipsilateral lung) while considering the treatment position. The results indicate that prone positioning lowers lung exposure in X-ray radiotherapy. However, particle beam therapies (PBTs) significantly reduce the dose to the heart and ipsilateral lung regardless of the patient’s position. Notably, negligible differences were observed between arc-delivery and static-delivery PBTs in terms of target conformity and OAR sparing. This study provides critical dosimetric evidence to facilitate informed decision-making regarding treatment techniques and positions.

Identification of oxidative stress signatures of lung adenocarcinoma and prediction of patient prognosis or treatment response with single-cell RNA sequencing and bulk RNA sequencing data

Lung adenocarcinoma (LUAD), the most common subtype of lung cancer globally, has seen improved prognosis with advancements in diagnostic, surgical, radiotherapy, and molecular therapy techniques, while its 5-year survival rate remains low. Molecular biomarkers provide prognostic value. Oxidative stress factors, such as reactive nitrogen species and ROS, are crucial in various stages of tumor progression, influencing cell transformation, proliferation, angiogenesis, and metastasis. ROS demonstrate dual roles, affecting tumor cells, hypoxia sensitivity, and the microenvironment. Comprehensive analysis of oxidative stress in LUAD has not been conducted to date. Therefore, we systematically investigated the regulatory patterns of oxidative stress in LUAD based on oxidative stress-related genes and correlated these patterns with cellular infiltration characteristics of the tumor immune microenvironment. The model utilizes single-factor Cox analysis to screen key differential genes with prognostic value and employs least absolute shrinkage and selection operator (LASSO) penalized Cox regression analysis to construct a prognostic-related prediction model. Ten candidate genes were selected based on this model. The risk score was constructed using the coefficients and expression levels of these ten genes. Furthermore, the impact of this risk score on overall survival (OS) was determined. Two genes with the most significant differential expression, SFTPB and S100P, were selected through qRT-PCR. Cell experiments including CCK-8, Edu, transwell assays confirmed their effects on lung cancer cells growth, consistent with the results of bioinformatics analysis. These findings suggested that this model held potential clinical value for evaluating the prognosis of lung adenocarcinoma.