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PURPOSE: In the rapidly expanding field of artificial intelligence (AI) there is a wealth of literature detailing the myriad applications of AI, particularly in the realm of deep learning. However, a review that elucidates the technical principles of deep learning as relevant to radiation oncology in an easily understandable manner is still notably lacking. This paper aims to fill this gap by providing a comprehensive guide to the principles of deep learning that is specifically tailored toward radiation oncology. METHODS: In light of the extensive variety of AI methodologies, this review selectively concentrates on the specific domain of deep learning. It emphasizes the principal categories of deep learning models and delineates the methodologies for training these models effectively. RESULTS: This review initially delineates the distinctions between AI and deep learning as well as between supervised and unsupervised learning. Subsequently, it elucidates the fundamental principles of major deep learning models, encompassing multilayer perceptrons (MLPs), convolutional neural networks (CNNs), recurrent neural networks (RNNs), transformers, generative adversarial networks (GANs), diffusion-based generative models, and reinforcement learning. For each category, it presents representative networks alongside their specific applications in radiation oncology. Moreover, the review outlines critical factors essential for training deep learning models, such as data preprocessing, loss functions, optimizers, and other pivotal training parameters including learning rate and batch size. CONCLUSION: This review provides a comprehensive overview of deep learning principles tailored toward radiation oncology. It aims to enhance the understanding of AI-based research and software applications, thereby bridging the gap between complex technological concepts and clinical practice in radiation oncology.
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Accurate Magnetic Resonance Imaging (MRI) simulation is fundamental for high-precision stereotactic radiosurgery and fractionated stereotactic radiotherapy, collectively referred to as stereotactic radiotherapy (SRT), to deliver doses of high biological effectiveness to well-defined cranial targets. Multiple MRI hardware related factors as well as scanner configuration and sequence protocol parameters can affect the imaging accuracy and need to be optimized for the special purpose of radiotherapy treatment planning. MRI simulation for SRT is possible for different organizational environments including patient referral for imaging as well as dedicated MRI simulation in the radiotherapy department but require radiotherapy-optimized MRI protocols and defined quality standards to ensure geometrically accurate images that form an impeccable foundation for treatment planning. For this guideline, an interdisciplinary panel including experts from the working group for radiosurgery and stereotactic radiotherapy of the German Society for Radiation Oncology (DEGRO), the working group for physics and technology in stereotactic radiotherapy of the German Society for Medical Physics (DGMP), the German Society of Neurosurgery (DGNC), the German Society of Neuroradiology (DGNR) and the German Chapter of the International Society for Magnetic Resonance in Medicine (DS-ISMRM) have defined minimum MRI quality requirements as well as advanced MRI simulation options for cranial SRT.
Subject(s)
Radiation Oncology , Radiosurgery , Humans , Radiosurgery/methods , Magnetic Resonance Imaging , Radiotherapy Dosage , Imaging, Three-DimensionalABSTRACT
PURPOSE: Many patients with glioblastoma suffer from tumor-related seizures. However, there is limited data on the characteristics of tumor-related epilepsy achieving seizure freedom. The aim of this study was to characterize the course of epilepsy in patients with glioblastoma and the factors that influence it. METHODS: We retrospectively analyzed the medical records of glioblastoma patients treated at the University Hospital Erlangen between 01/2006 and 01/2020. RESULTS: In the final cohort of patients with glioblastoma (n = 520), 292 patients (56.2 %) suffered from tumor-related epilepsy (persons with epilepsy, PWE). Levetiracetam was the most commonly used first-line antiseizure medication (n = 245, 83.9 % of PWE). The onset of epilepsy was preoperative in 154/292 patients (52.7 %). 136 PWE (46.6 %) experienced only one single seizure while 27/292 PWE (9.2 %) developed drug-resistant epilepsy. Status epilepticus occurred in 48/292 patients (16.4 %). Early postoperative onset (within 30 days of surgery) of epilepsy and total gross resection (compared with debulking) were independently associated with a lower risk of further seizures. We did not detect dose-dependent pro- or antiseizure effects of radiochemotherapy. CONCLUSION: Tumor-related epilepsy occurred in more than 50% of our cohort, but drug-resistant epilepsy developed in less than 10% of cases. Epilepsy usually started before tumor surgery.
Subject(s)
Anticonvulsants , Brain Neoplasms , Epilepsy , Glioblastoma , Humans , Glioblastoma/complications , Glioblastoma/therapy , Male , Female , Retrospective Studies , Middle Aged , Brain Neoplasms/complications , Brain Neoplasms/therapy , Anticonvulsants/therapeutic use , Epilepsy/complications , Epilepsy/epidemiology , Epilepsy/etiology , Aged , Adult , Levetiracetam/therapeutic use , Drug Resistant Epilepsy/etiology , Drug Resistant Epilepsy/epidemiology , Drug Resistant Epilepsy/therapy , Seizures/etiologyABSTRACT
PURPOSE: Glioblastoma multiforme (GBM) is the most aggressive primary brain tumor, with an overall poor prognosis after diagnosis. Conventional treatment includes resection, chemotherapy with temozolomide (TMZ), and concomitant radiotherapy (RT). The recent success of immunotherapy approaches in other tumor entities, particularly with immune checkpoint inhibitors, could not be clinically transferred to GBM treatment so far. Therefore, preclinical analyses of the expression of both immune-suppressive and immune-stimulatory checkpoint molecules following treatment of human glioblastoma cells with RT and/or temozolomide is needed to design feasible radio(chemo)immunotherapy trials for GBM in the future. METHODS: Five human glioblastoma cell lines (H4, HROG-06, U118, U138, U251) were analyzed regarding their clonogenic survival and cell death forms after chemotherapy (CT) with TMZ and/or normofractionated RT (5â¯× 2â¯Gy) via multicolor flow cytometry. Further, the tumor cell surface expression of immune-activating (OX40L, CD137L, CD70, and ICOSL) and immune-suppressive (PD-L1, PD-L2, HVEM) checkpoint molecules and of an oncogenic molecule (EGFR) were measured via multicolor flow cytometry after CT and RT alone or after RCT. RESULTS: Normofractionated RT and not TMZ was the trigger of induction of predominantly necrosis in the glioblastoma cells. Notably, clonogenicity did not correlate with cell death induction by RT. The basal expression level of immune-suppressive PD-L1, PD-L2, and HVEM varied in the analyzed glioblastoma cells. RT, but not TMZ, resulted in a significant upregulation of PD-L1 and PD-L2 in all tumor cells investigated. Also, the expression of HVEM was increased after RT in most of the GBM cell lines. In contrast, normofractionated RT individually modulated expression of the stimulating immune checkpoint molecules CD70, CD137L, OX40L, and ICOSL1. The oncogenic factor EGFR was significantly increased by irradiation in all examined cell lines, albeit to a different extent. None of the investigated molecules were downregulated after the treatments. CONCLUSION: Normofractionated radiotherapy modulates the immunogenic as well as the oncogenic phenotype of glioblastoma cells, partly individually. Therefore, not only PD-L1 and PD-L2, but also other immunogenic molecules expressed on the surface of glioblastoma cells could serve as targets for immune checkpoint blockade in combination with RT in the future.
Subject(s)
Brain Neoplasms , Glioblastoma , Humans , Temozolomide/pharmacology , Temozolomide/therapeutic use , Glioblastoma/therapy , Glioblastoma/genetics , B7-H1 Antigen , Cell Line, Tumor , Brain Neoplasms/therapy , Brain Neoplasms/genetics , ErbB Receptors/therapeutic useABSTRACT
PURPOSE: Auxiliary devices such as immobilization systems should be considered in synthetic CT (sCT)-based treatment planning (TP) for MRI-only brain radiotherapy (RT). A method for auxiliary device definition in the sCT is introduced, and its dosimetric impact on the sCT-based TP is addressed. METHODS: T1-VIBE DIXON was acquired in an RT setup. Ten datasets were retrospectively used for sCT generation. Silicone markers were used to determine the auxiliary devices' relative position. An auxiliary structure template (AST) was created in the TP system and placed manually on the MRI. Various RT mask characteristics were simulated in the sCT and investigated by recalculating the CT-based clinical plan on the sCT. The influence of auxiliary devices was investigated by creating static fields aimed at artificial planning target volumes (PTVs) in the CT and recalculated in the sCT. The dose covering 50% of the PTV (D50) deviation percentage between CT-based/recalculated plan (∆D50[%]) was evaluated. RESULTS: Defining an optimal RT mask yielded a ∆D50[%] of 0.2⯱ 1.03% for the PTV and between -1.6⯱ 3.4% and 1.1⯱ 2.0% for OARs. Evaluating each static field, the largest ∆D50[%] was delivered by AST positioning inaccuracy (max: 3.5⯱ 2.4%), followed by the RT table (max: 3.6⯱ 1.2%) and the RT mask (max: 3.0⯱ 0.8% [anterior], 1.6⯱ 0.4% [rest]). No correlation between ∆D50[%] and beam depth was found for the sum of opposing beams, except for (45°â¯+ 315°). CONCLUSION: This study evaluated the integration of auxiliary devices and their dosimetric influence on sCT-based TP. The AST can be easily integrated into the sCT-based TP. Further, we found that the dosimetric impact was within an acceptable range for an MRI-only workflow.
Subject(s)
Magnetic Resonance Imaging , Radiotherapy Planning, Computer-Assisted , Humans , Retrospective Studies , Radiotherapy Dosage , Radiotherapy Planning, Computer-Assisted/methods , Magnetic Resonance Imaging/methods , Brain/diagnostic imagingABSTRACT
Osteoarthritis (OA) is one of the most common and socioeconomically relevant diseases, with rising incidence and prevalence especially with regard to an ageing population in the Western world. Over the decades, the scientific perception of OA has shifted from a simple degeneration of cartilage and bone to a multifactorial disease involving various cell types and immunomodulatory factors. Despite a wide range of conventional treatment modalities available, a significant proportion of patients remain treatment refractory. Low-dose radiotherapy (LDRT) has been used for decades in the treatment of patients with inflammatory and/or degenerative diseases and has proven a viable option even in cohorts of patients with a rather poor prognosis. While its justification mainly derives from a vast body of empirical evidence, prospective randomized trials have until now failed to prove the effectiveness of LDRT. Nevertheless, over the decades, adaptions of LDRT treatment modalities have evolved using lower dosages with establishment of different treatment schedules for which definitive clinical proof is still pending. Preclinical research has revealed that the immune system is modulated by LDRT and very recently osteoimmunological mechanisms have been described. Future studies and investigations further elucidating the underlying mechanisms are an essential key to clarify the optimal patient stratification and treatment procedure, considering the patients' inflammatory status, age, and sex. The present review aims not only to present clinical and preclinical knowledge about the mechanistic and beneficial effects of LDRT, but also to emphasize topics that will need to be addressed in future studies. Further, a concise overview of the current status of the underlying radiobiological knowledge of LDRT for clinicians is given, while seeking to stimulate further translational research.
Subject(s)
Osteoarthritis , Humans , Radiotherapy Dosage , Prospective Studies , Osteoarthritis/radiotherapy , Prognosis , ForecastingABSTRACT
OBJECTIVE: Epilepsy is a common comorbidity of glioblastoma. Seizures may occur in various phases of the disease. We aimed to assess potential risk factors for seizures in accordance with the point in time at which they occurred. METHODS: We retrospectively analyzed medical files of adult patients with de novo glioblastoma treated at our institution between January 2006 and January 2020. We categorized seizures as preoperative seizures (POS), early postoperative seizures (EPS; before initiation of radio[chemo]therapy [RCT]), seizures during radiotherapy (SDR; during or <30 days after RCT), and posttherapeutic seizures (PTS; ≥30 days after completion of RCT). We addressed associations between patients' characteristics and their seizures. RESULTS: In the final cohort (N = 520), 292 patients experienced seizures. POS, EPS, SDR, and/or PTS occurred in 29.6% (154/520), 6.0% (31/520), 13.8% (70/509), and 36.1% (152/421) of patients, respectively. POS occurred more frequently in patients with higher Karnofsky Performance Scale scores (odds ratio [OR] = 3.27, p = .001) and tumor location in the temporal lobe (OR = 1.51, p = .034). None of the parameters we analyzed was related to the occurrence of EPS. SDR were independently associated with tumor location (parietal lobe, OR = 1.86, p = .027) and POS, but not EPS, and were independent of RCT. PTS were independently associated with tumor progression (OR = 2.32, p < .001) and with occurrence of SDR (OR = 3.36, p < .001), and negatively correlated with temporal lobe location (OR = .58, p < .014). In patients with tumors exclusively located in the temporal lobe, complete tumor resection was associated with a decreased risk of postoperative seizures. SIGNIFICANCE: Seizures in glioblastoma patients have various, time-dependent risk factors. Temporal lobe localization was a risk factor for preoperative seizures; surgery may have had a protective effect in these patients. RCT did not have dose-dependent pro- or anticonvulsive effects. PTS were associated with tumor progression.
Subject(s)
Brain Neoplasms , Epilepsy , Glioblastoma , Adult , Humans , Glioblastoma/complications , Retrospective Studies , Seizures/etiology , Seizures/complications , Epilepsy/epidemiology , Epilepsy/complications , Risk Factors , Brain Neoplasms/complications , Brain Neoplasms/epidemiology , Brain Neoplasms/pathologyABSTRACT
Optimal doses for the treatment of adrenal metastases with stereotactic radiotherapy (SBRT) are unknown. We aimed to identify dose-volume cut-points associated with decreased local recurrence rates (LRR). A multicenter database of patients with adrenal metastases of any histology treated with SBRT (biologically effective dose, BED10 ≥50 Gy, ≤12 fractions) was analyzed. Details on dose-volume parameters were required (planning target volume: PTV-D98%, PTV-D50%, PTV-D2%; gross tumor volume: GTV-D50%, GTV-mean). Cut-points for LRR were optimized using the R maxstat package. One hundred and ninety-six patients with 218 lesions were included, the largest histopathological subgroup was adenocarcinoma (n = 101). Cut-point optimization resulted in significant cut-points for PTV-D50% (BED10: 73.2 Gy; P = .003), GTV-D50% (BED10: 74.2 Gy; P = .006), GTV-mean (BED10: 73.0 Gy; P = .007), and PTV-D2% (BED10: 78.0 Gy; P = .02) but not for the PTV-D98% (P = .06). Differences in LRR were clinically relevant (LRR ≥ doubled for cut-points that were not achieved). Further dose-escalation was not associated with further improved LRR. PTV-D50%, GTV-D50%, and GTV-mean cut-points were also associated with significantly improved LRR in the adenocarcinoma subgroup. Separate dose optimizations indicated a lower cut-point for the PTV-D50% (BED10: 69.1 Gy) in adenocarcinoma lesions, other values were similar (<2% difference). Associations of cut-points with overall survival (OS) and progression-free survival were not significant but durable freedom from local recurrence was associated with OS in a landmark model (P < .001). To achieve a significant improvement of LRR for adrenal SBRT, a moderate escalation of PTV-D50% BED10 >73.2 Gy (adenocarcinoma: 69.1 Gy) should be considered.
Subject(s)
Adenocarcinoma , Adrenal Gland Neoplasms , Lung Neoplasms , Neoplasms, Second Primary , Radiosurgery , Adenocarcinoma/radiotherapy , Adrenal Gland Neoplasms/radiotherapy , Adrenal Gland Neoplasms/secondary , Humans , Lung Neoplasms/pathology , Radiosurgery/methods , Radiotherapy Dosage , Retrospective StudiesABSTRACT
PURPOSE: Improvements of heat-delivery systems have led to hyperthermia (HT) being increasingly recognized as an adjunct treatment modality also for brain tumors. But how HT affects the immune phenotype of glioblastoma cells is only scarcely known. MATERIALS AND METHODS: We therefore investigated the effect of in vitro HT, radiotherapy (RT), and the combination of both (RHT) on cell death modalities, immune checkpoint molecule (ICM) expression and release of the danger signal HSP70 of two human glioblastoma cell lines (U87 and U251) by using multicolor flow cytometry and ELISA. Hyperthermia was performed once or twice for 60-minute sessions reaching temperatures of 39 °C, 41 °C, and 44 °C, respectively. RT was administered with 5 x 2 Gy. RESULTS: A hyperthermia chamber for cell culture t-flasks regulating the temperature via a contact sensor was developed. While the glioblastoma cells were rather radioresistant, particularly in U251 cells, the combination of RT with HT significantly increased the percentage of apoptotic and necrotic cells for all temperatures examined and for both, single and double HT application. In line with that, an increased release of HSP 70 was seen only in U251 cells, mainly following treatment with HT at temperatures of 44 °C alone or in combination with RT. In contrast, immune suppressive (PD-L1, PD-L2, HVEM) and immune stimulatory (ICOS-L, CD137-L and Ox40-L) ICMs were significantly increased mostly on U87 cells, and particularly after RHT with 41 °C. CONCLUSIONS: Individual assessment of the glioblastoma immune cell phenotype with regard to the planned treatment is mandatory to optimize multimodal radio-immunotherapy protocols including HT.
Subject(s)
Glioblastoma , Hyperthermia, Induced , Cell Death , Combined Modality Therapy , Glioblastoma/radiotherapy , HSP70 Heat-Shock Proteins/metabolism , Humans , Hyperthermia , Necrosis , PhenotypeABSTRACT
INTRODUCTION: The aim of this study was to present our concept in the management of extracranial temporal bone paragangliomas and demonstrate the outcome after primary surgical management of the middle ear component, with an individualized indication for adjuvant radiotherapy. MATERIALS AND METHODS: The records of all patients treated for extracranial jugulotympanic paragangliomas by means of primary surgical management between 2010 and 2021 were studied retrospectively. RESULTS: Twenty-nine patients made up our study sample (mean age 58.8 years). 15 cases were managed solely by means of surgery. Out of the remaining 14 cases with reduction of the middle ear component, adjuvant irradiation was performed in 11 cases, whereas a wait-and-scan strategy was adopted at the patient's request in three cases. No further growth was detected in our study cases. CONCLUSION: Our protocol seems to be associated with an acceptable quality of life and a satisfactory oncologic outcome.
Subject(s)
Ear, Middle/surgery , Organ Sparing Treatments/methods , Otologic Surgical Procedures/methods , Paraganglioma/surgery , Radiotherapy, Adjuvant , Skull Neoplasms/surgery , Temporal Bone/surgery , Tympanoplasty/methods , Adult , Combined Modality Therapy , Female , Hearing Loss/etiology , Hearing Loss/surgery , Humans , Male , Middle Aged , Paraganglioma/complications , Paraganglioma/radiotherapy , Quality of Life , Retrospective Studies , Skull Neoplasms/complications , Skull Neoplasms/radiotherapy , Tinnitus/etiology , Tinnitus/surgery , Treatment OutcomeABSTRACT
To report outcome (freedom from local progression [FFLP], overall survival [OS] and toxicity) after stereotactic, palliative or highly conformal fractionated (>12) radiotherapy (SBRT, Pall-RT, 3DCRT/IMRT) for adrenal metastases in a retrospective multicenter cohort within the framework of the German Society for Radiation Oncology (DEGRO). Adrenal metastases treated with SBRT (≤12 fractions, biologically effective dose [BED10] ≥ 50 Gy), 3DCRT/IMRT (>12 fractions, BED10 ≥ 50 Gy) or Pall-RT (BED10 < 50 Gy) were eligible for this analysis. In addition to unadjusted FFLP (Kaplan-Meier/log-rank), we calculated the competing-risk-adjusted local recurrence rate (CRA-LRR). Three hundred twenty-six patients with 366 metastases were included by 21 centers (median follow-up: 11.7 months). Treatment was SBRT, 3DCRT/IMRT and Pall-RT in 260, 27 and 79 cases, respectively. Most frequent primary tumors were non-small-cell lung cancer (NSCLC; 52.5%), SCLC (16.3%) and melanoma (6.7%). Unadjusted FFLP was higher after SBRT vs Pall-RT (P = .026) while numerical differences in CRA-LRR between groups did not reach statistical significance (1-year CRA-LRR: 13.8%, 17.4% and 27.7%). OS was longer after SBRT vs other groups (P < .05) and increased in patients with locally controlled metastases in a landmark analysis (P < .0001). Toxicity was mostly mild; notably, four cases of adrenal insufficiency occurred, two of which were likely caused by immunotherapy or tumor progression. Radiotherapy for adrenal metastases was associated with a mild toxicity profile in all groups and a favorable 1-year CRA-LRR after SBRT or 3DCRT/IMRT. One-year FFLP was associated with longer OS. Dose-response analyses for the dataset are underway.
Subject(s)
Adrenal Gland Neoplasms/radiotherapy , Adrenal Gland Neoplasms/secondary , Carcinoma, Non-Small-Cell Lung/radiotherapy , Lung Neoplasms/radiotherapy , Small Cell Lung Carcinoma/radiotherapy , Aged , Aged, 80 and over , Databases, Factual , Female , Humans , Male , Middle Aged , Palliative Care , Radiosurgery , Radiotherapy Dosage , Radiotherapy, Conformal , Retrospective Studies , Survival Analysis , Treatment OutcomeABSTRACT
PURPOSE: Radiotherapy represents an effective treatment option in Graves' ophthalmopathy (GO), leading to palliation of clinical symptoms. However, there are only a limited number of trials comparing the effectiveness of low- vs. high-dose radiotherapy. METHODS: We analyzed 127 patients treated with radiotherapy for stage 3/4 GO (NOSPECS classification). Patients were treated with single doses of 2.0â¯Gy (cumulative dose 20â¯Gy) until 2007, afterwards a single dose of 0.8â¯Gy (cumulative dose 4.8â¯Gy) was applied. With a median follow-up-time of 9.0 years, the treatment efficacy (overall improvement, sense of eye pressure, lid edema, ocular motility, exophthalmos, subjective vision, and diplopia) and adverse effects were analyzed by a standardized survey. RESULTS: Overall, 63.8% described improvement of symptoms after radiotherapy. No significant differences in overall treatment response and improvement of main outcome measures between low- or high-dose radiotherapy treatments are detectable, while low-dose radiotherapy leads significantly more often to retreatment (13.1% vs. 1.7%, pâ¯= 0.016). The main independent predictor of treatment response is the presence of lid edema (odds ratio, OR, 3.53; pâ¯= 0.006). CONCLUSION: At long-term follow-up, the majority of patients reported palliation of symptoms with limited adverse effects, suggesting clinical effectiveness of radiotherapy for amelioration of GO symptoms independent of low- or high-dose radiotherapy.
Subject(s)
Exophthalmos , Graves Ophthalmopathy , Diplopia/radiotherapy , Graves Ophthalmopathy/drug therapy , Graves Ophthalmopathy/radiotherapy , Humans , Retrospective Studies , Treatment OutcomeABSTRACT
PURPOSE: To share our experiences in implementing a dedicated magnetic resonance (MR) scanner for radiotherapy (RT) treatment planning using a novel coil setup for brain imaging in treatment position as well as to present developed core protocols with sequences specifically tuned for brain and prostate RT treatment planning. MATERIALS AND METHODS: Our novel setup consists of two large 18-channel flexible coils and a specifically designed wooden mask holder mounted on a flat tabletop overlay, which allows patients to be measured in treatment position with mask immobilization. The signal-to-noise ratio (SNR) of this setup was compared to the vendor-provided flexible coil RT setup and the standard setup for diagnostic radiology. The occurrence of motion artifacts was quantified. To develop magnetic resonance imaging (MRI) protocols, we formulated site- and disease-specific clinical objectives. RESULTS: Our novel setup showed mean SNR of 163⯱ 28 anteriorly, 104⯱ 23 centrally, and 78⯱ 14 posteriorly compared to 84⯱ 8 and 102⯱ 22 anteriorly, 68⯱ 6 and 95⯱ 20 centrally, and 56⯱ 7 and 119⯱ 23 posteriorly for the vendor-provided and diagnostic setup, respectively. All differences were significant (pâ¯> 0.05). Image quality of our novel setup was judged suitable for contouring by expert-based assessment. Motion artifacts were found in 8/60 patients in the diagnostic setup, whereas none were found for patients in the RT setup. Site-specific core protocols were designed to minimize distortions while optimizing tissue contrast and 3D resolution according to indication-specific objectives. CONCLUSION: We present a novel setup for high-quality imaging in treatment position that allows use of several immobilization systems enabling MR-only workflows, which could reduce unnecessary dose and registration inaccuracies.
Subject(s)
Brain Neoplasms/radiotherapy , Brain/diagnostic imaging , Magnetic Resonance Imaging/methods , Radiotherapy, Image-Guided/methods , Brain/radiation effects , Brain Neoplasms/diagnostic imaging , Equipment Design , Humans , Magnetic Resonance Imaging/instrumentation , Neuroimaging/instrumentation , Neuroimaging/methods , Patient Positioning , Radiotherapy Planning, Computer-Assisted/instrumentation , Radiotherapy Planning, Computer-Assisted/methods , Radiotherapy, Image-Guided/instrumentationABSTRACT
Colloidal nanocrystals are the ideal building blocks for the fabrication of functional materials. Using various assembly, patterning or processing techniques, the nanocrystals can be arranged with unprecedented flexibility in 1-, 2- or 3-dimensional architectures over several orders of length scales, providing access to ordered or disordered, porous or non-porous, and simple as well as hierarchical structures. Careful selection of colloidal nanocrystals allows the properties of the final materials to be predefined. Moreover, by combining different nanocrystals, these properties can be fine-tuned for a specific application, opening up fascinating opportunities to create new materials for energy storage and conversion, catalysis, photocatalysis, biomedicine or optics. Indeed, functional materials made of preformed nanoparticles have been realized for metals, polymers, semiconductors, and ceramics, as well as for composites and organic-inorganic hybrids. In this review article, we introduce some concepts for the fabrication of colloidal nanocrystals and their assembly into dense and porous 3-dimensional structures. Porosity is a particularly important material property that strongly influences its application potential. Therefore, we pay special attention to this aspect and compare porous materials synthesized from nanoparticles with those from molecular routes. An additional focus is set on the degree of structural order that can be achieved on different length scales.
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PURPOSE: To investigate the dosimetric influence of daily interfractional (inter) setup errors and intrafractional (intra) target motion on the planning target volume (PTV) and the possibility of an offline adaptive radiotherapy (ART) method to correct larger patient positioning uncertainties in image-guided radiotherapy for prostate cancer (PCa). MATERIALS AND METHODS: A CTV (clinical target volume)-to-PTV margin ranging from 15â¯mm in LR (left-right) and SI (superior-inferior) and 5-10â¯mm in AP (anterior-posterior) direction was applied to all patients. The dosimetric influence of this margin was retrospectively calculated by analysing systematic and random components of inter and intra errors of 31 consecutive intermediate- and high-risk localized PCa patients using daily cone beam computed tomography and kV/kV (kilo-Voltage) imaging. For each patient inter variation was assessed by observing the first 4 treatment days, which led to an offline ART-based treatment plan in case of larger variations. RESULTS: Systematic inter uncertainties were larger (1.12 in LR, 2.28 in SI and 1.48â¯mm in AP) than intra systematic errors (0.44 in LR, 0.69 in SI and 0.80â¯mm in AP). Same findings for the random error in SI direction with 3.19 (inter) and 2.30â¯mm (intra), whereas in LR and AP results were alike with 1.89 (inter) and 1.91â¯mm (intra) and 2.10 (inter) and 2.27â¯mm (intra), respectively. The calculated margin revealed dimensions of 4-5â¯mm in LR, 8-9â¯mm in SI and 6-7â¯mm in AP direction. Treatment plans which had to be adapted showed smaller variations with 1.12 (LR) and 1.72â¯mm (SI) for Σ and 4.17 (LR) and 3.75â¯mm (SI) for σ compared to initial plans with 1.77 and 2.62â¯mm for Σ and 4.46 and 5.39â¯mm for σ in LR and SI, respectively. CONCLUSION: The currently clinically used margin of 15â¯mm in LR and SI and 5-10â¯mm in AP direction includes inter and intra uncertainties. The results show that offline ART is feasible which becomes a necessity with further reductions in PTV margins.
Subject(s)
Adenocarcinoma/radiotherapy , Artifacts , Cone-Beam Computed Tomography/methods , Patient Positioning , Prostatic Neoplasms/radiotherapy , Radiotherapy Dosage , Radiotherapy Planning, Computer-Assisted , Radiotherapy Setup Errors , Radiotherapy, Image-Guided/methods , Radiotherapy, Intensity-Modulated/methods , Adenocarcinoma/blood , Adenocarcinoma/diagnostic imaging , Adenocarcinoma/surgery , Aged , Aged, 80 and over , Combined Modality Therapy , Dose Fractionation, Radiation , Fiducial Markers , Humans , Male , Motion , Organs at Risk/radiation effects , Prostate-Specific Antigen/blood , Prostatectomy , Prostatic Neoplasms/blood , Prostatic Neoplasms/diagnostic imaging , Prostatic Neoplasms/surgery , Rectum/radiation effects , Retrospective Studies , UncertaintyABSTRACT
Due to its superior soft tissue contrast, magnetic resonance imaging (MRI) is essential for many radiotherapy treatment indications. This is especially true for treatment planning in intracranial tumors, where MRI has a long-standing history for target delineation in clinical practice. Despite its routine use, care has to be taken when selecting and acquiring MRI studies for the purpose of radiotherapy treatment planning. Requirements on MRI are particularly demanding for intracranial stereotactic radiotherapy, where accurate imaging has a critical role in treatment success. However, MR images acquired for routine radiological assessment are frequently unsuitable for high-precision stereotactic radiotherapy as the requirements for imaging are significantly different for radiotherapy planning and diagnostic radiology. To assure that optimal imaging is used for treatment planning, the radiation oncologist needs proper knowledge of the most important requirements concerning the use of MRI in brain stereotactic radiotherapy. In the present review, we summarize and discuss the most relevant issues when using MR images for target volume delineation in intracranial stereotactic radiotherapy.
Subject(s)
Brain Neoplasms/radiotherapy , Magnetic Resonance Imaging/methods , Radiosurgery/methods , Radiotherapy Planning, Computer-Assisted/methods , Germany , Humans , Quality Assurance, Health Care , Radiotherapy DosageABSTRACT
INTRODUCTION: Despite a large number of trials, the role of bevacizumab (BEV) in the treatment of recurrent high-grade gliomas is still controversial. Evidence regarding an effect on overall survival in this context is ultimately inconclusive. At the Department of Radiation Oncology at Erlangen, Germany we treated a large cohort of patients with recurrent gliomas where bevacizumab use was determined exclusively by the health care provider's approval of reimbursement. METHODS: 61 patients (between 06/2008 and 01/2014) with recurrent high-grade gliomas had reimbursement requests for BEV sent to their health insurance. 37 patients out of 61 (60.7%) had their requests approved and therefore received bevacizumab (BEV-arm) as part of their treatment. The remaining 24 (39.3%) patients received standard therapy without bevacizumab (non-BEV-arm). Survival endpoints were defined with reference to the first BEV request to the health insurance provider. RESULTS: Median overall survival (OS) for the whole cohort was 7.0 months. OS was significantly better for BEV vs. Non-BEV patients (median, 10.3 vs. 4.2 months, logrank p = 0.023). There was an increased BEV benefit in cases of higher-order recurrences (first order recurrence BEV vs. Non-BEV, 12.5 vs. 10.2 months, p = 0.578) (second or higher order of recurrence, 9.9 vs. 2.6 months, p = 0.010). On multivariate analysis for overall survival the prognostic impact of bevacizumab (HR = 0.43, p = 0.034) remained significant. CONCLUSION: Our results suggest an influence of BEV on overall survival in a heavily pretreated patient population suffering from high-grade gliomas with BEV benefit being greatest in case of second or later recurrence.
Subject(s)
Antineoplastic Agents, Immunological/therapeutic use , Bevacizumab/therapeutic use , Brain Neoplasms/drug therapy , Glioma/drug therapy , Neoplasm Recurrence, Local/drug therapy , Adult , Aged , Female , Humans , Insurance, Health , Male , Middle Aged , Retrospective Studies , Treatment Outcome , Young AdultABSTRACT
In situ small angle scattering is used to study the pore filling mechanism and the adsorption induced deformation of a silica sample with hierarchical porosity upon water adsorption. The high structural order of the cylindrical mesopores on a 2D hexagonal lattice allows obtaining adsorption induced strains from the shift of the corresponding Bragg peaks measured by in situ small-angle X-ray scattering (SAXS). However, apparent strains due to scattering contrast induced changes of the Bragg peak shapes emerge in SAXS. In contrast, small-angle neutron scattering (SANS) allows determining the real adsorption induced strains by employing a H2O/D2O adsorbate with net coherent scattering length density of zero. This allows separating the apparent strains from the real strains experimentally and comparing them with strains obtained from model calculations of the SAXS intensity. It is shown that the apparent strains cannot be described at all by a simple mesopore model of film growth and capillary condensation. A hierarchical model taking the scattering of the micropores and the outer surface of the mesoporous struts in the hierarchically porous sample properly into account, together with a modified mesopore filling mechanism based on a corona model, leads to satisfactory description of both, the adsorption isotherm and the measured apparent strains as derived by SAXS.
ABSTRACT
Low-dose radiation therapy (LDRT) has been successfully established for decades as an alternative analgesic treatment option for patients suffering from chronic degenerative and inflammatory diseases. In this study, 483 patients were undergoing LDRT for degenerative joint disease of the fingers and thumb at the University Hospital Erlangen between 2004 and 2019. Radiotherapy was applied according to the German guidelines for LDRT. Several impact factors on therapeutic success, such as the age and gender, the number of affected fingers, the single and cumulative dose, as well as the number of series, were investigated. In summary, 70% of the patients showed an improvement of their pain following LDRT. No significant impact was found for the factors age, gender, the number of series or the cumulative dosage. Patients with an involvement of the thumb showed a significantly worse outcome compared to patients with an isolated affection of the fingers. In this cohort, patients receiving a single dose of 0.5 Gy reported a significantly better outcome than patients receiving 1.0 Gy, strongly suggesting a reduction in the total dose. In summary, LDRT is a good alternative treatment option for patients suffering from degenerative and inflammatory joint disease of the fingers.
Subject(s)
Fingers/pathology , Fingers/radiation effects , Joint Diseases/complications , Joint Diseases/radiotherapy , Pain/etiology , Pain/radiotherapy , Radiotherapy Dosage , Aged , Dose-Response Relationship, Radiation , Female , Humans , Logistic Models , Male , Multivariate Analysis , Retrospective Studies , Treatment OutcomeABSTRACT
PURPOSE: To report on the Erlangen (UK-Er) experience with linear accelerator stereotactic body radiation therapy (LINAC SBRT) for adrenal metastasis from various primary tumors. MATERIALS AND METHODS: 33 patients were treated. Primary sites included lung (nâ¯= 19), melanoma (nâ¯= 8), colorectal (nâ¯= 2), hepatocellular (nâ¯= 1), esophageal (nâ¯= 2), and breast cancer (nâ¯= 1). 14 patients were treated palliatively, 19 patients were treated with local curative intent. RADIATION TREATMENT: Treatment planning was done based on an exhale, mid-ventilation, and inspiration CT series. Further planning CTs were done to check for the correctness of the breathing pattern. Irradiation was performed using a NOVALIS (Varian, Palo Alto, CA, USA; Brainlab AG, München, Germany) linear accelerator. The isocenter was verified before each treatment session using the BrainLab ExacTrac® (Brainlab AG, München, Germany) system to minimize setup errors. Dose was prescribed to the planning target volume (PTV) surrounding 90% isodose. FOLLOW-UP: Depending on their overall performance status and prognosis, patients received clinical check-ups and radiological imaging. Median follow-up was 11 months. STATISTICAL ANALYSIS: IBM SPSS v. 24 was used for univariate analysis using Kaplan-Meier curves, nonparametric Kruskal-Wallis test, and the chi-square test for frequency distributions. Toxicity was graded according to NCI CTCAE v4.0. Depending on radiologic imaging, patients were classified as stable, regression, and progression. RESULTS: Median survival was 11 months, median PFS was 5 months. Median local failure-free survival was 21 months. Patients who were treated with curative intent showed a better survival curve (pâ¯< 0.0001) and PFS (pâ¯= 0.004). BED ranged from 42 to 108.8â¯Gy, median BED was 67.2â¯Gy. Three BED groups were formed. Overall survival curves differed significantly (pâ¯= 0.046), favoring the high-dose group. 21 patients were free from any adverse events or discomfort. In 7 cases, a grade I toxicity was noted.