CT respiratory motion synthesis using joint supervised and adversarial learning.

Objective.Four-dimensional computed tomography (4DCT) imaging consists in reconstructing a CT acquisition into multiple phases to track internal organ and tumor motion. It is commonly used in radiotherapy treatment planning to establish planning target volumes. However, 4DCT increases protocol complexity, may not align with patient breathing during treatment, and lead to higher radiation delivery.Approach.In this study, we propose a deep synthesis method to generate pseudo respiratory CT phases from static images for motion-aware treatment planning. The model produces patient-specific deformation vector fields (DVFs) by conditioning synthesis on external patient surface-based estimation, mimicking respiratory monitoring devices. A key methodological contribution is to encourage DVF realism through supervised DVF training while using an adversarial term jointly not only on the warped image but also on the magnitude of the DVF itself. This way, we avoid excessive smoothness typically obtained through deep unsupervised learning, and encourage correlations with the respiratory amplitude.Main results.Performance is evaluated using real 4DCT acquisitions with smaller tumor volumes than previously reported. Results demonstrate for the first time that the generated pseudo-respiratory CT phases can capture organ and tumor motion with similar accuracy to repeated 4DCT scans of the same patient. Mean inter-scans tumor center-of-mass distances and Dice similarity coefficients were 1.97 mm and 0.63, respectively, for real 4DCT phases and 2.35 mm and 0.71 for synthetic phases, and compares favorably to a state-of-the-art technique (RMSim).Significance.This study presents a deep image synthesis method that addresses the limitations of conventional 4DCT by generating pseudo-respiratory CT phases from static images. Although further studies are needed to assess the dosimetric impact of the proposed method, this approach has the potential to reduce radiation exposure in radiotherapy treatment planning while maintaining accurate motion representation. Our training and testing code can be found athttps://github.com/cyiheng/Dynagan.

Radiotherapy in the management of lung oligometastases.

In recent years, the development of both medical imaging and new systemic agents (targeted therapy and immunotherapy) have revolutionized the field of oncology, leading to a new entity: oligometastatic disease. Adding local treatment of oligometastases to systemic treatment could lead to prolonged survival with no significant impact on quality of life. Given the high prevalence of lung oligometastases and the new systemic agents coming with increased pulmonary toxicity, this article provides a comprehensive review of the current state-of-art for radiotherapy of lung oligometastases. After reviewing pretreatment workup, the authors define several radiotherapy regimen based on the localization and size of the oligometastases. A comment on the synergistic combination of medical treatment and radiotherapy is also made, projecting on future steps in this specific clinical setting.

[Last year of residency for radiation oncologists in France: Overview and perspectives]. / Phase de consolidation (docteur junior) en oncologie­radiothérapie en France : état des lieux et perspectives.

PURPOSE: The last year of the radiotherapy oncology internship in France has become a phase of empowerment, called "junior doctor", allowing interns to validate acts previously reserved only for senior doctors. This study focused on the responsibilities given to the first promotion of junior doctors in France and their feelings on this new status. MATERIAL AND METHODS: A cross-sectional survey was carried out by the French associations of interns and young doctors in oncology, Aerio and SFjRO. A questionnaire was sent to the class referents of each city for transmission to the junior doctors of the year 2021-2022 from September 1st to November 30th, 2022. The questions concerned training, the modalities of this year and the feelings. Responses were analyzed anonymously using R. 4.3.1 software. RESULTS: For radiation oncology, 33 responses were obtained from 21 cities. For most junior doctors, three to four localizations (51%) were performed with an average of five new patients per week. The contours were reviewed either systematically (51%) or only at the beginning (32%). Dosimetry was reported as never countersigned in 19%; 80% of junior doctors described having been the only radiation oncologist during multidisciplinary staff meetings. The two main areas of improvement were theoretical training (45%) and legal frameworks/contracts (42%). CONCLUSION: These results relating to the first class of junior doctors showed an overall agreement with the recommendations of the Cnec. Feedback from interns was positive. The supervision of brachytherapy and dosimetry activities, the presence alone in multidisciplinary panel remained points of vigilance.

Radiotherapy modification based on artificial intelligence and radiomics applied to (18F)-fluorodeoxyglucose positron emission tomography/computed tomography.

Over the last decades, the refinement of radiation therapy techniques has been associated with an increasing interest for individualized radiation therapy with the aim of increasing or maintaining tumor control and reducing radiation toxicity. Developments in artificial intelligence (AI), particularly machine learning and deep learning, in imaging sciences, including nuclear medecine, have led to significant enthusiasm for the concept of "rapid learning health system". AI combined with radiomics applied to (18F)-fluorodeoxyglucose positron emission tomography/computed tomography ([18F]-FDG PET/CT) offers a unique opportunity for the development of predictive models that can help stratify each patient's risk and guide treatment decisions for optimal outcomes and quality of life of patients treated with radiation therapy. Here we present an overview of the current contribution of AI and radiomics-based machine learning models applied to (18F)-FDG PET/CT in the management of cancer treated by radiation therapy.

Stereotactic radiotherapy for ultracentral lung tumours.

Ultracentral (UC) lung lesions are generally defined by the presence of the tumour or the Planning Target Volume (PTV) abutting proximal bronchial tree (PBT) or the esophagus. Initial reports rose awareness regarding the potential toxicity of stereotactic body radiotherapy (SBRT) when delivered to UC lesions. Major concerns include necrosis, stenosis, and bleeding of the PBT. Technological improvements now enable the delivery of more accurate treatments, possibly redefining the historical "no-fly zone". In this review, studies focusing on the treatment of UC lesions with SBRT are presented. The narrow therapeutic window requires a multidisciplinary approach.

Dose escalation by brachytherapy for gynecological cancers.

Brachytherapy (BT), a type of focal cancer radiation therapy, delivers a highly focused dose of radiation to localized tumors, sparing surrounding normal tissue. Brachytherapy has been used to treat gynecologic malignancies, particularly cervical cancer, for over 100 years. From the first gynecologic brachytherapy treatments in the early 20th century to the modern era, significant transformations have taken place, largely due to advances in technology. The development of high-dose-rate sources, remote afterloaders, new applicators, and three-dimensional image guidance has increased tumor dose and, consequently, local control and survival, reinforcing brachytherapy's role as an integral component of gynecologic cancer treatment. Current research efforts involving biomarker research, integration of new imaging modalities, radiosensitizing therapies are aimed at further personalizing the dose delivered in BT to further improve local control and reduce treatment's related toxicities.

Unrecognized thoracic radiotherapy toxicity: A review of literature.

Radiotherapy remains an important treatment modality for patients with chest malignancies; this is particularly true in patients with breast cancer and Hodgkin lymphoma as well as lung, esophageal, and other mediastinal tumors. More than half of patients with these conditions receive radiotherapy at some point. With the development of new treatment modalities, we are witnessing an improvement of overall survival requiring carefully watching of acute and chronic toxicity of radiation therapy. The challenge is not to ignore radiotherapy's side effects in order to explore and prevent them in the future. Strategies for optimizing thoracic radiotherapy and the advent of innovative techniques may represent an encouraging way to decrease thoracic toxicities. We reviewed the literature to identify these cases of toxicity, which are sometimes forgotten, and others, which have recently been described but remain poorly known.

Predicting response to radiotherapy of head and neck squamous cell carcinoma using radiomics from cone-beam CT images.

INTRODUCTION: Radiotherapy (RT) for head and neck cancer is now guided by cone-beam computed tomography (CBCT). We aim to identify a CBCT radiomic signature predictive of progression to RT. MATERIAL AND METHODS: A cohort of 93 patients was split into training (n = 60) and testing (n = 33) sets. A total of 88 features were extracted from the gross tumor volume (GTV) on each CBCT. Receiver operating characteristic (ROC) curves were used to determine the power of each feature at each week of treatment to predict progression to radio(chemo)therapy. Only features with AUC > 0.65 at each week were pre-selected. Absolute differences were calculated between features from each weekly CBCT and baseline CBCT1 images. The smallest detectable change (C = 1.96 × SD, SD being the standard deviation of differences between feature values calculated on CBCT1 and CBCTn) with its confidence interval (95% confidence interval [CI]) was determined for each feature. The features for which the change was larger than C for at least 5% of patients were then selected. A radiomics-based model was built at the time-point that showed the highest AUC and compared with models relying on clinical variables. RESULTS: Seven features had an AUC > 0.65 at each week, and six exhibited a change larger than the predefined CI 95%. After exclusion of inter-correlated features, only one parameter remains, Coarseness. Among clinical variable, only hemoglobin value was significant. AUC for predicting the treatment response were 0.78 (p = .006), 0.85 (p < .001), and 0.99 (p < .001) for clinical, CBCT4-radiomics (Coarseness) and clinical + radiomics based models respectively. The mean AUC of this last model on a 5-fold cross-validation was 0.80 (±0.09). On the testing cohort, the best prediction was given by the combined model (balanced accuracy [BAcc] 0.67 , p < .001). CONCLUSIONS: We described a feature selection methodology for delta-radiomics that is able to select reproducible features which are informative due to their change during treatment. A selected delta radiomics feature may improve clinical-based prediction models.

Integration of functional imaging in brachytherapy.

Functional imaging allows the evaluation of numerous biological properties that could be considered at all steps of the therapeutic management of patients treated with brachytherapy. Indeed, it enables better initial staging of the disease, and some parameters may also be used as predictive biomarkers for treatment response, allowing better selection of patients eligible for brachytherapy. It may also improve the definition of target volumes with the aim of dose escalations by dose-painting. Finally, it could be useful during the follow-up to assess response to treatment. In this review, we report how functional imaging is integrated at the present time during the brachytherapy procedure, and what are its potential future contributions in the main tumour locations where brachytherapy is recommended. Functional imaging has great potential in the contact of brachytherapy, but still, several issues remain to be resolved before integrating it into clinical practice, especially as a biomarker or in dose painting strategies.

Radiotherapy of benign intracranial tumours.

We present the updated recommendations of the French Society for Radiation Oncology on benign intracranial tumours. Most of them are meningiomas, vestibular schwannomas, pituitary adenomas, craniopharyngiomas, and glomus tumours. Some grow very slowly, and can be observed without specific treatment, especially if they are asymptomatic. Symptomatic or growing tumours are treated by surgery, which is the reference treatment. When surgery is not possible, due to the location of the lesion, or general conditions, radiotherapy can be applied, as it is if there is a postoperative growing residual tumour, or a local relapse. Indications have to be discussed at a multidisciplinary panel, with precise evaluation of the benefit and risks of the treatments. The techniques to be used are the most modern ones, as multimodal imaging and image-guided radiation therapy. Stereotactic treatments, using fractionated or single doses depending on the size or the location of the tumours, are commonly realized, to avoid as much a possible the occurrence of late side effects.

[Application of the « Junior Doctor ¼ status in Radiation Oncology]. / Guide du Docteur Junior en oncologie-radiothérapie.

Introduced in 2017, the reform of the 3rd cycle has modified the organization of the residency in all specialties, and in particular radiation oncology. The residency was thus divided into 3 phases with increasing knowledge and responsibilities. The latter, carried out under the status of "junior doctor", created and defined by decree n°2018-571 of July 3, 2018 and the decree of January 16, 2020, is a phase of supervised autonomy of the resident. Radiotherapy is a singular specialty, with multiple and complex activities, and requires multiple skills. A guide defining the status of the "Junior Doctor" in radiation oncology therefore appears necessary, defining each resident's role and obligations. This guide is of an advisory nature and must be adapted to the particularities of each department. This guide aims to help the implementation of the reform of the 3rd cycle in radiation oncology and especially the final year called the consolidation phase. It is destined to evolve, expanded by individual and collective feedback and the constant renewal of our speciality.

Radiomics analysis of 3D dose distributions to predict toxicity of radiotherapy for lung cancer.

PURPOSE: (Chemo)-radiotherapy (RT) is the gold standard treatment for patients with locally advanced lung cancer non accessible for surgery. However, current toxicity prediction models rely on clinical and dose volume histograms (DVHs) and remain unsufficient. The goal of this work is to investigate the added predictive value of the radiomics approach applied to dose maps regarding acute and late toxicities in both the lungs and esophagus. METHODS: Acute and late toxicities scored using the CTCAE v4.0 were retrospectively collected on patients treated with RT in our institution. Radiomic features were extracted from 3D dose maps considering Gy values as grey-levels in images. DVH and usual clinical factors were also considered. Three toxicity prediction models (clinical only, clinical + DVH and combined, i.e., including clinical + DVH + radiomics) were incrementally trained using a neural network on 70% of the patients for prediction of grade ≥2 acute and late pulmonary toxicities (APT/LPT) and grade ≥2 acute esophageal toxicities (AET). After bootstrapping (n = 1000), optimal cut-off values were determined based on the Youden Index. The trained models were then evaluated in the remaining 30% of patients using balanced accuracy (BAcc). RESULTS: 167 patients were treated from 2015 to 2018: 78% non small-cell lung cancers, 14% small-cell lung cancers and 8% other histology with a median age at treatment of 66 years. Respectively, 22.2%, 16.8% and 30.0% experienced APT, LPT and AET. In the training set (n = 117), the corresponding BAcc for clinical only/clinical + DVH/combined were 0.68/0.79/0.92, 0.66/0.77/0.87 and 0.68/0.73/0.84. In the testing evaluation (n = 50), these trained models obtained a corresponding BAcc of 0.69/0.69/0.92, 0.76/0.80/0.89 and 0.58/0.73/0.72. CONCLUSION: In patients with a lung cancer treated with RT, radiomic features extracted from 3D dose maps seem to surpass usual models based on clinical factors and DVHs for the prediction of APT and LPT.

Use of radiomics in the radiation oncology setting: Where do we stand and what do we need?

Radiomics is a field that has been growing rapidly for the past ten years in medical imaging and more particularly in oncology where the primary objective is to contribute to personalised and predictive medicine. This short review aimed at providing some insights regarding the potential value of radiomics for cancer patients treated with radiotherapy. Radiomics may contribute to each stage of the patients' management: diagnosis, planning, treatment monitoring and post-treatment follow-up (toxicity and response). However, its applicability in clinical routine is currently hindered by several factors, including lack of automation, standardisation and harmonisation. A major effort must be carried out to automate the workflow, standardise radiomics good practices and carry out large-scale studies before any transfer to daily clinical practice.

Kilovoltage intrafraction monitoring during normofractionated prostate cancer radiotherapy.

PURPOSE: During radiotherapy (RT) for prostate cancer (PCa), interfraction and intrafraction movements can lead to decreased target dose coverage and unnecessary over-exposure of organs at risk. New image-guided RT techniques accuracy allows planning target volume (PTV) margins reduction. We aim to assess the feasibility of a kilovoltage intrafraction monitoring (KIM) to track the prostate during RT. METHODS AND MATERIALS: Between November 2017 and April 2018, 44 consecutive patients with PCa were included in an intrafraction prostate motion study using the Truebeam Auto Beam Hold® tracking system (Varian Medical Systems, United State) triggered by gold fiducials localization on kilovoltage (kV) imaging. A 5-mm PTV was considered. A significant gating event (SGE) was defined as the occurrence of an automatic beam interruption requiring patient repositioning following the detection of one fiducial outside a 5-mm target area around the marker during more than 45seconds. RESULTS: Six patients could not benefit from the KIM because of technical issues (loss of one fiducial marker=1, hip prosthesis=4, morbid obesity causing table movements=1). The mean rate of SGE per patient was 14±19%, and the fraction average delivery time was increased by 146±86seconds. For a plan of 39 fractions of 2Gy, the additional radiation dose increased by 0.13±0.09Gy. The mean rates of SGE were 2% and 18% (P=0.002) in patients with planned fraction<90 and>90seconds respectively, showing that duration of the session strongly interfered with prostate intrafraction movements. No other significant clinical and technical parameter was correlated with the occurrence of SGE. CONCLUSION: Automated intrafraction kV imaging can effectively perform autobeam holds due to intrafraction movement of the prostate in the large majority of patients. The additional radiation dose and delivery time are acceptable. This technique may be a cost-effective alternative to electromagnetic transponder guidance.

Cancer of the oesophagus and lymph nodes management in the neoadjuvant or definitive radiochemotherapy setting.

Despite representing a 1% of diagnosed cancer cases in the USA and up to 5% in eastern Asia and Africa, oesophageal cancer still holds numerous questions concerning the best therapeutic management. For squamous cell carcinoma, while radiochemotherapy has proven itself to be the gold standard as part of the trimodality or alone as a definitive treatment, radiotherapy modalities are still debated especially regarding lymph node irradiation. Involved nodes irradiation was developed with the aim of maintaining clinical outcomes and enhancing quality of life but lacks grade 1 evidence. In this article, we aim to summarize the state of art regarding lymph node irradiation, discuss the impact of target definition, delivery techniques, concomitant treatment and the perspectives. Being highly connected to the lymph vessels, lymphatic metastases are frequent and can locate from the neck to the coeliac area with each node having a different prognostic significance. Regarding the comparison between elective nodal irradiation and involved nodes irradiation, evidence-based medicine mostly relies on retrospective studies. Pooled, it suggests similar clinical outcomes with lower acute toxicities in favour of involved nodes irradiation. However, delivery techniques, doses and concomitant treatment were not consensual. Studies are ongoing evaluating the impact of radiation delivery techniques and the choice of concomitant treatment, i.e. immunotherapy. Modern techniques of imaging, radiation therapy progressing each day and alternative treatment modalities being tested, the need of randomized controlled trials has never been so high. Elective nodal irradiation should remain the standard of care while phase 3 trials explore the safety of involved nodal irradiation.