G. Chiloiro

Automatic delineation for replanning in nasopharynx radiotherapy: What is the agreement among experts to be considered as benchmark?

Abstract Background and purpose. Anatomic changes during head and neck radiotherapy require replanning. The primary aim of this study is the definition of the agreement among experts in the head and neck automatic delineation frame to use as benchmark. The secondary goal is to assess the reliability of automatic delineation for nasopharynx radiotherapy and time saving. Material and methods. A computed tomography (CT) scan was acquired in 10 nasopharynx patients along intensity-modulated radiotherapy (IMRT) treatment for replanning. Deformable registration with replanning autocontouring of the structures was performed using VelocityAI 2.3© software defining Structure Set A. The optimization of these contours was obtained through revision by a skilled operator, drawing Structure Set B. An ex novo Structure Set C was segmented on the replanning CT-scan by an expert delineation team. The mean Dices Similarity Index (mDSI) was calculated between Structure Set A and B, A and C, and between B and C for each volume. All segmentation times for organs at risk (OARs) and clinical target volume (CTV) were recorded and compared. Results. We validated the replanning autocontoured Structure Sets for 10 patients. For volumetric analysis we observed mDSI values of 0.87 for the OARs, 0.70 for nodes, 0.90 for CTV in the Structure Set A-B comparison and respectively of 0.74, 0.63 and 0.78 for the Structure Set A-C one, and 0.78, 0.78 and 0.85 for Structure Set B-C, which represents the existing expert based benchmark. We calculated a mean saved time in Structure Set B of 30 minutes. Conclusions. Autocontouring procedures offer considerable segmentation time saving with acceptable reliability of the contours, even if an independent check procedure for their optimization is still required to increase their adherence to referential benchmark gold standard among experts, which stands at a 0.80 DSI value.

International consensus guidelines on Clinical Target Volume delineation in rectal cancer

INTRODUCTION The delineation of Clinical Target Volume (CTV) is a critical step in radiotherapy. Several guidelines suggest different subvolumes and anatomical boundaries in rectal cancer (RC), potentially leading to a misunderstanding in the CTV definition. International consensus guidelines (CG) are needed to improve uniformity in RC CTV delineation. MATERIAL AND METHODS The 7 radiation oncologist experts defined a roadmap to produce RC CG. Step 1: revision of the published guidelines. Step 2: selection of RC cases with different clinical stages. Step 3: delineation of cases using Falcon following previously published guidelines. Step 4: meeting in person to discuss the initial delineation outcome, followed by a CTV proposal based on revised and if needed, adapted anatomical boundaries. Step 5: peer review of the agreed consensus. Step 6: peer review meeting to validate the final outcome. Step 7: completion of RC delineation atlases. RESULTS A new ontology of structure sets was defined and the related table of anatomical boundaries was generated. The major modifications were about the lateral lymph nodes and the ischio-rectal fossa delineation. Seven RC cases were made available online as consultation atlases. CONCLUSION The definition of international CG for RC delineation endorsed by international experts might support a future homogeneous comparison between clinical trial outcomes.

Time to surgery and pathologic complete response after neoadjuvant chemoradiation in rectal cancer: A population study on 2094 patients

Highlights • A large population based analysis to evaluate pathologic response according to time of surgery.• LARC patients were treated with modern techniques of radiotherapy and surgery.• The rate of pCR increased according to time interval from 12.6% to 31.1%.• The pCR increasing was 1.5% (about 0.2%/die) per each week of waiting.• Lengthening the interval (>13 weeks) significantly improved the pathological response.

Automatic segmentation software in locally advanced rectal cancer: READY (REsearch program in Auto Delineation sYstem)-RECTAL 02: prospective study.

To validate autocontouring software (AS) in a clinical practice including a two steps delineation quality assurance (QA) procedure. The existing delineation agreement among experts for rectal cancer and the overlap and time criteria that have to be verified to allow the use of AS were defined. Median Dice Similarity Coefficient (MDSC), Mean slicewise Hausdorff Distances (MSHD) and Total-Time saving (TT) were analyzed. Two expert Radiation Oncologists reviewed CT-scans of 44 patients and agreed the reference-CTV: the first 14 consecutive cases were used to populate the software Atlas and 30 were used as Test. Each expert performed a manual (group A) and an automatic delineation (group B) of 15 Test patients. The delineations were compared with the reference contours. The overlap between the manual and automatic delineations with MDSC and MSHD and the TT were analyzed. Three acceptance criteria were set: MDSC ≥ 0.75, MSHD ≤1mm and TT sparing ≥ 50%. At least 2 criteria had to be met, one of which had to be TT saving, to validate the system. The MDSC was 0.75, MSHD 2.00 mm and the TT saving 55.5% between group A and group B. MDSC among experts was 0.84. Autosegmentation systems in rectal cancer partially met acceptability criteria with the present version.

Radiomics for rectal cancer

Diagnosis and treatment of locally advanced rectal cancer is mainly based on multimodal approach for staging, planning and treatment. The modern radiological and imaging techniques offer, day after day, the possibility to characterize tumor lesions in a more precise and prognostically valuable way. In rectal cancer, extending often the characterization to colon cancer, literature offers some evidences that quantitative and “radiomics” analysis of tumor images might improve the prognostic evaluation of the tumor and the patients’ characterization. Unfortunately, as in other fields of radiomics, the rise of new evidence and models based on single institution case series don’t offer the practical chance to apply them universal data set. Greater efforts in the direction of model evaluation and validation, above all using an external validation approach, are expected to be shown in the coming years for validation of methodology.

Preliminary Data Analysis in Healthcare Multicentric Data Mining: a Privacy-preserving Distributed Approach

The new era of cognitive health care systems offers a large amount of patient data that can be used to develop prediction models and clinical decision support systems. In this frame, the multi-institutional approach is strongly encouraged in order to reach more numerous samples for data mining and more reliable statistics. For these purposes, shared ontologies need to be developed for data management to ensure database semantic coherence in accordance with the various centers’ ethical and legal policies. Therefore, we propose a privacy-preserving distributed approach as a preliminary data analysis tool to identify possible compliance issues and heterogeneity from the agreed multi-institutional research protocol before training a clinical prediction model. This kind of preliminary analysis appeared fast and reliable and its results corresponded to those obtained using the traditional centralized approach. A real time interactive dashboard has also been presented to show analysis results and make the workflow swifter and easier.

Predicting tumour motion during the whole radiotherapy treatment: a systematic approach for thoracic and abdominal lesions based on real time MR

INTRODUCTION Aim of this study was to investigate the ability of pre-treatment four dimensional computed tomography (4DCT) to capture respiratory-motion observed in thoracic and abdominal lesions during treatment. Treatment motion was acquired using full-treatment cine-MR acquisitions. Results of this analysis were compared to the ability of 30 seconds (s) cine Magnetic Resonance (MR) to estimate the same parameters. METHODS A 4DCT and 30 s cine-MR (ViewRay, USA) were acquired on the simulation day for 7 thoracic and 13 abdominal lesions. Mean amplitude, intra- and inter-fraction amplitude variability, and baseline drift were extracted from the full treatment data acquired by 2D cine-MR, and correlated to the motion on pre-treatment 30 s cine-MR and 4DCT. Using the full treatment data, safety margins on the ITV, necessary to account for all motion variability from 4DCT observed during treatment, were calculated. Mean treatment amplitudes were 2 ± 1 mm and 5 ± 3 mm in the anteroposterior (AP) and craniocaudal (CC) direction, respectively. Differences between mean amplitude during treatment and amplitude on 4DCT or during 30 s cine-MR were not significant, but 30 s cine-MR was more accurate than 4DCT. Intra-fraction amplitude variability was positively correlated with both 30 s cine-MR and 4DCT amplitude. Inter-fraction amplitude variability was minimal. RESULTS Mean baseline drift over all fractions and patients equalled 1 ± 1 mm in both CC and AP direction, but drifts per fraction up to 16 mm (CC) and 12 mm (AP) were observed. Margins necessary on the ITV ranged from 0 to 8 mm in CC and 0 to 5 mm in AP direction. Neither amplitude on 4DCT nor during 30 s cine MR is correlated to the magnitude of drift or the necessary margins in both directions. CONCLUSION Lesions moving with small amplitude show limited amplitude variability throughout treatment, making passive motion management strategies seem adequate. However, other variations such as baseline drifts and shifts still cause significant geometrical uncertainty, favouring real-time monitoring and an active approach for all lesions influenced by respiratory motion.

How Do We Collect Data in the Perspective of New Personalize Medicine Tools in Rectal Cancer

During the last two decades, we have witnessed a remarkable transformation of the internal medicine concept with the establishment of the new idea of the personalized medicine. Starting from an inflexible “one size fits all similar group” approach, where the same treatment is used for the same kind of tumor, clinical practice is moving toward a personalized medicine with an essential role of decision support systems (DSS). Besides the widely accepted and daily used clinical guidelines, results of thousands of randomized clinical trials (RCTs), systematic reviews, or meta-analyses conducted in the last 15 years, population-based observational studies are progressively emerging as a complementary form of research, often named “Rapid Learning Health Care” (RLHC) [1–3]. The long time requested to evaluate new drugs or treatment strategies in a RCT, the possibility to enroll only selective subgroups of general population, and the high heterogeneity (in terms of outcomes, methodology, patient’s characteristics, data storing systems, etc.) between different studies justify the key role of observational studies in ensuring not only if the practice has changed appropriately during the time but also if the result of clinical trials translates into tangible benefits in the general population [1].

Use of Indirect Target Gating in Magnetic Resonance-guided Liver Stereotactic Body Radiotherapy: Case Report of an Oligometastatic Patient

The case of a 73-year-old woman affected by anal canal cancer with concomitant liver metastases is presented here. The patient was addressed to stereotactic body radiotherapy (SBRT) on two hepatic secondary lesions after the first radiochemotherapy treatment of the primary tumor. A Tri-60-Co magnetic resonance hybrid radiotherapy unit was used for SBRT treatment delivery. Both liver lesions were not clearly visible on the setup magnetic resonance imaging (MRI) due to their limited dimensions (maximum diameter 13 mm); however, the presence of two cysts adjacent to the metastases allowed the use of an indirect target gating approach. Treatment was delivered in deep inspiration breath-hold conditions using the visual feedback technique for breathing control optimization. Post radiotherapy imaging assessed the complete response.

Phase I and II trial on infusional 5-fluorouracil and gefitinib in combination with preoperative radiotherapy in rectal cancer: 10-years median follow-up

Highlights • We report the long-term results of addiction of gefitinib to preoperative chemoradiotherapy in locally advanced rectal cancer.• We wanted to see if the hight rate of pCR, already shown in previous studies, influenced survival outcomes.• The first promising results have not been confirmed by a significant improvement in outcomes.