Long-term follow-up of protective effects on salivary and swallowing structures and improvement of late xerostomia and dysphagia by level IIb optimisation in clinical target volume of nasopharyngeal carcinoma.

BACKGROUND: This study aimed to assess the long-term effect of level IIb clinical target volume (CTV) optimisation on survival, xerostomia, and dysphagia in patients with nasopharyngeal carcinoma (NPC). METHODS: Clinical data of 415 patients with NPC treated with intensity-modulated radiotherapy between December 2014 and October 2018 were retrospectively analysed. The patients were categorised into modified and comparison groups. Late xerostomia and dysphagia were evaluated using Radiation Therapy Oncology Group/European Organisation for Research and Treatment of Cancer scoring. Survival analysis was performed using the Kaplan-Meier method. Differences in late toxicity and dose parameters between both groups were compared. Prognostic factors for survival and late toxicity were assessed using regression analyses. RESULTS: Patients in the modified group developed late xerostomia and dysphagia less frequently than those in the comparison group did (P < 0.001). The mean dose (Dmean) and V26 of parotid glands; Dmean and V39 of submandibular glands; and Dmean of sublingual glands, oral cavity, larynx, and superior, middle, and lower pharyngeal constrictor muscles were lower in the modified group than those in the comparison group (all P < 0.001). Both groups had no significant differences in overall, local recurrence-free, distant metastasis-free, or progression-free survival. The Dmean of the parotid and sublingual glands was a risk factor for xerostomia. The Dmean of the parotid and sublingual glands and middle pharyngeal constrictor muscle was a risk factor for dysphagia. CONCLUSIONS: Level IIb optimisation in NPC patients who meet certain criteria specially the exclusion of positive retropharyngeal nodes treated with intensity-modulated radiotherapy has the potential to better protect the salivary and swallowing structures, decreasing the development of late radiation-induced xerostomia and dysphagia while maintaining long-term survival.

Application of 3D ResSE-Unet-based intelligent delineation of clinical target volume in postoperative radiotherapy for breast cancer / 中华放射医学与防护杂志

Objective:To evaluate the effectiveness and feasibility of 3D ResSE-Unet-based intelligent delineation of clinical target volume (CTV) in postoperative adjuvant radiotherapy for breast cancer.Methods:A total of 974 cases of breast cancer treated in the Cancer Diagnosis and Treatment Center of the Fourth Affiliated Hospital of Guangxi Medical University from September 2018 to June 2022 were enrolled in this study, including 614 cases receiving total mastectomy and 360 cases treated with breast-conserving surgery. They were divided into a training set, a validation set, and a testing set. The training set consisted of 874 cases and was used to build a model of 3D ResSE-Unet-based intelligent CTV delineation. The validation set comprised 40 cases and was used to evaluate the feasibility and effectiveness of the clinical application of AI-based CTV design in the radiotherapy for breast cancer. The testing set was composed of 60 cases and was used to test the accuracy of intelligent CTV. The Wilcoxon rank test was used to compare the Dice similarity coefficient (DSC), 95% Hausdorff distance (HD95), and average surface distance (ASD) obtained using the intelligent delineation model.Results:The intelligent delineation model showed high precision. The CTV of cases treated with total mastectomy (CTV cw) and the CTV of cases treated with breast-conserving surgery (CTV b) had DSCs greater than 0.80 and greater than 0.88, respectively. Therefore, compared with CTV cw, CTV b had a higher DSC (0.91 ± 0.03 vs.0.83 ± 0.05, t = 7.11, P < 0.05). Both CTV cw and CTV b had lower HD 95 [(7.56 ± 3.42) mm vs.(8.77 ± 5.89) mm] and ASD [(1.85 ± 0.71) mm vs.(1.86 ± 0.83)mm], without statistically significant difference ( P > 0.05). The left/right supraclavicular and infraclavicular CTV (CTV2) had DSCs greater than 0.8. CTV2 also had low average HD95 and ASD, without statistically significant difference ( P > 0.05). Conclusions:The 3D ResSE-Unet-based intelligent CTV delineation has better consistency and feasibility in postoperative adjuvant radiotherapy for breast cancer, especially the CTVs after breast-conserving surgery.

Clinical target volume automatic segmentation based on lymph node stations for lung cancer with bulky lump lymph nodes.

BACKGROUND: The lack of standardized delineation of lymph node station in lung cancer radiotherapy leads to nonstandard clinical target volume (CTV) contouring, especially in patients with bulky lump gross target volume lymph nodes (GTVnd). This study defines lymph node region boundaries in radiotherapy for lung cancer and automatically contours lymph node stations based on the International Association for the Study of Lung Cancer (IASLC) lymph node map. METHODS: Computed tomography (CT) scans of 200 patients with small cell lung cancer were collected. The lymph node zone boundaries were defined based on the IASLC lymph node map, with adjustments to meet radiotherapy requirements. Contours of lymph node stations were confirmed by two experienced oncologists. A model (DiUNet) was constructed by incorporating the contours of GTVnd to precisely contour the boundaries. Quantitative evaluation metrics and clinical evaluations were conducted. RESULTS: The mean 3D Dice similarity coefficient (Dice similarity coefficient) values of DiUNet in most lymph node stations was greater than 0.7, 98.87% of the lymph node station slices are accepted. The mean DiUNet score was not significantly different from that of the man contoured in the evaluation of lymph node stations and CTV. CONCLUSION: This is the first study to propose a method that automatically contours lymph node regions station by station based on the IASLC lymph node map with bulky lump GTVnd. Delineation of lymph node stations based on the DiUNet model is a promising strategy to obtain accuracy and efficiency for CTV delineation in lung cancer patients, especially for bulky lump GTVnd.

Clinical Evaluation of an Auto-Segmentation Tool for Spine SBRT Treatment.

Purpose: Spine SBRT target delineation is time-consuming due to the complex bone structure. Recently, Elements SmartBrush Spine (ESS) was developed by Brainlab to automatically generate a clinical target volume (CTV) based on gross tumor volume (GTV). The aim of this project is to evaluate the accuracy and efficiency of ESS auto-segmentation. Methods: Twenty spine SBRT patients with 21 target sites treated at our institution were used for this retrospective comparison study. Planning CT/MRI images and physician-drawn GTVs were inputs for ESS. ESS can automatically segment the vertebra, split the vertebra into 6 sectors, and generate a CTV based on the GTV location, according to the International Spine Radiosurgery Consortium (ISRC) Consensus guidelines. The auto-segmented CTV can be edited by including/excluding sectors of the vertebra, if necessary. The ESS-generated CTV contour was then compared to the clinically used CTV using qualitative and quantitative methods. The CTV contours were compared using visual assessment by the clinicians, relative volume differences (RVD), distance of center of mass (DCM), and three other common contour similarity measurements such as dice similarity coefficient (DICE), Hausdorff distance (HD), and 95% Hausdorff distance (HD95). Results: Qualitatively, the study showed that ESS can segment vertebra more accurately and consistently than humans at normal curvature conditions. The accuracy of CTV delineation can be improved significantly if the auto-segmentation is used as the first step. Conversely, ESS may mistakenly split or join different vertebrae when large curvatures in anatomy exist. In this study, human interactions were needed in 7 of 21 cases to generate the final CTVs by including/excluding sectors of the vertebra. In 90% of cases, the RVD were within ±15%. The RVD, DCM, DICE, HD, and HD95 for the 21 cases were 3% ± 12%, 1.9 ± 1.5 mm, 0.86 ± 0.06, 13.34 ± 7.47 mm, and 4.67 ± 2.21 mm, respectively. Conclusion: ESS can auto-segment a CTV quickly and accurately and has a good agreement with clinically used CTV. Inter-person variation and contouring time can be reduced with ESS. Physician editing is needed for some occasions. Our study supports the idea of using ESS as the first step for spine SBRT target delineation to improve the contouring consistency as well as to reduce the contouring time.

Deep learning-based auto-segmentation of clinical target volumes for radiotherapy treatment of cervical cancer.

OBJECTIVES: Because radiotherapy is indispensible for treating cervical cancer, it is critical to accurately and efficiently delineate the radiation targets. We evaluated a deep learning (DL)-based auto-segmentation algorithm for automatic contouring of clinical target volumes (CTVs) in cervical cancers. METHODS: Computed tomography (CT) datasets from 535 cervical cancers treated with definitive or postoperative radiotherapy were collected. A DL tool based on VB-Net was developed to delineate CTVs of the pelvic lymph drainage area (dCTV1) and parametrial area (dCTV2) in the definitive radiotherapy group. The training/validation/test number is 157/20/23. CTV of the pelvic lymph drainage area (pCTV1) was delineated in the postoperative radiotherapy group. The training/validation/test number is 272/30/33. Dice similarity coefficient (DSC), mean surface distance (MSD), and Hausdorff distance (HD) were used to evaluate the contouring accuracy. Contouring times were recorded for efficiency comparison. RESULTS: The mean DSC, MSD, and HD values for our DL-based tool were 0.88/1.32 mm/21.60 mm for dCTV1, 0.70/2.42 mm/22.44 mm for dCTV2, and 0.86/1.15 mm/20.78 mm for pCTV1. Only minor modifications were needed for 63.5% of auto-segmentations to meet the clinical requirements. The contouring accuracy of the DL-based tool was comparable to that of senior radiation oncologists and was superior to that of junior/intermediate radiation oncologists. Additionally, DL assistance improved the performance of junior radiation oncologists for dCTV2 and pCTV1 contouring (mean DSC increases: 0.20 for dCTV2, 0.03 for pCTV1; mean contouring time decrease: 9.8 min for dCTV2, 28.9 min for pCTV1). CONCLUSIONS: DL-based auto-segmentation improves CTV contouring accuracy, reduces contouring time, and improves clinical efficiency for treating cervical cancer.

Automated clinical target volume delineation using deep 3D neural networks in radiation therapy of Non-small Cell Lung Cancer.

BACKGROUND AND PURPOSE: Clinical targeted volume (CTV) delineation accounting for the patient-specific microscopic tumor spread can be a difficult step in defining the treatment volume. We developed an intelligent and automated CTV delineation system for locally advanced non-small cell lung carcinoma (NSCLC) to cover the microscopic tumor spread while avoiding organs-at-risk (OAR). MATERIALS AND METHODS: A 3D UNet with a customized loss function was used, which takes both the patients' respiration-correlated ("4D") CT scan and the physician contoured internal gross target volume (iGTV) as inputs, and outputs the CTV delineation. Among the 84 identified patients, 60 were randomly selected to train the network, and the remaining as testing. The model performance was evaluated and compared with cropped expansions using the shape similarities to the physicians' contours (the ground-truth) and the avoidance of critical OARs. RESULTS: On the testing datasets, all model-predicted CTV contours followed closely to the ground truth, and were acceptable by physicians. The average dice score was 0.86. Our model-generated contours demonstrated better agreement with the ground-truth than the cropped 5 mm/8 mm expansion method (median of median surface distance of 1.0 mm vs 1.9 mm/2.0 mm), with a small overlap volume with OARs (0.4 cm3 for the esophagus and 1.2 cm3 for the heart). CONCLUSIONS: The CTVs generated by our CTV delineation system agree with the physician's contours. This approach demonstrates the capability of intelligent volumetric expansions with the potential to be used in clinical practice.

Evaluation on Auto-segmentation of the Clinical Target Volume (CTV) for Graves' Ophthalmopathy (GO) with a Fully Convolutional Network (FCN) on CT Images.

CDATA[Purpose: The aim of this study is to evaluate the accuracy and dosimetric effects for auto- segmentation of the CTV for GO in CT images based on FCN. METHODS: An FCN-8s network architecture for auto-segmentation was built based on Caffe. CT images of 121 patients with GO who have received radiotherapy at the West China Hospital of Sichuan University were randomly selected for training and testing. Two methods were used to segment the CTV of GO: treating the two-part CTV as a whole anatomical region or considering the two parts of CTV as two independent regions. Dice Similarity Coefficient (DSC) and Hausdorff Distance (HD) were used as evaluation criteria. The auto-segmented contours were imported into the original treatment plan to analyse the dosimetric characteristics. RESULTS: The similarity comparison between manual contours and auto-segmental contours showed an average DSC value of up to 0.83. The max HD values for segmenting two parts of CTV separately was a little bit smaller than treating CTV with one label (8.23±2.80 vs. 9.03±2.78). The dosimetric comparison between manual contours and auto-segmental contours showed there was a significant difference (p<0.05) with the lack of dose for auto-segmental CTV. CONCLUSION: Based on deep learning architecture, the automatic segmentation model for small target areas can carry out auto contouring tasks well. Treating separate parts of one target as different anatomic regions can help to improve the auto-contouring quality. The dosimetric evaluation can provide us with different perspectives for further exploration of automatic sketching tools.

Is clinical target volume necessary?-a failure pattern analysis in patients with locally advanced non-small cell lung cancer treated with concurrent chemoradiotherapy using intensity-modulated radiotherapy technique.

BACKGROUND: Our previous dosimetric study showed that for locally advanced non-small cell lung cancer (LA-NSCLC), radiotherapy with intensity-modulated radiotherapy (IMRT) technique could deliver sufficient dose coverage to subclinical regions and reduce the dose to normal tissues with the omission of clinical target volume (CTV). To further clinically validate this strategy, we conducted the current study to analyze the failure pattern for patients with LA-NSCLC treated with concurrent chemotherapy and CTV-omitted IMRT. We also investigated the effects of target volumes on lymphopenia during radiotherapy to further test the potential benefits of CTV omission in anti-tumor immunotherapy. METHODS: A total of 63 patients with LA-NSCLC treated with CTV-omitted IMRT with concurrent chemotherapy were enrolled in this study. Their planning target volume (PTV) (also PTV-g) was expanded directly from gross tumor volume (GTV). A virtual CTV was expanded from GTV, and the PTV generated from virtual CTV was named planning target volume with CTV expansion (PTV-c). Treatment failures were divided into local, regional, and distant failures, and local-regional recurrences were classified into inside PTV-g (IN-PTV-g), between PTV-g and PTV-c (PTV-g-c), and outside PTV-c (OUT-PTV-c). The relationship between lymphopenia during radiotherapy and the target volumes was also evaluated using Spearman's correlation analysis. RESULTS: Among the 60 patients with detailed follow-up data for recurrences, 46 (76.7%) experienced recurrences, with 18 (30.0%) being local recurrence, 5 (8.4%) being regional failure, and 33 (55.0%) being distant failure. For the 21 patients with local-regional recurrences, 16, 6, and 1 were IN-PTV-g, OUT-PTV-c, and PTV-g-c recurrences, respectively. Lymphopenia during radiotherapy was associated with both GTV and PTV, with larger volumes linked to severe lymphopenia. CONCLUSIONS: CTV omission is feasible for LA-NSCLC treated with concurrent chemoradiotherapy and does not compromise failure inside the subclinical region. The radiation volumes were associated with lymphopenia during radiotherapy, with larger volumes related to severe lymphopenia. This finding supports the further exploration of CTV omission for immunotherapy.

Recommendation regarding the cranial upper border of level IIb in delineating clinical target volumes (CTV) for nasopharyngeal carcinoma.

PURPOSE: To recommend a cranial border for level IIb in delineating clinical target volumes (CTV) for nasopharyngeal carcinoma (NPC) patients receiving intensity-modulated radiotherapy and to help reach a consensus on contouring level IIb in CTV. METHODS: From 2012 to 2016, 331 nonmetastatic NPC patients treated with IMRT were retrospectively enrolled. Based on the AJCC 8th staging system of NPC, there were 15 stage I, 76 stage II, 103 stage III, and 137 stage IV patients. The distribution of cervical lymph nodes in NPC was assessed based on imaging. Comparisons of the safety and parotid dose parameters between patients with and without a reduction in the size of level IIb were conducted using SPSS 25.0 and R 2.14.2 software. RESULTS: Metastasis rates in the most commonly involved lymph nodes, the lateral retropharyngeal and IIb nodes, were 82.8% and 64.0%, respectively. Among patients with level IIb involvement, the upper borders of the metastatic nodes were beyond the caudal edge of C1 in 13.7% of cases. The parotid gland D50 and V26 values were significantly reduced after modifying the upper bound of level IIb used to delineate the CTV (P = 0.000). CONCLUSION: In principle, the upper bound of level IIb should reach the lateral skull base during delineation of the cervical CTV for NPC. To protect the parotid glands, however, individualized reduction of the upper bound of level IIb is recommended for patients who meet certain criteria.

Understanding the pattern of lymph node metastasis for trans-segmental thoracic esophageal cancer to develop precise delineation of clinical target volume for radiotherapy.

BACKGROUND: This study was conducted to explore the lymph node metastasis (LNM) pattern of thoracic esophageal cancer (TEC) depending upon the location of the primary tumor and provide a reference for the design of clinical target volume (CTV). METHODS: The data of patients who underwent radical esophagectomy and three-field lymph node dissection at Fujian Cancer Hospital from 2006 to 2010 were retrospectively analyzed. We segmented the esophagus according to the anatomical landmarks on computed tomography (CT) and defined the transsegmental and mono-segmental esophageal carcinoma. The LNM pattern in trans-segmental and monosegmental esophageal cancer was explored and the CTV delineation was determined based on LNM pattern. RESULTS: A total of 852 patients were included in this study. The top five sites of LNM for upper-middle TEC were cervical, upper and middle paraesophageal, and zone 1, 2, 4 regions. The most common sites of LNM for lower-middle TEC were cervical and middle paraesophageal, group 3, 7, and zone 7 regions. The top five sites of LNM for middle-upper TEC were cervical, middle paraesophageal, zone 1, 7, and group 7 regions. The most common sites of LNM for middle-lower TEC were cervical, middle paraesophageal, zone 7, and group 2, 7 regions. The top five sites of LNM for TEC involving all the segments were cervical, middle paraesophageal, zone 7, group 2 and 7 regions. CONCLUSIONS: LNM pattern of trans-segmental and mono-segmental TEC varies depending upon the primary tumor location. The irradiation field must be designed according to the primary tumor location.

First report on extended distance between tumor lesion and adjacent organs at risk using interventionally applied balloon catheters: a simple procedure to optimize clinical target volume covering effective isodose in interstitial high-dose-rate brachytherapy of liver malignomas.

PURPOSE: Organs at risk (OARs), which are very close to a clinical target volume (CTV), can compromise effective tumor irradiation. The present study investigated the feasibility and safety of a novel approach, in particular, the extent of the dosimetric effect of distancing CTV from adjacent OARs by means of interventionally applied balloon catheters. MATERIAL AND METHODS: Patients with peripheral hepatic malignancies, in whom the critical proximity of an OAR to the CTV in the assessment by contrast-enhanced magnetic resonance imaging (MRI) scans and the preplanning process were included. Additionally, patients underwent placement of an interventional balloon catheter during computed tomography (CT)-guided application of interstitial brachytherapy (iBT) catheters inserted into the tissue between hepatic capsule and adjacent OAR. The virtual position of an OAR without balloon catheter was anticipated and contoured in addition to contouring of CTV and OAR. The calculated dose values for CTV as well as 1 cc of the relevant OAR (D1cc) with and without balloon were recorded. The D1cc of the realized irradiation plan was statistically compared to the D1cc of the virtually contoured OARs. RESULTS: In 31 cases, at least one balloon catheter was administered. The mean D1cc of the OAR in the group with balloon(s) was 12.6 Gy compared with 16 Gy in the virtual cohort without the device, therefore significantly lower (p < 0.001). Overall, there were no acute complications. Severe (> 2 CTCAEv4.03) late complications observed in 3/31 (9.6%) patients during follow-up period after brachytherapy were most certainly not due to the balloon application. Side effects were probably associated with pre-existing serious diseases and potentially additional local late effects of the irradiation in general rather than with the balloon catheters. CONCLUSIONS: The distancing of the adjacent OARs allows a higher D100 value of CTV, therefore allowing for more efficient local control.

Measurement of the distance of microfoci from a rectal gross tumor in a pathological specimen / 中国肿瘤临床

Objective: To measure the distance of the lateral, inferior, and superior microfoci from a gross tumor in a pathological speci-men and to provide scientific evidence for margin extension to form the clinical target volume (CTV) in high-dose radiotherapy for rec-tal cancer. Methods: Twenty-eight surgical specimens were collected from patients with rectal cancer who underwent total mesorectal excision (TME) in Hunan Cancer Hospital between October 2016 and April 2017. The nearest distance of the farthest peripheral micro-foci from the gross tumor was measured. The in vivo-in vitro tumor retraction factor (R1) was calculated by measuring the ratio of the tumor's perpendicular depth based on magnetic resonance imaging and immediate surgical specimens. The retraction factor (R2) in the process of pathological specimen makeup was calculated by knot labeling. The distance of microfoci extension was calculated based on that measured in pathological specimens including corrections with R1 and R2 and record as microcarcinoma extension mea-sured in vivo,MEin vivo. Results: Among the 28 pathological specimens, lateral, inferior, and superior microfoci were found in 17 (60.7%), 3 (10.7%), and 0 cases, respectively. The mean R1 was 0.913 and mean R2 was 0.803. The farthest distance measured inferiorly was 28 mm in vivo after correction. The maximum, minimum, and mean measured lateral distances were 12.03 mm, 3.03 mm, and 7.50 mm after correction, respectively. The 95% frequency value was within 10 mm. Conclusions: The lateral microfoci extension was within 10 mm for 95% of the rectal cancer patients. The margin expansion to form the CTV was suggested to be 10 mm for a late-course boost of high-dose radiotherapy for rectal cancer.

Assessing Novel Drugs and Radiation Technology in the Chemoradiation of Oropharyngeal Cancer.

Integrating immunotherapy, proton therapy and biological dose escalation into the definitive chemoradiation of oropharyngeal cancer poses several challenges. Reliable and reproducible data must be obtained in a timely fashion. However, despite recent international radiotherapy contouring guidelines, controversy persists as to the applicability of such guidelines to all cases. Similarly, a lack of consensus exists concerning both the definition of the organ at risk for oral mucositis and the most appropriate endpoint to measure for this critical toxicity. Finally, the correlation between early markers of efficacy such as complete response on PET CT following treatment and subsequent survival needs elucidation for biological subsets of oropharyngeal cancer.

Delineation of the primary tumour Clinical Target Volumes (CTV-P) in laryngeal, hypopharyngeal, oropharyngeal and oral cavity squamous cell carcinoma: AIRO, CACA, DAHANCA, EORTC, GEORCC, GORTEC, HKNPCSG, HNCIG, IAG-KHT, LPRHHT, NCIC CTG, NCRI, NRG Oncology, PHNS, SBRT, SOMERA, SRO, SSHNO, TROG consensus guidelines.

PURPOSE: Few studies have reported large inter-observer variations in target volume selection and delineation in patients treated with radiotherapy for head and neck squamous cell carcinoma. Consensus guidelines have been published for the neck nodes (see Grégoire et al., 2003, 2014), but such recommendations are lacking for primary tumour delineation. For the latter, two main schools of thoughts are prevailing, one based on geometric expansion of the Gross Tumour Volume (GTV) as promoted by DAHANCA, and the other one based on anatomical expansion of the GTV using compartmentalization of head and neck anatomy. METHOD: For each anatomic location within the larynx, hypopharynx, oropharynx and oral cavity, and for each T-stage, the DAHANCA proposal has been comprehensively reviewed and edited to include anatomic knowledge into the geometric Clinical Target Volume (CTV) delineation concept. A first proposal was put forward by the leading authors of this publication (VG and CG) and discussed with opinion leaders in head and neck radiation oncology from Europe, Asia, Australia/New Zealand, North America and South America to reach a worldwide consensus. RESULTS: This consensus proposes two CTVs for the primary tumour, the so called CTV-P1 and CVT-P2, corresponding to a high and lower tumour burden, and which should be associated with a high and a lower dose prescription, respectively. CONCLUSION: Implementation of these guidelines in the daily practice of radiation oncology should contribute to reduce treatment variations from clinicians to clinicians, facilitate the conduct of multi-institutional clinical trials, and contribute to improved care of patients with head and neck carcinoma.

International guideline for the delineation of the clinical target volumes (CTV) for nasopharyngeal carcinoma.

PURPOSE: Target delineation in nasopharyngeal carcinoma (NPC) often proves challenging because of the notoriously narrow therapeutic margin. High doses are needed to achieve optimal levels of tumour control, and dosimetric inadequacy remains one of the most important independent factors affecting treatment outcome. METHOD: A review of the available literature addressing the natural behaviour of NPC and correlation between clinical and pathological aspects of the disease was conducted. Existing international guidelines as well as published protocols specified by clinical trials on contouring of clinical target volumes (CTV) were compared. This information was then summarized into a preliminary draft guideline which was then circulated to international experts in the field for exchange of opinions and subsequent voting on areas with the greatest controversies. RESULTS: Common areas of uncertainty and variation in practices among experts experienced in radiation therapy for NPC were elucidated. Iterative revisions were made based on extensive discussion and final voting on controversial areas by the expert panel, to formulate the recommendations on contouring of CTV based on optimal geometric expansion and anatomical editing for those structures with substantial risk of microscopic infiltration. CONCLUSION: Through this comprehensive review of available evidence and best practices at major institutions, as well as interactive exchange of vast experience by international experts, this set of consensus guidelines has been developed to provide a practical reference for appropriate contouring to ensure optimal target coverage. However, the final decision on the treatment volumes should be based on full consideration of individual patients' factors and facilities of an individual centre (including the quality of imaging methods and the precision of treatment delivery).

Is a clinical target volume (CTV) necessary for locally advanced non-small cell lung cancer treated with intensity-modulated radiotherapy? -a dosimetric evaluation of three different treatment plans.

BACKGROUND: The aim of this study was to determine the feasibility of omitting the clinical target volume (CTV) in patients with locally advanced non-small cell lung cancer (NSCLC) treated with intensity-modulated radiotherapy (IMRT) by comparing dosimetric characteristics of three different IMRT plans with or without CTV implementation. METHODS: Thirteen patients with stage III NSCLC were reviewed. Target volumes were contoured such that the planning target volume (PTV) derived from the gross tumor volume (GTV) directly was named PTV_g and that from GTV plus CTV margin was named PTV_c. The PTV margin to generate PTV_g or PTV_c was the same within each case. Three IMRT plans were retrospectively generated to deliver: (I) 60 Gy to PTV_g in plan_routine; (II) 60 Gy to PTV_c in plan_CTV, and (III) 50 Gy to PTV_c while the dose was simultaneously escalated to 60 Gy to PTV_g in plan_SIB, achieved using the simultaneous integrated boost (SIB) technique. Optimization was performed to minimize the dose volumes of the irradiated normal lung, heart, esophagus, and spinal cord. Dose distributions and dosimetric indexes for the target volumes and critical structures in the three plans were computed and compared. RESULTS: In plan_routine, the 50-Gy isodose line covered at least 95% of the GTV plus CTV margins in all 13 patients. The statistics showed better sparing of the organs at risk (OAR) in plan_routine than in plan_CTV, and the best OAR sparing in plan_SIB. CONCLUSIONS: In patients with locally advanced lung cancer, IMRT planning without CTV implementation provides sufficient dose coverage of subclinical disease while reducing the dose to normal tissues. The omission of CTV was feasible in our cohort of patients. However, when CTV was implemented, IMRT planning that included the SIB technique had further dosimetric benefits to the patients. This strategy thus merits further evaluation in clinical trials.

Definition of lymph node areas for radiotherapy of prostate cancer: A critical literature review by the French Genito-Urinary Group and the French Association of Urology (GETUG-AFU).

PURPOSE: Recommendations for pelvic lymph node (LN) contouring rely on relatively dated studies that defined the Clinical Target Volume (CTV) of interest proposed for radiotherapy. The aim of this article was to review these recommendations with a critical analysis of published data on prostate cancer drainage. METHODS: We performed a review of data on LN drainage in prostate cancer, based on anatomy texts and studies on lymphography, pelvic LN dissections, sentinel LN techniques, magnetic resonance imaging, computed tomography and functional imaging. We also present the GETUG experts' opinion, based on a survey on nodal CTV definition. RESULTS: For lymphatic drainage of prostate cancers, pelvic LN areas classically considered are: distal common iliac, external iliac, internal iliac and obturator regions. Recently published data allow a mapping of sites at risk of pathological LN invasion. In 10-70% of cases, these sites are not included in the pelvic LN CTVs defined in consensuses. In accordance with other cooperative groups, the GETUG experts' survey showed that proximal common iliac, para-aortic, para-rectal and pre-sacral regions could include sites at risk of invasion in extended LN CTV, but were not considered in CTV contouring common practice. New recommendations are needed for nodal CTV in radiotherapy of prostate cancer. CONCLUSIONS: The assessment of the efficacy and safety of LN radiotherapy is still the subject of several randomised studies. Whether or not meaningful results are obtained depends directly on the quality and homogeneity of the data analysed. A new consensus for delineation of LN regions appears necessary.