Radiotherapy In Lung Cancer Patients Research Articles

Practice Recommendations for Lung Cancer Radiotherapy During the COVID-19 Pandemic: An ESTRO-ASTRO Consensus Statement

BackgroundThe COVID-19 pandemic has caused radiotherapy resource pressures and led to increased risks for lung cancer patients and healthcare staff. An international group of experts in lung cancer radiotherapy established this practice recommendation pertaining to whether and how to adapt radiotherapy for lung cancer in the COVID-19 pandemic.MethodsFor this ESTRO & ASTRO endorsed project, 32 experts in lung cancer radiotherapy contributed to a modified Delphi consensus process. We assessed potential adaptations of radiotherapy in two pandemic scenarios. The first, an early pandemic scenario of risk mitigation, is characterized by an altered risk–benefit ratio of radiotherapy for lung cancer patients due to their increased susceptibility for severe COVID-19 infection, and minimization of patient travelling and exposure of radiotherapy staff. The second, a later pandemic scenario, is characterized by reduced radiotherapy resources requiring patient triage. Six common lung cancer cases were assessed for both scenarios: peripherally located stage I NSCLC, locally advanced NSCLC, postoperative radiotherapy after resection of pN2 NSCLC, thoracic radiotherapy and prophylactic cranial irradiation for limited stage SCLC and palliative thoracic radiotherapy for stage IV NSCLC.ResultsIn a risk-mitigation pandemic scenario, efforts should be made not to compromise the prognosis of lung cancer patients by departing from guideline-recommended radiotherapy practice. In that same scenario, postponement or interruption of radiotherapy treatment of COVID-19 positive patients is generally recommended to avoid exposure of cancer patients and staff to an increased risk of COVID-19 infection. In a severe pandemic scenario characterized by reduced resources, if patients must be triaged, important factors for triage include potential for cure, relative benefit of radiation, life expectancy, and performance status. Case-specific consensus recommendations regarding multimodality treatment strategies and fractionation of radiotherapy are provided.ConclusionThis joint ESTRO-ASTRO practice recommendation established pragmatic and balanced consensus recommendations in common clinical scenarios of radiotherapy for lung cancer in order to address the challenges of the COVID-19 pandemic.

The association between IDO activity and clinical prognosis in patients with early stage non-small cell lung cancer after stereotactic body radiotherapy.

e21054 Background: Immunity affects the efficacy of radiotherapy of lung cancer patients. Indoleamine 2,3-dioxygenase (IDO) is a key enzyme that converts tryptophan (T) into heparin (K), which can promote immune suppression and assist tumor cells in immune evasion. The purpose of this study was to quantitatively analyze the immune activity of IDO in serum before and after SBRT, and to explore the changes in immune activity of IDO mediated by SBRT and its relationship with patient's survival. Methods: High-performance liquid chromatography and mass spectrometry were used to determine serum K and T in 30 patients with early non-small cell lung cancer before and after SBRT treatment. K: T stands for IDO activity. The Kaplan-Meier method and log-rank test were used to evaluate the correlation between overall survival (OS), progression-free survival (PFS), and IDO activity. Cox proportional hazards model was used for univariate and multivariate analyses. Results: The median follow-up time was 37.4 months. The median PFS was 37.5 (95% CI, 31.0-44.0) months. The median survival was not reached. In all patients, lower post/pre kynurenine ratio correlated significantly with better PFS (HR = 0.31, 95% CI = 0.11-0.90, P = 0.032). The lower K: T ratio at post-RT received longer OS (HR = 0.27, 95% CI = 0.079-0.95, P = 0.042). In multivariate analysis, smoking < 30 packs / year (P = 0.030), higher BED (P < 0.001), and lower post/pre kynurenine (P = 0.043) were associated with better PFS. Lower K: T ratio post-RT (P = 0.040) and higher BED (P < 0.001) were significantly associated with better OS. Conclusions: SBRT could alter IDO-mediated antitumor immune activity. The lower level of post/pre kynurenine ratio was significantly related with better PFS. The lower K: T ratio at post-RT was related with better OS. This study shows that IDO is a potentially valuable biomarker for monitoring the immune status and predicting survival in early NSCLC patients after SBRT.

Practice recommendations for lung cancer radiotherapy during the COVID-19 pandemic: An ESTRO-ASTRO consensus statement

BackgroundThe COVID-19 pandemic has caused radiotherapy resource pressures and led to increased risks for lung cancer patients and healthcare staff. An international group of experts in lung cancer radiotherapy established this practice recommendation pertaining to whether and how to adapt radiotherapy for lung cancer in the COVID-19 pandemic. MethodsFor this ESTRO & ASTRO endorsed project, 32 experts in lung cancer radiotherapy contributed to a modified Delphi consensus process. We assessed potential adaptations of radiotherapy in two pandemic scenarios. The first, an early pandemic scenario of risk mitigation, is characterized by an altered risk–benefit ratio of radiotherapy for lung cancer patients due to their increased susceptibility for severe COVID-19 infection, and minimization of patient travelling and exposure of radiotherapy staff. The second, a later pandemic scenario, is characterized by reduced radiotherapy resources requiring patient triage. Six common lung cancer cases were assessed for both scenarios: peripherally located stage I NSCLC, locally advanced NSCLC, postoperative radiotherapy after resection of pN2 NSCLC, thoracic radiotherapy and prophylactic cranial irradiation for limited stage SCLC and palliative thoracic radiotherapy for stage IV NSCLC. ResultsIn a risk-mitigation pandemic scenario, efforts should be made not to compromise the prognosis of lung cancer patients by departing from guideline-recommended radiotherapy practice. In that same scenario, postponement or interruption of radiotherapy treatment of COVID-19 positive patients is generally recommended to avoid exposure of cancer patients and staff to an increased risk of COVID-19 infection. In a severe pandemic scenario characterized by reduced resources, if patients must be triaged, important factors for triage include potential for cure, relative benefit of radiation, life expectancy, and performance status. Case-specific consensus recommendations regarding multimodality treatment strategies and fractionation of radiotherapy are provided. ConclusionThis joint ESTRO-ASTRO practice recommendation established pragmatic and balanced consensus recommendations in common clinical scenarios of radiotherapy for lung cancer in order to address the challenges of the COVID-19 pandemic.

MA08.07 The Concordance Between Patient Reported Outcomes and Clinician Reported Outcomes During Radiotherapy in Lung Cancer Patients

MA08.07 The Concordance Between Patient Reported Outcomes and Clinician Reported Outcomes During Radiotherapy in Lung Cancer Patients

Application of the ExacTrac System in Respiratory Gated Radiotherapy for Lung Cancer Patients

Application of the ExacTrac System in Respiratory Gated Radiotherapy for Lung Cancer Patients

Effectiveness of different rescanning techniques for scanned proton radiotherapy in lung cancer patients

Non-small cell lung cancer (NSCLC) is a tumour type thought to be well-suited for proton radiotherapy. However, the lung region poses many problems related to organ motion and can for actively scanned beams induce severe interplay effects. In this study we investigate four mitigating rescanning techniques: (1) volumetric rescanning, (2) layered rescanning, (3) breath-sampled (BS) layered rescanning, and (4) continuous breath-sampled (CBS) layered rescanning. The breath-sampled methods will spread the layer rescans over a full breathing cycle, resulting in an improved averaging effect at the expense of longer treatment times. In CBS, we aim at further improving the averaging by delivering as many rescans as possible within one breathing cycle.The interplay effect was evaluated for 4D robustly optimized treatment plans (with and without rescanning) for seven NSCLC patients in the treatment planning system RayStation. The optimization and final dose calculation used a Monte Carlo dose engine to account for the density heterogeneities in the lung region. A realistic treatment delivery time structure given from the IBA ScanAlgo simulation tool served as basis for the interplay evaluation. Both slow (2.0 s) and fast (0.1 s) energy switching times were simulated.For all seven studied patients, rescanning improves the dose conformity to the target. The general trend is that the breath-sampled techniques are superior to layered and volumetric rescanning with respect to both target coverage and variability in dose to OARs. The spacing between rescans in our breath-sampled techniques is set at planning, based on the average breathing cycle length obtained in conjunction with CT acquisition. For moderately varied breathing cycle lengths between planning and delivery (up to 15%), the breath-sampled techniques still mitigate the interplay effect well. This shows the potential for smooth implementation at the clinic without additional motion monitoring equipment.

OC-0307: Workflow optimization of image-guided adaptive radiotherapy in lung cancer patients

OC-0307: Workflow optimization of image-guided adaptive radiotherapy in lung cancer patients

Body Fluids-Derived Exosomes: Paving the Novel Road to Lung Cancer Diagnosis and Therapy.

Lung cancer is a major human malignancy. Nowadays, the lack of specific diagnostic markers of lung cancer restricts the early diagnosis and therapy of patients. Exosomes, as spherical 30-100 nm microvesicles, are released by normal and cancer cells in both physiological and pathological circumstances. Exosomes carry various molecular cargos such as miRNA, proteins, mRNA, DNA and lipids. Therefore, analysis of the molecular profiles of exosomes may provide beneficial biomarkers for disease diagnosis. Exosomes can be transported by body fluids. The molecules (miRNAs and proteins) detected in body fluid exosomes may contribute to lung cancer diagnosis. In this review, we summarize typical molecules (miRNAs and proteins) in body fluids-derived exosomes to reveal the potential biomarkers in lung cancer. Besides, the role and the application of exosomes in chemotherapy and radiotherapy of lung cancer patients have also been discussed in this review.

Stereotactic body radiotherapy for lung cancer patients with idiopathic interstitial pneumonias

PurposeTo compare toxicity and survival after stereotactic body radiotherapy (SBRT) between lung cancer patients with or without idiopathic interstitial pneumonias (IIPs), and to investigate the potential value of SBRT for the patients. MethodsAmong lung cancer patients receiving SBRT between 2005 and 2016, we evaluated those treated with a total dose of 40–60Gy in five fractions with curative intent who either were staged as cT1-4N0M0 or experienced postoperative isolated local recurrence. We analyzed the incidence of radiation pneumonitis (RP) in all patients and local recurrence and overall survival (OS) in T1a-2a patients. ResultsA total of 508 patients were eligible, including 42 with IIPs. The median follow-up was 32.3 (6.0–120.9) months. Significantly more patients with IIPs had grade ≥3RP than did those without IIPs (12% vs. 3%, p=0.009). The 2-year local recurrence rate was low in both groups (3.4% vs. 5.6%, p=0.38). The 2-year OS rate was significantly lower in the patients with IIPs (42.2% vs. 80.9%, p<0.001), although death from lung cancer was comparable (p=0.74). ConclusionSBRT achieved excellent local control with acceptable pulmonary toxicity in lung cancer patients with IIPs. SBRT can be a reasonable option for early lung cancer patients with IIPs.

Automated four-dimensional Monte Carlo workflow using log files and real-time motion monitoring

With emerging techniques for tracking and gating methods in radiotherapy of lung cancer patients, there is an increasing need for efficient four-dimensional Monte Carlo (4DMC) based quality assurance (QA). An automated and flexible workflow for 4DMC QA, based on the 4DdefDOSXYZnrc user code, has been developed in python. The workflow has been tested and verified using an in-house developed dosimetry system comprised of a dynamic thorax phantom constructed for plastic scintillator dosimetry. The workflow is directly compatible with any treatment planning system and can also be triggered by the appearance of linac log files. It has minimum user interaction and, with the use of linac log files, it provides a method for verification of the actually delivered dose in the patient geometry.

OC-0437: Scatter imaging: promising modality for image guided ablation radiotherapy for lung cancer patients

OC-0437: Scatter imaging: promising modality for image guided ablation radiotherapy for lung cancer patients

Time-resolved plastic scintillator dosimetry in a dynamic thorax phantom

Motion managed and dynamic radiotherapy of lung cancer patients is increasingly complex and subject to challenges related to respiratory motion and heterogeneous tissue densities. This puts high demands on methods for quality assurance and especially time-resolved dose verification of the treatment delivery. The aim of this study was to develop a novel dynamic thorax phantom for time-resolved plastic scintillator dosimetry. The in-house developed phantom has a well-known geometry mimicking a lung cancer patient with a reproducible (within 0.04 mm), respiratory-like motion of a tumor embedded in a lung. The phantom motion was controlled by a script in-house developed using LabVIEW (National Instruments) and synchronized with the in-house developed ME40 scintillator dosimetry system (DTU Nutech). The dose in the center of the tumor was measured, using a BCF-60 plastic scintillator detector (Saint-Gobain Ceramics & Plastics Inc.), during dynamic 6 MV half-arc treatments on a TrueBeam linear accelerator (Varian Medical Systems). Deviations of ∼2% from the corresponding dose calculated by the treatment planning system (TPS) were detected. The results emphasize the shortcomings of commercial TPSs to handle respiratory motion and lack of lateral charged particle equilibrium, motivating quality assurance based on a system like the one presented in this study. It has specifically been demonstrated that reliable time-resolved scintillator dosimetry in a dynamic thorax phantom can play an essential role in dose verification of lung cancer radiotherapy.

SC13.04 Limitations by COPD for Treatment

The most common cause of death among patients with COPD is lung cancer as well as respiratory failure, and COPD often co-exists with lung cancer with a range of 40 to 70%.1 While lung cancer survival is generally very low, survival is even lower among patients with COPD, i.e. in one study, it is reported that 26% of lung cancer patients without COPD were still alive 3 years after their diagnosis compared to 15% of lung cancer patients with COPD.2 One of the reasons why prognoses of lung cancer patients with COPD are worse is that treatment options are limited due to affected lung function. For surgical treatment for lung cancer patients with COPD, post-operative residual lung function should be maintained within a certain level. Therefore, patients with severely reduced lung function may be rejected for surgical treatment, or at least they may not able to receive standard surgical procedures. For patients rejected for surgery because of poor lung function, radiotherapy is an alternative treatment option. However, radiotherapy itself affects lung function because of post treatment radiation pneumonia. For drug therapy, drug-induced lung toxicities are emerging issues, especially due to the use of EGF receptor tyrosine kinase inhibitors, ALK inhibitors or immune check point inhibitors.3 In cases whose lung function is severely affected, drug-induced lung toxicities may be lethal, and special attention should be payed to such patients. Therefore, to overcome these limitations of treatment is an urgent issue in the daily practice. For surgical treatment, assessment of preoperative lung function is essential to judge its indication. Both predicted post-operative lung function and DLco values are mainly used as parameters for the indication of surgical treatment. Therefore, optimization of these functions by medical therapy, pulmonary rehabilitation and smoking cessation may extend the opportunities of surgical treatment, resulting in better patients’ outcomes. Regarding with medical therapy, the Global Initiative for Chronic Obstructive Lung Disease (GOLD)4 and American Thoracic Society and the European Respiratory Society guidelines for COPD management point out the usefulness of bronchodilators as well as inhaled corticosteroids. In addition, pulmonary rehabilitations would be recommended for pre-operative lung cancer patients with poor lung function because of its safety, although there are no data clearly showing the efficacy of pulmonary rehabilitations on patients’ outcome. For radiotherapy for lung cancer patients with COPD, newly developed devices appear to show promising outcome. Both stereotactic body radiotherapy (SBRT) and ion beam radiotherapy have such a nice radiation dose distribution that high doses of irradiation are possible with low impact to normal tissues. Some reports suggest that patients’ outcomes by these treatment modalities may be not worse or sometimes better than surgical treatment.5 In addition, smoking cessation is, of course, important issue as a pre- and post- operative management. Since lung cancer patients with COPD are increasing over all area in the world, appropriate treatment should be chosen with the utmost care and attention. In addition, it is an urgent issue to establish more effective and safe treatment modalities to these patients. 1. Young RP, Hopkins RJ, Christmas T, et al. COPD prevalence is increased in lung cancer, independent of age, sex and smoking history. Eur Respir J. 2009;34(2):380-6. 2. Kiri VA, Soriano J, Visick G, Fabbri L. Recent trends in lung cancer and its association with COPD: an analysis using the UK GP Research Database. Prim Care Respir J. 2010;19(1):57-61. 3. De Sanctis A, Taillade L, Vignot S, et al. Pulmonary toxicity related to systemic treatment of nonsmall cell lung cancer. Cancer. 2011;117(14):3069-80. 4. Rabe KF, Hurd S, Anzueto A, Barnes PJ, et al. Global strategy for the diagnosis, management, and prevention of chronic obstructive pulmonary disease: GOLD executive summary. Am J Respir Crit Care Med. 2007;176(6):532-55. 5. Chehade S and Palma DA. Stereotactic radiotherapy for early lung cancer: Evidence-based approach and future directions. Rep Pract Oncol Radiother. 2015;20(6):403-10. bronchodilator, stereotactic body radiotherapy, Surgery, lung function

128: 90-day mortality after radical radiotherapy and 30-day mortality after high dose palliative radiotherapy in lung cancer patients at the University Hospitals Birmingham

128: 90-day mortality after radical radiotherapy and 30-day mortality after high dose palliative radiotherapy in lung cancer patients at the University Hospitals Birmingham

DDB2 increases radioresistance of NSCLC cells by enhancing DNA damage responses.

Radiotherapy resistance is one of the major factors limiting the efficacy of radiotherapy in lung cancer patients. The extensive investigations indicate the diversity in the mechanisms underlying radioresistance. Here, we revealed that DNA damage binding protein 2 (DDB2) is a potential regulator in the radiosensitivity of non-small cell lung cancer (NSCLC) cells. DDB2, originally identified as a DNA damage recognition factor in the nucleotide excision repair, promotes the survival and inhibits the apoptosis of NSCLC cell lines upon ionizing radiation (IR). Mechanistic investigations demonstrated that DDB2 is able to facilitate IR-induced phosphorylation of Chk1, which plays a critical role in the cell cycle arrest and DNA repair in response to IR-induced DNA double-strand breaks (DSBs). Indeed, knockdown of DDB2 compromised the G2 arrest in the p53-proficient A549 cell line and reduced the efficiency of homologous recombination (HR) repair. Taken together, our data indicate that the expression of DDB2 in NSCLC could be used as a biomarker to predict radiosensitivity of the patients. Targeting Chk1 can be used to increase the efficacy of radiotherapy in patients of NSCLC possessing high levels of DDB2.

SU‐F‐J‐67: Dosimetric Changes During Radiotherapy in Lung Cancer Patients with Atelectasis

Purpose:Large geometric changes which occur during thoracic radiotherapy alter normal anatomy and target position and may induce clinically important dose changes. This study investigates variation of organ‐at‐risk (OAR) dose caused by atelectasis resolution during radiotherapy.Methods:3D IMRT treatment plans were obtained for 14 non‐small‐cell lung cancer patients. Dose of the clinical plan was recalculated on a baseline scan in which lung was collapsed and on a midtreatment scan in which lung re‐aeration had occurred. The changes in OAR doses were compared between the two time points. RTOG‐0617 and inhouse dose‐volume constraints were chosen for investigation and included spinal cord, esophagus, heart, and healthy lung.Results:17 dose metrics were evaluated. The mean (SD) of change in mean lung dose, from baseline to mid‐treatment (average taken across all patients), was 0.2 Gy (2.2 Gy) and ranged from −3.2 Gy to 6.0 Gy. 50% of patients experienced relative changes in mean lung dose of greater than 5% of baseline value. The mean (SD) of changes in heart V40, V45, and V60 were 3.2% (3.4%), 3.0% (2.9%), and 1.4% (2.1%), respectively, and were significant for the study cohort (Wilcoxon signed‐rank test, p=0.0107 for V40, p=0.0052 for V45, and p= 0.0353 for V60. Ranges in changes of Heart V40, V45, and V60 were −1.9% to 8.6%, −1.7% to 7.5%, and −2.1% to 4.5%, respectively. The mean (SD) of changes in Esophagus PRV Dmean and V60 were 0.3 Gy (3.3 Gy) and 0.8% (7.7%), respectively, and ranged from −4.8 Gy to 6.8 Gy for Dmean and −15.2% to 14.6% for V60.Conclusion:Patients with atelectasis present at the start of radiotherapy experience significant increases in heart dose. Substantial increases in mean lung dose also occur in a subset of patients.This work supported by the National Cancer Institute of National Institutes of Health under Award Number R01CA166119. Disclosures: Phillips Medical systems (Hugo, Weiss), National Institutes of Health (Hugo, Weiss, Christensen), and Roger Koch (Christensen) support, UpToDate (Weiss) royalties, and Varian Medical Systems (Hugo, Weiss) license. No potential conflicts of interest.

Radiation-induced miR-208a increases the proliferation and radioresistance by targeting p21 in human lung cancer cells.

BackgroundLung cancer has long been the most dangerous malignant tumor among males in both well developed and poorly developed countries. Radiotherapy plays a critical role in the curative management of inoperable non-small cell lung cancer (NSCLC) and is also used as a post-surgical treatment in lung cancer patients. Radioresistance is an important factor that limits the efficacy of radiotherapy for NSCLC patients. Increasing evidence suggests that microRNAs (miRNAs) possess diverse cellular regulatory roles in radiation responses.MethodsIn this study, we used miRNA microarray technology to identify serum miRNAs that were differentially expressed before and after radiotherapy in lung cancer patients. We further examined the biological function of miR-208a on cell viability, apoptotic death and cell cycle distribution in human lung cancer cells and explored the probable mechanism.ResultsNine miRNAs, including miR-29b-3p, miR-200a-3p, and miR-126-3p were significantly down-regulated, whereas miR-208a was the only miRNA that was up-regulated in the serum of the patients after radiation treatment (P < 0.05). The expression of miR-208a could be induced by X-ray irradiation in lung cancer cells. Forced expression of miR-208a promoted cell proliferation and induced radioresistance via targeting p21 with a corresponding activation of the AKT/mTOR pathway in lung cancer cells, whereas down-regulation of miR-208a resulted in the opposite effects. In addition, down-regulation of miR-208a increased the percentage of cells undergoing apoptosis and inhibited the G1 phase arrest in NSCLC cells. Moreover, miR-208a from the serum exosome fraction of lung cancer patients could shuttle to A549 cells in a time-dependent manner, which was likely to contribute to the subsequent biological effects.ConclusionsThe present study provides evidence that miR-208a can affect the proliferation and radiosensitivity of human lung cancer cells by targeting p21 and can be transported by exosomes. Thus, miR-208a may serve as a potential therapeutic target for lung cancer patients.Electronic supplementary materialThe online version of this article (doi:10.1186/s13046-016-0285-3) contains supplementary material, which is available to authorized users.

Adaptation requirements due to anatomical changes in free-breathing and deep-inspiration breath-hold for standard and dose-escalated radiotherapy of lung cancer patients

ABSTRACTBackground. Radiotherapy of lung cancer patients is subject to uncertainties related to heterogeneities, anatomical changes and breathing motion. Use of deep-inspiration breath-hold (DIBH) can reduce the treated volume, potentially enabling dose-escalated (DE) treatments. This study was designed to investigate the need for adaptation due to anatomical changes, for both standard (ST) and DE plans in free-breathing (FB) and DIBH.Material and methods. The effect of tumor shrinkage (TS), pleural effusion (PE) and atelectasis was investigated for patients and for a CIRS thorax phantom. Sixteen patients were computed tomography (CT) imaged both in FB and DIBH. Anatomical changes were simulated by CT information editing and re-calculations, of both ST and DE plans, in the treatment planning system. PE was systematically simulated by adding fluid in the dorsal region of the lung and TS by reduction of the tumor volume.Results. Phantom simulations resulted in maximum deviations in mean dose to the GTV-T (<D>GTV-T) of −1% for 3 cm PE and centrally located tumor, and + 3% for TS from 5 cm to 1 cm diameter for an anterior tumor location. For the majority of the patients, simulated PE resulted in a decreasing <D>GTV-T with increasing amount of fluid and increasing <D>GTV-T for decreasing tumor volume. Maximum change in <D>GTV-T of -3% (3 cm PE in FB for both ST and DE plans) and + 10% (2 cm TS in FB for DE plan) was observed. Large atelectasis reduction increased the <D>GTV-T with 2% for FB and had no effect for DIBH.Conclusion. Phantom simulations provided potential adaptation action levels for PE and TS. For the more complex patient geometry, individual assessment of the dosimetric impact is recommended for both ST and DE plans in DIBH as well as in FB. However, DIBH was found to be superior over FB for DE plans, regarding robustness of <D>GTV-T to TS.

Anatomical landmarks accurately determine interfractional lymph node shifts during radiotherapy of lung cancer patients

Background and purposeLow contrast in the cone-beam computed tomography (CBCT) scans hampers fast online evaluation of interfractional changes in the lymph node position on a daily basis. In this study we have investigated whether high-contrast anatomical landmarks in the vicinity of the nodes may be used as surrogates for the lymph node positions. Materials and methodsForty lung cancer patients were treated with an online CBCT-based setup strategy involving soft-tissue match on the primary tumor. One hundred and sixteen lymph nodes were delineated separately on the planning-CT scans and categorized according to the lymph node stations. Five anatomical landmarks were selected as surrogate structures and assigned to the individual nodes. In addition, the carina was delineated. Registrations between the planning-CT and the daily CBCTs were performed retrospectively and positional deviations between the nodes and the surrogate structures or the carina were registered. ResultsThe mean displacement between lymph nodes and surrogate structures was 1.6mm with systematic/random errors of 0.7/0.7mm, significantly smaller than the mean displacement between nodes and the carina. ConclusionsThe position of the lymph nodes can be evaluated using selected anatomical landmarks on a daily basis using CBCT.

PO-0662: Role of SPECT in predicting the risk of lung toxicity after radiotherapy in lung cancer patients. a prospective study

PO-0662: Role of SPECT in predicting the risk of lung toxicity after radiotherapy in lung cancer patients. a prospective study