A new method to assess pulmonary changes using 18F-fluoro-2-deoxyglucose positron emission tomography for lung cancer patients following radiotherapy (original) (raw)
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Impact of FDG-PET on radiation therapy volume delineation in non–small-cell lung cancer
International Journal of Radiation Oncology*Biology*Physics, 2004
Purpose: Locoregional failure remains a significant problem for patients receiving definitive radiation therapy alone or combined with chemotherapy for non-small-cell lung cancer (NSCLC). Positron emission tomography (PET) with [ 18 F]fluoro-2-deoxy-D-glucose (FDG) has proven to be a valuable diagnostic and staging tool for NSCLC. This prospective study was performed to determine the impact of treatment simulation with FDG-PET and CT on radiation therapy target volume definition and toxicity profiles by comparison to simulation with computed tomography (CT) scanning alone. Methods: Twenty-six patients with Stages I-III NSCLC were studied. Each patient underwent sequential CT and FDG-PET simulation on the same day. Immobilization devices used for both simulations included an alpha cradle, a flat tabletop, 6 external fiducial markers, and a laser positioning system. A radiation therapist participated in both simulations to reproduce the treatment setup. Both the CT and fused PET/CT image data sets were transferred to the radiation treatment planning workstation for contouring. Each FDG-PET study was reviewed with the interpreting nuclear radiologist before tumor volumes were contoured. The fused PET/CT images were used to develop the three-dimensional conformal radiation therapy (3DCRT) plan. A second physician, blinded to the results of PET, contoured the gross tumor volumes (GTV) and planning target volumes (PTV) from the CT data sets, and these volumes were used to generate mock 3DCRT plans. The PTV was defined by a 10-mm margin around the GTV. The two 3DCRT plans for each patient were compared with respect to the GTV, PTV, mean lung dose, volume of normal lung receiving >20 Gy (V20), and mean esophageal dose. Results: The FDG-PET findings altered the AJCC TNM stage in 8 of 26 (31%) patients; 2 patients were diagnosed with metastatic disease based on FDG-PET and received palliative radiation therapy. Of the 24 patients who were planned with 3DCRT, PET clearly altered the radiation therapy volume in 14 (58%), as follows. PET helped to distinguish tumor from atelectasis in all 3 patients with atelectasis. Unsuspected nodal disease was detected by PET in 10 patients, and 1 patient had a separate tumor focus detected within the same lobe of the lung. Increases in the target volumes led to increases in the mean lung dose, V20, and mean esophageal dose. Decreases in the target volumes in the patients with atelectasis led to decreases in these normal-tissue toxicity parameters. Conclusions: Radiation targeting with fused FDG-PET and CT images resulted in alterations in radiation therapy planning in over 50% of patients by comparison with CT targeting. The increasing availability of integrated PET/CT units will facilitate the use of this technology for radiation treatment planning. A confirmatory multicenter, cooperative group trial is planned within the Radiation Therapy Oncology Group.
Scientific reports, 2018
Quantitative measurement and analysis of tumor metabolic activities could provide a more optimal solution to personalized accurate dose painting. We collected PET images of 58 lung cancer patients, in which the tumor exhibits heterogeneous FDG uptake. We design an automated delineation and quantitative heterogeneity measurement of the lung tumor for dose-escalation. For tumor delineation, our algorithm firstly separates the tumor from its adjacent high-uptake tissues using 3D projection masks; then the tumor boundary is delineated with our stopping criterion of joint gradient and intensity affinities. For dose-escalation, tumor sub-volumes with low, moderate and high metabolic activities are extracted and measured. Based on our quantitative heterogeneity measurement, a sub-volume oriented dose-escalation plan is implemented in intensity modulated radiation therapy (IMRT) planning system. With respect to manual tumor delineations by two radiation oncologists, the paired t-test demons...
Asia Oceania journal of nuclear medicine & biology, 2017
18 F-fluorodeoxyglucose positron emission tomography/computed tomography (18 F-FDG PET-CT) is a well-used and established technique for lung cancer staging. Radiation therapy requires accurate target volume delineation, which is difficult in most cases due to coexisting atelectasis. The present study was performed to compare the 18 F-FDG PET-CT with contrast enhanced computed tomography (CECT) in target volume delineation and investigate their impacts on radiotherapy planning. Methods: Eighteen patients were subjected to 18 F-FDG PET-CT and CECT in the same position. Subsequently, the target volumes were separately delineated on both image sets. In addition, the normal organ doses were compared and evaluated. Results: The comparison of the primary gross tumour volume (GTV) between the 18 F-FDG PET-CT and CECT imaging revealed that 88.9% (16/18) of the patients had a quantitative change on the 18 F-FDG PET-CT. Out of these patients, 77% (14/18) of the cases had a decrease in volume, while 11% (2/18) of them had an increase in volume on the 18 F-FDG PET-CT. Additionally, 44.4% (8/18) of the patients showed a decrease by > 50 cm 3 on the 18 F-FDG PET-CT. The comparison of the GTV lymph node between the 18 F-FDG PET-CT and CECT revealed that the volume changed in 89% (16/18) of the patients: it decreased and increased in 50% (9/18) and 39% (7/18) on the 18 F-FDG PET-CT. New nodes were identified in 27% (5/18) of the patients on the 18 F-FDG PET-CT. The decrease in the GTV lymph node on the 18 F-FDG PET-CT was statistically significant. The decreased target volumes made radiotherapy planning easier with improved sparing of normal tissues. Conclusion: GTV may either increase or decrease with the 18 F-FDG PET-CT, compared to the CECT. However, the 18 F-FDG PET-CT-based contouring facilitates the accurate delineation of tumour volumes, especially at margins, and detection of new lymph node volumes. The non-FDG avid nodes can be omitted to avoid elective nodal irradiation, which can spare the organs at risk and improve accurate staging and treatment.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2007
This work represents our effort to test feasibility of FDG-based PET/CT on target volume delineation in radiotherapy treatment planning of NSCLC patients. Different methods have been developed to enable more precise target outlining using PET: Qualitative Visual Method, CTV ¼ 2.5 SUV units, linear SUV threshold function method, and CTV ¼ 40% Iso of Maximum Uptake Value. We are proposing reconstruction of three biological target volumes: necrotic BTV (same as PTV created by radiation oncologist using CT data), proliferating BTV (based on PET signal to background ratio 1:3) and hypoxic BTV (based on PET signal to background ratio of 1:19). Two IMRT plans were created and compared to the conventional treatment plan: ''conservative'' IMRT plan delivers 52.5 Gy to the necrotic BTV and 65 Gy to the hypoxic BTV; ''radical'' IMRT plan delivers 30 Gy to necrotic BTV, 52.5 Gy to proliferating BTV and 65 Gy to hypoxic BTV. Use of BTVs in IMRT plans is attractive because it increases dose to targets considered to need higher doses. It reduces considerably dose to heart and spinal cord, organs considered to limit dose escalation approaches in NSCLC treatment. ''Conservative'' IMRT approach can be understood as a PET/CT-based concomitant boost to the tumor expressing the highest FDG uptake. ''Radical'' plan implies deviation from the traditional uniform dose target coverage approach, with the intention of achieving better surrounding tissue sparing and ultimately allowing for dose escalation protocols relying on biologically based treatment planning. r
Acta Oncologica, 2017
Background: Dose painting (DP) aims to improve radiation therapy (RT) outcome by targeting radioresistant tumour regions identified through functional imaging, e.g., positron emission tomography (PET). Importantly, the expected benefit of DP relies on the ability of PET imaging to identify tumour areas which could be consistently targeted throughout the treatment. In this study, we analysed the spatial stability of two potential DP targets in lung cancer patients undergoing RT: the tumour burden surrogate [ 18 F]fluorodeoxyglucose (FDG) and the hypoxia surrogate [ 18 F]fluoroazomycin arabinoside (FAZA). Materials and methods: Thirteen patients with unresectable lung tumours underwent FDG and FAZA 4D-PET/CT before (pre), and during the second (w2) and third (w3) weeks of RT. All PET/CT were reconstructed in their time-averaged midposition (MidP) for further analysis. The metabolic tumour volume (MTV: FDG standardised uptake value (SUV) > 50% SUV max) and the hypoxic volume (HV: FAZA SUV >1.4) were delineated within the gross tumour volume (GTV CT). The stability of FDG and FAZA PET uptake distributions during RT was subsequently assessed through volume-overlap analysis and voxelbased correlation analysis. Results: The volume-overlap analysis yielded median overlapping fraction (OF) of 0.86 between MTV pre and MTV w2 and 0.82 between MTV pre and MTV w3. In patients with a detectable HV, median OF was 0.82 between HV pre and HV w2 and 0.90 between HV pre and HV w3. The voxel-based correlation analysis yielded median Spearman's correlation coefficient (r S) of 0.87 between FDG pre and FDG w2 and 0.83 between FDG pre and FDG w3. Median r S was 0.78 between FAZA pre and FAZA w2 and 0.79 between FAZA pre and FAZA w3. Conclusions: FDG and FAZA PET uptake distributions were spatially stable during the 3 first weeks of RT in patients with unresectable lung cancer, both based on volume-and voxel-based indicators. This might allow for a consistent targeting of high FDG or FAZA PET uptake regions as part of a DP strategy.
— Purpose: The aim of this study was to evaluate the possible role of fused images (anatomical CT and functional FDG-PET), acquired with a combined PET-CT scanner, in delineating gross tumour volume (GTV) and clinical target volume (CTV). Materials and Methods: Twenty-nine patients with small cell or non-small cell lung cancer were studied. CT and FDG-PET images were obtained in treatment position in a combined PET/CT scanner. FDG-PET and CT images were transferred to a workstation for contouring. Gross Tumor Volumes (GTV) and Clinical Target Volumes (CTV) were defined first using the CT data alone and then using the registered CT and FDG-PET data. For each patients two three Dimensional Conformal Radiotherapy (3DCRT) plans were made and they were compared with respect to the GTV, CTV, mean lung dose and volume of normal lung receiving ≥20 Gy (V lung20Gy) Results: Out of these 29 patients, PET clearly changed GTV in 17 patients. PET increased CTV in 7 patients. Additional unsuspected regional nodal disease was included in these patients. In 16 patients with atelectasis, decrease in CTV led to reduced radiation dose to the lung. Likewise, with additional PET information, CTV was enlarged and values of MLD and V lung20Gy were increased in 5 patients. Conclusion: The use of PET/CT images in radiotherapy is helpful in defining tumor location more precisely, possibly sparing more normal lung tissues and also helpful in differentiating tumor from atelectasis lung. The increasing availability of combined PET/CT units will facilitate the use of this technology for radiation treatment planning.
Current concepts in F18 FDG PET/CT-based radiation therapy planning for lung cancer
Frontiers in oncology, 2012
Radiation therapy is an important component of cancer therapy for early stage as well as locally advanced lung cancer. The use of F18 FDG PET/CT has come to the forefront of lung cancer staging and overall treatment decision-making. FDG PET/CT parameters such as standard uptake value and metabolic tumor volume provide important prognostic and predictive information in lung cancer. Importantly, FDG PET/CT for radiation planning has added biological information in defining the gross tumor volume as well as involved nodal disease. For example, accurate target delineation between tumor and atelectasis is facilitated by utilizing PET and CT imaging. Furthermore, there has been meaningful progress in incorporating metabolic information from FDG PET/CT imaging in radiation treatment planning strategies such as radiation dose escalation based on standard uptake value thresholds as well as using respiratory-gated PET and CT planning for improved target delineation of moving targets. In addit...
Role of 18F-FDG PET in Assessment of Response in Non-Small Cell Lung Cancer
Journal of Nuclear Medicine, 2009
Despite recognized limitations, structural imaging with CT remains the standard technique for evaluating the response of lung cancer to both chemotherapy and radiotherapy. This evaluation has become increasingly important with the advent of neoadjuvant therapy before surgery. The high uptake of 18 F-FDG in most lung cancers and the demonstration that successful treatment reduces uptake have led to increasing enthusiasm for the use of PET and PET/CT to assess the therapeutic response. In this review, theoretic considerations and current evidence supporting the role of 18 F-FDG PET are discussed.
International Journal of Radiation Oncology*Biology*Physics, 2005
Purpose: Positron emission tomography (PET) with the glucose analog [18F]fluro-2-deoxy-D-glucose (FDG) has been accepted as a valuable tool for the staging of lung cancer, but the use of PET/CT in radiation treatment planning is still not yet clearly defined. By the use of (PET/computed tomography (CT) images in treatment planning, we were able to define a new gross treatment volume using anatomic biologic contour (ABC), delineated directly on PET/CT images. We prospectively addressed three issues in this study: (1) How to contour treatment volumes on PET/CT images, (2) Assessment of the degree of correlation between CT-based gross tumor volume/planning target volume (GTV/PTV) (GTV-CT and PTV-CT) and the corresponding PET/CT-based ABC treatment volumes (GTV-ABC and PTV-ABC), (3) Magnitude of interobserver (radiation oncologist planner) variability in the delineation of ABC treatment volumes (using our contouring method). Methods and Materials: Nineteen patients with Stages II-IIIB non-small-cell lung cancer were planned for radiation treatments using a fully integrated PET/CT device. Median patient age was 74 years (range: 52-82 years), and median Karnofsky performance status was 70. Thermoplastic or vacuum-molded immobilization devices required for conformal radiation therapy were custom fabricated for the patient before the injection of [18]f-FDG. Integrated, coregistered PET/CT images were obtained and transferred to the radiation planning workstation (Xeleris). While the PET data remained obscured, a CT-based gross tumor volume (GTV-CT) was delineated by two independent observers. The PTV was obtained by adding a 1.5-cm margin around the GTV. The same volumes were recontoured using PET/CT data and termed GTV-ABC and PTV-ABC, correspondingly. Results: We observed a distinct "halo" around areas of maximal standardized uptake value (SUV). The halo was identified by its distinct color at the periphery of all areas of maximal SUV uptake, independent of PET/CT gain ratio; the halo had an SUV of 2 ؎ 0.4 and thickness of 2 mm ؎ 0.5 mm. Whereas the center of our contoured treatment volume expressed the maximum SUV level, a steady decline of SUV was noted peripherally until SUV levels of 2 ؎ 0.4 were reached at the peripheral edge of our contoured volume, coinciding with the observed halo region. This halo was always included in the contoured GTV-ABC. Because of the contribution of PET/CT to treatment planning, a clinically significant (>25%) treatment volume modification was observed between the GTV-CT and GTV-ABC in 10/19 (52%) cases, 5 of which resulted in an increase in GTV-ABC volume vs. GTV-CT. The modification of GTV between CT-based and PET/CT-based treatment planning resulted in an alteration of PTV exceeding 20% in 8 out of 19 patients (42%). Interobserver GTV variability decreased from a mean volume difference of 28.3 cm 3 (in CT-based planning) to 9.12 cm 3 (in PET/CT-based planning) with a respective decrease in standard deviation (SD) from 20.99 to 6.47. Interobserver PTV variability also decreased from 69.8 cm 3 (SD ؎ 82.76) in CT-based planning to 23.9 cm 3 (SD ؎ 15.31) with the use of PET/CT in planning. The concordance in treatment planning between observers was increased by the use of PET/CT; 16 (84%) had <10% difference from mean of GTVs using PET/CT compared to 7 cases (37%) using CT alone (p ؍ 0.0035). Conclusions: Position emission tomography/CT-based radiation treatment planning is a useful tool resulting in modification of GTV in 52% and improvement of interobserver variability up to 84%. The use of PET/CT-based ABC can potentially replace the use of GTV. The anatomic biologic halo can be used for delineation of volumes.