Jorge Gomez

Quantification of incidental mediastinal and hilar irradiation delivered during definitive stereotactic body radiation therapy for peripheral non-small cell lung cancer

To determine the amount of incidental radiation dose received by the mediastinal and hilar nodes for patients with non-small cell lung cancer (NSCLC) treated with stereotactic body radiation therapy (SBRT). Fifty consecutive patients with NSCLC, treated using an SBRT technique, were identified. Of these patients, 38 had a prescription dose of 60 Gy in 20-Gy fractions and were eligible for analysis. For each patient, ipsilateral upper (level 2) and lower (level 4) paratracheal, and hilar (level 10) nodal regions were contoured on the planning computed tomography (CT) images. Using the clinical treatment plan, dose and volume calculations were performed retrospectively for each nodal region. SBRT to upper lobe tumors resulted in an average total ipsilateral mean dose of between 5.2 and 7.8 Gy for the most proximal paratracheal nodal stations (2R and 4R for right upper lobe lesions, 2L and 4L for left upper lobe lesions). SBRT to lower lobe tumors resulted in an average total ipsilateral mean dose of between 15.6 and 21.5 Gy for the most proximal hilar nodal stations (10R for right lower lobe lesions, 10 l for left lower lobe lesions). Doses to more distal nodes were substantially lower than 5 Gy. The often substantial incidental irradiation, delivered during SBRT for peripheral NSCLC of the lower lobes to the most proximal hilar lymph nodes may be therapeutic for low-volume, subclinical nodal disease. Treatment of peripheral upper lobe lung tumors delivers less incidental irradiation to the paratracheal lymph nodes with lower likelihood of therapeutic benefit.

Level-set segmentation of pulmonary nodules in megavolt electronic portal images using a CT prior

PURPOSE Pulmonary nodules present unique problems during radiation treatment due to nodule position uncertainty that is caused by respiration. The radiation field has to be enlarged to account for nodule motion during treatment. The purpose of this work is to provide a method of locating a pulmonary nodule in a megavolt portal image that can be used to reduce the internal target volume (ITV) during radiation therapy. A reduction in the ITV would result in a decrease in radiation toxicity to healthy tissue. METHODS Eight patients with nonsmall cell lung cancer were used in this study. CT scans that include the pulmonary nodule were captured with a GE Healthcare LightSpeed RT 16 scanner. Megavolt portal images were acquired with a Varian Trilogy unit equipped with an AS1000 electronic portal imaging device. The nodule localization method uses grayscale morphological filtering and level-set segmentation with a prior. The treatment-time portion of the algorithm is implemented on a graphical processing unit. RESULTS The method was retrospectively tested on eight cases that include a total of 151 megavolt portal image frames. The method reduced the nodule position uncertainty by an average of 40% for seven out of the eight cases. The treatment phase portion of the method has a subsecond execution time that makes it suitable for near-real-time nodule localization. CONCLUSIONS A method was developed to localize a pulmonary nodule in a megavolt portal image. The method uses the characteristics of the nodule in a prior CT scan to enhance the nodule in the portal image and to identify the nodule region by level-set segmentation. In a retrospective study, the method reduced the nodule position uncertainty by an average of 40% for seven out of the eight cases studied.

Effects of selenomethionine on acute toxicities from concurrent chemoradiation for inoperable stage III non-small cell lung cancer.

AIM To prospectively determine the safety and tolerability of oral L-selenomethionine (SLM) with concurrent chemoradiation (CCRT) for Stage III non-small cell lung cancer (NSCLC) and estimate if the incidence and/or severity of adverse events could be reduced by its use. METHODS Sixteen patients with stage III NSCLC were accrued to this single arm, phase II study. CCRT consisted of radiation given at 2 Gy per fraction for 30-33 fractions, 5 d per week with concurrent weekly IV paclitaxel 50 mg/m(2) followed by carboplatin dosed at an area under the time-concentration curve of 2. SLM was dosed in a loading phase at 4800 μg twice daily for one week prior to CCRT followed by once daily dosing during treatment. RESULTS No selenium-related toxicity was observed. Analysis revealed grade 3 or higher esophagitis in 3 of 16 patients (19%), pneumonitis in 0, leukopenia in 2 (12.5%), and anemia in 1 (6%); the latter two were significantly reduced when compared to the protocol-stated expected rate of 35% (P = 0.045 for leukopenia, and P < 0.01 for anemia). Median overall survival was 14.9 mo and median failure-free survival was 9 mo (95%CI: 3.3-21.5). CONCLUSION There may be some protective benefit of selenium in the setting of CCRT for inoperable NSCLC. The data suggests decreased rates of myelosuppression when compared to similarly-treated historical and contemporary controls. Further evaluation of selenium in this setting may be warranted.

Convex probe endobronchial ultrasound placement of fiducial markers for central lung nodule (with video)

Kassem Harris1,2, Jorge Gomez3, Samjot Singh Dhillon1,2, Abdul Hamid Alraiyes1, Anthony Picone4 1Department of Medicine, Interventional Pulmonary Section, Roswell Park Cancer Institute, 2Department of Medicine, Division of Pulmonary, Critical Care and Sleep Medicine, University at Buffalo, State University of New York, Departments of 3Radiation Oncology and 4Thoracic Surgery, Roswell Park Cancer Institute, Buffalo, New York, USA

Minimally invasive rib-sparing video-assisted thoracoscopic surgery resections with high-dose-rate intraoperative brachytherapy for selected chest wall tumors

BACKGROUND By avoiding chest wall resection, iridium-192 (Ir-192) high-dose-rate (HDR) intraoperative brachytherapy (IOBT) and video-assisted thoracoscopic surgery (VATS) might improve outcomes for high-risk patients requiring surgical resection for pulmonary malignancy with limited pleura and/or chest wall involvement. METHODS AND MATERIALS Seven patients with non-small cell lung cancer involving the pleura or chest wall underwent VATS pulmonary resections combined with HDR IOBT. After tumor extraction, an Ir-192 source was delivered via a Freiburg applicator to intrathoracic sites with potential for R1-positive surgical margins. The number of catheters, dwell position along each catheter, prescription depth, and dose were customized based on clinical needs. RESULTS Six patients had pT3N0M0 non-small cell lung cancers. A seventh case was a recurrent sarcomatoid carcinoma. One case required conversion to open thoracotomy for pneumonectomy with en bloc chest wall resection. There were no intraoperative complications and average operative time was 5.8 hours. Five of seven patients without transmural chest wall involvement underwent rib-sparing resection. Four of the 6 patients treated with VATS and IORT remain alive in follow-up without evidence of local recurrence (median follow-up, 25 months). Noted toxicities were recurrent postoperative pneumothorax, pleural effusion with persistent chest wall pain, avid fibrosis at 2 years of follow-up, and a late traumatic rib fracture. CONCLUSIONS HDR IOBT with Ir-192 via VATS is technically feasible and safe for intrathoracic disease with pleural and/or limited chest wall involvement. Short-term morbidity associated with chest wall resection may be reduced. Additional study is required to define long-term benefits.

Transcervical Extended Mediastinal Lymphadenectomy: Experience From a North American Cancer Center

BACKGROUND Accurate staging of the mediastinum is a critical element of therapeutic decision making in non-small cell lung cancer. We sought to determine the utility of transcervical extended mediastinal lymphadenectomy (TEMLA) in staging non-small cell lung cancer for large central tumors and after induction therapy. METHODS A retrospective record review was performed of all patients who underwent TEMLA at our institution from 2010 to 2015. Clinical stage as assessed by positron emission tomography integrated with computed tomography (PET-CT), stage as assessed by TEMLA, final pathologic stage, lymph node yield, and clinical characteristics of tumors were assessed along with TEMLA-related perioperative morbidity. Accuracy of staging by TEMLA for restaging the mediastinum after neoadjuvant therapy was compared with that of PET-CT. RESULTS Of 164 patients who underwent TEMLA, 157 (95.7%) were completed successfully. Combined surgical resection along with TEMLA was performed in 138 of these patients, with 131 (94.2%) undergoing a video-assisted thoracoscopic resection. The recurrent laryngeal nerve injury rate was 6.7%. TEMLA was performed in 118 of 164 patients for restaging after neoadjuvant therapy, and 101 of these patients were also restaged by PET-CT. Based on TEMLA, 7 patients did not go on to have resection. Of the 101 patients who did have a resection, TEMLA was more accurate than PET-CT in staging the mediastinum (95% vs 73%, p < 0.0001). However, the pneumonia rate in this subgroup of patients was 13%. CONCLUSIONS TEMLA is a safe procedure and superior to PET-CT for restaging of the mediastinum after neoadjuvant therapy for non-small cell lung cancer. However, this increased accuracy comes with a high postoperative pneumonia rate.

SU-G-JeP3-13: Use of Volumetric Indices to Study the Viability of Respiratory Gating in Conjunction with Abdominal Compression in the Management of Non-Small Cell Lung Cancer Tumors Using Stereotactic Body Radiation Therapy Under the Conditions of Controlled Breathing

PURPOSE AAPM TG-76 report advises lung patients experiencing tumor motion >5mm to use some form of motion management with even smaller limit for complex/special procedures like SBRT. Generally, either respiratory gating or abdominal compression is used for motion management. In this retrospective study, we are using an innovative index, Volumetric Indices (VI) = (GTVnn AND GTV50+ Xmm)/(GTVnn) to quantify how much of the tumor remains within 1, 2, and 3mm margins throughout the breathing cycle using GTV50+ Xmm margin on GTV50 [nn=0,10,20,…90]. Using appropriate limits, VI can provide tumor motion information and to check if RPM gates could have been used in conjunction with abdominal compression to better manage tumor motion. METHODS 64 SBRT patients with a total of 67 lung tumors were studied. 4DCT scans were taken, fully capturing tumor motion throughout the 10 phases of the breathing cycle. For each phase, Gross Tumor Volume (GTV) was segmented and appropriates structures were defined to determine VI values. For the 2mm margin, VI values less than 0.95 for peripheral lesions and 0.97 for central lesions indicate tumor movement greater than 4mm. VI values for 1mm and 3mm margins were also analyzed signifying tumor motion of 2mm & 6mm, respectively. RESULTS Of the 64 patients, 35 (55%) had motion greater than 4mm & could have benefited from respiratory gating. For 5/8 (63%) middle lobe lesions, 21/27 (78%) lower lobe lesions, and 10/32 (31%) upper lobe lesions, gating could have resulted in smaller ITV. 32/55 (58%) peripheral lesions and 4/12 (33%) central lesions could have had gating. Average ITV decreased by 1.25cc (11.43%) and average VI increased by 0.11. CONCLUSION Out of 64 patients, 55% exhibited motion greater than 4mm even with abdominal compression. Even with abdominalcompression, lung tumors can move >4mm as the degree of pressure which a patient can tolerate, is patient specific.

SU‐E‐T‐452: Impact of Abdominal Compression on the Tumor Motion in the Treatment of NSCLC Using Stereotactic Body Radiosurgery

PURPOSE Involuntary motion of the tumor during the treatment of NSCLC using stereotactic body radiosurgery presents its own unique challenges. In this study, we quantify the impact of abdominal compression technique to minimize tumor motion as a function of location of tumor in a patient. METHODS 25 patients (5 in each lung lobe viz. RUL, RML, RLL, LUL and LLL) were retrospectively analyzed. A 4DCT study encompassing the tumor was used on a 16 slice GE CT scanner along with Varian RPM gating system. The images were retrospectively binned in 10 phases. The motion of tumor was analyzed phase by phase in transverse, sagittal & coronal projections of the 3D image. This gave us 2 values for anterior-posterior, superior-inferior and lateral-medial motions each and was averaged out. RESULTS Analysis of data reveals that the motion (mean ± 1SD) in the superior-inferior direction was 1.8 ± 0.9, 4.2±2.8, 7.4±2.3, 1.5±0.8, 3.1±2.8 mm for tumors located in RUL, RML, RLL, LUL and LLL, respectively. Along the anterior-posterior direction the respective values were 2.5 ± 1.9, 2.4 ± 1.1, 2.7 ± 1.3, 1.4 ± 0.2 and 1.8 ± 1 mm. Similarly, along the lateral direction, the respective values were 2.1 ± 1.1, 1.9 ± 1.1, 1.6 ± 1.3, 1.1 ± 0.3 and 1.8 ± 0.7 mm. When the data was analyzed removing the location of the tumor in the thorax, the median displacement along the superior-inferior, anterior-posterior, lateral direction was 2.3, 1.6 and 1.5 mm, respectively while the respective maximum value were 9.2, 5 & 3.8 mm. CONCLUSIONS The use of abdominal compression provides a simple inexpensive yet easily tolerable device to control the motion of the tumor in the management of NSCLC for SBRT treatments. This will allows the treatment of the tumor without resorting to complex and time consuming gated treatments.

WE‐C‐BRB‐05: Tracking of Thoracic Tumor Using EPID for Respiratory Gating Purposes: A Retrospective Feasibility Study

Purpose: Conventional respiratory gating relies on an external surrogate which might provide suboptimal tracking of the tumor in many cases. In the present study, an attempt has been made to exploit the density differences between the tumor and its surrounding lungtissue to gate treatments directly using electronic portal imaging device[EPID]. Material & Methods: Varian Trilogy unit equipped with EPID [AS1000, resolution 1024×1024] was used. During treatment, a custom designed image acquisition template captured the portal images. The treatment plan along with the raw scan data and structures was also exported. DRRs for each field with the tumor [hereafter referred as nodule] projection overlaid on it, were also exported and were used as a shaped prior. Nodule was segmented in each portal image using a level set segmentation algorithm which includes an energy term that is minimized when the shape of the segmented region matches the shape prior. Results: The nodule segmentation algorithm was evaluated on a series of 20 portal images of a nodule located just above the diaphragm. The nodule has an average distance from the center of the portal of 5.68 mm with the standard deviation, minimum, and maximum distance of 1.79, 2.44, and 9.13 mm, respectively. The distance between the nodule and segmented region center was 1.98 mm and the standard deviation, minimum, and maximum distance being 0.96, 0.13, and 4.12 mm, respectively. The average & maximum position error between the portal and nodule center could be reduced by 35% & 45%, respectively, using the nodule segmentation algorithm. Present runtime of 4 seconds will be reduced to real‐time as the algorithm is being ported to graphic cards [GPUs]. Conclusion: The proposed method utilizes the tumor motion directly, thereby, eliminating an external surrogate system and its associated inaccuracies and offers promise for respiratory gating treatment delivery.