- Email: [email protected]
Radiation Pneumonitis Following Simplified Intensity Modulated Radiation Therapy for Lung Cancer
S504
International Journal of Radiation Oncology Biology Physics
degree related research position. One hundred sixty-two of 173 (94%) of all applicants listed publication citations on their applications compared to 42% in 2004. Sixty-four percent of 2011 applicants listed peer-reviewed publications or abstracts. In total, 1597 citations were listed, of which 523 (33%) were recorded as peer-reviewed manuscripts. We found a total of 125 (23.9%) incorrect manuscript citations submitted by 39 applicants (22.5% of all applicants) compared to 9% of all applicants listing incorrect citations in 2004. Types of misrepresentation included: change in authorship order (20.4%), incorrect title of publication (18.4%), not in peerreviewed journal (6.1%), incorrect journal listed in citation (12.2%), manuscript not published at time of application (8.2%), unable to find publication using search tools (16.3%) and other (18.4%). Even though applicants with more research experience were more likely to have a larger number of publications (p Z 0.001), they were not more likely to misrepresent (p Z 0.25). Conclusions: Publication misrepresentations are increasingly seen in applications to radiation oncology. Future study will focus on specific applicant factors that may predict for ethical breaches and ways to mitigate misrepresentation among applicants. Author Disclosure: S.R. Amarnath: None. A.D. Trister: None. R.D. Ermoian: None.
years with subtle increases for Asians and Females, and either decrease (Blacks) or no significant changes (AI/AN, NH/PI, and Hispanics) for traditionally underrepresented groups in medicine. Author Disclosure: C. Deville: None. W. Hwang: None. S. Both: None. C. Thomas: None. C.H. Chapman: None.
2788 United States Radiation Oncology Residency Diversity Over the Past 20 Years C. Deville, W. Hwang, S. Both, C. Thomas, and C.H. Chapman; University of Pennsylvania, Philadelphia, PA Purpose/Objective(s): Women and traditionally underrepresented groups in medicine (URM) e Blacks, American Indians and Alaska Natives (AI/ AN), Native Hawaiians and Pacific Islanders (NH/PI), and Hispanics e are currently underrepresented in the US Radiation Oncology physician workforce. The purpose of this study was to assess changes in Radiation Oncology resident diversity by race, Hispanic ethnicity, and sex, over the past 20 years. Materials/Methods: Racial groups included: White; Black or African American, referred to as Black; Asian or Asian American, referred to as Asian; AI/AN; NH/PI; and Other, here defined as any person with unknown racial information and/or not classifiable into previous categories. Ethnic groups included Hispanic and non-Hispanic. Resident data for academic years 1991-1992 to 2011-2012 were accumulated from annual Journal of the American Medical Association (AMA) supplements, reporting AMA/AAMC database information on Accreditation Council for Graduate Medical Education training programs. Data for Asian, Black, Other, and Hispanics were first reported for 1995-1996, and for AI/AN and NH/PI in 2001-2002. To assess the changes in the percentages of different race, ethnicity, and sex in residents over 20 academic years, the slope and the associated 95% confidence intervals for each group were estimated using a simple linear regression model where year was used as independent variable. Results: Minimum and maximum percentages (in the most recent year recorded) were for: males 65.2% (2007), 78.9% (1999); Whites 50.7% (1999), 63.8% (1995); Asians 21.3% (1995), 35.8% (2001); females 27.2% (1996), 34.8% (2007); Hispanics 1.6% (1997), 5.2% (2001); Blacks 2.6% (2008), 6.4% (1998); AI/AN 0.0% (2003), 0.4% (2005); and NH/PI 0.0% (2011), 0.9% (2007). When analyzing differences over time (change in percent/year; 95% CI; p value), representation was found to be increasing for Asians (0.6544; 0.2688, 1.0223; p Z 0.002) and females (0.2650; 0.1349, 0.395; p < 0.001), unchanged for Whites (0.1994; 0.2141, 0.6128; p Z 0.320), AI/AN (0.0183; 0.0113, 0.0478; p Z 0.196), NH/PI (0.0446; 0.0969, 0.0078; p Z 0.087), and Hispanics (0.0551; 0.0483, 0.1584; p Z 0.274), and decreasing for Blacks ( 0.1353; 0.2227, 0.0480; p Z 0.005) and other ( 0.5214; 0.9093, 0.1335; p Z 0.012). Conclusions: Despite the ongoing diversification of medical school graduates over the past 20 years, overall diversity by race, ethnicity, and sex, of Radiation Oncology residents has changed minimally over the past 20
2789 WITHDRAWN
2790 Correlation of Clinical and Dosimetric Parameters With Radiographic Lung Injury Following Stereotactic Body Radiation Therapy A. Kishan, J. Wang, V. Yu, D. Ruan, M. Cao, S. Tenn, D. Low, and P. Lee; University of California - Los Angeles, Los Angeles, CA Purpose/Objective(s): Radiographic lung density changes occur in over half of patients treated with stereotactic body radiation therapy (SBRT) and correlate histopathologically with injury. We sought to quantify radiographic lung density changes at 3, 6 and 12 months, and investigate the relationship between the volume of density change and various clinical and dosimetric parameters. Materials/Methods: The primary study population consisted of patients treated with SBRT to the lung for stage I primary lung cancers (n Z 39) or oligometastatic lesions (n Z 17). Fractionation schemes included three fractions of 10, 12, 14, or 18 Gy and four fractions of 12 or 12.5 Gy prescribed to cover 95% of the planning target volume (PTV). Initial planning computed tomography (CT) scans were rigidly registered to follow-up CT scans obtained at intervals of 3, 6, and 12 months. Regions of density change, as determined by two investigators (A.K. and P.L.), were contoured on the follow-up scans. A threshold dose (TD) was defined as the dose to the total lung corresponding to the volume of the density change normalized to the treatment dose. The percentage of overlap between density changes and isodose curves were compared at 6 and 12 months. Associations between the volume of density changes and clinical and dosimetric parameters were investigated using multivariable linear regression. Results: Follow-up data were available for 65 and 47 lesions at 6 and 12 months, respectively. Age, years since quitting smoking, and GOLD score (if applicable) were significantly associated with increasing volume of density change (p < 0.05). The total dose, PTV, and volumetric parameters (V0 to V55) were also significantly associated with increasing volumes of density change (p < 0.01). The strength of the association was strongest at V55. The average TD was 84.0% and 90.1% of the treatment dose at 6 and 12 months, respectively. The average percentage of overlap between density changes and the 90% isodose curves was 45.0% and 48.7% at 6 and 12 months, respectively. Conclusions: Age, significant smoking history, and GOLD score were significantly associated with increasing volumes of radiographic density change following SBRT. Further, there is a strong dose-response relationship between the volume of lung exposed to a certain dose and the volume of density change. The overlapping regions between the density changes and the 90% isodose curves correspond to nearly 50% of the density changes, volumetrically, while the TD that would theoretically create a volume equaling that of the density changes at 6 and 12 months is between 84% and 90% of the treatment dose. Author Disclosure: A. Kishan: None. J. Wang: None. V. Yu: None. D. Ruan: None. M. Cao: None. S. Tenn: None. D. Low: None. P. Lee: None.
2791 Radiation Pneumonitis Following Simplified Intensity Modulated Radiation Therapy for Lung Cancer L. Zhou,1 J. Liu,2 Y. Zhang,3 Y. Gong,1 S. Bai,3 and Y. Lu1; 1Department of Thoracic Cancer, Cancer Center and State Key Laboratory of Biotherapy, West China Hospital of Sichuan University, Chengdu, China,
Volume 87 Number 2S Supplement 2013 2
Department of Oncology, Chengdu First People’s Hospital, Chengdu, China, 3Center of Radiation Physics, Cancer Center and State Key Laboratory of Biotherapy, West China Hospital of Sichuan University, Chengdu, China Purpose/Objective(s): To retrospectively analyze risk factors for radiation pneumonitis (RP) following simplified intensity-modulated radiation therapy (sIMRT) to patients with lung cancer. Materials/Methods: sIMRT was defined in our department as below: the number of beams 5, the total number of segments 25, the area of each segment 5 square centimeter, and the number of machine monitor for each segment 5. From January 2011 to May 2012, 47 male patients and 19 female patients with lung cancer (included NSCLC and SCLC) completed thoracic sIMRT 50 Gy/25f (with or without chemotherapy) in our department. There were 42 patients without surgery history and 24 patients following lobectomy, the median age was 60 years (range, 31-75 years). We analyzed clinical and dosimetric risk factors for the Common Terminology Criteria for Adverse Events (CTC AE) V3.0 grade 2 RP. Results: After the median follow-up time of 14 months (range, 6-23 months), 50% (33/66) of patients had interstitial inflammation change in their CT scans after radiation therapy, and the median time to detection of pulmonary imaging changes after radiation therapy was 3 months (0-6 months). 22.7% (15/66) of patients had grade 2 RP, and the median time to RP after radiation therapy was 3 months (range, 0-5 months). 90.9% (30/33) of patients with interstitial inflammation change after radiation therapy and 86.7% (13/15) of patients with grade 2 RP had their imaging changes in regions receiving 40 Gy. Risk factors of grade 2 RP in whole group were pulmonary infection (infection vs noninfection: OR Z 15.625, p Z 0.030) and higher N stage (N2-3 vs N0-1: OR Z 15.627, p Z 0.039). For patients following lobectomy, the percentages of total and ipsilateral lung volume receiving 40 Gy, 45 Gy and 50 Gy (V40, V45 and V50) were associated with grade 2 RP. V40, V45 and V50 of total lung in patients with grade 2 RP were higher than patients with grade 0-1 RP: 10.51% 4.83% vs 6.84% 3.09% (p Z 0.046), 8.65% 4.39% VS. 4.97% 2.54% (p Z 0.022), 6.78% 3.80% vs 3.43% 2.07% (p Z 0.014). V40, V45 and V50 of ipsilateral lung in patients with grade 2 RP were also higher than patients with grade 0-1 RP: 24.86% 12.48% VS. 15.12% 6.71% (p Z 0.027), 20.48% 10.61% vs 11.38% 5.83% (p Z 0.017), 15.84% 9.05% vs 8.08% 5.08% (p Z 0.018). Conclusions: The incidence of grade 2 RP following sIMRT was similar to three-dimensional conformal radiation therapy and intensity-modulated radiation therapy. Pulmonary imaging changes in patients after radiation therapy was predominantly in regions receiving 40 Gy. Pulmonary infection and N2-3 were risk factors of grade 2 RP. For patients following lobectomy, V40, V45 and V50 of total and ipsilateral lung were associated with grade 2 RP. Author Disclosure: L. Zhou: None. J. Liu: None. Y. Zhang: None. Y. Gong: None. S. Bai: None. Y. Lu: None.
2792 Spontaneous Pneumothorax After Stereotactic Body Radiation Therapy for Lung Tumor K. Asai, Y. Shioyama, K. Nakamura, T. Sasaki, S. Ohga, T. Yoshitake, M. Shinoto, H. Hirata, and H. Honda; Kyushu University, Fukuoka, Japan Purpose/Objective(s): To clarify the clinical feature of spontaneous pneumothorax after stereotactic body radiation therapy (SBRT) for lung tumor. Materials/Methods: Five hundred fifty patients treated with SBRT for lung tumors between April 2004 and July 2012 at Kyushu University Hospital were enrolled in this study. We reviewed the follow-up CT images and detected the patients developed pneumothorax after SBRT. We evaluated the followings as the patient’s factor, diagnosis (primary lung cancer or metastatic lung tumor), age, gender, radiation dose, T-
Poster Viewing Abstracts S505 category, histology, type of tumor appearance (GGO or solid or solid and GGO), tumor location, severity of radiation pneumonitis. We also evaluated presence or absence of emphysema, overlapping of PTV and pleura, rib fracture. As the clinical feature of pneumothorax after SBRT, we also evaluated the time to onset, severity, treatment and outcome. Patients who had a history of pneumothorax before SBRT were excluded. Results: There were 8 patients (1.5%) who developed a pneumothorax after SBRT. All pneumothorax occurred in the ipsilateral lung. All the patients’ diagnosis was primary lung cancer. Age was 64 to 86 (median; 80) years old. Gender was male in 7 and female in 1 patient. SBRT was given using 7-8 non-coplanar beams with 45 to 48 Gy in 4 fractions during 4-8 (median; 6) days. T-stage was T1a in 0, T1b in 5 and T2a in 3 patients. Histology was adenocarcinoma in two, squamous carcinoma in two, non-small cell lung cancer in two, unknown in two. Type of tumor appearance was solid in 3, solid and GGO in 5. Tumor location was upper lobe in 4, lower lobe in 4. Severity of radiation pneumonitis was G0 in 1, G1 in 5, G2 in 1. Seven patients had emphysema. PTV and pleura were overlapped in all cases except one case in which distance between PTV and pleura was 0.1 cm. Rib fracture was observed in 3 cases. The time to onset of pneumothorax after SBRT was 4 to 84 (median: 17) months. The severity of pneumothorax was G0 in 7, G3 in 1. To treat the most severe case, the patient was intubated and a chest tube was placed. All the other patients needed no intervention to treat. In all 5 patients we could follow, pneumothorax was self-limiting and there was no recurrence. Conclusions: Spontaneous pneumothorax was a rare late adverse effect after SBRT. It was generally tolerable and self-limiting but severe case was existed. Emphysema and overlapping of PTV and pleura could be the risk factor of pneumothorax after SBRT. Author Disclosure: K. Asai: None. Y. Shioyama: None. K. Nakamura: None. T. Sasaki: None. S. Ohga: None. T. Yoshitake: None. M. Shinoto: None. H. Hirata: None. H. Honda: None.
2793 Studies on the Mobility Rules of Lung Tumors and the Influencing Factors Y. Song, Y. Zhiyong, D. Yang, W. Wei, and W. Ping; Tianjin Medical University Institute & Hospital, Tianjin, China Purpose/Objective(s): To investigate the mobility rules and influencing factors in lung tumors in order to guide for precisely defining the margin that CTV (clinical target volume) is to be expanded to PTV during stereotactic radiation therapy for lung tumors. Materials/Methods: A total 83 tumors in 70 cases of patients with primary or metastatic lung cancer were chosen who were subject to robotic radiosurgery including 7 cases of patients with a total of 7 tumors invading the chest wall. Under the guidance by CT, the pure gold mark (tumors) was implanted into or nearby the tumor. With the X-ray simulator system, the range of motion of the gold mark (cancer) was measured. One week later, 16-slice spiral lung CT scan was conducted (1.25 mm thick). According to anatomical borderlines, apex, middle, bottom of the lung were classified. The data on the motion of lung tumors in x (right-left), y (anterior-posterior) and z (superior-inferior) direction was recorded. Results: For 76 lung lesions of 63 patients, the moving distance of apex, middle, and bottom was 1.6 0.8, 2.6 1.1, and 2.8 1.7 mm (F Z 1.76, p Z 0.179) in x-axis; 2.0 1.3, 4.3 2.8, and 4.0 2.0 mm (F Z 2.06, p Z 0.135) in y-axis; 2.7 0.8, 7.3 3.6, and 12.0 5.3 mm (F Z 16.33, p Z 0.000) in z-axis respectively. For 7 lesions invading the chest wall, their moving distance was very small (i.e., 0.9 0.7, 0.7 0.7, and 2.0 0.6 mm, respectively). The correlation analysis showed the moving distance in all directions was related with the patient’s sex, age, height, weight and 1s breathing rate (r Z 0.001-0.136, p> 0.05). Conclusions: The moving distance due to breathing is mainly affected by the location of the tumor and the status of chest wall involvement.
International Journal of Radiation Oncology Biology Physics
degree related research position. One hundred sixty-two of 173 (94%) of all applicants listed publication citations on their applications compared to 42% in 2004. Sixty-four percent of 2011 applicants listed peer-reviewed publications or abstracts. In total, 1597 citations were listed, of which 523 (33%) were recorded as peer-reviewed manuscripts. We found a total of 125 (23.9%) incorrect manuscript citations submitted by 39 applicants (22.5% of all applicants) compared to 9% of all applicants listing incorrect citations in 2004. Types of misrepresentation included: change in authorship order (20.4%), incorrect title of publication (18.4%), not in peerreviewed journal (6.1%), incorrect journal listed in citation (12.2%), manuscript not published at time of application (8.2%), unable to find publication using search tools (16.3%) and other (18.4%). Even though applicants with more research experience were more likely to have a larger number of publications (p Z 0.001), they were not more likely to misrepresent (p Z 0.25). Conclusions: Publication misrepresentations are increasingly seen in applications to radiation oncology. Future study will focus on specific applicant factors that may predict for ethical breaches and ways to mitigate misrepresentation among applicants. Author Disclosure: S.R. Amarnath: None. A.D. Trister: None. R.D. Ermoian: None.
years with subtle increases for Asians and Females, and either decrease (Blacks) or no significant changes (AI/AN, NH/PI, and Hispanics) for traditionally underrepresented groups in medicine. Author Disclosure: C. Deville: None. W. Hwang: None. S. Both: None. C. Thomas: None. C.H. Chapman: None.
2788 United States Radiation Oncology Residency Diversity Over the Past 20 Years C. Deville, W. Hwang, S. Both, C. Thomas, and C.H. Chapman; University of Pennsylvania, Philadelphia, PA Purpose/Objective(s): Women and traditionally underrepresented groups in medicine (URM) e Blacks, American Indians and Alaska Natives (AI/ AN), Native Hawaiians and Pacific Islanders (NH/PI), and Hispanics e are currently underrepresented in the US Radiation Oncology physician workforce. The purpose of this study was to assess changes in Radiation Oncology resident diversity by race, Hispanic ethnicity, and sex, over the past 20 years. Materials/Methods: Racial groups included: White; Black or African American, referred to as Black; Asian or Asian American, referred to as Asian; AI/AN; NH/PI; and Other, here defined as any person with unknown racial information and/or not classifiable into previous categories. Ethnic groups included Hispanic and non-Hispanic. Resident data for academic years 1991-1992 to 2011-2012 were accumulated from annual Journal of the American Medical Association (AMA) supplements, reporting AMA/AAMC database information on Accreditation Council for Graduate Medical Education training programs. Data for Asian, Black, Other, and Hispanics were first reported for 1995-1996, and for AI/AN and NH/PI in 2001-2002. To assess the changes in the percentages of different race, ethnicity, and sex in residents over 20 academic years, the slope and the associated 95% confidence intervals for each group were estimated using a simple linear regression model where year was used as independent variable. Results: Minimum and maximum percentages (in the most recent year recorded) were for: males 65.2% (2007), 78.9% (1999); Whites 50.7% (1999), 63.8% (1995); Asians 21.3% (1995), 35.8% (2001); females 27.2% (1996), 34.8% (2007); Hispanics 1.6% (1997), 5.2% (2001); Blacks 2.6% (2008), 6.4% (1998); AI/AN 0.0% (2003), 0.4% (2005); and NH/PI 0.0% (2011), 0.9% (2007). When analyzing differences over time (change in percent/year; 95% CI; p value), representation was found to be increasing for Asians (0.6544; 0.2688, 1.0223; p Z 0.002) and females (0.2650; 0.1349, 0.395; p < 0.001), unchanged for Whites (0.1994; 0.2141, 0.6128; p Z 0.320), AI/AN (0.0183; 0.0113, 0.0478; p Z 0.196), NH/PI (0.0446; 0.0969, 0.0078; p Z 0.087), and Hispanics (0.0551; 0.0483, 0.1584; p Z 0.274), and decreasing for Blacks ( 0.1353; 0.2227, 0.0480; p Z 0.005) and other ( 0.5214; 0.9093, 0.1335; p Z 0.012). Conclusions: Despite the ongoing diversification of medical school graduates over the past 20 years, overall diversity by race, ethnicity, and sex, of Radiation Oncology residents has changed minimally over the past 20
2789 WITHDRAWN
2790 Correlation of Clinical and Dosimetric Parameters With Radiographic Lung Injury Following Stereotactic Body Radiation Therapy A. Kishan, J. Wang, V. Yu, D. Ruan, M. Cao, S. Tenn, D. Low, and P. Lee; University of California - Los Angeles, Los Angeles, CA Purpose/Objective(s): Radiographic lung density changes occur in over half of patients treated with stereotactic body radiation therapy (SBRT) and correlate histopathologically with injury. We sought to quantify radiographic lung density changes at 3, 6 and 12 months, and investigate the relationship between the volume of density change and various clinical and dosimetric parameters. Materials/Methods: The primary study population consisted of patients treated with SBRT to the lung for stage I primary lung cancers (n Z 39) or oligometastatic lesions (n Z 17). Fractionation schemes included three fractions of 10, 12, 14, or 18 Gy and four fractions of 12 or 12.5 Gy prescribed to cover 95% of the planning target volume (PTV). Initial planning computed tomography (CT) scans were rigidly registered to follow-up CT scans obtained at intervals of 3, 6, and 12 months. Regions of density change, as determined by two investigators (A.K. and P.L.), were contoured on the follow-up scans. A threshold dose (TD) was defined as the dose to the total lung corresponding to the volume of the density change normalized to the treatment dose. The percentage of overlap between density changes and isodose curves were compared at 6 and 12 months. Associations between the volume of density changes and clinical and dosimetric parameters were investigated using multivariable linear regression. Results: Follow-up data were available for 65 and 47 lesions at 6 and 12 months, respectively. Age, years since quitting smoking, and GOLD score (if applicable) were significantly associated with increasing volume of density change (p < 0.05). The total dose, PTV, and volumetric parameters (V0 to V55) were also significantly associated with increasing volumes of density change (p < 0.01). The strength of the association was strongest at V55. The average TD was 84.0% and 90.1% of the treatment dose at 6 and 12 months, respectively. The average percentage of overlap between density changes and the 90% isodose curves was 45.0% and 48.7% at 6 and 12 months, respectively. Conclusions: Age, significant smoking history, and GOLD score were significantly associated with increasing volumes of radiographic density change following SBRT. Further, there is a strong dose-response relationship between the volume of lung exposed to a certain dose and the volume of density change. The overlapping regions between the density changes and the 90% isodose curves correspond to nearly 50% of the density changes, volumetrically, while the TD that would theoretically create a volume equaling that of the density changes at 6 and 12 months is between 84% and 90% of the treatment dose. Author Disclosure: A. Kishan: None. J. Wang: None. V. Yu: None. D. Ruan: None. M. Cao: None. S. Tenn: None. D. Low: None. P. Lee: None.
2791 Radiation Pneumonitis Following Simplified Intensity Modulated Radiation Therapy for Lung Cancer L. Zhou,1 J. Liu,2 Y. Zhang,3 Y. Gong,1 S. Bai,3 and Y. Lu1; 1Department of Thoracic Cancer, Cancer Center and State Key Laboratory of Biotherapy, West China Hospital of Sichuan University, Chengdu, China,
Volume 87 Number 2S Supplement 2013 2
Department of Oncology, Chengdu First People’s Hospital, Chengdu, China, 3Center of Radiation Physics, Cancer Center and State Key Laboratory of Biotherapy, West China Hospital of Sichuan University, Chengdu, China Purpose/Objective(s): To retrospectively analyze risk factors for radiation pneumonitis (RP) following simplified intensity-modulated radiation therapy (sIMRT) to patients with lung cancer. Materials/Methods: sIMRT was defined in our department as below: the number of beams 5, the total number of segments 25, the area of each segment 5 square centimeter, and the number of machine monitor for each segment 5. From January 2011 to May 2012, 47 male patients and 19 female patients with lung cancer (included NSCLC and SCLC) completed thoracic sIMRT 50 Gy/25f (with or without chemotherapy) in our department. There were 42 patients without surgery history and 24 patients following lobectomy, the median age was 60 years (range, 31-75 years). We analyzed clinical and dosimetric risk factors for the Common Terminology Criteria for Adverse Events (CTC AE) V3.0 grade 2 RP. Results: After the median follow-up time of 14 months (range, 6-23 months), 50% (33/66) of patients had interstitial inflammation change in their CT scans after radiation therapy, and the median time to detection of pulmonary imaging changes after radiation therapy was 3 months (0-6 months). 22.7% (15/66) of patients had grade 2 RP, and the median time to RP after radiation therapy was 3 months (range, 0-5 months). 90.9% (30/33) of patients with interstitial inflammation change after radiation therapy and 86.7% (13/15) of patients with grade 2 RP had their imaging changes in regions receiving 40 Gy. Risk factors of grade 2 RP in whole group were pulmonary infection (infection vs noninfection: OR Z 15.625, p Z 0.030) and higher N stage (N2-3 vs N0-1: OR Z 15.627, p Z 0.039). For patients following lobectomy, the percentages of total and ipsilateral lung volume receiving 40 Gy, 45 Gy and 50 Gy (V40, V45 and V50) were associated with grade 2 RP. V40, V45 and V50 of total lung in patients with grade 2 RP were higher than patients with grade 0-1 RP: 10.51% 4.83% vs 6.84% 3.09% (p Z 0.046), 8.65% 4.39% VS. 4.97% 2.54% (p Z 0.022), 6.78% 3.80% vs 3.43% 2.07% (p Z 0.014). V40, V45 and V50 of ipsilateral lung in patients with grade 2 RP were also higher than patients with grade 0-1 RP: 24.86% 12.48% VS. 15.12% 6.71% (p Z 0.027), 20.48% 10.61% vs 11.38% 5.83% (p Z 0.017), 15.84% 9.05% vs 8.08% 5.08% (p Z 0.018). Conclusions: The incidence of grade 2 RP following sIMRT was similar to three-dimensional conformal radiation therapy and intensity-modulated radiation therapy. Pulmonary imaging changes in patients after radiation therapy was predominantly in regions receiving 40 Gy. Pulmonary infection and N2-3 were risk factors of grade 2 RP. For patients following lobectomy, V40, V45 and V50 of total and ipsilateral lung were associated with grade 2 RP. Author Disclosure: L. Zhou: None. J. Liu: None. Y. Zhang: None. Y. Gong: None. S. Bai: None. Y. Lu: None.
2792 Spontaneous Pneumothorax After Stereotactic Body Radiation Therapy for Lung Tumor K. Asai, Y. Shioyama, K. Nakamura, T. Sasaki, S. Ohga, T. Yoshitake, M. Shinoto, H. Hirata, and H. Honda; Kyushu University, Fukuoka, Japan Purpose/Objective(s): To clarify the clinical feature of spontaneous pneumothorax after stereotactic body radiation therapy (SBRT) for lung tumor. Materials/Methods: Five hundred fifty patients treated with SBRT for lung tumors between April 2004 and July 2012 at Kyushu University Hospital were enrolled in this study. We reviewed the follow-up CT images and detected the patients developed pneumothorax after SBRT. We evaluated the followings as the patient’s factor, diagnosis (primary lung cancer or metastatic lung tumor), age, gender, radiation dose, T-
Poster Viewing Abstracts S505 category, histology, type of tumor appearance (GGO or solid or solid and GGO), tumor location, severity of radiation pneumonitis. We also evaluated presence or absence of emphysema, overlapping of PTV and pleura, rib fracture. As the clinical feature of pneumothorax after SBRT, we also evaluated the time to onset, severity, treatment and outcome. Patients who had a history of pneumothorax before SBRT were excluded. Results: There were 8 patients (1.5%) who developed a pneumothorax after SBRT. All pneumothorax occurred in the ipsilateral lung. All the patients’ diagnosis was primary lung cancer. Age was 64 to 86 (median; 80) years old. Gender was male in 7 and female in 1 patient. SBRT was given using 7-8 non-coplanar beams with 45 to 48 Gy in 4 fractions during 4-8 (median; 6) days. T-stage was T1a in 0, T1b in 5 and T2a in 3 patients. Histology was adenocarcinoma in two, squamous carcinoma in two, non-small cell lung cancer in two, unknown in two. Type of tumor appearance was solid in 3, solid and GGO in 5. Tumor location was upper lobe in 4, lower lobe in 4. Severity of radiation pneumonitis was G0 in 1, G1 in 5, G2 in 1. Seven patients had emphysema. PTV and pleura were overlapped in all cases except one case in which distance between PTV and pleura was 0.1 cm. Rib fracture was observed in 3 cases. The time to onset of pneumothorax after SBRT was 4 to 84 (median: 17) months. The severity of pneumothorax was G0 in 7, G3 in 1. To treat the most severe case, the patient was intubated and a chest tube was placed. All the other patients needed no intervention to treat. In all 5 patients we could follow, pneumothorax was self-limiting and there was no recurrence. Conclusions: Spontaneous pneumothorax was a rare late adverse effect after SBRT. It was generally tolerable and self-limiting but severe case was existed. Emphysema and overlapping of PTV and pleura could be the risk factor of pneumothorax after SBRT. Author Disclosure: K. Asai: None. Y. Shioyama: None. K. Nakamura: None. T. Sasaki: None. S. Ohga: None. T. Yoshitake: None. M. Shinoto: None. H. Hirata: None. H. Honda: None.
2793 Studies on the Mobility Rules of Lung Tumors and the Influencing Factors Y. Song, Y. Zhiyong, D. Yang, W. Wei, and W. Ping; Tianjin Medical University Institute & Hospital, Tianjin, China Purpose/Objective(s): To investigate the mobility rules and influencing factors in lung tumors in order to guide for precisely defining the margin that CTV (clinical target volume) is to be expanded to PTV during stereotactic radiation therapy for lung tumors. Materials/Methods: A total 83 tumors in 70 cases of patients with primary or metastatic lung cancer were chosen who were subject to robotic radiosurgery including 7 cases of patients with a total of 7 tumors invading the chest wall. Under the guidance by CT, the pure gold mark (tumors) was implanted into or nearby the tumor. With the X-ray simulator system, the range of motion of the gold mark (cancer) was measured. One week later, 16-slice spiral lung CT scan was conducted (1.25 mm thick). According to anatomical borderlines, apex, middle, bottom of the lung were classified. The data on the motion of lung tumors in x (right-left), y (anterior-posterior) and z (superior-inferior) direction was recorded. Results: For 76 lung lesions of 63 patients, the moving distance of apex, middle, and bottom was 1.6 0.8, 2.6 1.1, and 2.8 1.7 mm (F Z 1.76, p Z 0.179) in x-axis; 2.0 1.3, 4.3 2.8, and 4.0 2.0 mm (F Z 2.06, p Z 0.135) in y-axis; 2.7 0.8, 7.3 3.6, and 12.0 5.3 mm (F Z 16.33, p Z 0.000) in z-axis respectively. For 7 lesions invading the chest wall, their moving distance was very small (i.e., 0.9 0.7, 0.7 0.7, and 2.0 0.6 mm, respectively). The correlation analysis showed the moving distance in all directions was related with the patient’s sex, age, height, weight and 1s breathing rate (r Z 0.001-0.136, p> 0.05). Conclusions: The moving distance due to breathing is mainly affected by the location of the tumor and the status of chest wall involvement.