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Temporal Lobe Sparing in Craniopharyngioma Radiotherapy with Cyst Growth
Proceedings of the 52nd Annual ASTRO Meeting
2871
Multidisciplinary Management with Whole Abdominal IMRT of Desmoplastic Small Round Cell Tumor
A. Mahajan, P. Anderson, M. McAleer, E. P. Sulman, C. Pinnix, S. Y. Woo, C. Herzog, A. Hayes-Jordan M.D. Anderson Cancer Center, Houston, TX Purpose/Objective(s): Desmoplastic small round cell tumor (DSCRT) is an uncommon tumor with a poor prognosis most commonly affecting adolescent males. We report our results with aggressive multi-modality therapy including whole abdominal IMRT (WA-IMRT). Materials/Methods: The medical records of all patients with DSCRT who received WA-IMRT as part of the definitive treatment at our institution were reviewed. Disease status and baseline renal, liver and nutritional status was compared to these outcomes at 1 year after completion of WA-IMRT. Results: A total of 8 patients (all male) were treated between 2006 and 2010 with WA-IMRT for DSCRT. The median age was 14 (range, 6-23y) at the time of radiotherapy. The median follow-up was 17mo (range, 0-25mo) from the end of RT. All 8 patients received multiple courses of chemotherapy followed by attempted surgical resection of all intra-abdominal disease. 7 of the 8 patients received intraoperative hyperthermic cisplatinum. 30 Gy WA-IMRT was delivered at a median of 66 days after surgery. 7 of the 8 patients received concurrent chemotherapy (temozolomide 5/7, bevacizumab 3/7, other 4/7). The CTV was defined as the abdomino-pelvic cavity sparing the liver and kidney parenchyma (median volume 3352cc). The median mean dose to the CTV was 32 Gy, 95% of the CTV received a median of 28 Gy (range, 24-30 Gy). 3 patients received a simultaneous integrated boost to the site(s) of gross residual disease with an additional 6-10 Gy. The median mean doses to the right kidney, left kidney and liver were 16.8 Gy, 18.5 Gy and 23.3 Gy, respectively. The median liver V30 was 20%.The median weight loss during RT was 1.3% of the baseline weight (range, 0.8-4.1%). There was no significant nausea, vomiting, diarrhea noted during RT, though all patients were given odansetron as needed. RBC transfusions were required in 3 patients to maintain Hb.10, otherwise, no significant cytopenias were noted. For the six patients with at least one year followup, 4 patients had stable or increasing weight. Two patients had 15% loss of weight at this time, but both had recurrent disease. No significant creatinine elevation was noted at 6 or 12 months. One patient with recurrent liver disease had elevation of LFTs at one year. At last follow-up, 2 patients have died of disease at 17 and 20 months, 5 patients are alive with disease and 1 patient has no evidence of disease. Conclusions: DSCRT is an aggressive disease that is difficult to manage. Even after multiagent chemotherapy, aggressive surgery with intraperitoneal chemotherapy, WA-IMRT with concurrent chemotherapy was tolerated well with no evidence of significant GI, renal or hepatic injury thus far. Author Disclosure: A. Mahajan, None; P. Anderson, None; M. McAleer, None; E.P. Sulman, None; C. Pinnix, None; S.Y. Woo, None; C. Herzog, None; A. Hayes-Jordan, None.
2872
Outcome of Pediatric Female Genital Tract Rhabdomyosarcoma Based on Analysis of Cases Registered in SEER Database
N. Esiashvili1, C. Kirsh2, M. Goodman3 1 Department of Radiation Oncology, Winship Cancer Institute of Emory University, Atlanta, GA, 2Medical College of Georgia, Augusta, GA, 3School of Public Health, Emory University, Atlanta, GA
Purpose/Objective(s): To analyze outcome of Rhabdomyosarcoma (RMS) of female genital track in children using data available from Surveillance Epidemiology and End Result (SEER) database. The data was evaluated for epidemiological trends, outcome by patient and disease variable and survival of patients based on local treatment delivered upfront. Materials/Methods: The SEER database was searched for female genital RMS cases diagnosed at age 0-19 years between 1973 and 2006. Differences in the distribution of primary site, race, stage, histology, surgery and radiation therapy (RT) across the two age groups (0-9 vs. 10-19 year old) were examined using chi square tests. Kaplan-Meier survival curves were constructed to compare survival by histology, stage and primary sites. Results: A total of 67 cases were identified; the incidence did not change significantly during study period. Age distribution was as follows: 5 cases in \1 year old, 33 in 1- 9, 29 in 10- 19 year olds. 38.8% cases were with localized, 16.2% regional, 28.4% with distant stage and 28.4% unstaged. 85% of cases had embryonal type, remaining 15% included 4 alveolar, 2 mixed, 1 pleomorphic, 1 with ganglionic differentiation and 2 not otherwise specified (NOS). Twenty cases had tumor originated in the vagina, 26 in cervix/ uterus, 6 in vulva/labia, 5 in ovaries, and 1 case in an area NOS. Only 15% of cases received RT and it was not affected by patients’ or disease characteristics. The two age groups were no significantly different by race, cancer stage, histology and surgery and RT. The majority of cases in the younger age group (68.4%) had vaginal RMS, whereas older age group (65.5%) had RMS of the cervix or uterus (p \ 0.001). The survival of embryonal RMS was superior compared to other types (p = 0.035); localized genital RMS demonstrated more favorable outcome compared to more advanced stages (p = 0.025). There was no discernable difference in survival by primary tumor site or use of RT. The most of the RMS deaths occurred within first 4-5 years from diagnosis. Conclusions: Incidence of pediatric female genital RMS remains stable. Significant number of patients is diagnosed with disease spread. Younger patients present with vaginal tumors while older patients have more cervix/uterine presentation. Factors like age, histology, stage and location impact the outcome of these patients. Radiotherapy is underutilized in study population and can be a potential reason for inferior survival found in study population compared to institutional and cooperative group reports. Author Disclosure: N. Esiashvili, None; C. Kirsh, None; M. Goodman, None.
2873
Temporal Lobe Sparing in Craniopharyngioma Radiotherapy with Cyst Growth
A. R. Godley, M. Bedi, S. Firat, X. Li Medical College of Wisconsin, Milwaukee, WI Purpose/Objective(s): The target volume increases drastically during the course of radiotherapy for craniopharyngioma patients, leading to the use of generous margins. We investigate how to improve temporal lobe sparing by using reduced treatment margins, while maintaining acceptable target coverage.
S593
I. J. Radiation Oncology d Biology d Physics
S594
Volume 78, Number 3, Supplement, 2010
Materials/Methods: Daily kVCT data (29 fractions) collected for one craniopharyngioma patient treated with IGRT using a CTon-Rails (CTVision, Siemens) and weekly kVCT data for three further patients treated with TomoTherapy were analyzed retrospectively. The GTV was delineated on the daily and weekly CTs manually to track the cyst growth. Patients were treated with a prescription of 52.2 Gy to 90% of the PTV. A PTV margin of 7 mm was used in the treatment plans to account for the cyst growth during treatment. Additional plans were generated with the same prescription but with a reduced PTV margin of 3 mm to spare the temporal lobes. Delivered doses of the 7 and 3 mm margin plans were reconstructed by applying their treatment beams to the daily or weekly CTs. All the daily/weekly doses delivered by the two plans were then accumulated for each patient by deformable image registration. Daily and accumulated target coverage was assessed based on the D95 and D100 of the GTV. (PTV coverage was equivalent between the 7 and 3 mm plans.) Results: Using a 3 mm margin reduced the V30 (volume receiving 30 Gy) of the temporal lobes by an average of 23%, the V50 of the brain stem by 40% and the V52 of the optic chiasm by 46% compared to the 7 mm plan. The size of the reduction was inversely related to the size of the cyst. The cysts grew at an average rate of 0.25 cc per day (R = 0.956). For the 7 mm plans, the planned and delivered GTV D95 and D100 were both within 1%. Daily variations were also within 1%. For the 3 mm plans the daily GTV D95 can be under dosed by up to 3.5%, and the accumulated dose by 1.3% compared to the plan. The accumulated delivered GTV D100 is lower than the plan by 2.5%. By the first fraction, 8 to 15 days after the planning CT, the cysts had already grown enough to reduce the GTV D95 and D100 of the 3 mm plan by 0.5% and 2.0%, respectively. Conclusions: The 7 mm margin combined with IGRT alignment was sufficient to treat the growing cysts without a critical reduction in the delivered dose or re-planning. To take advantage of the substantially lower doses to critical structures provided by the 3 mm plan, adaptive planning is necessary to maintain GTV coverage. For the cases studied, reducing the time between acquiring the planning CT and delivering the first fraction to 2-3 days, and re-planning at fraction 15 would be sufficient to achieve the equivalent GTV coverage of the 7 mm plan. We expect to present additional cases with full daily CT sets. Author Disclosure: A.R. Godley, None; M. Bedi, None; S. Firat, None; X. Li, None.
2874
Comparison of Treatment Plans between 3D-CRT and Helical Tomotherapy Based on Integral Dose Delivered to Pediatric Patients Receiving Craniospinal Irradiation
S. Barra1, M. Gusinu1, F. Cavagnetto1, F. Giannelli1, P. Torielli2, F. Vallerga2, M. Zeverino1, R. Corvo`2 1
Ist - Genoa, Genoa, Italy, 2University Genoa, Genoa, Italy
Purpose/Objective(s): The use of Helical Tomotherapy for craniospinal irradiation in pediatric patient remains nowadays issue of discussion. In this study we have evaluated the integral dose (ID) to organs at risk (OARs) and the whole body delivered either with three dimensional conformal radiotherapy (3D-CRT) or Helical Tomotherapy for pediatric patients and compared according to different whole body volumes. Materials/Methods: We selected 5 patients with medulloblastoma undergoing craniospinal irradiation. The patients had different body volumes: 8836 cc, 10.717cc, 26.678 cc, 41.732 cc and 42.903 cc. Plans of 3DCRT and Helical Tomotherapy were performed for each patient. The integral doses to OARs and whole body were compared. Statistical analyses were performed to determine differences. Results: We have divided the OARs in two different groups: the first one include the organs placed sideways to target (lungs, kidneys, eyes) and the second one include the organs placed in front of the target (heart, liver, thyroid, esophagus, vertebra, oral cavity). ID Tomo/3D ratio was more in lung (1.83, p \ 0.05), kidneys (2.36, p \ 0.05) and eyes (1.2). ID Tomo/3D ratio was less in heart (0.42, p\0.05), liver (0.97), thyroid (0.36, p\0.001), esophagus (0.49, p\0.001) and axis vertebrae (0.9). We noticed that the variations of ID depend only on the different anatomical location of the organs relatively to the target. The ID of the body increased with large volume both in Helical Tomotherapy and in 3D-CRT plans but in Tomotherapy plan ID increased significantly more with large volumes than with small ones. With 8836 cc, 10717 cc, 26678 cc, 41732 cc, 42903 cc the increased ID values in Tomotherapy plan were 0%, 12.5%, 10.93%, 20.2% and 15.21% respectively. We calculated that 1.33 was the maximum ratio observed between Tomotherapy and 3D-CRT in relationship with the body volume. With whole body volumes \20.000 cc, .20.000, # 30.000 cc and .30.000 cc the correction factors to calculate the increased values of ID in Tomotherapy were 1.04-1.11, 1.11-1.16, 1.16-1.33. Conclusions: Results show that the Tomotherapy plan offers lower integral doses to OARs opposed to target but causes an increase of ID in the organs placed sideways to the target. There are not differences to use Tomotherapy or 3D-CRT with small body volumes while we found differences with large volumes even if the ratio has never been more than 1.33. These results indicate that the best radiation technique should be evaluated also in relationship with the whole body volumes. Author Disclosure: S. Barra, None; M. Gusinu, None; F. Cavagnetto, None; F. Giannelli, None; P. Torielli, None; F. Vallerga, None; M. Zeverino, None; R. Corvo`, None.
2875
The Role of Early Post Radiation MRI Scans in Children with Diffuse Intrinsic Pontine Glioma (DIPG) 1
A. Kaushal , C. Ko1, D. Hammoud2, E. Steffan-Smith3, D. Citrin1, K. Camphausen1, K. Warren3 1
NIH - NCI Radiation Oncology Branch, Bethesda, MD, 2Radiology and Imaging Sciences, Bethesda, MD, 3NIH - NCI Pediatric Oncology Branch, Bethesda, MD
Purpose/Objective(s): To look at the optimal timing of assessing early post-radiation radiographic response on MRI scans in pediatric patients with DIPG. Materials/Methods: Patients were treated on an ongoing prospective study evaluating the pathophysiologic effects of radiation therapy at the National Cancer Institute (Protocol #06-C-0219). Seven patients with DIPG were evaluated; six were treated EBRT to 55.8 Gy and one patient received 54 Gy with a GTV to PTV expansion of 1.8-2.0 cm. Follow-up MRIs were performed after the completion of radiation treatment per protocol at 2 weeks and 6-8 weeks post treatment.
2871
Multidisciplinary Management with Whole Abdominal IMRT of Desmoplastic Small Round Cell Tumor
A. Mahajan, P. Anderson, M. McAleer, E. P. Sulman, C. Pinnix, S. Y. Woo, C. Herzog, A. Hayes-Jordan M.D. Anderson Cancer Center, Houston, TX Purpose/Objective(s): Desmoplastic small round cell tumor (DSCRT) is an uncommon tumor with a poor prognosis most commonly affecting adolescent males. We report our results with aggressive multi-modality therapy including whole abdominal IMRT (WA-IMRT). Materials/Methods: The medical records of all patients with DSCRT who received WA-IMRT as part of the definitive treatment at our institution were reviewed. Disease status and baseline renal, liver and nutritional status was compared to these outcomes at 1 year after completion of WA-IMRT. Results: A total of 8 patients (all male) were treated between 2006 and 2010 with WA-IMRT for DSCRT. The median age was 14 (range, 6-23y) at the time of radiotherapy. The median follow-up was 17mo (range, 0-25mo) from the end of RT. All 8 patients received multiple courses of chemotherapy followed by attempted surgical resection of all intra-abdominal disease. 7 of the 8 patients received intraoperative hyperthermic cisplatinum. 30 Gy WA-IMRT was delivered at a median of 66 days after surgery. 7 of the 8 patients received concurrent chemotherapy (temozolomide 5/7, bevacizumab 3/7, other 4/7). The CTV was defined as the abdomino-pelvic cavity sparing the liver and kidney parenchyma (median volume 3352cc). The median mean dose to the CTV was 32 Gy, 95% of the CTV received a median of 28 Gy (range, 24-30 Gy). 3 patients received a simultaneous integrated boost to the site(s) of gross residual disease with an additional 6-10 Gy. The median mean doses to the right kidney, left kidney and liver were 16.8 Gy, 18.5 Gy and 23.3 Gy, respectively. The median liver V30 was 20%.The median weight loss during RT was 1.3% of the baseline weight (range, 0.8-4.1%). There was no significant nausea, vomiting, diarrhea noted during RT, though all patients were given odansetron as needed. RBC transfusions were required in 3 patients to maintain Hb.10, otherwise, no significant cytopenias were noted. For the six patients with at least one year followup, 4 patients had stable or increasing weight. Two patients had 15% loss of weight at this time, but both had recurrent disease. No significant creatinine elevation was noted at 6 or 12 months. One patient with recurrent liver disease had elevation of LFTs at one year. At last follow-up, 2 patients have died of disease at 17 and 20 months, 5 patients are alive with disease and 1 patient has no evidence of disease. Conclusions: DSCRT is an aggressive disease that is difficult to manage. Even after multiagent chemotherapy, aggressive surgery with intraperitoneal chemotherapy, WA-IMRT with concurrent chemotherapy was tolerated well with no evidence of significant GI, renal or hepatic injury thus far. Author Disclosure: A. Mahajan, None; P. Anderson, None; M. McAleer, None; E.P. Sulman, None; C. Pinnix, None; S.Y. Woo, None; C. Herzog, None; A. Hayes-Jordan, None.
2872
Outcome of Pediatric Female Genital Tract Rhabdomyosarcoma Based on Analysis of Cases Registered in SEER Database
N. Esiashvili1, C. Kirsh2, M. Goodman3 1 Department of Radiation Oncology, Winship Cancer Institute of Emory University, Atlanta, GA, 2Medical College of Georgia, Augusta, GA, 3School of Public Health, Emory University, Atlanta, GA
Purpose/Objective(s): To analyze outcome of Rhabdomyosarcoma (RMS) of female genital track in children using data available from Surveillance Epidemiology and End Result (SEER) database. The data was evaluated for epidemiological trends, outcome by patient and disease variable and survival of patients based on local treatment delivered upfront. Materials/Methods: The SEER database was searched for female genital RMS cases diagnosed at age 0-19 years between 1973 and 2006. Differences in the distribution of primary site, race, stage, histology, surgery and radiation therapy (RT) across the two age groups (0-9 vs. 10-19 year old) were examined using chi square tests. Kaplan-Meier survival curves were constructed to compare survival by histology, stage and primary sites. Results: A total of 67 cases were identified; the incidence did not change significantly during study period. Age distribution was as follows: 5 cases in \1 year old, 33 in 1- 9, 29 in 10- 19 year olds. 38.8% cases were with localized, 16.2% regional, 28.4% with distant stage and 28.4% unstaged. 85% of cases had embryonal type, remaining 15% included 4 alveolar, 2 mixed, 1 pleomorphic, 1 with ganglionic differentiation and 2 not otherwise specified (NOS). Twenty cases had tumor originated in the vagina, 26 in cervix/ uterus, 6 in vulva/labia, 5 in ovaries, and 1 case in an area NOS. Only 15% of cases received RT and it was not affected by patients’ or disease characteristics. The two age groups were no significantly different by race, cancer stage, histology and surgery and RT. The majority of cases in the younger age group (68.4%) had vaginal RMS, whereas older age group (65.5%) had RMS of the cervix or uterus (p \ 0.001). The survival of embryonal RMS was superior compared to other types (p = 0.035); localized genital RMS demonstrated more favorable outcome compared to more advanced stages (p = 0.025). There was no discernable difference in survival by primary tumor site or use of RT. The most of the RMS deaths occurred within first 4-5 years from diagnosis. Conclusions: Incidence of pediatric female genital RMS remains stable. Significant number of patients is diagnosed with disease spread. Younger patients present with vaginal tumors while older patients have more cervix/uterine presentation. Factors like age, histology, stage and location impact the outcome of these patients. Radiotherapy is underutilized in study population and can be a potential reason for inferior survival found in study population compared to institutional and cooperative group reports. Author Disclosure: N. Esiashvili, None; C. Kirsh, None; M. Goodman, None.
2873
Temporal Lobe Sparing in Craniopharyngioma Radiotherapy with Cyst Growth
A. R. Godley, M. Bedi, S. Firat, X. Li Medical College of Wisconsin, Milwaukee, WI Purpose/Objective(s): The target volume increases drastically during the course of radiotherapy for craniopharyngioma patients, leading to the use of generous margins. We investigate how to improve temporal lobe sparing by using reduced treatment margins, while maintaining acceptable target coverage.
S593
I. J. Radiation Oncology d Biology d Physics
S594
Volume 78, Number 3, Supplement, 2010
Materials/Methods: Daily kVCT data (29 fractions) collected for one craniopharyngioma patient treated with IGRT using a CTon-Rails (CTVision, Siemens) and weekly kVCT data for three further patients treated with TomoTherapy were analyzed retrospectively. The GTV was delineated on the daily and weekly CTs manually to track the cyst growth. Patients were treated with a prescription of 52.2 Gy to 90% of the PTV. A PTV margin of 7 mm was used in the treatment plans to account for the cyst growth during treatment. Additional plans were generated with the same prescription but with a reduced PTV margin of 3 mm to spare the temporal lobes. Delivered doses of the 7 and 3 mm margin plans were reconstructed by applying their treatment beams to the daily or weekly CTs. All the daily/weekly doses delivered by the two plans were then accumulated for each patient by deformable image registration. Daily and accumulated target coverage was assessed based on the D95 and D100 of the GTV. (PTV coverage was equivalent between the 7 and 3 mm plans.) Results: Using a 3 mm margin reduced the V30 (volume receiving 30 Gy) of the temporal lobes by an average of 23%, the V50 of the brain stem by 40% and the V52 of the optic chiasm by 46% compared to the 7 mm plan. The size of the reduction was inversely related to the size of the cyst. The cysts grew at an average rate of 0.25 cc per day (R = 0.956). For the 7 mm plans, the planned and delivered GTV D95 and D100 were both within 1%. Daily variations were also within 1%. For the 3 mm plans the daily GTV D95 can be under dosed by up to 3.5%, and the accumulated dose by 1.3% compared to the plan. The accumulated delivered GTV D100 is lower than the plan by 2.5%. By the first fraction, 8 to 15 days after the planning CT, the cysts had already grown enough to reduce the GTV D95 and D100 of the 3 mm plan by 0.5% and 2.0%, respectively. Conclusions: The 7 mm margin combined with IGRT alignment was sufficient to treat the growing cysts without a critical reduction in the delivered dose or re-planning. To take advantage of the substantially lower doses to critical structures provided by the 3 mm plan, adaptive planning is necessary to maintain GTV coverage. For the cases studied, reducing the time between acquiring the planning CT and delivering the first fraction to 2-3 days, and re-planning at fraction 15 would be sufficient to achieve the equivalent GTV coverage of the 7 mm plan. We expect to present additional cases with full daily CT sets. Author Disclosure: A.R. Godley, None; M. Bedi, None; S. Firat, None; X. Li, None.
2874
Comparison of Treatment Plans between 3D-CRT and Helical Tomotherapy Based on Integral Dose Delivered to Pediatric Patients Receiving Craniospinal Irradiation
S. Barra1, M. Gusinu1, F. Cavagnetto1, F. Giannelli1, P. Torielli2, F. Vallerga2, M. Zeverino1, R. Corvo`2 1
Ist - Genoa, Genoa, Italy, 2University Genoa, Genoa, Italy
Purpose/Objective(s): The use of Helical Tomotherapy for craniospinal irradiation in pediatric patient remains nowadays issue of discussion. In this study we have evaluated the integral dose (ID) to organs at risk (OARs) and the whole body delivered either with three dimensional conformal radiotherapy (3D-CRT) or Helical Tomotherapy for pediatric patients and compared according to different whole body volumes. Materials/Methods: We selected 5 patients with medulloblastoma undergoing craniospinal irradiation. The patients had different body volumes: 8836 cc, 10.717cc, 26.678 cc, 41.732 cc and 42.903 cc. Plans of 3DCRT and Helical Tomotherapy were performed for each patient. The integral doses to OARs and whole body were compared. Statistical analyses were performed to determine differences. Results: We have divided the OARs in two different groups: the first one include the organs placed sideways to target (lungs, kidneys, eyes) and the second one include the organs placed in front of the target (heart, liver, thyroid, esophagus, vertebra, oral cavity). ID Tomo/3D ratio was more in lung (1.83, p \ 0.05), kidneys (2.36, p \ 0.05) and eyes (1.2). ID Tomo/3D ratio was less in heart (0.42, p\0.05), liver (0.97), thyroid (0.36, p\0.001), esophagus (0.49, p\0.001) and axis vertebrae (0.9). We noticed that the variations of ID depend only on the different anatomical location of the organs relatively to the target. The ID of the body increased with large volume both in Helical Tomotherapy and in 3D-CRT plans but in Tomotherapy plan ID increased significantly more with large volumes than with small ones. With 8836 cc, 10717 cc, 26678 cc, 41732 cc, 42903 cc the increased ID values in Tomotherapy plan were 0%, 12.5%, 10.93%, 20.2% and 15.21% respectively. We calculated that 1.33 was the maximum ratio observed between Tomotherapy and 3D-CRT in relationship with the body volume. With whole body volumes \20.000 cc, .20.000, # 30.000 cc and .30.000 cc the correction factors to calculate the increased values of ID in Tomotherapy were 1.04-1.11, 1.11-1.16, 1.16-1.33. Conclusions: Results show that the Tomotherapy plan offers lower integral doses to OARs opposed to target but causes an increase of ID in the organs placed sideways to the target. There are not differences to use Tomotherapy or 3D-CRT with small body volumes while we found differences with large volumes even if the ratio has never been more than 1.33. These results indicate that the best radiation technique should be evaluated also in relationship with the whole body volumes. Author Disclosure: S. Barra, None; M. Gusinu, None; F. Cavagnetto, None; F. Giannelli, None; P. Torielli, None; F. Vallerga, None; M. Zeverino, None; R. Corvo`, None.
2875
The Role of Early Post Radiation MRI Scans in Children with Diffuse Intrinsic Pontine Glioma (DIPG) 1
A. Kaushal , C. Ko1, D. Hammoud2, E. Steffan-Smith3, D. Citrin1, K. Camphausen1, K. Warren3 1
NIH - NCI Radiation Oncology Branch, Bethesda, MD, 2Radiology and Imaging Sciences, Bethesda, MD, 3NIH - NCI Pediatric Oncology Branch, Bethesda, MD
Purpose/Objective(s): To look at the optimal timing of assessing early post-radiation radiographic response on MRI scans in pediatric patients with DIPG. Materials/Methods: Patients were treated on an ongoing prospective study evaluating the pathophysiologic effects of radiation therapy at the National Cancer Institute (Protocol #06-C-0219). Seven patients with DIPG were evaluated; six were treated EBRT to 55.8 Gy and one patient received 54 Gy with a GTV to PTV expansion of 1.8-2.0 cm. Follow-up MRIs were performed after the completion of radiation treatment per protocol at 2 weeks and 6-8 weeks post treatment.