Clinical Experience with 4D PET/CT to Account for Intrafraction Motion in Radiation Oncology
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3040 Evaluation of Dose to Critical Structures in CT-based Endobronchial High-dose-rate Brachytherapy Planning Y. Kim 1 , 2 , A. Colonias 1,2 , D. S. Parda 1,2 , M. Miften 1,2 1 Allegheny General Hospital, Pittsburgh, PA, 2 Drexel University College of Medicine, Allegheny Campus, Pittsburgh, PA Purpose/Objective(s): With computed tomography (CT) based endobronchial high dose rate (EB-HDR) brachytherapy planning, organs at risk (OARs) can be delineated and dose volume histograms (DVHs) can be analyzed. This DVH information can provide guidelines to reduce the risk of complications and possibly improve outcomes. Materials/Methods: From May 2006 to January 2008, 20 plans were generated for 9 patients (pts) with thoracic malignancies: 3 fractions (fxs) for 4 pts, 2 fxs for 3 pts and 1 fx for 2 pts. Seven pts had non small cell lung cancer, 1 had small cell lung cancer, and 1 had metastatic adenoid cystic cancer. The clinical stage breakdown was: 1 pt with stage IIB, 2 pts with stage IIIA, 3 pts with stage IIIB and 3 pts with stage IV. Six pts had prior external beam radiation therapy (EBRT) to the chest. One pt received EBRT con- currently with the HDR. Another received EBRT after HDR and the last pt did not receive any EBRT. The prescribed dose per fraction was 4, 5 or 7 Gy to a depth of 1 cm with active source length ranging from 5.5 cm to 11 cm depending on the location and stage of cancer. Retrospectively, OARs such as ipsilateral and contralateral lung, esophagus, heart and spinal cord were con- toured and their DVHs were analyzed. The mean dose (D m ) was calculated for all OARs. Furthermore, the dose received by the OAR volume of 1cc (D 1cc ) value relative to the prescription dose was calculated. The D 1cc was used a metric instead of maximum dose because it is clinically more relevant. Results: The ipsilateral lung received a D m of 0.4 Gy (range, of 0.1 - 0.9 Gy) with a D 1cc value of 79% (15% - 187%) because it included the target volume. The contralateral lung D m was 0.1 Gy (0.03 - 0.2 Gy) with a D 1cc value of 8% (2% - 15%). The esoph- agus D m was 0.8 Gy (0.1 - 1.9 Gy) with a D 1cc value of 52% (9% - 119%) due to its proximity to the bronchus. The heart D m was 0.25 Gy (0.06 - 0.5 Gy) while the D 1cc value was 42% (11% - 85%). The spinal cord D m was 0.25 Gy (0.1 - 0.4 Gy) and the D 1cc value was 8% (4% - 13%). The average minimum distance from the spinal cord to the active dwell position was 3.3 cm (2.5 cm - 4.6 cm). Conclusions: The spinal cord and contralateral lung dose was quite small since they were located away from the endobronchial catheter. Despite their low mean dose, the D 1cc value for ipsilateral lung, esophagus and heart received more than 50% of the pre- scribed dose in half of cases due to the close proximity of the catheter. This OAR dosimetric data may be a useful guideline for EB- HDR clinical procedures. Author Disclosure: Y. Kim, None; A. Colonias, None; D.S. Parda, None; M. Miften, None. 3041 Clinical Experience with 4D PET/CT to Account for Intrafraction Motion in Radiation Oncology A. P. Shah, A. P. Santhanam, T. R. Willoughby, P. A. Kupelian, S. L. Meeks M.D. Anderson Cancer Center Orlando, Orlando, FL Purpose/Objective(s): To report on the feasibility of respiratory-gated lung and liver radiotherapy with dependence on 4D-PET and 4D-CT for treatment planning rather than simulation with conventional CT. Materials/Methods: Respiratory-correlated data from a PET/CT system (Siemens Biograph 64) was acquired. Gated acquisition was performed with the Anzai system for respiratory gating. Correlation was measured between 4D-CT and 4D-PET, in phantom, based on respiratory phase by calculating the deviation from the mean tumor position for each phase relative to a fixed position (similar to bony anatomy). The accuracy of the external surrogate was also tested, in phantom against the Calypso Medical local- ization system. Treatment planning and gated delivery were performed using two treatment planning systems in conjunction with a Varian linear accelerator. An end-to-end test for gated radiotherapy was performed and has shown reliable delivery of the in- tended plan developed from 4D-PET/CT imaging. Ten patients (both lung and liver cancer) have recently received respiratory- gated treatment using this methodology. Results: When comparing between phases, less than 5% uncertainty in the phantom study provided good correlation between the 4D-CT and 4D-PET data. Insignificant differences were measured between the surrogate systems used for gated acquisition. Im- provements of dose distributions on the moving targets improved with gated delivery. Localization uncertainty of the moving target was less than 3 mm. Conclusions: We conclude that 4D PET/CT studies yield accurate respiratory-correlated information (spatial and temporal) of the tumor region. Also proven is the integration of a Siemens PET/CT system with BrainLAB and Varian systems for gated radiother- apy. Author Disclosure: A.P. Shah, Siemens Medical Systems, C. Other Research Support; A.P. Santhanam, None; T.R. Willoughby, None; P.A. Kupelian, Siemens Medical Systems, C. Other Research Support; S.L. Meeks, None. 3042 Does Changing Image Guidance Processes Impact Patient Setup Practice? W. Li, D. Moseley, D. Jaffray Princess Margaret Hospital, Toronto, ON, Canada Purpose/Objective(s): To investigate whether the implementation of various daily image-guidance processes have altered initial (pre-imaging) patient setup practice for thoracic radiotherapy patients. Materials/Methods: Daily cone-beam CT (CBCT) images of 73 thoracic patients undergoing radical radiotherapy were retrospec- tively reviewed under ethics approval. For analysis, these patients were divided into 3 consecutive cohorts determined by the image-guidance process used during their radiotherapy. After initial alignment of skin marks and lasers; Process A (24 patients) Proceedings of the 50th Annual ASTRO Meeting S637
Transcript of Clinical Experience with 4D PET/CT to Account for Intrafraction Motion in Radiation Oncology
Proceedings of the 50th Annual ASTRO Meeting S637
3040 Evaluation of Dose to Critical Structures in CT-based Endobronchial High-dose-rate Brachytherapy
PlanningY. Kim1,2, A. Colonias1,2, D. S. Parda1,2, M. Miften1,2
1Allegheny General Hospital, Pittsburgh, PA, 2Drexel University College of Medicine, Allegheny Campus, Pittsburgh, PA
Purpose/Objective(s): With computed tomography (CT) based endobronchial high dose rate (EB-HDR) brachytherapy planning,organs at risk (OARs) can be delineated and dose volume histograms (DVHs) can be analyzed. This DVH information can provideguidelines to reduce the risk of complications and possibly improve outcomes.
Materials/Methods: From May 2006 to January 2008, 20 plans were generated for 9 patients (pts) with thoracic malignancies: 3fractions (fxs) for 4 pts, 2 fxs for 3 pts and 1 fx for 2 pts. Seven pts had non small cell lung cancer, 1 had small cell lung cancer, and 1had metastatic adenoid cystic cancer. The clinical stage breakdown was: 1 pt with stage IIB, 2 pts with stage IIIA, 3 pts with stageIIIB and 3 pts with stage IV. Six pts had prior external beam radiation therapy (EBRT) to the chest. One pt received EBRT con-currently with the HDR. Another received EBRT after HDR and the last pt did not receive any EBRT. The prescribed dose perfraction was 4, 5 or 7 Gy to a depth of 1 cm with active source length ranging from 5.5 cm to 11 cm depending on the locationand stage of cancer. Retrospectively, OARs such as ipsilateral and contralateral lung, esophagus, heart and spinal cord were con-toured and their DVHs were analyzed. The mean dose (Dm) was calculated for all OARs. Furthermore, the dose received by theOAR volume of 1cc (D1cc) value relative to the prescription dose was calculated. The D1cc was used a metric instead of maximumdose because it is clinically more relevant.
Results: The ipsilateral lung received a Dm of 0.4 Gy (range, of 0.1 - 0.9 Gy) with a D1cc value of 79% (15% - 187%) because itincluded the target volume. The contralateral lung Dm was 0.1 Gy (0.03 - 0.2 Gy) with a D1cc value of 8% (2% - 15%). The esoph-agus Dm was 0.8 Gy (0.1 - 1.9 Gy) with a D1cc value of 52% (9% - 119%) due to its proximity to the bronchus. The heart Dm was0.25 Gy (0.06 - 0.5 Gy) while the D1cc value was 42% (11% - 85%). The spinal cord Dm was 0.25 Gy (0.1 - 0.4 Gy) and the D1cc
value was 8% (4% - 13%). The average minimum distance from the spinal cord to the active dwell position was 3.3 cm (2.5 cm - 4.6cm).
Conclusions: The spinal cord and contralateral lung dose was quite small since they were located away from the endobronchialcatheter. Despite their low mean dose, the D1cc value for ipsilateral lung, esophagus and heart received more than 50% of the pre-scribed dose in half of cases due to the close proximity of the catheter. This OAR dosimetric data may be a useful guideline for EB-HDR clinical procedures.
Author Disclosure: Y. Kim, None; A. Colonias, None; D.S. Parda, None; M. Miften, None.
3041 Clinical Experience with 4D PET/CT to Account for Intrafraction Motion in Radiation Oncology
A. P. Shah, A. P. Santhanam, T. R. Willoughby, P. A. Kupelian, S. L. Meeks
M.D. Anderson Cancer Center Orlando, Orlando, FL
Purpose/Objective(s): To report on the feasibility of respiratory-gated lung and liver radiotherapy with dependence on 4D-PETand 4D-CT for treatment planning rather than simulation with conventional CT.
Materials/Methods: Respiratory-correlated data from a PET/CT system (Siemens Biograph 64) was acquired. Gated acquisitionwas performed with the Anzai system for respiratory gating. Correlation was measured between 4D-CT and 4D-PET, in phantom,based on respiratory phase by calculating the deviation from the mean tumor position for each phase relative to a fixed position(similar to bony anatomy). The accuracy of the external surrogate was also tested, in phantom against the Calypso Medical local-ization system. Treatment planning and gated delivery were performed using two treatment planning systems in conjunction witha Varian linear accelerator. An end-to-end test for gated radiotherapy was performed and has shown reliable delivery of the in-tended plan developed from 4D-PET/CT imaging. Ten patients (both lung and liver cancer) have recently received respiratory-gated treatment using this methodology.
Results: When comparing between phases, less than 5% uncertainty in the phantom study provided good correlation between the4D-CT and 4D-PET data. Insignificant differences were measured between the surrogate systems used for gated acquisition. Im-provements of dose distributions on the moving targets improved with gated delivery. Localization uncertainty of the moving targetwas less than 3 mm.
Conclusions: We conclude that 4D PET/CT studies yield accurate respiratory-correlated information (spatial and temporal) of thetumor region. Also proven is the integration of a Siemens PET/CT system with BrainLAB and Varian systems for gated radiother-apy.
Author Disclosure: A.P. Shah, Siemens Medical Systems, C. Other Research Support; A.P. Santhanam, None; T.R. Willoughby,None; P.A. Kupelian, Siemens Medical Systems, C. Other Research Support; S.L. Meeks, None.
3042 Does Changing Image Guidance Processes Impact Patient Setup Practice?
W. Li, D. Moseley, D. Jaffray
Princess Margaret Hospital, Toronto, ON, Canada
Purpose/Objective(s): To investigate whether the implementation of various daily image-guidance processes have altered initial(pre-imaging) patient setup practice for thoracic radiotherapy patients.
Materials/Methods: Daily cone-beam CT (CBCT) images of 73 thoracic patients undergoing radical radiotherapy were retrospec-tively reviewed under ethics approval. For analysis, these patients were divided into 3 consecutive cohorts determined by theimage-guidance process used during their radiotherapy. After initial alignment of skin marks and lasers; Process A (24 patients)
