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Feasibility of a Navigator Channel Bilinear Adaptation Technique to Generate 3D Heart Volumes from 2D Hodgkin Lymphoma Planning Data
Proceedings of the 51st Annual ASTRO Meeting
2971
Feasibility of a Navigator Channel Bilinear Adaptation Technique to Generate 3D Heart Volumes from 2D Hodgkin Lymphoma Planning Data
A. Ng1, T. N. Nguyen2, J. Moseley1, D. Hodgson1,3, M. Sharpe1,3, K. Brock1,3 Radiation Medicine Program, Princess Margaret Hospital, Toronto, ON, Canada, 2Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada, 3Department of Radiation Oncology, University of Toronto, Toronto, ON, Canada 1
Purpose/Objective(s): A major barrier to the application of biophysical models to estimate RT-related late toxicity is the absence of 3D dosimetry on historically treated patients, for whom late toxicity outcomes are available. The purpose of this work is to investigate a Navigator Channel (NC) adaptation technique to generate 3D heart volumes from 2D radiotherapy plans for outcomes assessment. Materials/Methods: A NC technique utilizing extracted patient-specific organ information from 2D images to adapt a 3D population model into patient-specific volumetric heart data has been developed. Forty-five HL patients with 3D images were acquired. Six patients were used to construct a population heart model, which was then registered, using a biomechanical model-based deformable registration algorithm, MORFEUS, into 24 additional HL ’reference’ patients to develop a heart motion model. This model was refined to describe the 3D heart volume and position of 15 HL ’test’ patients, using only information in the 2D digitally reconstructed radiographs constructed from 3D images. The refinement was performed by: 1) matching a reference patient to each test patient (using lung width and length measurements), 2) placing six NCs (1 superior/inferior, 2 right/left) or small regions of interest, on the heart boundary of the reference patient and automatically placing the corresponding NC on the test image in the same geometric position, 3) converting the image intensity in the NC into a 1D shift to match that location, 4) bilinear adaptation of the heart motion model using the six 1D shifts to describe the 3D volume and position of the test patient’s heart. The refined heart model was then compared to the actual 3D heart contour of the 15 test patients by computing the volume overlap (VOL). To compare the results with the volumetric changes observed during patients breathing cycle, VOL was also calculated for 15 sets of inhale and exhale heart volumes. Results: The average percentage overlapping (POL) and non-overlapping (PNOL) volumes between the NC-refined heart model and test hearts were 90.2% and 10.2%, respectively, a statistically significant improvement to the shape of the population heart model (T-test: p \ 0.05). Comparable results were observed between inhale and exhale heart volumes (POL=89.1% and PNOL=9.8%). Conclusions: This technique will be used to regenerate 3D heart volumes for HL patients treated with 2D planning. The volume uncertainty is comparable to that during respiratory motion. A better understanding of the dose-volume association could provide valuable insight on the dose-risk relationship between RT and various late effects. Author Disclosure: A. Ng, None; T.N. Nguyen, None; J. Moseley, None; D. Hodgson, None; M. Sharpe, None; K. Brock, None.
2972
Rapid Reviews Reduce the Rate of Protocol Deviations
J. Leif, J. Roll, C. Davis, G. Ibbott M.D. Anderson Cancer Center, Houston, TX Purpose/Objective(s): One of the missions of the Radiological Physics Center (RPC) is to assist the Cooperative Groups in limiting the deviation rates of national clinical trials. This is accomplished through credentialing, rapid reviews, chart reviews, and feedback to the radiation oncologists enrolling the patients on a study. The RPC decided to look at how the rapid review process has helped limit the deviation rates on two studies. Materials/Methods: The rapid review process is completed prior to the start of a patient’s treatment. The RPC performed rapid reviews of 99 patient treatment plans for two different studies. The institutions submitted their patient data electronically to the Image-Guided Therapy Center (ITC). Via the ITC’s remote review tools, the RPC compared the institutions’ DVHs, PTVs, and normal tissue volumes with the protocol specifications. The RPC then sent the review to the study PI who reviewed the clinical volumes. Once the review was completed, the institution was provided feedback on the patient case and was either asked to make the appropriate changes and resubmit or was given approval to treat the patient. Results: Of the 99 patients reviewed, 66% had to be resubmitted due to a clinical discrepancy. Eleven percent were required to resubmit because the dose deviation exceeded the tolerances specified by the protocol. Of the 11%, more than half were judged acceptable upon resubmission. Conclusions: It appears that study groups can reduce the frequency of deviations on a protocol by requiring institutions to participate in the rapid review process. The rapid review allows a patient treatment plan to be discussed and modified prior to the start of treatment, thereby avoiding most protocol deviations. QA has been shown to be an important component of clinical trials. The rapid review procedure can be a valuable component of clinical trial QA. This work was supported by PHS grants CA 10953 and CA081647 awarded by NCI, DHHS. Author Disclosure: J. Leif, None; J. Roll, None; C. Davis, None; G. Ibbott, None.
2973
Dose Prescription and Treatment Planning Based on [18F]FMISO-PET Hypoxia
I. Toma-Dasu1, J. Uhrdin2, A. Dasu3, S. Roels4, P. Dirix4, T. Depuydt4, S. Nuyts4, K. Haustermans4, A. Brahme5 Karolinska Institutet and Stockholm University, Stockholm, Sweden, 2RaySearch Laboratories AB, Stockholm, Sweden, 3Umea˚ University, Umea˚, Sweden, 4Leuven University Hospitals, Leuven, Belgium, 5Karolinska Institutet, Stockholm, Sweden 1
Purpose/Objective(s): This study presents a method to incorporate [18F]FMISO-PET hypoxia information into the treatment planning. The aim of this study was the determination of the dose distribution that should be delivered to the clinical target in order to achieve a preset level of tumor control probability (TCP) at the end of the treatment accounting for the radiation resistance assessed from the imaged tumor hypoxia. The clinical outcome of the prescribed dose distribution has been compared in terms of tumor control probability for different treatment planning approaches.
S617
2971
Feasibility of a Navigator Channel Bilinear Adaptation Technique to Generate 3D Heart Volumes from 2D Hodgkin Lymphoma Planning Data
A. Ng1, T. N. Nguyen2, J. Moseley1, D. Hodgson1,3, M. Sharpe1,3, K. Brock1,3 Radiation Medicine Program, Princess Margaret Hospital, Toronto, ON, Canada, 2Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada, 3Department of Radiation Oncology, University of Toronto, Toronto, ON, Canada 1
Purpose/Objective(s): A major barrier to the application of biophysical models to estimate RT-related late toxicity is the absence of 3D dosimetry on historically treated patients, for whom late toxicity outcomes are available. The purpose of this work is to investigate a Navigator Channel (NC) adaptation technique to generate 3D heart volumes from 2D radiotherapy plans for outcomes assessment. Materials/Methods: A NC technique utilizing extracted patient-specific organ information from 2D images to adapt a 3D population model into patient-specific volumetric heart data has been developed. Forty-five HL patients with 3D images were acquired. Six patients were used to construct a population heart model, which was then registered, using a biomechanical model-based deformable registration algorithm, MORFEUS, into 24 additional HL ’reference’ patients to develop a heart motion model. This model was refined to describe the 3D heart volume and position of 15 HL ’test’ patients, using only information in the 2D digitally reconstructed radiographs constructed from 3D images. The refinement was performed by: 1) matching a reference patient to each test patient (using lung width and length measurements), 2) placing six NCs (1 superior/inferior, 2 right/left) or small regions of interest, on the heart boundary of the reference patient and automatically placing the corresponding NC on the test image in the same geometric position, 3) converting the image intensity in the NC into a 1D shift to match that location, 4) bilinear adaptation of the heart motion model using the six 1D shifts to describe the 3D volume and position of the test patient’s heart. The refined heart model was then compared to the actual 3D heart contour of the 15 test patients by computing the volume overlap (VOL). To compare the results with the volumetric changes observed during patients breathing cycle, VOL was also calculated for 15 sets of inhale and exhale heart volumes. Results: The average percentage overlapping (POL) and non-overlapping (PNOL) volumes between the NC-refined heart model and test hearts were 90.2% and 10.2%, respectively, a statistically significant improvement to the shape of the population heart model (T-test: p \ 0.05). Comparable results were observed between inhale and exhale heart volumes (POL=89.1% and PNOL=9.8%). Conclusions: This technique will be used to regenerate 3D heart volumes for HL patients treated with 2D planning. The volume uncertainty is comparable to that during respiratory motion. A better understanding of the dose-volume association could provide valuable insight on the dose-risk relationship between RT and various late effects. Author Disclosure: A. Ng, None; T.N. Nguyen, None; J. Moseley, None; D. Hodgson, None; M. Sharpe, None; K. Brock, None.
2972
Rapid Reviews Reduce the Rate of Protocol Deviations
J. Leif, J. Roll, C. Davis, G. Ibbott M.D. Anderson Cancer Center, Houston, TX Purpose/Objective(s): One of the missions of the Radiological Physics Center (RPC) is to assist the Cooperative Groups in limiting the deviation rates of national clinical trials. This is accomplished through credentialing, rapid reviews, chart reviews, and feedback to the radiation oncologists enrolling the patients on a study. The RPC decided to look at how the rapid review process has helped limit the deviation rates on two studies. Materials/Methods: The rapid review process is completed prior to the start of a patient’s treatment. The RPC performed rapid reviews of 99 patient treatment plans for two different studies. The institutions submitted their patient data electronically to the Image-Guided Therapy Center (ITC). Via the ITC’s remote review tools, the RPC compared the institutions’ DVHs, PTVs, and normal tissue volumes with the protocol specifications. The RPC then sent the review to the study PI who reviewed the clinical volumes. Once the review was completed, the institution was provided feedback on the patient case and was either asked to make the appropriate changes and resubmit or was given approval to treat the patient. Results: Of the 99 patients reviewed, 66% had to be resubmitted due to a clinical discrepancy. Eleven percent were required to resubmit because the dose deviation exceeded the tolerances specified by the protocol. Of the 11%, more than half were judged acceptable upon resubmission. Conclusions: It appears that study groups can reduce the frequency of deviations on a protocol by requiring institutions to participate in the rapid review process. The rapid review allows a patient treatment plan to be discussed and modified prior to the start of treatment, thereby avoiding most protocol deviations. QA has been shown to be an important component of clinical trials. The rapid review procedure can be a valuable component of clinical trial QA. This work was supported by PHS grants CA 10953 and CA081647 awarded by NCI, DHHS. Author Disclosure: J. Leif, None; J. Roll, None; C. Davis, None; G. Ibbott, None.
2973
Dose Prescription and Treatment Planning Based on [18F]FMISO-PET Hypoxia
I. Toma-Dasu1, J. Uhrdin2, A. Dasu3, S. Roels4, P. Dirix4, T. Depuydt4, S. Nuyts4, K. Haustermans4, A. Brahme5 Karolinska Institutet and Stockholm University, Stockholm, Sweden, 2RaySearch Laboratories AB, Stockholm, Sweden, 3Umea˚ University, Umea˚, Sweden, 4Leuven University Hospitals, Leuven, Belgium, 5Karolinska Institutet, Stockholm, Sweden 1
Purpose/Objective(s): This study presents a method to incorporate [18F]FMISO-PET hypoxia information into the treatment planning. The aim of this study was the determination of the dose distribution that should be delivered to the clinical target in order to achieve a preset level of tumor control probability (TCP) at the end of the treatment accounting for the radiation resistance assessed from the imaged tumor hypoxia. The clinical outcome of the prescribed dose distribution has been compared in terms of tumor control probability for different treatment planning approaches.
S617