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High Dose-Rate Tandem and Ovoid Brachytherapy in Cervical Cancer: Dosimetric Predictors of Disease Control and Toxicity
Abstracts / Brachytherapy 16 (2017) S14eS118 D90 at target was 85.07 3.73 Gy (EQD210). Mean D2cc in EQD23 for rectum, sigmoid and bladder were respectively: 63.386.68 Gy, 63.347.50 Gy and 74.279.14 Gy. The incidences of local failure, locoregional failure and distant failure were respectively: 5.36% (3), 8.93% (5) and 23.21% (13). The 2 years CSS and OS were 80.9% and 77.5%. No grade 4 or higher late toxicity was diagnosed. Late grade 3 toxicity developed in 11 patients (4 GI, 4 GU, 2 vaginal fistulas and 1 pulmonary embolism). Conclusions: IGBT boost using IPSA, combined with EBRT and concomitant chemotherapy, in locally advanced cervical cancer, is as effective as other optimization methods to provide excellent local control and minimal severe toxicities.
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brachytherapy treatment in defining the target for cervical cancer. We continue to work on the clinical application of the MORFEUS DIR algorithm for patients with cervical cancer. High accuracy and reliability can be achieved with consistent rectum and bladder volumes, as well as consistent relative ROI locations between pre-MR and post-CT images.
PO33 Feasibility of a Biomechanical Model Based Deformable Image Registration for MRI Guided CTBased Brachytherapy for Locally Advanced Cervical Cancer Yi Rong, PhD, Brandon A. Dyer, MD, Cari Wright, CMD, Stanley H. Benedict, PhD, Jyoti S. Mayadev, MD. Radiation Oncology, University of California Davis Comprehensive Cancer Center, Sacramento, CA, USA. Purpose: Pre-implantation magnetic resonance image is readily available to guide high-dose-rate (HDR) brachytherapy treatment for cervical cancer patients, but is historical fraught with difficulty in utilization due to variations in target volume introduced by the brachytherapy applicators. To increase the value of target delineation and efficiency in image guided brachytherapy for cervical cancer, deformable image registration of the pre-implantation MRI and planning CT scans for brachytherapy continues to be appealing. We propose that the pre-MRI can be used to guide CTbased brachytherapy following a workflow using a commercially available biomechanical model based (MORFEUS) deformable image registration (DIR) for cervical cancer treatments. Materials and Methods: In this retrospective pilot study, five cervical cancer patients previously treated with HDR brachytherapy were included. Each patient received an MRI without the brachytherapy applicator (pre-MRI) and a CT image prior to treatment with the applicator inserted (post-CT). A set of structures, including rectum, bladder, uterus, vagina, and femoral heads were contoured on both MRI and CT images for each patient. The high risk clinical target volume (HRCTV-MRI) and gross target volume (GTV-MRI) were delineated by the attending on the pre-MRI image. The post-CT image had a prospectively drawn HRCTV-CT during the time of brachytherapy treatment. The contours from the MRI and CT were then converted to model-based segmentations (MBS) for deformation use. The pre-MRI was registered with and deformed to the post-CT based on the MBS structures in the Raystation treatment planning system. A deformed GTV was then projected on the post-CT image (GTV-CT), and correlated with the HRCTV-CT. The deformation accuracy of this approach was also evaluated using volume and center of mass (COM) differences. Results: Morfeus algorithm required controlling regions of interests (ROIs) in the MBS form for image deformation between MR and CT images. Bladder, rectum, cervix, and uterus ROIs were used for each DIR. We found no improvement in terms of DIR accuracy with including the femoral heads. When compared the physician-drawn structures to the DIR-mapped structures, the volume differences on CT ranged from 1.22 to 2.85 cc for uterus, and 0.01 to 25.69 cc for cervix. The differences in COM between physician-drawn HR-CTV and DIR-mapped GTV on CT images ranged from 0.42 cm to 1.95 cm. The uterus was found to be the most relevant structure with the COM difference (p50.11), since it is enclosing the subject of interest (GTV). Results demonstrated that the accuracy and integrity of the DIR were superior when the volumes of rectum and bladder, as well as the locations of ROIs relative to each other remained consistent between pre-MRI and post-CT scans. Conclusions: In the era of value based medicine and image guidance in gynecologic brachytherapy, we strive to increase efficiency and target accuracy with deformable image registration. The results from our pilot study indicate that it is feasible to utilize the pre-MRI through the biomechanical model based image deformation for guiding the CT-based
PO34 High Dose-Rate Tandem and Ovoid Brachytherapy in Cervical Cancer: Dosimetric Predictors of Disease Control and Toxicity Daniel M. Trifiletti, MD1, M. Sean Peach, MD, PhD1, Bethany J. Horton, PhD2, Neil R. Shah, MPH1, Bruce Libby, PhD1, Timothy N. Showalter, MD, MPH1. 1Radiation Oncology, University of Virginia Health System, Charlottesville, VA, USA; 2Department of Public Health Sciences, University of Virginia Health System, Charlottesville, VA, USA. Purpose: To investigate the rate of and factors influencing gastrointestinal (GI) and genitourinary (GU) toxicity following high dose-rate (HDR) tandem and ovoid brachytherapy in the treatment of locally advanced cervical cancer. Materials and Methods: A retrospective chart review of patients with locally advanced cervical cancer treated at our institution was performed. Inclusion criteria included patients treated with HDR and with CT-based planning. Statistical analyses aimed to develop clinical and dosimetric predictors for GI and GU toxicity following HDR brachytherapy according to CTCAE v4.0 grading criteria. Cumulative doses were calculated using the linear-quadratic model and compared to published American Brachytherapy Society (ABS) guidelines. Results: Fifty-six women met inclusion criteria. Eight patients (14.3%) developed a grade 3þ GI toxicity, 4 patients (7.2%) developed a grade 3þ GU toxicity, 3 patients (5.4%) developed a grade 3þ hematologic toxicity, and 4 patients (7.2%) developed a grade 3þ non-hematologic/GI/ GU toxicity. Among patients with grade 3þ GU toxicity, 1 (25%) had dose of 80 Gy or less, 1 (25%) had dose between 80 and 90 Gy, and 2 (50%) had dose greater than 90 Gy. A cumulative bladder D2cc threshold of 90 Gy permitted a 5.6 % rate of grade 3þ GU toxicity, compared to a 3.6 % rate of grade 3þ GU toxicity if a threshold of 80 Gy is adhered to (Figure). Among patients with grade 3þ GI toxicity: 2 (25%) had rectal D2cc of 65 Gy or less, 3 (37.5%) had dose between 65 and 75 Gy, and 3 (37.5%) had dose greater than 75 Gy; 1 (12.5%) had dose of 65 Gy or less, 5 (62.5%) had dose between 65 and 75 Gy, and 2 (25%) had dose greater than 75 Gy. A cumulative rectal D2cc threshold of 75 Gy resulted in a 16.1 % rate of grade 3þ GI toxicity, versus a 18.2 % rate of grade 3þ GI toxicity if a threshold of 65 Gy is adhered to. A cumulative sigmoid D2cc threshold of 75 Gy permitted a 14.6 % rate of grade 3þ GI toxicity, compared to a 4.5 % rate of grade 3þ GI toxicity if a threshold of 65 Gy is adhered to. Conclusions: In clinical practice, a relatively high rate of GI and GU toxicity is possible even with adherence to current ABS guidelines for dosimetric objectives. Every attempt should be made to minimize dose to
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Abstracts / Brachytherapy 16 (2017) S14eS118
normal organs, including targeting cumulative D2cc organ doses well below standard objectives. Grade 3þ GI toxicities were observed even with cumulative rectal D2cc less than 65 Gy. We suggest considering more stringent cumulative D2cc dosimetric goals than in current ABS guidelines: less than 80 Gy for the bladder and less than 65 Gy (or as low as achievable without compromising local control) for the rectum and sigmoid.
MISCELLANEOUS POSTERS PO36 Investigation of a New Device to Improve Dosimetric Outcomes in Intravascular Brachytherapy Joseph M. DeCunha, B.Sc Candidate, Shirin Enger, PhD. Medical Physics Unit, McGill University, Montreal, QC, Canada. Purpose: Coronary artery disease is amongst the main causes of death in developed countries. Percutaneous Transluminal Coronary Angioplasty (PTCA or angioplasty) is a procedure used to open stenoted (narrowed) arteries. Restenosis (renarrowing) of the treated vessel is a major complication of PTCA. A metal mesh tube (stent) is expanded inside the vessel to prevent restenosis. Tissue stress incurred during angioplasty and stenting can provoke rapid proliferation of neointimal cells leading to in stent restenosis (ISR). Intravascular brachytherapy (IVBT), a form of internal radiotherapy, is used to treat ISR. Renewed interest in IVBT is being expressed as a treatment for patients with ISR in Drug Eluting Stents. Existing catheter based intravascular brachytherapy devices use a guidewire that is mounted on the outside of the delivery catheter. This has been shown to reduce the dose to target tissue behind the guidewire by as much as 35% from Sr-90/Y-90 based devices. If IVBT seeds with a hollow center were developed such that a guidewire could run interior to the seeds we hypothesize that localized dose reductions from guidewires in IVBT should vanish. Treatment times may also be reduced when using
IVBT devices with a guidewire in the center because the radioisotope can be placed closer to the edge of the delivery catheter which should increase the dose delivered per particle to the target arterial walls. The activity of a source can be increased by increasing the total amount of active core material in each seed. Cylindrical shell seeds should be able to carry more active material than seeds currently used in IVBT because area scales with r2. Each of these factors motivates the investigation of IVBT devices with cylindrical shell seeds and interior guidewires. We perform a dosimetric analysis to evaluate the viability of one such device. Materials and Methods: A dosimetric analysis of an experimental Sr-90/ Y-90 based device using cylindrical shell seeds with a guidewire in the center and of an existing Sr-90/Y-90 based device (Novoste Beta Cath) was performed in a Monte Carlo based particle simulation (Geant4). Absorbed dose was calculated in water as a function of distance from the source and theta. Results: Dose delivered around the experimental device in water is homogeneous as a function of theta. Dose delivered around the Novoste Beta Cath 3.5F with guidewire varies greatly with theta and is reduced by as much as 49% at 2 mm (the target distance) in regions behind the guidewire. Dose per particle from both devices are approximately equivalent. The amount of active core material in the experimental device was increased by 25% compared to the Novoste Beta Cath. Conclusions: The experimental device considered delivers a homogeneous dose as a function of theta around the device with the potential for 25% greater activity than the Novoste Beta Cath. New IVBT devices can rectify existing dosimetric issues and decrease treatment times which may help improve patient outcomes.
PO38 Clinical Study of CT-Guided 3D Print Coplanar Template and Bare Hand in Brachytherapy Qiang Cao, MD, Bin Huo, MD, Lei Wang, MD, Xiaodong Huo, MD, Jinhuan Wang, MD, Li Zang, MD, Dingkun Hou, MD, Hao Wang, MD, Lili Wang, MD, Haitao Wang, MD. Department of Oncology, The Second Hospital of Tianjin Medical University, Tianjin, China. Purpose: To observe the therapeutic and applicance effect of CT-guided 3D print coplanar template in brachytherapy. Materials and Methods: 20 patients were recruited in our study.Of all the patients,10 patients received brachytherapy by CT-guided 3D print coplanar template, an the rests,as the cntrol group,by manual methods. During two days before the surgery, the patients received the CT scan and the dicom image datas were collected.And then the preoperative plan was made and real-time plan in operation and dose verification after-operation were recorded and to see whether they satisfied quality evaluation system for particle implantation in Columbia Cancer Center. Descriptive and analytical statistics were performed using SPSS17.0 software.Comparisons for two pairs were performed using the Students-t test.Values of P!0.01 were considered to indicate statistically significant differences. Results: The dose error rate among the experimental group patients (who received brachytherapy by CT-guided 3D print coplanar template) and the control group(who received therapy by manual-assisted) has statistical significance ( P ! 0.01) .Statistics shows that the general operation time of experimental group was shorter than the control group.Compared preoperation and after- surgery,D90 and CI in experimental group and CI in control group had no statistical significance (P 50.155,P50.279,P50.147),while D90 and CI in the control group and EI in the experiment group had statistical significance ( P50.029,P50.002,P50.025). Conclusions: Brachytherapy using 3D print coplanar template could improve the accuracy of needle path and implanted particle position,obtaining better effect and safety than the manual methods. Works mentioned-above can not only ensured the needles distribution but also the uniformity of the intraoperative- and preoperative-plan-dose. The advantages such as reducing the frequency of CT scans,the operation time and the surgery study time can also easily observed. Operation on this kind can also ensure the optimum of source distribution, avoiding the cold area and hot spot of the dose distribution.
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brachytherapy treatment in defining the target for cervical cancer. We continue to work on the clinical application of the MORFEUS DIR algorithm for patients with cervical cancer. High accuracy and reliability can be achieved with consistent rectum and bladder volumes, as well as consistent relative ROI locations between pre-MR and post-CT images.
PO33 Feasibility of a Biomechanical Model Based Deformable Image Registration for MRI Guided CTBased Brachytherapy for Locally Advanced Cervical Cancer Yi Rong, PhD, Brandon A. Dyer, MD, Cari Wright, CMD, Stanley H. Benedict, PhD, Jyoti S. Mayadev, MD. Radiation Oncology, University of California Davis Comprehensive Cancer Center, Sacramento, CA, USA. Purpose: Pre-implantation magnetic resonance image is readily available to guide high-dose-rate (HDR) brachytherapy treatment for cervical cancer patients, but is historical fraught with difficulty in utilization due to variations in target volume introduced by the brachytherapy applicators. To increase the value of target delineation and efficiency in image guided brachytherapy for cervical cancer, deformable image registration of the pre-implantation MRI and planning CT scans for brachytherapy continues to be appealing. We propose that the pre-MRI can be used to guide CTbased brachytherapy following a workflow using a commercially available biomechanical model based (MORFEUS) deformable image registration (DIR) for cervical cancer treatments. Materials and Methods: In this retrospective pilot study, five cervical cancer patients previously treated with HDR brachytherapy were included. Each patient received an MRI without the brachytherapy applicator (pre-MRI) and a CT image prior to treatment with the applicator inserted (post-CT). A set of structures, including rectum, bladder, uterus, vagina, and femoral heads were contoured on both MRI and CT images for each patient. The high risk clinical target volume (HRCTV-MRI) and gross target volume (GTV-MRI) were delineated by the attending on the pre-MRI image. The post-CT image had a prospectively drawn HRCTV-CT during the time of brachytherapy treatment. The contours from the MRI and CT were then converted to model-based segmentations (MBS) for deformation use. The pre-MRI was registered with and deformed to the post-CT based on the MBS structures in the Raystation treatment planning system. A deformed GTV was then projected on the post-CT image (GTV-CT), and correlated with the HRCTV-CT. The deformation accuracy of this approach was also evaluated using volume and center of mass (COM) differences. Results: Morfeus algorithm required controlling regions of interests (ROIs) in the MBS form for image deformation between MR and CT images. Bladder, rectum, cervix, and uterus ROIs were used for each DIR. We found no improvement in terms of DIR accuracy with including the femoral heads. When compared the physician-drawn structures to the DIR-mapped structures, the volume differences on CT ranged from 1.22 to 2.85 cc for uterus, and 0.01 to 25.69 cc for cervix. The differences in COM between physician-drawn HR-CTV and DIR-mapped GTV on CT images ranged from 0.42 cm to 1.95 cm. The uterus was found to be the most relevant structure with the COM difference (p50.11), since it is enclosing the subject of interest (GTV). Results demonstrated that the accuracy and integrity of the DIR were superior when the volumes of rectum and bladder, as well as the locations of ROIs relative to each other remained consistent between pre-MRI and post-CT scans. Conclusions: In the era of value based medicine and image guidance in gynecologic brachytherapy, we strive to increase efficiency and target accuracy with deformable image registration. The results from our pilot study indicate that it is feasible to utilize the pre-MRI through the biomechanical model based image deformation for guiding the CT-based
PO34 High Dose-Rate Tandem and Ovoid Brachytherapy in Cervical Cancer: Dosimetric Predictors of Disease Control and Toxicity Daniel M. Trifiletti, MD1, M. Sean Peach, MD, PhD1, Bethany J. Horton, PhD2, Neil R. Shah, MPH1, Bruce Libby, PhD1, Timothy N. Showalter, MD, MPH1. 1Radiation Oncology, University of Virginia Health System, Charlottesville, VA, USA; 2Department of Public Health Sciences, University of Virginia Health System, Charlottesville, VA, USA. Purpose: To investigate the rate of and factors influencing gastrointestinal (GI) and genitourinary (GU) toxicity following high dose-rate (HDR) tandem and ovoid brachytherapy in the treatment of locally advanced cervical cancer. Materials and Methods: A retrospective chart review of patients with locally advanced cervical cancer treated at our institution was performed. Inclusion criteria included patients treated with HDR and with CT-based planning. Statistical analyses aimed to develop clinical and dosimetric predictors for GI and GU toxicity following HDR brachytherapy according to CTCAE v4.0 grading criteria. Cumulative doses were calculated using the linear-quadratic model and compared to published American Brachytherapy Society (ABS) guidelines. Results: Fifty-six women met inclusion criteria. Eight patients (14.3%) developed a grade 3þ GI toxicity, 4 patients (7.2%) developed a grade 3þ GU toxicity, 3 patients (5.4%) developed a grade 3þ hematologic toxicity, and 4 patients (7.2%) developed a grade 3þ non-hematologic/GI/ GU toxicity. Among patients with grade 3þ GU toxicity, 1 (25%) had dose of 80 Gy or less, 1 (25%) had dose between 80 and 90 Gy, and 2 (50%) had dose greater than 90 Gy. A cumulative bladder D2cc threshold of 90 Gy permitted a 5.6 % rate of grade 3þ GU toxicity, compared to a 3.6 % rate of grade 3þ GU toxicity if a threshold of 80 Gy is adhered to (Figure). Among patients with grade 3þ GI toxicity: 2 (25%) had rectal D2cc of 65 Gy or less, 3 (37.5%) had dose between 65 and 75 Gy, and 3 (37.5%) had dose greater than 75 Gy; 1 (12.5%) had dose of 65 Gy or less, 5 (62.5%) had dose between 65 and 75 Gy, and 2 (25%) had dose greater than 75 Gy. A cumulative rectal D2cc threshold of 75 Gy resulted in a 16.1 % rate of grade 3þ GI toxicity, versus a 18.2 % rate of grade 3þ GI toxicity if a threshold of 65 Gy is adhered to. A cumulative sigmoid D2cc threshold of 75 Gy permitted a 14.6 % rate of grade 3þ GI toxicity, compared to a 4.5 % rate of grade 3þ GI toxicity if a threshold of 65 Gy is adhered to. Conclusions: In clinical practice, a relatively high rate of GI and GU toxicity is possible even with adherence to current ABS guidelines for dosimetric objectives. Every attempt should be made to minimize dose to
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normal organs, including targeting cumulative D2cc organ doses well below standard objectives. Grade 3þ GI toxicities were observed even with cumulative rectal D2cc less than 65 Gy. We suggest considering more stringent cumulative D2cc dosimetric goals than in current ABS guidelines: less than 80 Gy for the bladder and less than 65 Gy (or as low as achievable without compromising local control) for the rectum and sigmoid.
MISCELLANEOUS POSTERS PO36 Investigation of a New Device to Improve Dosimetric Outcomes in Intravascular Brachytherapy Joseph M. DeCunha, B.Sc Candidate, Shirin Enger, PhD. Medical Physics Unit, McGill University, Montreal, QC, Canada. Purpose: Coronary artery disease is amongst the main causes of death in developed countries. Percutaneous Transluminal Coronary Angioplasty (PTCA or angioplasty) is a procedure used to open stenoted (narrowed) arteries. Restenosis (renarrowing) of the treated vessel is a major complication of PTCA. A metal mesh tube (stent) is expanded inside the vessel to prevent restenosis. Tissue stress incurred during angioplasty and stenting can provoke rapid proliferation of neointimal cells leading to in stent restenosis (ISR). Intravascular brachytherapy (IVBT), a form of internal radiotherapy, is used to treat ISR. Renewed interest in IVBT is being expressed as a treatment for patients with ISR in Drug Eluting Stents. Existing catheter based intravascular brachytherapy devices use a guidewire that is mounted on the outside of the delivery catheter. This has been shown to reduce the dose to target tissue behind the guidewire by as much as 35% from Sr-90/Y-90 based devices. If IVBT seeds with a hollow center were developed such that a guidewire could run interior to the seeds we hypothesize that localized dose reductions from guidewires in IVBT should vanish. Treatment times may also be reduced when using
IVBT devices with a guidewire in the center because the radioisotope can be placed closer to the edge of the delivery catheter which should increase the dose delivered per particle to the target arterial walls. The activity of a source can be increased by increasing the total amount of active core material in each seed. Cylindrical shell seeds should be able to carry more active material than seeds currently used in IVBT because area scales with r2. Each of these factors motivates the investigation of IVBT devices with cylindrical shell seeds and interior guidewires. We perform a dosimetric analysis to evaluate the viability of one such device. Materials and Methods: A dosimetric analysis of an experimental Sr-90/ Y-90 based device using cylindrical shell seeds with a guidewire in the center and of an existing Sr-90/Y-90 based device (Novoste Beta Cath) was performed in a Monte Carlo based particle simulation (Geant4). Absorbed dose was calculated in water as a function of distance from the source and theta. Results: Dose delivered around the experimental device in water is homogeneous as a function of theta. Dose delivered around the Novoste Beta Cath 3.5F with guidewire varies greatly with theta and is reduced by as much as 49% at 2 mm (the target distance) in regions behind the guidewire. Dose per particle from both devices are approximately equivalent. The amount of active core material in the experimental device was increased by 25% compared to the Novoste Beta Cath. Conclusions: The experimental device considered delivers a homogeneous dose as a function of theta around the device with the potential for 25% greater activity than the Novoste Beta Cath. New IVBT devices can rectify existing dosimetric issues and decrease treatment times which may help improve patient outcomes.
PO38 Clinical Study of CT-Guided 3D Print Coplanar Template and Bare Hand in Brachytherapy Qiang Cao, MD, Bin Huo, MD, Lei Wang, MD, Xiaodong Huo, MD, Jinhuan Wang, MD, Li Zang, MD, Dingkun Hou, MD, Hao Wang, MD, Lili Wang, MD, Haitao Wang, MD. Department of Oncology, The Second Hospital of Tianjin Medical University, Tianjin, China. Purpose: To observe the therapeutic and applicance effect of CT-guided 3D print coplanar template in brachytherapy. Materials and Methods: 20 patients were recruited in our study.Of all the patients,10 patients received brachytherapy by CT-guided 3D print coplanar template, an the rests,as the cntrol group,by manual methods. During two days before the surgery, the patients received the CT scan and the dicom image datas were collected.And then the preoperative plan was made and real-time plan in operation and dose verification after-operation were recorded and to see whether they satisfied quality evaluation system for particle implantation in Columbia Cancer Center. Descriptive and analytical statistics were performed using SPSS17.0 software.Comparisons for two pairs were performed using the Students-t test.Values of P!0.01 were considered to indicate statistically significant differences. Results: The dose error rate among the experimental group patients (who received brachytherapy by CT-guided 3D print coplanar template) and the control group(who received therapy by manual-assisted) has statistical significance ( P ! 0.01) .Statistics shows that the general operation time of experimental group was shorter than the control group.Compared preoperation and after- surgery,D90 and CI in experimental group and CI in control group had no statistical significance (P 50.155,P50.279,P50.147),while D90 and CI in the control group and EI in the experiment group had statistical significance ( P50.029,P50.002,P50.025). Conclusions: Brachytherapy using 3D print coplanar template could improve the accuracy of needle path and implanted particle position,obtaining better effect and safety than the manual methods. Works mentioned-above can not only ensured the needles distribution but also the uniformity of the intraoperative- and preoperative-plan-dose. The advantages such as reducing the frequency of CT scans,the operation time and the surgery study time can also easily observed. Operation on this kind can also ensure the optimum of source distribution, avoiding the cold area and hot spot of the dose distribution.