Robotically-assisted Minimally Invasive Brachytherapy: Pre-clinical Aspects
1
Results: Experimental results show that the volume calculation that was implemented in this thesis was within 2% of the values computed by Varian BrachyVision for the prostate, within 3% for the rectum and bladder and 6% for the urethra. The calculation of dose compared to BrachyVision was determined to be different by only 0.38%. Isodose curves were also generated and were found to be similar to BrachyVision. The comparison between Harmony Search and genetic algorithm showed that Harmony Search was over 4 times faster when compared over multiple data sets. The optimal Harmony Memory Size was found to be 5 or lower; the Harmony Memory Considering Rate was determined to be 0.95, and the Pitch Adjusting Rate was found to be 0.9. Conclusions: Harmony Search is a viable alternative to existing algorithms for use in HDR prostate brachytherapy optimization. Coupled with the optimal parameters for the algorithm, this combination has the capability to significantly decrease the time spent on minimizing optimization problems in the clinic that are time intensive, such as brachytherapy, IMRT and beam angle optimi- zation. Author Disclosure: A. Panchal, None; B. Tom, None. 3199 Robotically-assisted Minimally Invasive Brachytherapy: Pre-clinical Aspects L. Godfrey, J. Hanley, J. Napoli, J. Barbiere, M. Tuna, D. H. Smith Hackensack University Medical Center, Hackensack, NJ Purpose/Objective(s): To assess the feasibility of robotically-assisted minimally invasive (MI) brachytherapy for both post-op- erative and intraoperative radiotherapy protocols. Materials/Methods: A DaVinci S Robotic platform (Intuitive Surgical, Inc.) was used to manipulate minimally invasive applicators (MIAs) that were designed to deploy brachytherapy catheters in an operative field. Porcine subjects were used in the Robotic Surgery Training Center. Both high dose rate (HDR) catheters and the Axxent Electronic Brachyther- apy (EBX) Delivery system (Xoft Inc.) were used. First and second generation MIA prototypes were utilized. A 5 mm diameter articulating arm (Cambridge Endo) was used to manipulate the second generation prototype. In-vivo trials were visually assessed by a wide-angle endoscopic camera. Video and still images were obtained to assess catheter and applicator placement. A CT scan of the MIA was obtained to gauge reproducibility and potential compatibility with an atlas-based treatment planning approach. Treatment plans were generated using commercial software for both the Ir-192 HDR and the Xoft 50 kV sources. Ex-vivo dosimetry studies were performed. A Nucletron (Nucletron, Inc) HDR after- loader was used for brachytherapy delivery, and GafChromic EBT film (International Specialty Products) analysis was per- formed for verification. Results: The catheters, the EBX delivery arm, and the MIA prototypes were all found to be compatible with MI techniques. Gen- itourinary, gynecologic, gastrointestinal, and thoracic targets were amenable to post-operative and intraoperative radiotherapy pro- tocols. The brachytherapy catheters had greater length and flexibility, and proved ideal for post-operative MI brachytherapy. The more limited 30 cm length of the EBX delivery arm was best suited to an intraoperative en-face delivery technique. Applicator control and targeting were enhanced by attaching the applicator to an articulated arm. Film dosimetry demonstrated the ability of the MIAs to position the catheters reproducibly and to deliver a uniform dose. The en face approach of the EBX delivery system was insensitive to random deviations from normal incidence of the applicator (± 5 degrees). Conclusions: The DaVinci S Robotic platform in combination with MIAs can effectively implement minimally invasive brachy- therapy of complex targets. Both HDR catheters and the Axxent EBX delivery arm can be accurately deployed. Genitourinary, gynecologic, gastrointestinal, and thoracic targets are accessible. Ex-vivo dosimetry demonstrates the reproducibility of the MIAs, making them amenable to atlas-based planning for intraoperative radiotherapy. Additional porcine trials incorporating in vivo dosimetry with GafChromic film are needed. Author Disclosure: L. Godfrey, None; J. Hanley, None; J. Napoli, None; J. Barbiere, None; M. Tuna, None; D.H. Smith, None. 3200 Single Arc VMAT of H&N Cancer A. L. Bertelsen 1 , 2 , C. R. Hansen 3 , J. Johansen 4 , C. Brink 1,3 1 Faculty of Health Sciences, University of Southern Denmark, Odense, Denmark, 2 Laboratory of Radiation Physics, Odense University Hospital, Denmark, 3 Laboratory of Radiation Physics, Odense University Hospital, Odense, Denmark, 4 Dept. of Oncology, Odense University Hospital, Odense, Denmark Purpose/Objective(s): A few radiation treatment planning systems are currently able to plan volumetric modulated arc therapy (VMAT). The VMAT algorithm in Pinnacle 3 is called SmartArc. The capability of SmartArc to generate complex treatment plans for the head and neck (H&N) region was tested. Materials/Methods: This retrospective planning study includes patients with oropharyngeal or hypopharyngeal cancer previ- ously treated with IMRT by utilization of the Pinnacle 3 Ô treatment planning system and Elekta Synergy accelerators. Doses between 50Gy and 68Gy were prescribed to individual Planning Target Volumes (PTV). The patients were re-planned with VMAT using the SmartArc algorithm in Pinnacle 3 Ô 8.9c (research version). A constraint for the re-planning was to use only one single arc to create deliverable plans. The objectives were to achieve identical or better target coverage and sparing of the organs at risk (OAR) using VMAT compared to IMRT. The comparison was made by evaluating of 1) dose-volume histograms (DVHs) of PTVs and OARs, 2) monitor units, 3) treatment time, and 4) treatment accuracy as delivered on Elekta Synergy accelerators. Results: Preliminary results based on 11 patients showed that single arc VMAT plans satisfied all the re-planning objectives. The average maximum dose to the spinal cord was 42.1±0.7Gy and 43.4±0.5Gy for the VMAT and IMRT plans, respectively. V26 of the parotic glands was 45±4% with VMAT and 48±5% with IMRT. SmartArc generated VMAT treatment plans with an average conformity index (V95%/Vtarget) of 1.56±0.04 improving the conformity index of 1.71±0.07 by IMRT. This sig- nificantly reduced the size of high dose volumes (volumes which received more than 15Gy) in the surrounding normal tissues. VMAT reduced the number of MUs by 10% from mean 503±20MU to 449+/-22MU using IMRT and VMAT, respectively. Proceedings of the 51st Annual ASTRO Meeting S721
Transcript of Robotically-assisted Minimally Invasive Brachytherapy: Pre-clinical Aspects
Proceedings of the 51st Annual ASTRO Meeting S721
Results: Experimental results show that the volume calculation that was implemented in this thesis was within 2% of the valuescomputed by Varian BrachyVision for the prostate, within 3% for the rectum and bladder and 6% for the urethra. The calculation ofdose compared to BrachyVision was determined to be different by only 0.38%. Isodose curves were also generated and were foundto be similar to BrachyVision. The comparison between Harmony Search and genetic algorithm showed that Harmony Search wasover 4 times faster when compared over multiple data sets. The optimal Harmony Memory Size was found to be 5 or lower; theHarmony Memory Considering Rate was determined to be 0.95, and the Pitch Adjusting Rate was found to be 0.9.
Conclusions: Harmony Search is a viable alternative to existing algorithms for use in HDR prostate brachytherapy optimization.Coupled with the optimal parameters for the algorithm, this combination has the capability to significantly decrease the time spenton minimizing optimization problems in the clinic that are time intensive, such as brachytherapy, IMRT and beam angle optimi-zation.
Author Disclosure: A. Panchal, None; B. Tom, None.
3199 Robotically-assisted Minimally Invasive Brachytherapy: Pre-clinical Aspects
L. Godfrey, J. Hanley, J. Napoli, J. Barbiere, M. Tuna, D. H. Smith
Hackensack University Medical Center, Hackensack, NJ
Purpose/Objective(s): To assess the feasibility of robotically-assisted minimally invasive (MI) brachytherapy for both post-op-erative and intraoperative radiotherapy protocols.
Materials/Methods: A DaVinci S Robotic platform (Intuitive Surgical, Inc.) was used to manipulate minimally invasiveapplicators (MIAs) that were designed to deploy brachytherapy catheters in an operative field. Porcine subjects wereused in the Robotic Surgery Training Center. Both high dose rate (HDR) catheters and the Axxent Electronic Brachyther-apy (EBX) Delivery system (Xoft Inc.) were used. First and second generation MIA prototypes were utilized. A 5 mmdiameter articulating arm (Cambridge Endo) was used to manipulate the second generation prototype. In-vivo trialswere visually assessed by a wide-angle endoscopic camera. Video and still images were obtained to assess catheter andapplicator placement. A CT scan of the MIA was obtained to gauge reproducibility and potential compatibility with anatlas-based treatment planning approach. Treatment plans were generated using commercial software for both the Ir-192HDR and the Xoft 50 kV sources. Ex-vivo dosimetry studies were performed. A Nucletron (Nucletron, Inc) HDR after-loader was used for brachytherapy delivery, and GafChromic EBT film (International Specialty Products) analysis was per-formed for verification.
Results: The catheters, the EBX delivery arm, and the MIA prototypes were all found to be compatible with MI techniques. Gen-itourinary, gynecologic, gastrointestinal, and thoracic targets were amenable to post-operative and intraoperative radiotherapy pro-tocols. The brachytherapy catheters had greater length and flexibility, and proved ideal for post-operative MI brachytherapy. Themore limited 30 cm length of the EBX delivery arm was best suited to an intraoperative en-face delivery technique. Applicatorcontrol and targeting were enhanced by attaching the applicator to an articulated arm. Film dosimetry demonstrated the abilityof the MIAs to position the catheters reproducibly and to deliver a uniform dose. The en face approach of the EBX delivery systemwas insensitive to random deviations from normal incidence of the applicator (± 5 degrees).
Conclusions: The DaVinci S Robotic platform in combination with MIAs can effectively implement minimally invasive brachy-therapy of complex targets. Both HDR catheters and the Axxent EBX delivery arm can be accurately deployed. Genitourinary,gynecologic, gastrointestinal, and thoracic targets are accessible. Ex-vivo dosimetry demonstrates the reproducibility of theMIAs, making them amenable to atlas-based planning for intraoperative radiotherapy. Additional porcine trials incorporatingin vivo dosimetry with GafChromic film are needed.
Author Disclosure: L. Godfrey, None; J. Hanley, None; J. Napoli, None; J. Barbiere, None; M. Tuna, None; D.H. Smith, None.
3200 Single Arc VMAT of H&N Cancer
A. L. Bertelsen1,2, C. R. Hansen3, J. Johansen4, C. Brink1,3
1Faculty of Health Sciences, University of Southern Denmark, Odense, Denmark, 2Laboratory of Radiation Physics, OdenseUniversity Hospital, Denmark, 3Laboratory of Radiation Physics, Odense University Hospital, Odense, Denmark, 4Dept. ofOncology, Odense University Hospital, Odense, Denmark
Purpose/Objective(s): A few radiation treatment planning systems are currently able to plan volumetric modulated arc therapy(VMAT). The VMAT algorithm in Pinnacle3 is called SmartArc. The capability of SmartArc to generate complex treatment plansfor the head and neck (H&N) region was tested.
Materials/Methods: This retrospective planning study includes patients with oropharyngeal or hypopharyngeal cancer previ-ously treated with IMRT by utilization of the Pinnacle3� treatment planning system and Elekta Synergy accelerators. Dosesbetween 50Gy and 68Gy were prescribed to individual Planning Target Volumes (PTV). The patients were re-planned withVMAT using the SmartArc algorithm in Pinnacle3� 8.9c (research version). A constraint for the re-planning was to useonly one single arc to create deliverable plans. The objectives were to achieve identical or better target coverage and sparingof the organs at risk (OAR) using VMAT compared to IMRT. The comparison was made by evaluating of 1) dose-volumehistograms (DVHs) of PTVs and OARs, 2) monitor units, 3) treatment time, and 4) treatment accuracy as delivered on ElektaSynergy accelerators.
Results: Preliminary results based on 11 patients showed that single arc VMAT plans satisfied all the re-planning objectives.The average maximum dose to the spinal cord was 42.1±0.7Gy and 43.4±0.5Gy for the VMAT and IMRT plans, respectively.V26 of the parotic glands was 45±4% with VMAT and 48±5% with IMRT. SmartArc generated VMAT treatment plans withan average conformity index (V95%/Vtarget) of 1.56±0.04 improving the conformity index of 1.71±0.07 by IMRT. This sig-nificantly reduced the size of high dose volumes (volumes which received more than 15Gy) in the surrounding normal tissues.VMAT reduced the number of MUs by 10% from mean 503±20MU to 449+/-22MU using IMRT and VMAT, respectively.
