- Email: [email protected]
323 poster A radiobiological model for the relative biological effectiveness of high dose rate Cf-252 brachytherapy
Posters
S 137
Conclusion: Adjuvant intravaginal HDR BT for endometrial adenocarcinoma was a effective treatment to local control with a low rate toxicity. 322 poster Conservative Treatment of Intra-Ocular Melanoma with Iodine-125 Brachytherapy
A.C. Pe//izzon1'2, R, Ferrigno 1, M. Maia 1, R. Fogaro/f 'z, J. Sa/vajo/i 1, P. Novaes 1, M. Motono ~, M. Chodjaniack 1 ~ACCamargo Hospital, Radiation Oncology, Sac Paulo, Brasil 21AVC, Radiation Oncology, Sac Paulo, Brasil Objective: this is a retrospective analysis of patients with choroidal melanoma (MC) who underwent to conservative therapy, using episcleral Iodine-125 (model 6711, Amershan) plaque therapy. Methods: There were 49 patients with MC treated in the Hospital do Cancer, SAc Paulo, Brazil, from March, 2001 to January, 2003. The following clinical parameters were analyzed and correlated to local control and survival: sex, age, lesion dimensions, treatment time, as well as doses in apex and base of the tumors. Results: The maximum base diameter and height of tumors treated were 17 mm and 12ram. Doses at those points, ranged from 213 to 463 Gy (median 347 Gy) and 51 to 250 Gy (median 91 Gy), respectively. The crude ocular preservation rate, disease free survival and the ocular preservation, actuarial in 2years, were 96%, 93.5% and 96.3%, respectively. Univariate analysis showed tumor height lesser than 6 mm as the only predictive factor for local control (p= 0.0348). Conclusion: Brachytherapy achieved a very satisfactory rate of tumor local control, confirming that tumor height is one of the most important predictive factor for local control. De~ease
E
Free Survival
aa
Ct b=ort~ 12 M~h~
24
323 poster A radiobiological model for the relative biological effectiveness of high dose rate Cf-252 brachytherapy
M. Rivard, H. Zinkin, L. Stapleford, K. Evans, J. Mignano, D. Wazer Tufts - New England Medical Center, Dept. of Radiation Oncology, Box #246, Boston, U.S.A. Purpose: While there is significant clinical experience using high-dose rate (HDR) 2~2Cfbrachytherapy, there is minimal data regarding values for the relative biological effectiveness (RBE). The aim of this research was to derive a radiobiological model for 2S2Cf RBE and to compare these results with RBE values used clinically in Russia. Materials and Methods: The linear-quadratic (L-Q) model was used as the basis to characterize cell survival following irradiation, with identical cell killing rates between 252Cf neutrons and photons used for derivation of RBE. Using this equality, a
relationship among neutron dose and L-Q radiobiological components (i.e., alpha and beta parameters) was obtained without need to specify the photon dose. These results were used to derive the 2S2Cf neutron RBE and compare with Russian RBE values. Results: The 2520f neutron RBE was determined after incorporating the L-Q radiobiological components as obtained from cell survival studies with fast neutrons and teletherapy photons. For single-fraction HDR neutron doses of 0.5, 1.0, and 1.5 Gy, the total (neutron plus photon) doses were 3.5, 6.0, and 8.1 Gy, with 2S~Cf neutron RBE values of 6.4, 5.5, and 4.9, respectively. Russian clinicians obtained HDR 252Cf neutron RBE values ranging from 6.3 to 4.4 for similar doses and fractionation schemes. They also observed that 2520f neutron RBE increases with the number of fractions and was dose rate dependent. Conclusion: The ZS~Cf neutron RBE and relationship among neutron dose and L-Q radiobiological components was derived using mathematical principles. Comparison of results obtained using these relationships were within the uncertainties of the component value, and were in concordance with RBE values from Russian clinical experience. 324 poster MEDARPA -Implantation of brachytherapy-catheters using augmented reality
S. Rodd~qe/, D. Baltas I, G. SakaJ, M. Schnaide~, S. Wesarg2, P. Zogal2, BI Schwal~, H. Seibert 3, R. Kurek 1, N. Zamboglou ~ ~Klinikum Offenbach, Radiooncology, Offenbach a.M., Germany 2MedCom, Darmstadt, Germany ~Fraunhofer IGD, Darmstadt, Germany Purpose: To evaluate a prototype consistent of a flexible semitransparent display, a computer and a hybrid tracking system (infrared and electromagnetic). This prototype was designed for the project MEDARPA in order to facilitate the navigation of brachytherapy-catheters during the procedure of implantation. Material & Methods: A cubic phantom was used and filled with stearin gel and objects resembling tumour and organs at risk. 10 CT-markers were fixed on the surface and a CT-scan (2 mm slice distance) was done. After transfer of CT-data to the computer, the phantom and the handle of the catheter were registered using the electromagnetic tracking system, physician and display were registered using the infrared tracking system. The display was placed above the phantom and catheters were implanted guided by the 3D model of the phantom shown on the display and overlayered with the image of catheter and handle. The virtual positions of the catheters were fixed, catheters were left in place. After another CT-scan, virtual and real positions of the catheters" tips as well as equidistant points along the catheters were reconstructed and compared. Results & Conclusion: The systems is easy to handle and needs - after installation - 6 minutes (3.5-10.0) for the set-up (calibration of tracking systems and registration of the phantom). Median variation of the catheter tip was 6.3 mm (4.5-12.0) and 8.3 mm (6.2-10.2) for equidistant points. The MEDARPA-prototype enables the physician to implant brachytherapy-catheters guided by augmented reality. Furthermore, target regions inside the tumour can be defined by preplanning. The puncture of organs at risk can be avoided. The accuracy of the system wilt be further improved and first tests with patients will be presented.
S 137
Conclusion: Adjuvant intravaginal HDR BT for endometrial adenocarcinoma was a effective treatment to local control with a low rate toxicity. 322 poster Conservative Treatment of Intra-Ocular Melanoma with Iodine-125 Brachytherapy
A.C. Pe//izzon1'2, R, Ferrigno 1, M. Maia 1, R. Fogaro/f 'z, J. Sa/vajo/i 1, P. Novaes 1, M. Motono ~, M. Chodjaniack 1 ~ACCamargo Hospital, Radiation Oncology, Sac Paulo, Brasil 21AVC, Radiation Oncology, Sac Paulo, Brasil Objective: this is a retrospective analysis of patients with choroidal melanoma (MC) who underwent to conservative therapy, using episcleral Iodine-125 (model 6711, Amershan) plaque therapy. Methods: There were 49 patients with MC treated in the Hospital do Cancer, SAc Paulo, Brazil, from March, 2001 to January, 2003. The following clinical parameters were analyzed and correlated to local control and survival: sex, age, lesion dimensions, treatment time, as well as doses in apex and base of the tumors. Results: The maximum base diameter and height of tumors treated were 17 mm and 12ram. Doses at those points, ranged from 213 to 463 Gy (median 347 Gy) and 51 to 250 Gy (median 91 Gy), respectively. The crude ocular preservation rate, disease free survival and the ocular preservation, actuarial in 2years, were 96%, 93.5% and 96.3%, respectively. Univariate analysis showed tumor height lesser than 6 mm as the only predictive factor for local control (p= 0.0348). Conclusion: Brachytherapy achieved a very satisfactory rate of tumor local control, confirming that tumor height is one of the most important predictive factor for local control. De~ease
E
Free Survival
aa
Ct b=ort~ 12 M~h~
24
323 poster A radiobiological model for the relative biological effectiveness of high dose rate Cf-252 brachytherapy
M. Rivard, H. Zinkin, L. Stapleford, K. Evans, J. Mignano, D. Wazer Tufts - New England Medical Center, Dept. of Radiation Oncology, Box #246, Boston, U.S.A. Purpose: While there is significant clinical experience using high-dose rate (HDR) 2~2Cfbrachytherapy, there is minimal data regarding values for the relative biological effectiveness (RBE). The aim of this research was to derive a radiobiological model for 2S2Cf RBE and to compare these results with RBE values used clinically in Russia. Materials and Methods: The linear-quadratic (L-Q) model was used as the basis to characterize cell survival following irradiation, with identical cell killing rates between 252Cf neutrons and photons used for derivation of RBE. Using this equality, a
relationship among neutron dose and L-Q radiobiological components (i.e., alpha and beta parameters) was obtained without need to specify the photon dose. These results were used to derive the 2S2Cf neutron RBE and compare with Russian RBE values. Results: The 2520f neutron RBE was determined after incorporating the L-Q radiobiological components as obtained from cell survival studies with fast neutrons and teletherapy photons. For single-fraction HDR neutron doses of 0.5, 1.0, and 1.5 Gy, the total (neutron plus photon) doses were 3.5, 6.0, and 8.1 Gy, with 2S~Cf neutron RBE values of 6.4, 5.5, and 4.9, respectively. Russian clinicians obtained HDR 252Cf neutron RBE values ranging from 6.3 to 4.4 for similar doses and fractionation schemes. They also observed that 2520f neutron RBE increases with the number of fractions and was dose rate dependent. Conclusion: The ZS~Cf neutron RBE and relationship among neutron dose and L-Q radiobiological components was derived using mathematical principles. Comparison of results obtained using these relationships were within the uncertainties of the component value, and were in concordance with RBE values from Russian clinical experience. 324 poster MEDARPA -Implantation of brachytherapy-catheters using augmented reality
S. Rodd~qe/, D. Baltas I, G. SakaJ, M. Schnaide~, S. Wesarg2, P. Zogal2, BI Schwal~, H. Seibert 3, R. Kurek 1, N. Zamboglou ~ ~Klinikum Offenbach, Radiooncology, Offenbach a.M., Germany 2MedCom, Darmstadt, Germany ~Fraunhofer IGD, Darmstadt, Germany Purpose: To evaluate a prototype consistent of a flexible semitransparent display, a computer and a hybrid tracking system (infrared and electromagnetic). This prototype was designed for the project MEDARPA in order to facilitate the navigation of brachytherapy-catheters during the procedure of implantation. Material & Methods: A cubic phantom was used and filled with stearin gel and objects resembling tumour and organs at risk. 10 CT-markers were fixed on the surface and a CT-scan (2 mm slice distance) was done. After transfer of CT-data to the computer, the phantom and the handle of the catheter were registered using the electromagnetic tracking system, physician and display were registered using the infrared tracking system. The display was placed above the phantom and catheters were implanted guided by the 3D model of the phantom shown on the display and overlayered with the image of catheter and handle. The virtual positions of the catheters were fixed, catheters were left in place. After another CT-scan, virtual and real positions of the catheters" tips as well as equidistant points along the catheters were reconstructed and compared. Results & Conclusion: The systems is easy to handle and needs - after installation - 6 minutes (3.5-10.0) for the set-up (calibration of tracking systems and registration of the phantom). Median variation of the catheter tip was 6.3 mm (4.5-12.0) and 8.3 mm (6.2-10.2) for equidistant points. The MEDARPA-prototype enables the physician to implant brachytherapy-catheters guided by augmented reality. Furthermore, target regions inside the tumour can be defined by preplanning. The puncture of organs at risk can be avoided. The accuracy of the system wilt be further improved and first tests with patients will be presented.