2862
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Author Disclosure: S.B. Awan, None; A.S. Meigooni, None; R. Mokhberiosgouei, None; M. Hussain, None. 2861 Ru-106 Eye Plaques for Treatment of Ocular Melanoma - Practical Issues F. Mourtada, J. Horton, D. Gombos, A. Garden M.D. Anderson Cancer Center, Houston, TX Purpose/Objective(s): At our institution, Ru-106 plaques have been used in to complement traditional I-125 COMS plaques for radiotherapy management of uveal melanoma. Over 45 patients have been treated with Ru-106 since the launch of this program in late 2003. We report on our experience with treatment planning considerations and quality assurance of Ru-106 beta-emitting plaques. Materials/Methods: Six sources (2 of each model: CCB, COB, and CCA, manufactured by BEBIG GmbH, Berlin, Germany) were commissioned since Dec. 2003. The CCB and CCA plaques are fully circular with a 20-mm and 15-mm diameter, respectively. The COB is 20 mm in diameter with a notch. Measurements of the absolute dose rate and relative dose uniformity were obtained using radiochromic films and a hemispherical eye phantom. A high resolution CCD densitometer (PeC 100, Photoelectron Co.) was used to digitize the films (0.13 mm pixel resolution). Sr-90/Y-90 source traceable to the National Institute of Standards and Technology (Gaithersburg, MD) was used for film calibration. A scaling function, for converting the measured dose rate in plastic to that in water, was estimated with Monte Carlo simulations (MCNPX code, Los Alamos National Lab., Los Alamos, NM)). Our overall measurement uncertainty is 11% (2 ). The measured dose distributions are used for plaque commissioning and treatment planning. Treatment planning was done using an Excel spreadsheet and a SURFER software program (Golden Software, Inc., Golden, CO) for isodose contour plotting. Results: The absolute dose rate, along the central axis, for each source model is found to be in good agreement (within 10%) with the manufacturer’s reported values. All 6 tested plaques were found to have good dose uniformity at measured a nominal depth of 2 mm from the inner surface of the plaque (within 10%). At our institution and over the last 3 years, the most commonly used plaque was the notched 20-mm COB (n 20), followed by the circular 20-mm CCB (n 15) and the 15-mm circular CCA (n 10). Relative to I-125 COMS, our results indicate that Ru-106 delivers lower dose to surrounding structures due to its steep depth dose curve; while reasonable doses are delivered to the sclera if tumor apical height within 5 mm is indicated. For tumors close to the edge of the optical disk, we found the notched COB plaque to deliver lower dose to the optical disk than I-125. Conclusions: We performed an independent verification of BEBIG Ru-106 plaques dosimetry. Implementation of this quality assurance program insures accurate Ru-106 radiotherapy treatment planning and delivery. We find Ru-106 plaque preparation logistics to be easier than I-125 COMS due to reusability over its one-year half-life and the allowable 50 sterilization cycles. Our surgeons also prefer Ru-106 for its thinner profile with easier insertions and less trauma to surrounding tissue. Author Disclosure: F. Mourtada, Eckert & Ziegler BEBIG Gmbh, C. Other Research Support; J. Horton, None; D. Gombos, None; A. Garden, None. 2862 Dosimetric Impact of Partial Gland Irradiation Utilizing Functional Image Guidance in Men Undergoing Brachytherapy for Localized Prostate Cancer B. Wang 1 , Y. Zhu 1 , S. J. DiBiase 1 , R. Parra 1 , J. Mammone 1 , Y. Feng 2 , C. Yu 2 , R. P. Gullapalli 2 1 Cooper University Hospital, Camden, NJ, 2 University of Maryland, Baltimore, MD Purpose/Objective(s): The objective of this simulation study was to provide proof of the dosimetric efficacy of using MRSI to guide partial gland irradiation in order to minimize the side effects and produce equivalent outcome. Materials/Methods: Eight subjects with localized prostate cancer treated on prospective Phase II study utilizing Magnetic Resonance Spectroscopic Imaging (MRSI) to guide prostate brachytherapy (PB) were simulated in this dosimetric impact study. All patients had histological confirmed adenocarcinoma of the prostate, clinical stage T1c or T2a, PSA 10, and Gleason score of 6 or less. Biologic tumor volumes (BTV) that were previously utilized in a Phase II prospective study were utilized for this dosimetric simulation study of partial gland irradiation. In this simulation study, only the BTV within the prostate gland was treated with I-125 radioactive seed implantation to a dose of 160 Gy. Results: The simulated dosimetry and DVH were analyzed and compared to whole gland brachytherapy. We found the dose to both urethra and rectum much reduced. As shown in Table 1, the median D90 for urethra was only 23.6 Gy for partial gland irradiation, while 159.1 Gy for whole gland irradiation. The median V100 for rectum was 21.6% for whole gland irradiation and it decreased to 2.0% for partial gland irradiation. S696 I. J. Radiation Oncology ● Biology ● Physics Volume 66, Number 3, Supplement, 2006
Transcript of 2862
Author Disclosure: S.B. Awan, None; A.S. Meigooni, None; R. Mokhberiosgouei, None; M. Hussain, None.
2861 Ru-106 Eye Plaques for Treatment of Ocular Melanoma - Practical Issues
F. Mourtada, J. Horton, D. Gombos, A. Garden
M.D. Anderson Cancer Center, Houston, TX
Purpose/Objective(s): At our institution, Ru-106 plaques have been used in to complement traditional I-125 COMS plaquesfor radiotherapy management of uveal melanoma. Over 45 patients have been treated with Ru-106 since the launch of thisprogram in late 2003. We report on our experience with treatment planning considerations and quality assurance of Ru-106beta-emitting plaques.
Materials/Methods: Six sources (2 of each model: CCB, COB, and CCA, manufactured by BEBIG GmbH, Berlin, Germany)were commissioned since Dec. 2003. The CCB and CCA plaques are fully circular with a 20-mm and 15-mm diameter,respectively. The COB is 20 mm in diameter with a notch. Measurements of the absolute dose rate and relative dose uniformitywere obtained using radiochromic films and a hemispherical eye phantom. A high resolution CCD densitometer (PeC 100,Photoelectron Co.) was used to digitize the films (0.13 mm pixel resolution). Sr-90/Y-90 source traceable to the NationalInstitute of Standards and Technology (Gaithersburg, MD) was used for film calibration. A scaling function, for converting themeasured dose rate in plastic to that in water, was estimated with Monte Carlo simulations (MCNPX code, Los Alamos NationalLab., Los Alamos, NM)). Our overall measurement uncertainty is �11% (2 ). The measured dose distributions are used forplaque commissioning and treatment planning. Treatment planning was done using an Excel spreadsheet and a SURFERsoftware program (Golden Software, Inc., Golden, CO) for isodose contour plotting.
Results: The absolute dose rate, along the central axis, for each source model is found to be in good agreement (within �10%)with the manufacturer’s reported values. All 6 tested plaques were found to have good dose uniformity at measured a nominaldepth of 2 mm from the inner surface of the plaque (within �10%). At our institution and over the last 3 years, the mostcommonly used plaque was the notched 20-mm COB (n� 20), followed by the circular 20-mm CCB (n� 15) and the 15-mmcircular CCA (n� 10). Relative to I-125 COMS, our results indicate that Ru-106 delivers lower dose to surrounding structuresdue to its steep depth dose curve; while reasonable doses are delivered to the sclera if tumor apical height within 5 mm isindicated. For tumors close to the edge of the optical disk, we found the notched COB plaque to deliver lower dose to the opticaldisk than I-125.
Conclusions: We performed an independent verification of BEBIG Ru-106 plaques dosimetry. Implementation of this qualityassurance program insures accurate Ru-106 radiotherapy treatment planning and delivery. We find Ru-106 plaque preparationlogistics to be easier than I-125 COMS due to reusability over its one-year half-life and the allowable 50 sterilization cycles.Our surgeons also prefer Ru-106 for its thinner profile with easier insertions and less trauma to surrounding tissue.
Author Disclosure: F. Mourtada, Eckert & Ziegler BEBIG Gmbh, C. Other Research Support; J. Horton, None; D. Gombos,None; A. Garden, None.
2862 Dosimetric Impact of Partial Gland Irradiation Utilizing Functional Image Guidance in Men UndergoingBrachytherapy for Localized Prostate Cancer
B. Wang1, Y. Zhu1, S. J. DiBiase1, R. Parra1, J. Mammone1, Y. Feng2, C. Yu2, R. P. Gullapalli2
1Cooper University Hospital, Camden, NJ, 2University of Maryland, Baltimore, MD
Purpose/Objective(s): The objective of this simulation study was to provide proof of the dosimetric efficacy of using MRSIto guide partial gland irradiation in order to minimize the side effects and produce equivalent outcome.
Materials/Methods: Eight subjects with localized prostate cancer treated on prospective Phase II study utilizing MagneticResonance Spectroscopic Imaging (MRSI) to guide prostate brachytherapy (PB) were simulated in this dosimetric impact study.All patients had histological confirmed adenocarcinoma of the prostate, clinical stage T1c or T2a, PSA �� 10, and Gleasonscore of 6 or less. Biologic tumor volumes (BTV) that were previously utilized in a Phase II prospective study were utilizedfor this dosimetric simulation study of partial gland irradiation. In this simulation study, only the BTV within the prostate glandwas treated with I-125 radioactive seed implantation to a dose of 160 Gy.
Results: The simulated dosimetry and DVH were analyzed and compared to whole gland brachytherapy. We found the doseto both urethra and rectum much reduced. As shown in Table 1, the median D90 for urethra was only 23.6 Gy for partial glandirradiation, while 159.1 Gy for whole gland irradiation. The median V100 for rectum was 21.6% for whole gland irradiationand it decreased to 2.0% for partial gland irradiation.
S696 I. J. Radiation Oncology ● Biology ● Physics Volume 66, Number 3, Supplement, 2006
Conclusions: With increased specificity and sensitivity of BTV identification based on endorectal MRI together with MRSI andother functional imaging modalities in the future, such partial prostate brachytherapy should be fully explored. Based on theseencouraging dosimetric results, our group has initiated a prospective partial gland irradiation clinical trial utilizing MRSIguidance in men with prostate cancer.
Author Disclosure: B. Wang, None; Y. Zhu, None; S.J. DiBiase, None; R. Parra, None; J. Mammone, None; Y. Feng, None;C. Yu, None; R.P. Gullapalli, None.
2863 Quality Assurance of Iodine 125 Seeds for Prostate Brachytherapy Using an Imaging Plate
S. Furutani1, H. Ikushima1, T. Saze2, K. Ozaki1, Y. Kishida1, M. Oita3, Y. Takegawa1, H. Nishitani1
1Department of Radiology, Tokushima University, Tokushima, Japan, 2Radioisotope Research Center, TokushimaUniversity, Tokushima, Japan, 3Department of Radiology, Hokkaido University Graduated School of Medicine, Sapporo,Japan
Purpose/Objective(s): OncoSeed is delivered in a sterile environment in the form of a cartridge, so it is impractical tore-sterilize and re-load seeds after calibration. We investigated a new method using an imaging plate dosimetry system tocalibrate all seeds in the OncoSeed cartridge in a sterile environment.
Materials/Methods: Seeds within the cartridge were placed on an imaging plate, and the imaging plate irradiated. To removescatter radiation, and improve spatial resolution of seed images, we used X-ray parallel cross grids. The irradiated imaging platewas scanned using a Bio-imaging Analyzer System, and radioactivity intensities of seed images were given in counts. Countscould be translated to profiles, and each seed within the cartridge was analyzed.
Results: Results showed a good correlation between counts and total radioactivity of the seeds within the cartridge. Thus, usinga least-squares line, it was possible to calibrate a cartridge with unknown radioactivity. By analyzing the profiles, it was possiblenot only to detect a miscalibrated seed in the cartridge from its relative difference in counts, but also to identify its position inthe cartridge. No significant changes in counts were seen between sterile and non-sterile environments.
Conclusions: Using an imaging plate dosimetry system, all seeds in a cartridge could be calibrated in a sterile environment.
PatientID 1 2 3 4 5 6 7 8
Partial Prostate BTVV130 99.98% 99.07% 99.90% 99.57% 99.74% 99.56% 98.90% 100.00%
UrethraD90 9.78 23.82 53.96 113.87 149.29 23.29 19.51 12.27
UrethraD30 84.71 55.23 112.69 168.73 159.25 50.93 64.73 32.54
UrethraD10 133.81 68.76 130.57 173.09 166.34 63.21 83.11 38.12
RectumV100 0 2.28% 11.30% 24.37% 14.01% 0.54% 0 1.62%
Whole Prostatewith BTVboost
BTVV130
99.98 99.88% 99.53% 100.00% 99.98% 99.93% 99.98% 100.00%
UrethraD90 167.41 149.05 126.84 150.87 188.39 175.24 146.53 168.11
UrethraD30 218.52 170.61 189.49 204.95 194.08 199.88 191.06 208.63
UrethraD10 220.73 174.71 196.34 208.33 200.02 214.86 197.06 213.7
RectumV100 48.89% 12.95% 34.48% 41.88% 26.98% 13.14% 7.78% 16.19%
Ratio of PartialProstate toWholeProstate
UrethraD90
6% 16% 43% 75% 79% 13% 13% 7%
UrethraD30
39% 32% 59% 82% 82% 25% 34% 16%
UrethraD10
61% 39% 67% 83% 83% 29% 42% 18%
RectumV100
0% 18% 33% 58% 52% 4% 0% 10%
S697Proceedings of the 48th Annual ASTRO Meeting
