PURPOSE: To determine the reproducibility and precision of postimplant dosimetry following (125)I prostate brachytherapy (PB) and to evaluate the effects of learning and experience in CT-based postimplant dosimetry. MATERIALS AND METHODS: One-month postimplant CT data from two patients who underwent PB alone or combined therapy (PB + EBRT) were sent to 28 institutions for postimplant dosimetry and analyzed in 2006 (study 1). Similarly, 1-month postimplant CT data from two other patients were also analyzed in 2008 (study 2; 23 institutions). For both modalities in studies 1 and 2, the variance of the difference between CT-based D90 at each institution and CT/MRI fusion-based D90 was estimated. RESULTS: In monotherapy, F test and Mann-Whitney U test revealed no significant difference in the variance in studies 1 and 2 (P = 0.72, 0.46). In combined therapy, the variance significantly converged in study 2 compared with study 1 (P < 0.05). Even in the two studies, however, the difference between the median CT-based D90 and fusion-based D90 was at least 20-30 Gy. CONCLUSION: Marked interobserver variability was seen in the prostate volume and D90 with CT alone. The precision of postimplant dosimetry based on CT alone was revealed to be limited.
PURPOSE: To determine the reproducibility and precision of postimplant dosimetry following (125)I prostate brachytherapy (PB) and to evaluate the effects of learning and experience in CT-based postimplant dosimetry. MATERIALS AND METHODS: One-month postimplant CT data from two patients who underwent PB alone or combined therapy (PB + EBRT) were sent to 28 institutions for postimplant dosimetry and analyzed in 2006 (study 1). Similarly, 1-month postimplant CT data from two other patients were also analyzed in 2008 (study 2; 23 institutions). For both modalities in studies 1 and 2, the variance of the difference between CT-based D90 at each institution and CT/MRI fusion-based D90 was estimated. RESULTS: In monotherapy, F test and Mann-Whitney U test revealed no significant difference in the variance in studies 1 and 2 (P = 0.72, 0.46). In combined therapy, the variance significantly converged in study 2 compared with study 1 (P < 0.05). Even in the two studies, however, the difference between the median CT-based D90 and fusion-based D90 was at least 20-30 Gy. CONCLUSION: Marked interobserver variability was seen in the prostate volume and D90 with CT alone. The precision of postimplant dosimetry based on CT alone was revealed to be limited.
Authors: K Kagawa; W R Lee; T E Schultheiss; M A Hunt; A H Shaer; G E Hanks Journal: Int J Radiat Oncol Biol Phys Date: 1997-05-01 Impact factor: 7.038
Authors: Juanita Crook; Michael Milosevic; Pamela Catton; Ivan Yeung; Tara Haycocks; Thao Tran; Charles Catton; Michael McLean; Tony Panzarella; Masoom A Haider Journal: Brachytherapy Date: 2002 Impact factor: 2.362
Authors: Patrick W McLaughlin; Sara Troyer; Sally Berri; Vrinda Narayana; Amichay Meirowitz; Peter L Roberson; James Montie Journal: Int J Radiat Oncol Biol Phys Date: 2005-10-01 Impact factor: 7.038
Authors: V Narayana; P L Roberson; A T Pu; H Sandler; R H Winfield; P W McLaughlin Journal: Int J Radiat Oncol Biol Phys Date: 1997-03-15 Impact factor: 7.038