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Title: MRI-Guided 3D Optimization Significantly Improves DVH Parameters of Pulsed-Dose-Rate Brachytherapy in Locally Advanced Cervical Cancer

Purpose: To compare dose-volume histogram parameters of standard Point A and magnetic resonance imaging-based three-dimensional optimized dose plans in 21 consecutive patients who underwent pulsed-dose-rate brachytherapy (PDR-BT) for locally advanced cervical cancer. Methods and Materials: All patients received external beam radiotherapy (elective target dose, 45 Gy in 25-30 fractions; tumor target dose, 50-60 Gy in 25-30 fractions). PDR-BT was applied with a tandem-ring applicator. Additional ring-guided titanium needles were used in 4 patients and a multichannel vaginal cylinder in 2 patients. Dose planning was done using 1.5 Tesla T{sub 1}-weighted and T{sub 2}-weighted paratransversal magnetic resonance imaging scans. T{sub 1}-weighted visible oil-containing tubes were used for applicator reconstruction. The prescribed standard dose for PDR-BT was 10 Gy (1 Gy/pulse, 1 pulse/h) for two to three fractions to reach a physical dose of 80 Gy to Point A. The total dose (external beam radiotherapy plus brachytherapy) was normalized to an equivalent dose in 2-Gy fractions using {alpha}/{beta} = 10 Gy for tumor, {alpha}/{beta} = 3 Gy for normal tissue, and a repair half-time of 1.5 h. The goal of optimization was dose received by 90% of the target volume (D{sub 90}) of {>=}85 Gy{sub {alpha}}{sub /{beta}}{sub 10} in the high-risk clinicalmore » target volume (cervix and remaining tumor at brachytherapy), but keeping the minimal dose to 2 cm{sup 3} of the bladder and rectum/sigmoid at <90 and <75 Gy{sub {alpha}}{sub /{beta}}{sub 3}, respectively. Results: Using three-dimensional optimization, all dose-volume histogram constraints were met in 16 of 21 patients compared with 3 of 21 patients with two-dimensional library plans (p < 0.001). Optimization increased the minimal target dose (D{sub 100}) of the high-risk clinical target volume (p < 0.007) and decreased the minimal dose to 2 cm{sup 3} for the sigmoid significantly (p = 0.03). For the high-risk clinical target volume, D{sub 90} was 91 {+-} 8 Gy{sub {alpha}}{sub /{beta}}{sub 10} and D{sub 100} was 76 {+-} 5 Gy{sub {alpha}}{sub /{beta}}{sub 10}. The minimal dose to 2 cm{sup 3} for the bladder, rectum, and sigmoid was 73 {+-} 6, 67 {+-} 6, and 69 {+-} 6 Gy{sub {alpha}}{sub /{beta}}{sub 3}, respectively. Conclusion: The results of our study have shown that magnetic resonance imaging-guided optimization of PDR-BT for locally advanced cervical cancer significantly improved the dose-volume histogram parameters.« less
Authors:
 [1] ; ;  [2] ;  [3] ;  [4]
  1. Department of Oncology, Aarhus University Hospital, Aarhus (Denmark), E-mail: jlind@as.aaa.dk
  2. Department of Medical Physics, Aarhus University Hospital, Aarhus (Denmark)
  3. Department of Biomedical Engineering, Aarhus University Hospital, Aarhus (Denmark)
  4. Department of Radiology, Aarhus University Hospital, Aarhus (Denmark)
Publication Date:
OSTI Identifier:
21124314
Resource Type:
Journal Article
Resource Relation:
Journal Name: International Journal of Radiation Oncology, Biology and Physics; Journal Volume: 71; Journal Issue: 3; Other Information: DOI: 10.1016/j.ijrobp.2007.10.032; PII: S0360-3016(07)04439-2; Copyright (c) 2008 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
62 RADIOLOGY AND NUCLEAR MEDICINE; BLADDER; BRACHYTHERAPY; CARCINOMAS; DOSE EQUIVALENTS; DOSE RATES; NMR IMAGING; OPTIMIZATION; PATIENTS; RADIATION DOSES; RECTUM; TITANIUM