Krishnamurthy Devan, Weinberg Vivian, Cunha J Adam M, Hsu I-Chow, Pouliot Jean
Department of Radiation Oncology, University of California San Francisco, UCSF Helen Diller Family Comprehensive Cancer Center, San Francisco, CA 94143-1708, USA.
Brachytherapy. 2011 Nov-Dec;10(6):461-5. doi: 10.1016/j.brachy.2011.01.012. Epub 2011 Mar 11.
Recent studies have identified that among different available radionuclides, the dose characteristics and shielding properties of ytterbium-169 ((169)Yb) and thulium-170 ((170)Tm) may suit high-dose rate (HDR) brachytherapy needs. The purpose of this work was to compare clinically optimized dose distributions using proposed (169)Yb and (170)Tm HDR sources with the clinical dose distribution from a standard microSelectron V2 HDR iridium-192 ((192)Ir) brachytherapy source (Nucletron B.V., Veenendaal, The Netherlands).
CT-based treatment plans of 10 patients having prostate volumes ranging from 17 to 92cm(3) were studied retrospectively. Clinical treatment of these patients involved 16 catheters and a microSelectron V2 HDR (192)Ir source. All dose plans were generated with inverse planning simulated annealing optimization algorithm. Dose objectives used for the (192)Ir radionuclide source were used for the other two radionuclides. The dose objective parameters were adjusted to obtain the same clinical target (prostate) volume coverage as the original (192)Ir radionuclide plan. A complete set of dosimetric indices was used to compare the plans from different radionuclides. A pairwise statistical analysis was also performed.
All the dose distributions optimized with specific (192)Ir, (169)Yb, and (170)Tm sources satisfied the standard clinical criteria for HDR prostate implants, such as those for the Radiation Therapy Oncology Group clinical trial 0321, for combined HDR and external beam treatment for prostate adenocarcinoma. For equivalent clinical target volume dose coverage, the specific (169)Yb and (170)Tm sources resulted in a statistically significant dose reduction to organs at risk compared with microSelectron V2 HDR (192)Ir source. This study indicates that a (170)Tm or (169)Yb radionuclide source may be an alternative to the (192)Ir radionuclide sources in HDR brachytherapy.
近期研究发现，在不同可用放射性核素中，镱 - 169（¹⁶⁹Yb）和铥 - 170（¹⁷⁰Tm）的剂量特性和屏蔽性能可能符合高剂量率（HDR）近距离放射治疗的需求。本研究的目的是将使用提议的¹⁶⁹Yb和¹⁷⁰Tm HDR源临床优化后的剂量分布与标准的microSelectron V2 HDR铱 - 192（¹⁹²Ir）近距离放射治疗源（荷兰维嫩达尔的Nucletron B.V.公司）的临床剂量分布进行比较。
回顾性研究了10例前列腺体积在17至92cm³之间患者基于CT的治疗计划。这些患者的临床治疗涉及16根导管和一个microSelectron V2 HDR ¹⁹²Ir源。所有剂量计划均采用逆向计划模拟退火优化算法生成。用于¹⁹²Ir放射性核素源的剂量目标也用于另外两种放射性核素。调整剂量目标参数以获得与原始¹⁹²Ir放射性核素计划相同的临床靶区（前列腺）体积覆盖。使用一整套剂量学指标来比较不同放射性核素的计划。还进行了成对统计分析。
所有使用特定的¹⁹²Ir、¹⁶⁹Yb和¹⁷⁰Tm源优化后的剂量分布均满足HDR前列腺植入的标准临床标准，例如放射治疗肿瘤学组临床试验0321中关于前列腺腺癌的HDR与外照射联合治疗的标准。对于等效的临床靶区体积剂量覆盖，与microSelectron V2 HDR ¹⁹²Ir源相比，特定的¹⁶⁹Yb和¹⁷⁰Tm源导致危及器官的剂量有统计学意义的降低。本研究表明，在HDR近距离放射治疗中，¹⁷⁰Tm或¹⁶⁹Yb放射性核素源可能是¹⁹²Ir放射性核素源的替代选择。
