Department of Radiation Oncology, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA.
Int J Radiat Oncol Biol Phys. 2011 Oct 1;81(2):545-51. doi: 10.1016/j.ijrobp.2010.11.030. Epub 2011 Jan 27.
To incorporate a quality control tool, according to previous planning experience and patient-specific anatomic information, into the intensity-modulated radiotherapy (IMRT) plan generation process and to determine whether the tool improved treatment plan quality.
A retrospective study of 42 IMRT plans demonstrated a correlation between the fraction of organs at risk (OARs) overlapping the planning target volume and the mean dose. This yielded a model, predicted dose = prescription dose (0.2 + 0.8 [1 - exp(-3 overlapping planning target volume/volume of OAR)]), that predicted the achievable mean doses according to the planning target volume overlap/volume of OAR and the prescription dose. The model was incorporated into the planning process by way of a user-executable script that reported the predicted dose for any OAR. The script was introduced to clinicians engaged in IMRT planning and deployed thereafter. The script's effect was evaluated by tracking δ = (mean dose-predicted dose)/predicted dose, the fraction by which the mean dose exceeded the model.
All OARs under investigation (rectum and bladder in prostate cancer; parotid glands, esophagus, and larynx in head-and-neck cancer) exhibited both smaller δ and reduced variability after script implementation. These effects were substantial for the parotid glands, for which the previous δ = 0.28 ± 0.24 was reduced to δ = 0.13 ± 0.10. The clinical relevance was most evident in the subset of cases in which the parotid glands were potentially salvageable (predicted dose <30 Gy). Before script implementation, an average of 30.1 Gy was delivered to the salvageable cases, with an average predicted dose of 20.3 Gy. After implementation, an average of 18.7 Gy was delivered to salvageable cases, with an average predicted dose of 17.2 Gy. In the prostate cases, the rectum model excess was reduced from δ = 0.28 ± 0.20 to δ = 0.07 ± 0.15. On surveying dosimetrists at the end of the study, most reported that the script both improved their IMRT planning (8 of 10) and increased their efficiency (6 of 10).
This tool proved successful in increasing normal tissue sparing and reducing interclinician variability, providing effective quality control of the IMRT plan development process.
根据先前的计划经验和患者特定的解剖信息，将质量控制工具纳入调强放疗（IMRT）计划生成过程，并确定该工具是否能提高治疗计划质量。
对 42 例 IMRT 计划进行回顾性研究，发现危及器官（OAR）的部分与计划靶区重叠与平均剂量之间存在相关性。这产生了一个模型，预测剂量=处方剂量（0.2+0.8[1-exp（-3 重叠计划靶区/ OAR 体积）]），根据计划靶区重叠/OAR 体积和处方剂量预测可实现的平均剂量。该模型通过一个可执行脚本的方式纳入规划过程，该脚本报告任何 OAR 的预测剂量。该脚本被引入到参与 IMRT 规划的临床医生手中，并在此后部署。通过跟踪δ=（平均剂量-预测剂量）/预测剂量，即平均剂量超过模型的分数，来评估脚本的效果。
所有受研究影响的 OAR（前列腺癌中的直肠和膀胱；头颈部癌症中的腮腺、食管和喉咙）的δ和变异性均减小。这些影响在腮腺中非常显著，其中之前的δ=0.28±0.24 降低到了δ=0.13±0.10。在腮腺有潜在挽救机会的病例亚组中，临床相关性最为明显（预测剂量<30Gy）。在脚本实施之前，平均有 30.1Gy 被输送到有挽救机会的病例中，平均预测剂量为 20.3Gy。在实施之后，平均有 18.7Gy 被输送到有挽救机会的病例中，平均预测剂量为 17.2Gy。在前列腺病例中，直肠模型过量从δ=0.28±0.20 降低到了δ=0.07±0.15。在研究结束时调查剂量师，大多数人报告该脚本既提高了他们的 IMRT 规划（10 人中的 8 人），又提高了他们的效率（10 人中的 6 人）。
该工具在增加正常组织的保护和减少临床医生间的变异性方面取得了成功，为 IMRT 计划开发过程提供了有效的质量控制。
