The Impact of Variation in Bladder Volume on the Doses of Target and Organ-at-Risk in Intensity-Modulated Radiation Therapy for Localized Prostate Cancer

Intensity-modulated radiation therapy (IMRT) has become the mainstay of treatment for localized prostate cancer. In IMRT, minimizing differences between the conditions used during planning CT and daily treatment is important to prevent adverse events in normal tissues. In the present study, we evaluated the impact of variation in bladder volume on the doses to various organs. A total of 35 patients underwent definitive radiotherapy at Saitama Medical Center. A Light Speed RT16 (GE Healthcare) was used for planning and to obtain examination CT images. Such images were acquired after 4 - 6 days of planning CT image acquisition. The IMRT plans were optimized using the planning CT data to satisfy the dose constraints set by our in-house protocols for the PTV and the OARs. The dose distributions were then re-calculated using the same IMRT beams, and checked on examination CT images. It was clear that bladder volume affected the doses to certain organs. We focused on the prostate, bladder, rectum, small bowel, and large bowel. Regression coefficients were calculated for variables that correlated strongly with bladder volume (p < 0.05). We found that variation in bladder volume [cm3] predicted deviations in the bladder V70Gy, V50Gy, and V30Gy [%];the maximum dose to the small bowel [cGy];and the maximum dose to the large bowel [cGy]. The regression coefficients were -0.065, -0.125, -0.180, -10.22, and -9.831, respectively. We evaluated the impacts of such variation on organ doses. These may be helpful when checking a patient’s bladder volume before daily IMRT for localized prostate cancer.

Evaluation of Quality of Life and Psychological Response in Recurrent and Metastatic Tumors Treated with Palliative Radiotherapy

Objective: We evaluated the effects of palliative radiotherapy for cancer recurrence or metastasis on patient QOL and psychophysiology. Materials and Methods: Sixty seven patients who received palliative radiotherapy between 2014 and 2015 were enrolled. Patient diseases were bone metastasis in 51 patients, lymph node metastasis in 7 patients, brain metastasis in 2 patients, local recurrence in 3 patients, and others in 4 patients. Median irradiated dose was 30 Gy in 10 fractions for palliative radiotherapy. We used the questionnaires EORTC-QLQ-C30 and EORTC-QLQ-C15-PAL to evaluate patient QOL and the Hospital Anxiety and Depression Scale to evaluate patient mental healthcare at the start and at the end of radiotherapy. Results: As compared to scores at the start of radiotherapy, at the end of radiotherapy, NRS and face scale significantly decreased. On the other hand, Eastern Cooperative Oncology Group Performance Status did not show any changes during palliative radiotherapy. In functional scales, average scores of RF2 and EF also improved. In symptom scales, average scores of FA, PA, and SL improved. In bone metastasis group, global health status/QOL, PA, and SL significantly improved. There was relationship between anxiety improvement and QOL improvement after palliative radiotherapy. Nausea and vomiting scores of EORTC-QLQ-C15-PAL were associated with the irradiated volume of palliative radiotherapy for pelvic region. Conclusion: Patient QOL of was improved by palliative radiotherapy regardless of PS. The possibility of palliative radiotherapy having a positive influence on patient psychophysiology was also suggested in younger age.

单次满肺活量吸入稳定氙气后屏息时使用双能CT进行通气成像

目的评估使用双能CT在虚拟实验和志愿者中实现单次屏息技术下的制图。材料和方法公共审查委员会批准了这项研究，并且得到了所有志愿者的书面知情同意。用装有锡过滤材料（100kV和Sn／140kV）的双源双能CT（80kV和140kV）扫描充满氙气（0％～35．4％）和氧气混合气体的橡胶袋。一个包含6个相同尺寸不同孔径的管道的气缸用35％氙气和65％氧气的混合气体通气1次并用双源方法扫描（80kV和Sn／140kV）。通过三材料分解的方法取得氙气增强图像。4名志愿者在2次单次满肺活量吸气并憋气后进行双源扫描（80kV和Sn／140kV），一次吸入空气（无增强），另一次吸入35％氙气。氙气增强的图像通过2种方法取得：三材料分解法和氙气增强图像的无增强减影法。在有效性级别设置在0．05的基础上，T实验和F实验衰退分析被应用在橡胶袋扫描的数据分析上。结果对于所有的X线管电压值（r^2=0，P〈0．00001），袋中气体的平均像素值与氙气浓度成线性关系。管道的氙气增强图像的像素值与其气孔尺寸的大小相关。类似的像素值（CV：0．22，0．23和0．34）在健康志愿者的肺部能检测到，气管的像素值较高，肺大疱的像素值较低。用三材料分解法计量的氙气增强图像在视觉对比上优于通过减影法得到的结果。结论氙气增强双源CT单次屏气技术可以在模体和4名志愿者身上描绘出通气图像。