Evaluation of Setup Errors at the Skin Surface Position for Whole Breast Radiotherapy of Breast Cancer Patients

We used image-processing software to analyze the setup errors at the skin surface position of breast cancer patients (n=66) who underwent post-operative whole breast irradiation at our hospital in 2014-2015. The sixty-six digital reconstructed radiographs (DRR) were created at the treatment planning for each patient. The lineacgraphies (n=377) were taken after the patients’ setup during radiotherapy. The lineacgraphies and DRR were superimposed at the skin surface position for each patient with the image-processing software. We measured the deviations of the isocenters for the nipple-lung (X) direction and craniocaudal (Y) direction and the deviation of the rotation angle of the XY axes between the lineacgraphy and DRR on the superimposed images. The systematic error (μ, Σ) and random error (σ) were calculated from the X and Y deviations and rotation angle deviation. The μ of X, Y, and rotation angle were 0.01 mm, −1.2 mm, and 0.05°, respectively. The Σ of X, Y, and rotation angle were 1.8 mm, 1.5 mm, and 0.9°, respectively. The σ of X, Y, and rotation angle were 2.0 mm, 1.5 mm, and 1.0°, respectively. Our analyses thus revealed that evaluations using image-processing software at the skin surface position in routine breast radiotherapy result in sufficiently small setup errors

Investigation into the Effect of Breast Volume on Irradiation Dose Distribution in Asian Women with Breast Cancer

Reports on irradiation dose distribution in breast cancer radiotherapy with sufficient sample size are limited in Asian patients. Elucidating dose distribution in Asian patients is particularly important as their breast volume differs compared to patients in Europe and North America. Here, we examined dose distribution in the irradiation field relative to breast volume for three irradiation methods historically used in our facility. We investigated the influence of breast volume on each irradiation method for Asian women. A total of 573 women with early-stage breast cancer were treated with breast-conserving surgery and adjuvant radiotherapy. Three methods were compared: wedge (W), field-in-field (FIF), and wedge-field-in-field (W-FIF). In patients with small breast volume, FIF decreased low- and high-dose areas within the planning target volume, and increased optimal dose area more than W. In patients with medium and large breast volumes, FIF decreased high-dose area more than W. The absolute values of correlation coefficients of breast volume to low-, optimal-, and high-dose areas and mean dose were significantly lower in FIF than in W. The correlation coefficients of V107% were 0.00 and 0.28 for FIF and W, respectively. FIF is an excellent irradiation method that is less affected by breast volume than W in Asian breast cancer patients

ショウワキチ ニ オケル チジョウ エアロゾルモニタリング

昭和基地において1996年2月から0.3 μm以上の大粒子の粒径分布,1997年4月から0.01 μm以上の凝結核濃度の連続観測を開始した.2008年12月までの観測結果より,凝結核濃度は夏に高濃度,大粒子は冬に高濃度となる1年周期の変動を繰り返し,経年的に濃度上昇をしている可能性が示唆された.微小粒子濃度,粗大粒子濃度は夏季に低濃度,冬季に高濃度となることに加え,冬期間中の0.3 μm以上の粒子数濃度が7月の前後で約2倍に急上昇していることが示された.Concentrations of condensation nuclei (>0.01 μm in diameter) and of aerosol particles larger than 0.3 μm in diameter were monitored at Syowa Station from February, 1996. Number concentrations of condensation nucleus were high in summer and low in winter. Concentrations increased at the rate of several partcles cm^3 per year. On the other hand, the concentrations of fine particles (>0.3 μm) and coarse particles (>1.0 μm) were low in summer and high in winter. Concentrations of fine particles 0.3 μm and larger after July were double those before July