Background Postmenopausal osteoporosis (PMOP) has long been a pervasive public health concern. With the aging Chinese population, the prevention, assessment and management of postmenopausal osteoporosis were particularly important. During the breastfeeding, a large amount of Calcium loss from maternal bone for infants’ growth. However, whether this loss is completely reversible remains controversial. As the relationship between breastfeeding and postmenopausal osteoporosis is different from society to society and is not clear from the literature, the purpose of this study was to determine whether breastfeeding was an independent factor for the development of PMOP based on Chinese postmenopausal population. Methods A retrospective cross-sectional investigation was conducted at Tianjin Xiaobailou health Community Healthcare Center between December 2017 and June 2018. Postmenopausal women over the age of 50 who underwent the annual health examination or visited the center to perform bone densitometry as a part of routine screening for disease were recruited. A trained community nurse administered a questionnaire to all participants by face-to-face interview. Participants were questioned about age, BMI, Vitamin D and calcium intake, the history of smoking, drinking and fracture, age of menarche, age of menopause, the number of pregnancy, parity, feeding pattern (breastfeeding, artificial feeding and mixed feeding) and overall breastfeeding duration. BMD measurements were carried out using quantitative ultrasound (QUS) at the bilateral radius. Results A total of 202 women who met the inclusive and exclusive criteria were enrolled. Univariate analysis revealed that overall breastfeeding more than 24 months increased the risk of osteoporosis (OR 39.00, 95%CI 2.40–634.65, p = 0.010). However, multivariate estimate of the risk of osteoporosis by overall breastfeeding duration suggested that when controlling for age, BMI, the number of pregnancy and parity, the overall breastfeeding duration was not an independent risk factor for postmenopausal osteoporosis (OR 5.22, 95%CI 0.18–147.76, p = 0.333). Additionally, age (OR 1.16, 95%CI 1.05–1.29, p = 0.003), BMI (OR 1.26, 95%CI 1.04–1.54, p = 0.021) and the number of pregnancy (OR 1.80, 95%CI 1.08–2.98, p = 0.024) were significant associated with postmenopausal osteoporosis. Conclusion Breastfeeding was not associated with postmenopausal osteoporosis, while age, BMI and the number of pregnancy may contribute to increasing risk of postmenopausal osteoporosis in Chinese women. Electronic supplementary material The online version of this article (10.1186/s12905-019-0808-0) contains supplementary material, which is available to authorized users.

Background An accurate, reproducible, and comfortable immobilization device is essential for stereotactic radiotherapy (SBRT) in patients with lung cancer. This study compared thermoplastic masks (TMP) and vacuum cushion (VCS) system to assess the differences in interfraction and intrafraction setup accuracy and the impact of body mass index (BMI) with respect to the immobilization choice. Methods This retrospective study was conducted on patients treated with lung SBRT between 2012 and 2015 at the Zhejiang cancer hospital. The treatment setup accuracy was analyzed in 121 patients. A total of 687 cone beam computed tomography (CBCT) scans before treatment and 126 scans after treatment were recorded to determine the uncertainties, and plan target volume margins. Data were further stratified and analyzed by immobilization methods and patients’ BMI. The t-test (Welch) was used to assess the differences between the two immobilization systems when stratified by the patients’ BMI. Results For patients with BMI ≥ 24, the mean displacements for the TMP and VCS systems were 1.4 ± 1.2 vs. 2.4 ± 2.0 mm at medial-lateral (ML) direction ( p < 0.001); 2.0 ± 1.9 vs. 2.0 ± 1.9 mm at cranial-caudal (CC) direction ( p = 0.917); and 2.4 ± 1.4 vs. 2.6 ± 2.1 mm at anterior-posterior (AP) direction, ( p = 0.546). The rate of acceptable errors increased dramatically when immobilized by TMP. In the case of patients with BMI < 24, the mean displacements for the TMP and VCS systems were 1.8 ± 1.4 vs. 2.1 ± 1.8 mm at ML direction ( p = 0.098); 2.9 ± 2.3 vs. 2.2 ± 2.2 mm at CC direction ( p = 0.001); and 1.8 ± 1.8 vs. 2.3 ± 2.0 mm at CC direction, ( p = 0.006). The proportion of acceptable errors increased after immobilization by VCS. No difference was detected in the intrafraction setup error by different immobilization methods. Conclusions The immobilization choice of SBRT for lung tumors depends on the BMI of the patients. For patients with BMI ≥ 24, TMP offers a better reproducibility with significantly less interfractional setup displacement than VCS, resulting in fewer CBCT scans. However, VCS may be preferred over TMP for the patients with BMI < 24. Therefore, an optimal immobilization system needs to be considered in different BMI groups for lung SBRT.

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