Objective:To verify radiation shielding effect of the maze of the CyberKnife room, so as to identify and correct the deficiencies in the shielding designs in certain circumstances.Methods:In line with the radiation protection shielding design scheme of the CyberKnife room provided by the producer, the consideradtions are focused on the useful beam that could mainly pass through the image center, but not the outer wall of the maze. However, during the inspection and acceptance of radiological protection in the built room, it was found that in a certain situations useful wire did not pass through the imaging center. Therefore, the additional shielding and protection facilities were built and verified.Results:After verification and acceptance on the scene, in the case where the useful beam was passing through the image center, the highest ambient dose equivalent rate at the concerned points 30 cm away from the outer wall of the maze was 0.31 μSv/h, less than the control level 10 μSv/h. In the opposite case, the highest ambient dose equivalent rate at the same points as above was 301.67 μSv/h, ablut 30 times as much as the control level. After the thickness in maze outer wall was enhanced, the highest ambient dose equivalent rate at the same as above was 2.14 μSv/h. This testing result met the concerned national standard.Conclusions:It is desirable that in designing the outer wall shielding in the maze in a CyberKnife room, attention should be paid to whether or not the useful beam could pass through the image center, or otherwise directly irradiate on the maze on the basis of the movement range of the accelerator. Shielding wall thickness should be calculated on the basis of the irradiation ragne and the distance between source location and the concerned points to ensure being in compliance with the requirements of the concerned national standard. Meanwhile, it should protect the workers occupying at the concerned locations from receiving higher radiation doses.

Objective:To study the level of CT dose to paediatric patients in Tianjin, and to provide basic data for establishing the diagnostic reference levels for paediatric patients from CT examinations in Tianjin.Methods:In 2022, a general survey was carried out of the CT doses to the head, chest, abdomen and pelvis of the scanned paediatric patients in two tertiary pediatric hospitals and seven tertiary general hospitals in Tianjin. The scanned pediatric patients were divided into four age groups in terms of the age of -1, -5, -10 and -15 years, and 20 patients were investigated in each age group in each hospital. The basic information were collected on the scanned patients, CT scanning parameters, volume CT dose index (CTDI vol), dose length product (DLP), and the differences in CTDI vol and DLP on the same site among different age groups and different types of hospitals were analyzed. Results:There were significant differences in CTDI vol and DLP between different age groups at the same site (head, chest, abdominal and pelvic, CTDI vol:χ2=296.51, 193.82, 291.72, P<0.001; DLP: χ2=291.22, 263.63, 344.97, P<0.001). There were significant differences in CTDI vol and DLP among different types of hospitals on the same site (head, chest, abdominal and pelvic, CTDI vol:Z=-13.13, -7.57, -15.27, P<0.001; DLP: Z=-9.07, -6.15, -11.57, P < 0.001). Conclusions:The 75 th percentile values of CTDI vol and DLP for pediatric head, chest, abdomen and pelvis CT scanning in tertiary hospitals in Tianjin are at a good level, and the dose on some examination sites are relatively high. Further optimization of pediatric CT scanning procedures is necessary.

Objective:To investigate the safety and efficacy of sacral neuromodulation(SNM)therapy for the treatment of lower urinary tract dysfunction(LUTD)in elderly patients.Methods:Clinical data of 91 elderly patients with LUTD from multiple medical institutions who received SNM during the period from January 2012 to December 2016 were retrospectively analyzed.Patients were divided into four groups: the interstitial cystitis(IC)group(n=28), the neurogenic bladder(NB)group(n=36), the overactive bladder syndrome(OAB)group(n=13)and the idiopathic dysuria(ID)group(n=14). Different sets of evaluation parameters were used for different diseases.Patients’ baseline data and data in stage I(test phase)and stage Ⅱ(permanent SNM)were recorded, statistically analyzed and compared.Results:Ninety-one people underwent SNM treatment.Of them, 53 patients received permanent implants(stage Ⅱ), and the total conversion rate of stage I to stage Ⅱ was 58.2%(53/91). Patients receiving permanent implants(stage Ⅱ)had a preoperative period ranging from 3 months to 30 years, and were followed up for 2 to 58 months after treatment, with an average follow-up of 19.6 months.The improvement rates in stage I for urinary urgency, daily urination frequency, daily nocturnal urination frequency, maximum urine volume, daily average urine volume, daily urine leakage frequency, and quality of life score were 35.4%, 31.6%, 33.7%, 32.6%, 49.2%, 43.2% and 13.2%, respectively.The improvement rates in stage Ⅱ for urinary urgency, daily urination frequency, daily nocturnal urination frequency, maximum urine volume, daily average urine volume, daily urine leakage frequency, and quality of life score were 43.2%, 40.0%, 37.8%, 50.5%, 70.5%, 70.4% and 43.2%, respectively.Three adverse events occurred, including 1 case of recurrent symptoms, 1 case of moderate infection, and 1 case of electrical lead dislocation.Conclusions:Sacral nerve stimulation has definitive and consistent curative effects on LUTD in elderly people.The follow-up time should be extended to further study the safety of sacral nerve stimulation.