Objective:To evaluate the short-term efficacy of modified laparoscopic extralevator abdominoperineal excision (L-ELAPE) for ultralow rectal cancer.Methods:The retrospective cohort study was conducted.The clinicopathological data of 60 patients with ultralow rectal cancer who underwent L-ELAPE in the Tangdu Hospital Affiliated to the Air Force Medical University from January 2014 to July 2018 were collected. There were 32 males and 28 females, aged (58±12)years, with a range from 38 to 75 years. Of the 60 patients, 30 patients undergoing modified L-ELAPE were allocated into modified group and 30 patients undergoing traditional L-ELAPE were allocated into control group. For patients in the modified group, the abdominal procedure is the same as the traditional L-ELAPE. The improvements were as follows: (1) when tumor was located in the anterior rectal wall, the patient was plased into the jackknife position before starting the perineal procedure. (2) In order to prevent the small intestine from falling into the presacral space after surgery, the pelvic floor peritoneum was closed under laparoscopy and the biological patch was placed if necessary. For patients in the control group, the whole procedure was performed in the lithotomy position and the biological patch was sutured at the levator ani muscle. Observation indicators: (1) surgical situations; (2) postoperative situations; (3) follow-up. Follow-up was conducted by outpatient examinations and pelvic computed tomography (CT) examination at 3 months after surgery to assess the small intestine falling into the presacral space up to January 2019. Measurement data with normal distribution were represented as Mean± SD, and comparison between groups was analyzed using the t test. Count data were described as absolute numbers, and comparison between groups was analyzed using the chi-square test or Fisher′s exact probability. Results:(1) Surgical situations: patients in the two groups completed surgeries successfully, without tranversion to laparostomy or death within 1 month after operation. The operation time, volume of intraoperative blood loss, the number of lymph node harvested, quality score of the whole group specimens, quality score of anterior wall tumor specimens were (359±105)minutes, (192±99)mL, 17±6, 4.1±0.8, 4.7±0.5 for the modified group, respectively, versus (268±37)minutes, (136±61)mL, 15±5, 3.5±0.7, 3.9±0.7 for the control group, respectively. There were significant differences in the operation time, the quality score of the whole group specimens and the quality score of anterior wall tumor specimens between the two groups ( t=2.613, 2.130, 2.871, P<0.05). There was no significant difference in the volume of intraoperative blood loss or the number of lymph node harvested between the two groups ( t=1.521, 0.864, P>0.05). (2) Postoperative situations: the time to first liquid food intake, time to urinary catheter removal, the level of C-reactive protein at the first postoperative day, duration of postoperative hospital stay and cases with perineal complications were (3.3±1.1)days, (8.7±4.8)days, (85±27)mg/L, (8.5±4.5)days and 4 for the modified group, respectively, versus (2.7±1.4)days, (7.7±2.8)days, (79±25)mg/L, (7.7±2.2)days and 5 for the control group. There was no significant difference in the time to first liquid food intake, time to urinary catheter removal, the level of C-reactive protein at the first postoperative day, duration of postoperative hospital stay between the two groups ( t=1.311, 1.520, 0.521, 0.509, P>0.05). There was no significant difference in the perineal complications between the two groups ( P>0.05). All patients with perineal complications were cured after drainage, wound management, nutritional support and extention of hospital stay. (3) Follow-up: all patients were followed up after surgery. The modified group and the control group had 2 cases and 19 cases of small intestine falling into the presacral space showed by the pelvic CT examination at the postoperative 3 months, respectively, showing a significant difference between the two groups ( χ2=21.172, P<0.05). Conclusions:Modified L-ELAPE is safe and feasible for the ultralow rectal cancer, which can provide a better exposure and specimen quality for the tumor located at anterior rectal wall and reduce the incidence of small intestine falling into the presacral space. However, it has longer operation time.

Objective Based on the anthropomorphic phantom experiment and Monte Carlo simulation, the patients’ skin dose, professionals’ dose, and spatial distribution of DSA (Digital Subtraction Angiography) radiation field in an intervention procedure, was performed, in order to provide the basis for the inference of patients’ skin injury and professionals’ radiation protection in intervention procedure. Methods In the simulation experiment, a PBU-60 anthropomorphic phantom was used as the patient and the skin dose of patient’s abdomen was measured by TLD (Thermoluminescence Dosimeters). X-ray and gamma radiation dosimeter (AT1121) was applied to measure the spatial distribution of DSA radiation field, which was verified using Monte Carlo software MCNP meanwhile. Furthermore, the radiation dosimetry of operative staffs at different stations and under different protection conditions was studied experimentally. Results The experimental measurements showed that the maximum skin dose of patients every 5-minute fluoroscopy was 18.62 mGy under the irradiation of PA in an abdominal interventional procedure. The results of Monte Carlo simulation and measurement experiments showed that the spatial distribution of DSA radiation fieldis similar to the butterfly distribution, which is related to distance and angle. The experimental results showed that the dose rate decreases exponentially with the increase of lead equivalent. Conclusion It is very significant to carry out skin dose measurementof patients during interventional surgery and follow-up patients with high dose after surgery. In interventional surgery, doctors should try to avoid the station of high dose rate. However, it is necessary to strengthen the radiation protection of the operator and the first assistant. Under the dual protections of bedside lead protective equipment and personal protective equipment, the exposure dose of intervention personnel can be significantly reduced.