ABSTRACT
Objective To evaluate the radiation dose from a dual energy X-ray absorptiometry (DXA) study. Methods A Radcal multifunctional dosimeter (1800 cc ionization chamber, USA) was used, for purpose of comparison, to measure the entrance surface doses (ESD) from Norland XR-800 DXA ( pencil beam scan, 100/46. 8 kVp, 1. 3 mA) and from Hologic Discovery A DXA ( fan beam scan, 140/100 kVp, 5. 0 mA) . Ambient dose equivalent rate at 1 m away from studied phantom center and at 1 m above floor was measured using the US 451P ionizaion chamber survey meter ( Fluke, USA). Results The ESD measured using a Radcal dosimeter for Norland XR-800 DXA was 0. 43 μGy in high speed mode and 0. 73 μGy in standard mode ( AP spine ) , 1. 93 μGy ( hip ) , 0. 40 μGy ( wrist ) and 1. 06 μGy ( mandible) . The ESD measured for Hologic Discovery A DXA was 65. 6 μGy ( AP spine) and 63. 9 μGy ( hip) . The ESD measured for Norland XR-800 at different scan types and scan speeds was <2 μGy while Hologic Discovery A DXA showed a result of <66 μGy ( AP spine and hip scan ) , which were both consistent with the data given in their own respective operational manual. A comparison of DXA scanners with fan beam and pencil beam indicated that ambient equivalent dose rate, measured with 451P survey meter, from fan beam scan was 65 times that from pencil beam scan. Conclusions Compared with other medical X-ray studies, the ESD to the phantom undergoing a DXA study is relatively low. DXA pencil beam scan doses to lumbar spine and hip were about 1/153-1/33 of those from DXA fan beam scan. Pencil beam scan dose to DXA staff was negligible and fan beam scan dose to DXA staff was lower than the personal dose limits of 20 mSv per year.
ABSTRACT
Objective To summarize the experience in transanal local excision (LE) for rectal cancer (RC). Methods The clinical data of 28 cases of RC treated by LE from 1988 to 1998 were analyzed retrospectively. Results In this series, five-year survival rate was 83.4?6.2%, and the local recurrence rate (LRR) was 17.8%. In well-differentiated carcinoma, 4 cases were convinced as local recurrence with a LRR of 17.4%(4/23); in moderately- differentiated carcinoma, one case with a LRR of 20.0%(1/5). The LRR in T 1 and T 2 group was 15.0% (3/20) and 25.0% (2/8) respectively. LRR was 16.7% (4/24) in patients with less than 1/3 bowel wall involved, LRR was 16.7%(4/24),whereas LRR was 25.0%(1/4) in more than 1/3 bowel wall involved group. In total bowel wall resection group the LRR was 16.7%(3/18) while in partial resection group was 20.0% (2/10). In patients with tumour size larger than 4 cm LRR was 22.2% (2/9), tumour size smaller than 4 cm LRR was 15.7% (3/19). Conclusion LE for RC might only be successfully performed in selected patients (T 1～T 2, N 0M 0, well or moderately-differentiated carcinoma,low RC within 6 cm from anal edge). The indications of transanal LE must be controlled strictly. Total excision of tumor and prevention of implantation of carcinoma are the main points in the prophylaxes of recurrence. Postoperative follow-up is needed in order to find local recurrence as early as possible.