In this paper is advanced a new type of collimator-dual sieve-mesh collimator.Its principle is to use scanned electronic beam to attack 400 matrix-arranged wolfram targets of the square holes on the upper side of the main collimator and created 400 small X-ray fields sized by 10mm×10mm.These X-ray fields will leave on its center 400 smaller X-ray fields sized by 5mm×5mm after being further collimated by a sub-collimator. What's more,16 different groups of such X-ray fields can be left on the center of the same field by controlling the all-round movement of the main collimator and sub-collimator in proper order and by scanning it round by round and mesh by mesh with electronic beams.It is these ting fields groups that make up various treatment fields with different energy (Dosage).This type of collimator can replace and simplify all other present collimators on accelerators and conformal-intensity modulation radiotherapy equipments. It has advantage of reducing the costs of radio-therapy equipment and making conformal and intensity modulation radiotherapy easier to perforn.

Neuropathic pain has been hypothesized to be the result of aberrant expression and function of sodium channels at the site of injury. To investigate the effects of NaV1.8 antisense oligonucleotide on the expression of sodium channel mRNA in dorsal root ganglion (DRG) neurons in chronic neuropathic pain. 24 Sprague-Dawley rats weighing 200-260 g were anesthetized with the in of sciatic nerve trunk by 4-0 chromic gut. The mechanical and thermal pain threshold were measured before operation and 1, 3, 5, 7, 9, 11, 13 days after operation. A PE-10 catheter was implanted in subarachnoid space at lumbar region. On the 7th postoperative day the animals were randomly divided into 4 groups. The drugs were injected intrathecally twice a day for 5 consecutive days in group 2-4. The animals were decapitated 14 days after the surgery. The L4-L6 DRG of the operated side was removed and crushed, and total RNA was extracted with Trizol reagent. The contralateral side was used as control. The change of NaV1.8 sodium channel transcripts was determined by RT-PCR. Pain threshold was significantly lowered after CCI as compared with that in control group and was elevated 3 days after antisense oligonucleotide injection. Sensory neuron specific TTX-R sodium channel NaV1.8 transcript was down-regulated after antisense oligonucleotide injection at the dosage of 45 μg as compared with that in CCI group (P＜0.01), and it was even greater at the dosage of 90 μg. The intrathecally injected NaV1.8 antisense oligonucleotide can reduce the mechanical allodynia and thermal hyperalgesia partially by downregulating the SNS transcript expression.