Objective To evaluate the patient dose from Hi-ART MV helical CT imaging in image-guided radiotherapy.Methods Weighted CT dose index (CTDI_W) was measured with PTW TM30009 CT ion chamber in head and body phantoms,respectively,for slice thicknesses of 2,4,6 mm with scanned range of 5 cm and 15 cm.Dose length products (DLP) were subsequently calculated.The CTDI_W and DLP were compared with XVI kV CBCT and ACQSim simulator CT for routine clinical protocols.Results An inverse relationship between CTDI and the slice thickness was found.The dose distribution was inhomogeneous owing to the attenuation of the couch.CTDI and DLP had close relationship with the slice thickness and the scanned range.Patient dose from MVCT was lower than XVI CBCT for head,but larger for body scan.Results CTDI_W can be used to assess the patient dose in MV helical CT due to its simplicity for measurement and reproducibility.Regular measurement should be performed in QA & QC program.Appropriate slice thickness and scan range should be chosen to reduce the patient dose.

OBJECTIVETo explore the dose-length product calibration method for pencil ionization chamber in cobalt beams.

METHODSThe PTW TM30009 ionization chamber was placed into the central hole of T40017 head phantom and irradiated 60 s in 20 cm x 20 cm cobalt beam. The charge was collected with UNIDOS electrometer. Absorbed doses were measured with TM30013 0.6 mL farmer-type chamber under the same condition. The CT chamber calibration factor was expressed in dose-length product. Dose linearity and spatial response were also investigated.

RESULTSThe calibration factor in dose-length product was derived from measured data. Dose linearity and spatial response were good in cobalt beams.

CONCLUSIONIt is feasible to calibrate the CT chamber in cobalt beams for patient dose evaluation in MVCT.

Objective To calculate the mean absorbed doses at celluar and subcellular levels for uniformly and non-uniformly distributed Auger electron emitters. Methods The energy deposited in cell or nucleus by Auger electrons was analytically calculated using the polynomial representation of energy loss.S-values were subsequently computed for several target-source combinations.The absorbed dose and dose distribution were calculated for spherically symmetric radionuclide distributions depending linearly and exponentially on the radial position.The dose profile as a function of the source radial coordinate was also evaluated for typical cell sizes.The contributions of photon radiation to absorbed dose in cells were ignored. Results The mean absorbed dose and dose distribution depend largely on the size of target cells,the radiation spectrum and intracellular localization and distribution of radionuclides.The contribution of intranuclear radionuclides to mean absorbed dose was larger than that of extranuclear ones. Conclusion Auger electrons can produce high local energy deposition in cells because of their very low energies and extremely short ranges.Our dose calculation method is simple.The results are reliable and can be used in many fields.

easurement should be performed in QA & QC program. Optimal image parameters should be chosen to reduce the scanning range and patient dose.

Objective To develop a new automatic detection algorithm of the diaphragm motion based on Canny edge detection and wavelet transform.Methods On-line fluoroscopic images under free breathing were enhanced by using the wavelet transform.After the wavelet transform,edge detection was carried out for the enhanced image.Canny edge detection algorithm was used to achieve the diaphragm edge.Programs were written in Matlab to track the position of the diaphragm.The diaphragm movement curves were derived to evaluate the characteristics of patients respiratory motion.Results Under calm free breathing,the amplitude and period of diaphragm motion acquired by means of the wavelet transform and Canny edge detection were in good agreement with manual measurement.There were six to seven respiratory cycles in a XVI MotionViewTM.The magnitude of diaphragm movement was not exactly the same in the cranio-caudal (CC) direction.The magnitude was from 6.7 mm to 8.0 mm with an average of 7.4 mm.The movements of the respiratory motion cycles had little variations in amplitude and period for the same patient between fractions except emotional excitement or cough.Conclusions The automatic diaphragm detection methods developed in this paper are precise,and can effectively reflect the characteristics of the respiratory motion.The method can save much time and improve the measure precision greatly compared with the manual measurement.

Hypoxia inducible factor-1α(HIF-1α) is usually highly expressed in tumor cells,and can promote tumor growth.HIF-1α is correlated with tumor condition,the diagnosis and the prognosis.Therefore,HIF-1α can be used for tumor treatment in the level of transcriprion,pro-transcriprion and target.It is possible to improve the treatment efficiency,and to lengthen patients lifespan.

Objective Explore the regulation of haw and Red Sage on blood lipid. Method Use high-lipid forage to make animal model, the bland group of 8 animals were administered with general forage(blank control); the high-lipid forage group of 42 with high-lipid forage; the model-making group was divided randomly into 5 groups, i.e. model, Shujiang, haw, Red Sage, haw and Red Sage groups. After 14 days, respectively measure serum TC,TG,HDL-C,LDL-C contents, as well as plasma SOD activity. Result Haw and Red Sage in combination can reduce TC,TG, LDL, raise HDL contents, and markedly lower SOD activity. Conclusion Haw and Red Sage in combination can function to regulate blood lipid.

Objective To compare the dosimetric differences between helical tomotherapy (HT) and volume-modulated arc therapy (VMAT) in the treatment of upper thoracic esophageal carcinoma (UTEC).Methods A total of 10 patients with UTEC were randomly selected.HT plan and double-arc VMAT plan were designed and optimized for each patient.The prescription dose was 50 Gy/30 fractions for gross target volume (GTV), 66 Gy/30 fractions for planned target volume (PTV).The dose distribution and conformal index (CI), homogeneity index (HI) of target volume, the D1％, D5％, Dg5％, D99％, and dose of organ at risk (OAR) were analyzed by using the dose volume histogram (DVH).The monitor units and delivery time were also evaluated.Results For GTV and PTV, the D99％ of HT plans were slightly higher than those of VMAT plans (t =4.476, 3.756, P ＜ 0.05) , but no significant differences in D1％ , D5％ , D95％ , HI and CI (P ＞ 0.05) were found.The V10, V15, V20 and mean lung dose (MLD) to the total-lung of HT plans were all significantly lower than those of VMAT plans (t =-3.369,-4.824, -4.869,-3.657, P ＜ 0.05).There were no significant differences for V5, V30 and Dmax of cord (P ＞ 0.05).The monitor units and delivery time of VMAT plans were significantly lower than those of HT plans (t =13.970, 7.982, P ＜ 0.05).Conclusions Both HT and VMAT are appropriate for esophageal cancer radiotherapy.HT significantly reduces the radiation dose of the total-lung, while VMAT has obvious advantages in efficiency.

Objective To study the effects of PHLDA2 overexpression on radiosensitivity and the underlying mechanisms in human osteosarcoma U2OS cell line.Methods To obtain the subclone,cells were exposed to G418 persistently after transfection of pEGFP-C3-PHLDA2 vector into U2OS cells.Three groups of blank control (U2OS),negative control (U2OS-neo) and transfected group (U2OS-PHLDA2) were used.The expression of PHLDA2 in the subclone cells was determined by Western blot.After exposure to X-ray irradiation,cellular growth activity and survival were detected by CKK-8 assay and colony formation assay,respectively.The cell apoptosis was measured by the Annexin V/PI staining,and the apoptotic protein was analyzed by Western blot.The in-vivo effects of PHLDA2 on irradiation were evaluated by xenografts.Results Compared with U2OS group and U2OS-neogroup,the sabclone cells were successfully obtained by G418 selection,in which the expression of PHLDA2 was upregulated(t =13.73,16.28,P ＜ 0.05).In vitro,PHLDA2 overexpression significantly enhanced the response to radiation in U2OS cells with a reduction of colony survival and proliferation with the increase of doses (t =5.00-8.23,P ＜0.05;t =-2.52--1.26,P ＜ 0.05).In vivo,PHLDA2-upregulated xenografts had more radiosensitivity than control groups with a significant inhibition of tumor growth (t =3.27,2.91,P ＜ 0.05).After 8 Gy irradiation,the apoptosis was significantly increased (t =10.11,9.61,P ＜ 0.05),accompanied with the activation of Caspased-3 in U2OS-PHLDA2 cells,which was presented by upregulation of cleaved Caspase-3 (t =11.26,10.72,P ＜ 0.05).Conclusions Exogenetic expression of PHLDA2 could significantly enhance the radiosensitivity of human osteosarcoma cells,which may be attributed to the activation of Caspase-3 that increases irradiation-induced apoptosis.

Objective To evaluate the variations of effective doges with the preset scanning parameters from linac-integrated kV cone beam CT( CBCT). Methods Weighted CT dose index(CTDIW) were measured with PTW TM30009 CT ion chamber in head phantom and body phantom, respectively, for different combinations of tube voltage, mAs, collimator and gantry rotation range. Dose length products(DLP) were derived from CTDIW and effective doses(E) were calculated by the DLP and EDLP. Results CTDIW and effective dose had the quadratical relationship with tube voltage, depending linearly on product of tube current and exposure time. Effective dose had close relationship with the collimator and the gantry rotation range. Both the DLP and ED for CBCT were lower than the reference dose level recommended for conventional CT. Conclusions Effective dose from CBCT has a close relationship with the scanning parameters. Optimal imaging parameters should be chosen according to the patient's anatomy to reduce patient dose.