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Objective To investigate the dosimetric properties of PTW 60019 synthetic diamond detector in small photon beams.Methods A PTW 60019 synthetic diamond detector was tested under 6 and 10 MV photon beams,respectively.Linearity with dose,dose rate dependence and off-axis ratio were measured and compared to those measured by an IBA SFD.Percentage depth doses were measured and compared to those measured by an IBA SFD and a PTW 31010 semiflex chamber.Total scatter factors were measured and compared to those measured by an IBA SFD and a PTW 31016 PinPoint chamber.Results The dose response of a PTW 60019 synthetic diamond detector showed a good linear behavior as a function of dose,with observed deviations below 0.2％ over a dose range from 100 to 1 000 MU.The dose rate response was almost independent,with deviations below 0.2％ in the dose rate range from 37 to 614 MU/min.For the fields of 20-100 mm in diameter,there were dose differences in percentage depth doses within 1％ as compared to an IBA SFD and a PTW 31010 semiflex chamber.For the 10 mm diameter field,the differences were up to 5.8％ in the build-up region.Off-axis ratios measurements showed a good agreement among the involved detectors (＜ 1％).The higher differences appeared in the penumbra region.A good agreement was also found in terms of total scatter factor measurements for the related detectors.Conclusions The observed dosimetric properties of the PTW 60019 synthetic diamond detector indicate that it is a suitable candidate for small photon beam dosimetry.
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Objective To study the prognostic factors of survival in patients with metastatic renal cell carcinoma (mRCC) treated with sunitinib.Methods From May 2008 to Dec 2012,the clinical data of 82 cases with mRCC adminstered by sunitinib were reviewed retrospectively.The study included 60 male patients and 22 female patients,whose age ranged from 29 to 82 years [mean (56.1±11.3) years].Among them,52 cases presented hematuria,flank pain and palpable mass.The size of renal tumor ranged from 2.0 to 18.0 cm [mean (8.0±3.0) cm].The location of tumor included 41 in left kidney,37 in right kidney and 4 in bilateral kidney.The pathological tissue obtained from the operation in 69 cases and from biopsy in 13 cases.The pathological results demonstrated renal cell carcinoma in 75 cases,papillary cell carcinoma in 2 cases,chromophobe cell carcinoma in 2 cases,sarcomatoid carcinoma in 2 cases,collecting duct carcinoma in one case.The site of metastasis included lung in 50 cases,liver in 11 cases,bone in 14 cases,pancrease in 3 cases,retroperitoneal lymph node in 31 cases.In 52 cases,the ECOG scores ranged from 1 to 2.The others scores were more than 3.The average level of hemoglobin,AKP,LDH and leukocyte were (132±24)g/L,(90±65) U/L,(168±114) U/L and (6.4±2.0)×109/L,respectively.Before treatment,the abnormal cases in those parameters were 59,9,6 and 2,respectively.According to the MSKCC risk model,14 cases were classified into the high risk group and 68 cases into medium risk group.74 cases were accepted the sunitinb therapy within one year after diagnosis and 8 cases were accepted same therapy until one year after diagnosis.The overall survival (OS) rates were calculated by Kaplan-Meier method and Cox regression model was used to analyze the relationship between the influencing factors and the prognosis.Results The average OS was (21.6± 14.1) months (ranged 2.8 to 64.1 months).The survival rate at 1 st,2nd and 3rd year were 71％,64％ and 58％,respectively.Single factor analysis showed that significant prognostic factors were as follows:ECOG performance status ≥ 2 (P =0.005),clinical symptom during first clinic visiting (P =0.031),without nephrectomy (P =0.012),the number of metastatic sites ≥ 2 (P =0.015),hemoglobin before treatment (P=0.005),serum AKP level before treatment (＞126 U/L) (P=0.007),MSKCC score≥ 3 (P =0.000),the presence of liver metastases (P =0.000) and bone metastases (P =0.000) and relative dose intensity in the first month (1M-RDI) of sunitinib ≥ 50％ (P=0.000).Cox regression model showed that the beneficial predictive factors were ECOG performance status＜2 (P=0.136),no symptom during the first clinic visiting (P=0.801),serum AKP ＜126 U/L (P=0.618) before treatment,the absence of bone (P =0.068) and pancreas metastases (P =0.265).Sunitinib 1M-RDI ≥ 50％ was the independent predictive factor (P=0.000).Conclusions In targeted therapy era,there is some change in the prognostic factors for mRCC and target drug play an important role in the prognosis of mRCC.Sunitinib 1M-RDI ≥50％ is the independent predictive factor for the prognosis of renal carcinoma.
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PURPOSE: The purpose of this study was to evaluate whether a GafChromic film applied to stereotactic radiosurgery with a linear accelerator could provide information on the value for acceptance testing and quality control on the absolute dose and relative dose measurements and/or calculation of treatment planning system. MATERIALS AND METHODS: A spherical acrylic phantom, simulating a patient's head, was constructed from three points. The absolute and relative dose distributions could be measured by inserting a GafChromic film into the phantom. We tested the use of a calibrated GafChromic film (MD-55-2, Nuclear Associate, USA) for measuring the optical density. These measurements were achieved by irradiating the films with a dose of 0-112 Gy employing 6 MV photon. To verify the accuracy of the prescribed dose delivery to a target isocenter using a five arc beams (irradiated in 3 Gy per one beam) setup, calculated by the Linapel planning system the absolute dose and relative dose distribution using a GafChromic film were measured. All the irradiated films were digitized with a Lumiscan 75 laser digitizer and processed with the RIT113 film dosimetry system. RESULTS: We verified the linearity of the Optical Density of a MD-55-2 GafChromic film, and measured the depth dose profile of the beam. The absolute dose delivered to the target was close to the prescribed dose of Linapel within an accuracy for the GafChromic film dosimetry (of +/- 3%), with a measurement uncertainty of +/- 1 mm for the 50~90% isodose lines. CONCLUSION: Our results have shown that the absolute dose and relative dose distribution curves obtained from a GafChromic film can provide information on the value for acceptance. To conclude the GafChromic film is a convenient and useful dosimetry tool for linac based radiosurgery.
Subject(s)
Film Dosimetry , Head , Particle Accelerators , Quality Control , Radiosurgery , UncertaintyABSTRACT
Ocular signs and serum vitamin A concentration are commonly used tor the diagnosis of vitamin A deficiency. Recently, impression cytology was suggested as a method for early detection of vitamin A status. Twenty patients with normal eyes and digestive disease, and 111 children with normal eyes were evaluated by serum vitamin A concentration, relative-dose-response and conjunctival impression cytology test. About 90% of the patients with normal conjunctival impression cytology has normal vitamin A status. About 70% of the patients with abnormal conjunctival impression cytology has abnormal vitamin A status despite their seemingly normal clinical ocular examination, and so did the children. These results suggest that impression cytology can identify individuals with preclinical vitamin A deficiency.