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Objective To investigate the physics technique and quality assurance (QA) during radiotherapy in the institutions from the East Guangdong province,aiming to provide reference for the construction of radiotherapy discipline and rational allocation of resources in the primary hospitals from the eastern Guangdong province.Methods From March 15 to May 20,2016,the general conditions,radiotherapy equipment,available technique and quality assurance (QA) in the medical institutions from eastern Guangdong were investigated and analyzed by online combined with on-spot surgery.Results There were 8 institutions which provided radiotherapy with 966 ward beds,a daily capacity of 632 patients and 222 radiotherapy practitioners.Radiotherapy equipment included 12 linear accelerators,5 after-loading devices,1γ-knife,8 CT simulators and 9 radiotherapy planning systems.Five institutions performed IMRT/VMAT,IGRT and ART.Dose verification was performed before precision radiotherapy delivery in all institutions except for 1 center.QA procedures were missing for the linear accelerators,CT simulators and after-loading devices.Short-term advanced studies and hand-by-hand teaching were the main approaches for staff professional training.Conclusions The resource allocation for radiotherapy in the medical centers from the eastern Guangdong province is scarce.The technique and QC levels greatly differ among different institutions.Standard QA protocols are urgently to be established and implemented.Extensive attentions should be paid to the the professional training for technicians.
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Objective To investigate the relationship of radiation dose with the volume and late toxicity of the sternocleidomastoid muscle ( SM) in patients with nasopharyngeal carcinoma. Methods SM was divided into upper part and lower part based on the lower edge of cricoid cartilage. Patients were divided into three groups according to the prescribed dose for clinical target volume at the lower neck ( CTV2 ) ( 0, 54,60 Gy) . The dosimetric parameters included Dmean , V66 , and V60 for the upper, lower, and whole SM. SM was delineated and the volume was calculated on computed tomography images in the treatment planning system before and at 6, 12, and 18 months after treatment. The anteroposterior and transversal diameters of SM at C3?C4 , C4?C5 , C5?C6 , and C6?C7 levels were measured and recorded. Late toxicity of neck skin and SM was evaluated according to the Common Terminology Criteria for Adverse Events V4 .0 criteria. Between?group comparison was made by t?test or Kruskal?Wallis non?parametric test. Between?group comparison of the sample rate was made by one?way analysis of variance. The correlation analysis was made by Spearman correlation. Results There were significant difference in SM volume between the three time points after treatment ( P=0. 000) . At 12 or 18 months after treatment, the volume of SM wasignificantly reduced ( P=0. 000,0. 000);the reduction in SM volume was significantly correlated with V66 of the SM and the upper SM ( P=0. 015,0. 020) . At 18 months after treatment, SM fibrosis was significantly correlated with V60 of the upper SM ( P=0. 030);the fibrosis of neck skin was significantly correlated with the Dmean and V60 of the upper SM ( P=0. 029,0. 005) . Conclusions In order to prevent the incidence of the fibrosis of neck skin and SM, the dose homogeneity should be as high as possible, while the number of hot spots should be as small as possible.
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Objective: To set up the procedures of performance test and quality assurance of TruebeamTM by measuring the mechanical parameters, field parameters, imaging isocenter and respiratory gating systems. Methods:Utilize level and graph paper to test the mechanical parameters; Utilize the film, 3D water tank and dosimeter to measure the corresponding field parameters;Utilize IsocCal phantom to test the shift of imaging isocenter and to use dosimeter to verify the beam on accuracy of respiratory gating systems. Results:All of the tested mechanical parameters were within the tolerance. The coincidence of light field and radiation field was less than 1.2 mm. The flatness was less than 105%except for the flattening filter free beam and the symmetry was less than 102%. The absolute dose error was less than 1%. The shift of imaging isocenter was less than 3 mm and the dose error was within 0.5‰when the respiratory gating function was implemented. Conclusion:TruebeamTM possesses superior mechanical performance and is very suitable to carry out complicated radiotherapy techniques.
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Objective To evaluate the dosimetric characteristics of base dose plan compensation (BDPC) optimization method applied on the intensity-modulated radiotherapy (IMRT) for upper esophageal carcinoma,based on the Eclipse treatment planning system.Methods Nineteen patients were included.For each case initial IMRT plan was generated and further optimized respectively by the two following methods:the BDPC method and hot and cold spot control (HCSC) method.Then the BDPC and HCSC plans were compared concerning planning-target-volume (PTV) coverage,conformity index (CI),and homogeneity index (HI),as well as organ-at-risk (OAR) sparing,planning time,monitor unit (MU) and delivery time.Results Compared with the HCSC plans,the BDPC plans provided superior CI and HI (Z =-3.662,-3.745,P ＜ 0.05),as well as lower D2％ (near-maximum dose) (Z =-3.823,P ＜ 0.05) and comparable D98％ (near-minimum dose) (P ＞ 0.05) for PTV64 (high-risk PTV),and provided superiorCI (Z=-3.340,P＜0.05),lower D95％ and D98％ (Z=-3.582,-2.616,P＜0.05) for PTV54 (low-risk PTV).The BDPC plans also provided slightly lower doses to the spinal cord and lung compared with the HCSC plans (Z =-3.625--3.369,P ＜ 0.05).Moreover,the planning time [(26.05 ±0.88) min] for BDPC plans was less than that of the HCSC plans [(33.73 ± 3.24) min] (Z =-3.823,P ＜0.05).The MU of the BDPC plans (1 019 ± 167) was higher than that of the HCSC plans (1 003 ±159) (Z=-2.616,P＜0.05),while the delivery time [(3.52 ±0.29) min] was more than that of the HCSC plans [(3.50±0.28) min] (Z=-2.548,P＜0.05).Conclusions The BDPC optimization method can significantly improve target dose homogeneity and conformity with effective reduction of the dose to OARs for upper esophageal carcinoma.Moreover,it is simple and can improve the treatment planning efficiency.