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Objective:To compare the difference between breast bracket combined with polyurethane foam and single polyurethane foam in the accuracy of immobilization, providing a better immobilization for breast cancer radiotherapy.Methods:Fifty breast cancer patients who received radiotherapy in Sun Yat-sen University Cancer Center from March 2021 to July 2021 were selected. Among them, 25 patients were immobilized with polyurethane foam (foam group), and the other 25 patients were immobilized with polyurethane foam combined with breast bracket (combination group). All patients were scanned by CBCT once a week to obtain setup errors in the SI, LR and AP directions for t-test. The formula M PTV=2.5 Σ+0.7 σ was used to calculate the margin of the planning target volume(M PTV). Results:The setup errors in the foam group were SI (2.0±3.26) mm, LR (0.88±2.76) mm, AP (1.22±3.55) mm, Rtn -0.24°±0.85°, Pitch 0.16°±1.11°, Roll -0.32°±1.05°, and the M PTV were 6.75 mm, 8.46 mm and 8.73 mm, respectively. The setup errors in the combination group were SI (1.0±3.01) mm, LR (0.62±2.74) mm, AP (1.82±3.21) mm, Rtn 0.64°±0.59°, Pitch 0.71°±1.22°, Roll 0.29°±0.73°, and the M PTV were 6.35 mm, 7.47 mm, and 7.61 mm, respectively. After comparing the setup errors in the three-dimensional directions between two groups, the t value of LR, SI, AP and Rtn, Pitch, Roll was -4.304, -2.681, 1.384, and -9.457, -3.683, -5.323, respectively. And the differences in the LR, SI, Rtn, Pitch and Roll directions were statistically significant (all P<0.05). Conclusions:The immobilization effect of polyurethane foam combined with breast bracket is better and the M PTV is also smaller than those of polyurethane foam alone. Therefore, it is recommended to use polyurethane foam combined with breast bracket for immobilization in breast cancer radiotherapy.
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Objective:To provide evidence for the selection of fixation devices and CTV to PTV margins (M ptv) in precision radiotherapy for pelvic tumors by analyzing three fixation devices in precision radiotherapy for prostate cancer. Methods:From April 2015 to December 2020, 133 prostate cancer patients treated with pelvic drainage area irradiation in our center were retrospectively analyzed. The patients were fixed with 1.2m vacuum bag (n=39), 1.8m vacuum bag (n=44) and personalized prone plate by our center (n=50). Each patient was asked to complete our bowel and bladder preparation process before positioning and radiotherapy. The registration of CBCT to planned CT before each treatment adopted the same registration box and algorithm. Setup errors in the SI, LR and AP directions under qualified bowel and bladder conditions were recorded. Setup errors in three directions under three fixation devices and corresponding M ptv values were analyzed. The correlation between setup errors with age and body mass index (BMI) was analyzed. Results:Analysis of 3333 setup errors data showed: in the SI and LR directions, the mean setup errors of 1.2m vacuum bag (3.26mm, 2.34mm) were greater than those of 1.8m vacuum bag (2.51mm, P<0.001; 1.90mm, P<0.001), and personalized prone plate (3.07mm, P=0.066; 2.10 mm, P=0.009). In the AP direction, the mean setup errors of 1.2m vacuum bag (supine)(2.20mm) were smaller than those of 1.8m vacuum bag (3.33mm, P<0.001) and personalized prone plate (3.61mm, P<0.001). The setup errors of 1.8m vacuum bag in all directions were smaller than those of personalized prone plate (P≤0.028). According to Van Herk's expansion formula, the M ptv of 1.2m vacuum bag in three directions was approximately 4 mm. The M ptv of 1.8m vacuum bag and personalized prone plate in the SI and LR directions was approximately 3 mm, and more than 5 mm in the AP direction. The setup errors were not correlated with age or BMI. Conclusions:From the setup errors results of three devices, 1.8m vacuum bag is the best, followed by personalized prone plate. And supine position is better than prone position in the AP direction.
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Objective:To investigate the manpower allocation and scientific research level of radiotherapists in radiotherapy units in mainland China, aiming to provide reference for the construction of radiotherapist teams.Methods:The questionnaire was designed and produced by the organizer, released in the professional committee, professional group and other channels of the radiotherapist industry, and filled out by the technical person in charge of the radiotherapy unit through the online questionnaire survey. The collection time started from mid-May 2021 to mid-June 2021.Results:A total of 558 effective questionnaires filled out by radiotherapy units. The radiotherapy institutions participating in the survey had a total of 5500 radiotherapists, including 3702 males and 1798 females, 3754 with a bachelor's degree, 371 who are currently studying or have obtained a master's degree, 21 who are currently studying or have already obtained a doctoral degree, 3642 with junior or lower titles, 1580 with intermediate titles, and 278 with senior titles. In 2020, radiotherapists from 193 units published articles, those from 81 units received project funding, and those from 56 units obtained patent authorization, and those from 15 units had scientific research transformation. The participating units had a total of 1080 large-scale radiation therapy equipment. In 2020, the daily average number of radiotherapy patients was 47 900, the average daily load of accelerator patients was 44.35, and the average workload index per capita was 8.71. The average daily radiotherapy patients in county-level or below, city-level, and provincial-level institutions were 25.78, 65.68, and 173.76, respectively, and the per capita workload index was 5.22, 8.09, and 10.11.Conclusions:Compared with the 2019 survey, the educational background of radiotherapists in mainland China has been improved, and the title structure has been optimized to a certain extent, and the workload of large-scale radiotherapy units is larger than that of grass-roots units.
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Objective:To investigate and analyze the basic occupational situation of Chinese radiotherapists and to provide references for the development and construction of the radiation therapist team in China.Methods:Between May 7, 2021 and June 15, 2021, this survey was conducted using a self-designed questionnaire, which was distributed and collected in the form of online survey to conduct a statistical analysis of the basic situation of radiotherapists in 30 provincial-level administrative regions in China.Results:A total of 2 928 valid questionnaires were collected from 30 provincial-level administrative regions. The ratio of male to female and average age of the participants were 69∶31 and 35 years (18-65), respectively. According to the survey result, 84.7% of the participants came from Tertiary A-level hospitals. In terms of educational background, the participants with doctoral, master, undergraduate, junior-college, and technical-secondary degrees accounted for 0.2%, 6.9%, 76.6%, 14.9%, and 1.4%, respectively. In terms of title, full senior technologists, associate senior technologist, technologist-in-charge, technologist, and technician in the participants accounted for 0.5%, 5.8%, 32.5%, 52.2%, and 8.2%, respectively. The participants with years of employment of 0-, 5-, 10-, 20-y accounted for 33.74%, 25.79%, 25.51%, and 14.96%, respectively. The majors of the participants included medical imaging/imaging technology (45.9%), clinical medicine (19.1%), and biomedical engineering (11.9%).Conclusions:Chinese radiotherapists tend to be younger and are rapidly increasing in number. Employers should attach importance to the career planningand continuing education of radiotherapists to improve their technical skills, in order to fully satisfy the demand for radiotherapists in the new era.
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Objective:To preliminarily observe the feasibility of different immobilization techniques for total skin irradiation (TSI) using helical tomotherapy.Methods:Three eczema scrophuloderma patients treated with TSI in Sun Yat-sen University Cancer Center were immobilized with low-temperature thermoplastic in a prone position, diving suit combined with negative pressure vacuum bag in a supine position, low-temperature thermoplastic combined with vacuum bag in a supine position, respectively. Different immobilization effects were observed. The conformity index (CI) of the target area, heterogeneity index (HI) of the target area, and the mean dose (D mean) of the target area were calculated. Results:Three immobilization methods could achieve satisfactory immobilization effects, and all the dosimetric parameters of radiation treatment plans met the clinical requirements. The average set-up errors in the left and right, head and foot, and abdomen and back directions of three patients were (0.26±3.40) mm, (-2.63±4.63) mm and (6.13±4.86) mm, respectively. The CI, HI andD mean were0.56±0.09, 1.186±0.059 and (2586.56±63.28) cGy. Conclusions:Low-temperature thermoplastic or diving suits can be combined with vacuum bags for immobilization in TSI. The epidermal dose can be increased with bolus through the dose-building effect, which can provide a safe and reliable method for TSI in helical tomotherapy.
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Objective To evaluate the effect of helical tomotherapy (HT) megavoltage CT (MVCT) under different acquisition pitch and registration conditions upon the accuracy of radiotherapy for used nasopharyngeal carcinoma,aiming to provide reference for image-guided radiotherapy (IGRT) for nasopharyngeal carcinoma.Methods MVCT scans were performed on an anthropomorphic head& neck phantom which was simulated the positioning errors in the x,y and z direction.The obtained images were registered with the planning CT images.Acquisition pitch was set as the coarse,normal and fine modes.Registration conditions were set as bone registration,bone and soft tissue registration and full-image registration.Registration accuracy was determined by comparing the measured value with the preset value.The accuracy of radiotherapy under different acquisition pitch and registration conditions was statistically compared.Results The 3D errors of bone,bone and soft tissue and full-image registration under different acquisition pitch (coarse,normal and fine) were (1.51±0.47,1.54±0.35,1.81±0.53) mm and (1.41± 0.37,1.53±0.36,1.56±0.39) mm and (1.51±0.27,1.57±0.32,1.73±0.33) mm,respectively.The bone registration yielded the highest accuracy (P＜0.05).When the registration condition was set as bone registration,the accuracy of three acquisition pitch did not significantly differ (all P＞0.05).The fine mode of acquisition pitch possessed the highest stability,whereas required the longest time.Conclusion The acquisition pitch and registration conditions should be selected during HT MVCT based on the clinical requirement of each patient with nasopharyngeal carcinoma.
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[Objective]To compare and contrast the dosimetry between Tomo planning and BrainLab planning for lung metasta-ses in stereotactic body radiation therapy(SBRT).[Methods]Four Patients with one,two,three and four metastases were selected. The PTV is 2.89 ± 1.15 cm3. Two plannings with total dose of 50 Gy to cover 95% of PTV ,5 Gy/Fraction and 10 fractions were designed using Tomo planning system and BrainLab planning system respectively. The DVH curves of spinal cord ,both lungs and normal tissue were compared. The conformity index andhomogeneityindex were analyzed as well.[Results]The homogeneity index (HI)and conformity index(CI)of the targets in Tomo planning system were 1.0314 ± 0.0700 and 0.687 ± 0.075,respectively. In BrainLab planning system the HI and CI of the targets were 1.0764 ± 0.1241 and 0.571 ± 0.042,respectively. To HI the P value in T test was less than 0.01 and the HI was better in Tomo than BrainLab and so was CI. The dose to spinal cord was higher in BrainLab planning system than that in Tomo. The dose to nomal tissue and both lungs were not different in the two planning systems and V20 of lung is as small as 10%.[Conclusions]For small volume lung metastases which longest diameter were less than 4 cm,the tomotherapy should be better choice.
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Objective To discuss the application value of DWI and ADC on predicting therapeutic effect of radiotherapy treatment in NPC. Methods Twenty four local recurrent cases and 38 non-recurrent cases after radiotherapy treatment in NPC were reviewed. MRI and DWI-MRI were performed at pre-radiotherapy and 3, 6, 12 months after treatment, the ADC values of the lesions were analyzed by SPSS 18.0 statistical software. ROC curves based on the ADC values were measured in 3, 6, 12 months after treatment plotted to analyze the threshold ADC value for confirming recurrence. Results The recurrent group and newly diagnosed group showed significantly high signal on DWI, while the non-recurrent group acquired low or mixed signal. The ADC values of the primary tumor in the recurrent group and the non-recurrent group were (0.709 ± 0.078) × 10-3 and (0.693 ± 0.089) × 10-3mm2/s, respectively, t=-0.717,P>0.05, respectively.The ADC values of the primary and recurrent tumor in the recurrent group were (0.730± 0.068) × 10-3mm2/s and (0.709 ± 0.078) × 10-3mm2/s, t=-1.000,P>0.05 , respectively.There were statistical differences between the recurrent group and the non-recurrent group for ADC in 3, 6, 12 months after treatment:(1.128 ± 0.179) × 10-3 and (1.358 ± 0.145) × 10-3mm2/s, t=5.567,P<0.01;(1.164 ± 0.174) and (1.450 ± 0.102) × 10-3mm2/s, t=7.310,P<0.01;(1.107 ± 0.180) × 10-3 and (1.584 ± 0.125) × 10-3mm2/s, t=11.189,P<0.01;respectively. Take 1.29 × 10-3 mm2/s,1.32 × 10-3mm2/s,1.37 × 10-3mm2/s respectively in 3, 6, 12months after treatment as the diagnostic threshold to predict tumor recurrence. The sensitive , specificity, and accuracy were (83.3%, 73.7%, 77.4%), (83.3%, 89.5%, 87.1%), (100.0%, 94.7%, 96.3%).Conclusions Both DWI and ADC value are important for diagnosing and predicting recurrent NPC after radiotherapy treatment, DWI and ADC can be used to regular follow-up after radiotherapy, to further improve the rate of early diagnosis of recurrent NPC.
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Objective To investigate an appropriate megavoltage computed tomography ( MVCT ) protocol to guide helical tomotherapy ( HT) for multiple metastases. Methods According to the location of target volume, 48 patients with multiple metastases undergoing HT were divided into head/chest group ( n=15), head/pelvis group (n=15), and chest/pelvis group (n=18). Each target volume received MVCT scans during the treatment. The obtained MVCT images were registered to CT images and the setup errors were recorded. The CTV?PTV margins were calculated. Comparison was made by paired t test. Results In the head/chest group, there was no significant difference in the setup error in x?axis between the head and chest (-0.15±1?25 vs. -0.21±2?34, P=0?71), while the head had significantly smaller setup errors in y?and z?axis than the chest (0.73±1?22 vs. 1.56±2?54, P=0?00;0.93±1?44 vs. 2.65±1?88, P=0?00). In the head/pelvis group, the head had significantly smaller setup errors in x?, y?, and z?axis than the pelvis (-0.16±1?31 vs. -1.29±3?72, P=0?00;0.81±1?34 vs. 3.20±3?90, P=0?00;1.24±1?75 vs. 5.49±2?80, P=0?00) . In the chest/pelvis group, there were no significant differences in setup errors in x?or y?axis between the chest and pelvis (-0.25± 2?90 vs. -0.22± 3?65, P=0?06;0.35± 3?60 vs. 0.38± 3?78, P=0?87), while the chest had a significantly smaller setup error in z?axis than the pelvis (1.95±2?81 vs. 3.35± 3?05, P=0?00) . In the three groups, the CTV?PTV margins of lower target volume were reduced in three dimensions after the correction of upper target volume, in which y?axis showed the largest reduction of CTV?PTV margins (5?13 vs. 4?01;9?17 vs. 8?30;8?52 vs. 7?13). Conclusions The setup error of individual target volume should not be used for correction of the overall setup error in HT for multiple metastases with isolated target volume. An MVCT protocol that provides image?based guidance for multiple target volumes is recommended.
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Objective To evaluate the feasibility of keeping the consistency of bladder filing by a Bladderscan ( BS ) device during radiotherapy for rectal cancer. Methods The bladder volume was measured using a BS device and recorded. To verify the reliability of the BS measurement, the urinary output was determined by a measuring glass after complete urinary discharge. The bladder volume of 42 patients determined by the planning computed tomography ( CT) scans was used as the standard urinary volume. The bladder volume was measured using the BS device before radiotherapy every day. The chief complaint urinary volume was determined as the bladder volume when a patient felt a strong urge to urinate. The controlled urinary volume was determined as the urinary output intervened by the BS device to reach the standard urinary volume. Comparison was made by t test and data was assessed by Pearson correlation analysis. Results There was no significant difference in obtained urinary volume between the BS device and the planning CT scan ( P=0?84) . The urinary volume measured by the measuring glass was correlated with that measured by the BS device ( P=0?00 ) . The ability to hold urine in all patients was gradually weakened during treatment. The controlled urinary volume had a significantly smaller decrease after 1, 2, 3, 4, and 5 weeks of treatment than the chief complaint urinary volume ( 5% vs. 21%;6% vs. 20%;6% vs. 20%, 4% vs. 21%;11% vs. 26%;all P=0?00) . Conclusions Patients have a gradually decreased urinary volume during treatment. The intervention by the BS device gives a bladder volume close to that in the planning system, which results in a consistent bladder filling.
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Objective To investigate the accuracy and reliability of the image automatic matching using X-ray volumetric image (ⅩⅥ) system with the accelerator Elekta Synergy and to compare the matches with different methods and area.Methods A simulation plan using the head and neck phantom was designed and sent to ⅩⅥ system for CBCT scanning.During the scanning,the couch for certain distance was moved and the data of ⅩⅥ image automatic Matching in different matching methods and area was collected.Results The result of ⅩⅥ image automatic matching is consistent and correct to direction and distance which the couch had been moved (x:(0.11 ± 0.41) mm,y:(-0.04± 2.6) mm,z:(0.28 ± 0.74 mm)).There are not significant differences between the results that matching in different matching methods and different matching area.Conclusions The automatic image Matching of ⅩⅥ is accuracy and high reliability in recognition of offset error.But there are some significant differences on the automatic image Matching in different matching methods and different matching area.