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Objective:To investigate the clinical features, treatment options and prognostic factors of extramedullary plasmacytoma of the head and neck.Methods:Clinical data of 31 cases of extramedullary plasmacytoma of the head and neck treated in Eye Ear Nose and Throat Hospital of Fudan University from January 2005 to January 2020 were retrospectively analyzed. According to the involvement sites, the lesions were divided into the Waldeyer's ring involvement and non-involvement groups. The differences between two groups were compared by one-way ANOVA. The overall survival (OS) was analyzed by Kaplan-Meier method. The OS rate and local recurrence free survival (LRFS) rate between two groups were compared by log-rank test.Results:All 31 patients received radiotherapy. The median follow-up time was 98 months (7-192 months). Among them, 16 patients received radiotherapy and surgery, 10 patients received radiochemotherapy, and 2 patients received surgery and radiochemotherapy. Waldeyer's ring involvement was found in 15 patients, and Waldeyer's ring was not involved in 16 patients. The 10-year OS rate was 84.8%. Two cases showed local recurrence and 2 cases progressed to multiple myeloma. The 10-year OS rate in patients ≤55 years old was 100% vs. 67% in those >55 years old ( P=0.039). The 10-year OS rates in patients with and without Waldeyer's ring involvement were 93.3% vs. 75.2% ( P=0.031). The 10-year LRFS rate in patients with Waldeyer's ring involvement was 100% vs. 66.7% in those without Waldeyer's ring involvement ( P=0.022). The 10-year OS rate was 95% and 35.7% for patients with longest diameter of tumor ≤5 cm and >5 cm before radiotherapy, respectively ( P=0.02). Conclusions:Extramedullary plasmacytoma of the head and neck patients with longest diameter of tumor ≤5 cm obtain higher 10-year OS rate. Those with Waldeyer's ring involvement have better 10-year OS and LRFS rates.
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Objective:To retrospectively analyze the relationship between patterns of local recurrence and radiotherapy target dose after adjuvant radiotherapy for the pancreatic ductal adenocarcinoma(PDAC), aiming to provide reference for exploring reasonable target and dosage.Methods:Clinical data of 138 patients with T 1-4N 0-2M 0 PDAC who underwent adjuvant radiotherapy after radical resection from April 2012 to December 2020 were analyzed retrospectively. The influencing factors of local recurrence and the correlation between local recurrence site and radiotherapy target dose were analyzed. Results:The median follow-up time was 37.2 months. The median overall survival (mOS) was 29.9 months. The 5-year OS rate was 27.4%. And the median progression-free survival (mPFS) was 13.9 months. There were 24 cases of local recurrence (17.4%), and 10 cases of local recurrence complicated with distant metastasis (7.2%). The correlation between local recurrence site and radiotherapy target dose could be evaluated in 19 patients with complete clinical data. The first local recurrence occurred near the para-aortic (Ao), the celiac axis (CA) and the superior mesenteric artery (SMA) were 8, 5 and 4 cases, respectively. The radiotherapy doses of 8 patients with local recurrence only in the PTV field were above 45 Gy. There were 8 cases of local recurrence both in and out of the PTV field, including 3 cases with dose line between 40 and 52 Gy, 2 cases with dose line between 20 and 47.5 Gy, and 3 cases with dose line between 0.5 and 52.5 Gy. There were 3 cases of local recurrence out of the PTV field, and the dose line ranged from 0 to 20 Gy.Conclusions:The local recurrence rate of PDAC after radical surgery combined with postoperative radiotherapy is low, but a small number of patients have recurrence in the high-dose range of radiation field and regional recurrence out of the field. For these patients, it may be necessary to explore a more appropriate target dose and range for adjuvant radiotherapy.
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Objective:To compare and analyze the differences of common dose indicators before and after operation of 3D-printing template assisted by CT-guided 125I seed implantation in the treatment of bone metastases to guide clinical application. Methods:A retrospective analysis of 12 lesions in the 10 patients (9 males and 1 female, median age 65 years), who underwent seed implantation surgery for bone metastases in the Tianjin Third Central Hospital from June 2019 to January 2021, was conducted. All the lesions were adopted for 3D-printing template to guide seed implantation and the prescribed dose was 120-140 Gy. The differences of common dose indicators between preoperative treatment plan and postoperative verification plan were compared, including D90 (dose received by 90% of the target volume), D100 (dose received by 100% of the target volume), V90 (the volume percent for tumor target volume receiving 90% of the prescribed dose), V100 (the volume percent for tumor target volume receiving 100% of the prescribed dose), V150 (the volume percent for tumor target volume receiving 150 % of the prescribed dose), as well as the quantity of seeds planned and actually used. The paired t-test was performed to compare and analyze those parameters. Results:There was no statistically significant difference in pre- and postoperative D90, D100, V90, V100, V150 ( P > 0.05). The actual quantity of seeds used after operation was more than that of the preoperative planned quantity and the difference was statistically significant ( t=-2.930, P < 0.05). Conclusions:The clinical use of 3D-printing template assisted by CT-guided 125I seed implantation for bone metastasis should be promoted since the dose is accurate and the requirements of preoperative plan can be achieved.
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Objective To compare the dose difference between the 12-bit and 16-bit CT images containing metallic implants calculated by different algorithms. Methods The titanium alloy rod was inserted into the phantom and subject to CT scan and then the 12-bit and 16-bit CT images were reconstructed. The CT images were online transmitted to the Monaco planning system and a 0° of single field was designed. The dose distribution was calculated by PB (Pencil Beam), CC (Collapsed Cone) and MC (Monte Carlo) algorithms, respectively. The CT-ED curve was expanded and the dose was recalculated. The depth dose curve through the center of the metallic implants along with the direction of the field was obtained by using the Matlab 8. 3 statistical software. The dose distribution curves between 12-bit and 16-bit CT images calculated by different algorithms and the dose difference of varying distances between the incident and the exit surfaces of metallic implants were statistically compared. The dose was measured by thimble chamber. Results The 16-bit CT images accurately read the CT values of the metallic implants. After the CT-ED curve was expanded, the dose on the incident surface of metallic implant was reduced by 5. 43% and that on the exit surface was increased by 25. 56% calculated by PB algorithm compared with MC algorithm. The dose on the posterior exit surface was higher than that of MC algorithm. The dose on the incident surface of metallic surface was decreased by 4. 5%, whereas that on the exit surface was reduced by 4. 31% using CC algorithm. The dose on the posterior exit surface was more significantly reduced. The calculated values by MC algorithm were the most close to the measured values. Conclusions Application of 16-bit CT image, CT-ED curve expansion of the treatment planning system combined with MC algorithm can enhance the accuracy of dose calculation for the patients containing metallic implants during radiotherapy.
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Objective To reconstruct 16?bit images of metal implants using the extended function of computed tomography ( CT) imaging, and to analyze the effect of the metal CT value on calculation of dose distribution by evaluation of metal CT values in different scanning conditions. Methods A stainless steel rod and a titanium rod were inserted in a phantom. The 12?and 16?bit images and CT value distribution of metal implants were obtained by scanning the phantom using 120 kV tube voltage and 230 mA tube current. The 16?bit images and CT value distribution of metal implants were obtained by scanning the phantom using fixed tube current ( 230 mA) with varied tube voltage ( 100, 120, and 140 kV) or fixed tube voltage ( 120 kV) with varied tube current ( 180, 230, and 280 mA) . In the Varian treatment planning system, a single?field plan and a parallel?opposed field plan were designed based on the CT images. The dose distribution was calculated and compared by the paired t test. Results The CT values of the stainless steel rod and the titanium rod were both 3 071 HU in 12?bit CT images. In 16?bit CT images;however, the CT value of the stainless steel rod was significantly larger than that of the titanium rod. There were no significant differences in CT value of 16?bit image and dose distribution in radiotherapy plan between three scanning conditions with different tube currents. Under three scanning conditions with different tube voltages, the maximum CT values were 13 568, 13 127, and 12 295 HU for the stainless steel rod and 8 420, 7 140, and 6 310 HU for the titanium rod, respectively. Conclusions High?density metal implants cannot be distinguished by 12?bit images, while the distribution of metal CT value can be obtained by 16?bit images. The dose distribution of metal implants based on 12?bit images is different from that based on 16?bit images. Changes in tube voltage cause substantial changes in the CT value for metal implants, leading to changes in dose distribution in radiotherapy. Variation of tube current within a certain range causes slight changes in metal CT value and dose distribution.
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Objective To investigate the dose and mechanical properties of medical electron linear accelerators in grass-roots radiotherapy units in Sichuan Province,China via sampling and inspection.Methods A total of eight radiotherapy units in Sichuan Province were selected by sampling,and the tests were performed for the dose and mechanical properties of the medical electron linear accelerators in use.Among these accelerators,there were 5 imported accelerators and 3 domestic accelerators.The test items and methods were determined according to the requirements in GB15213-94.Results Among the 14 test items,the items related to the flatness,symmetry,and overlap of radiation field.The other tests of dose accuracy and mechanical precision achieved good results.Conclusions There is a need to strengthen the daily quality control work for dose and mechanical accuracy of medical electron linear accelerators in grass-roots radiotherapy units in Sichuan Province and perfect the allocation of professional equipment and personnel and training of related personnel.With the support of Sichuan Radiotherapy Quality Control Center,quality control supervision and guidance should cover the whole province.
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Objective To verify the methodology for auditing dosimetric parameters in reference and non-reference conditions with thermoluminescent dosimeters (TLDs).Methods Under reference and non-reference conditions,the established TLD methods were used to observe the absorbed dose variations with depth,SSD,field size and 45 wedges for 10 photon beams at 5 hospitals.Dosimetric parameters,including doses at Dmax points in axis,on 5 electron beams of 9 MeV were measured.The measurement results were compared between the TLDs and plane parallel ionization chambers.Results For 6 MV photon beams,the relative deviation of between finger ionization chamber method and TLD chips was in the range of-1.7％ to 5.4％ under on-axis non-reference conditions,and-6.3％ to-0.6％ under off-axis non-reference conditions,respectively,all within the range of ≤ ± 7％ as required by the IAEA.The relative deviation between plane parallel chamber and TLD method was-2.3％ to 3.7％,within ± 5％ as required by the IAEA.Conclusions It is convenient and feasible to use TLD method for quality audits of dosimetric parameters in radiotherapy.
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ObjectiveTo explore the effect of radiation dose on survival for stage Ⅳ non-small cell lung cancer (NSCLC) treated with concurrent chemotherapy and thoracic three-dimensional radiotherapy (CCTTRT).Methods From Jan.2003 to Jul.2010,201 Stage Ⅳ NSCLC patients were enrolled.Nineteen patients who received only one cycle chemotherapy were not included in survival analysis.Of the 182 patients eligible for survival analysis,all patients received platinum-based chemotherapy of two drugs.The median number of cycles was 4.The median dose to planning target volume of primary tumor ( DTPTV )was 63 Gy. Survival was calculated by Kaplan-Meier method and compared using the Logrank. Cox regression models were used to examine the effect of DTPTV on overall survival.ResultsThe follow-up rate of 201 patients was 97.5％.with 201,170 and 134 patients finished ＜ 1,1 -2 and ≥3 years' follow-up.The 1-,2-,3-year overall survival rate and median survival time was 20％,14％,0％ and 7.1 months;27％,10％,3％ and 9.6 months;and 59％,22％,16％ and 14.9 months,respectively for patients treated with DTPTV ＜ 45.0 Gy,45.0 - 62.1 Gy and ≥63.0 Gy,respectively ( χ2 =27.88,P =0.000 ) ;43％,19％,0％and 1 1 months and 2 0 ％,1 1％,5 ％ and 8 months,respectively for those received 2 - 3 cycles of chemotherapy and radiation dose ≥63 Gy and ＜ 63 Gy,respectively (χ2 =2.99,P =0.084) ;66％,23％,19％ and 16 months and 29％,12％,0％ and 8.8 months,respectively for those received 4 - 5 cycles chemotherapy and radiation dose ≥ 63 Gy and ＜ 63 Gy,respectively (χ2=15.87,P=0.000).No significant difference was found for patients received 2 - 3 cycles chemotherapy concurrently with DTP,Tv ≥63 Gy and 4 -5 cycles chemotherapy concurrently with DTPTV ＜63 Gy,respectively (χ2 =1.93,P =0.165).Multivariate analysis showed that 4 -5 cycles chemotherapy concurrently with DTPTv ≥63 Gy ( β =0.243,P =0.019),and improved KPS after treatment ( β =1.268,P =0.000) were independent favorable factors for survival.ConclusionChemotherapy concurrent with CCTTRT can prolong survival time of patients with stage Ⅳ NSCLC,especially for those treated with DTPTV ≥63 Gy.
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Objective To investigate the dosimetric influence of pure carbon fiber treatment tabletop of Elekta Precise new linear accelerator in radiotherapy.Methods Surface-axis distance (SAD) technology was employed for the measurement.Two groups of fields were set and both of them were SAD opposed portals ( one of them went through the tabletop,while the other did not).A PTW electrometer and a 0.6 cm3 Farmer ionization chamber were utilized for comparison measurement.Then dose attenuation of the main table board,extended body board,the extended board for head,neck and shoulders,and the joints of these boards were calculated.Results Under the energy of 6 MV,the dose attenuations of the following locations were:1.4％ - 7.2％ at the main treatment table board; 2.8％ - 38.7％,1.4％ -30.1％,1.5％ -20.8％ and 1.4％ - 11.2％,respectively at distances of 1,4,7 and 8 cm from the joint of the main table board ;0.5％ - 5.0％ at the extended body board; 4.7％ - 15.4％ at distance of 1cm from the joint of the extended body board; 0.5％ -3.3％ at the neck position of the extended board for head,neck and shoulders; 5.3％ - 16.7％ at the shoulder positions; and 6.8％ -30.4％ at the joint between the extended boards and the main table board.Conclusions The dose attenuations of the new linear accelerator pure carbon fiber treatment tabletop vary at different locations. Considerable higher attenuations are observed at the table board joints than other locations.
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Objective To study the impact of implanted thermoseeds of magnetic induction hyperthermia on radiation dose distribution. Methods To simulate irradiation, an anthropomorphic phantom and three-dimensional treatment planning system were used. The impact of thermoseeds on radiation dose distribution was evaluated. Results The change of absorbed dose caused by the implantated thermoseeds was less than 1.5%. Conclusions The impact of implanted thermoseeds on radiation dose distribution is small and comes up to the requirements that the total target dose uncertainty must be less than 5%. Therefore, the impact of thermoseeds on the absorbed dose in tissue can be ignored in clinical practice.
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Objective To study the dose distribution of intra-cavitary NiTi metal-stent for correction in radiotherapy of esophageal carcinoma.Methods Thermoluminescence Dosimeter(TLD) with LiF dose units was used to simulate the dose variation in wax phantom with or without Chinese and Japanese metal stents in esophageal lumen on 60Co, 4 MV X-ray and 6 MV X-ray machines. The dose distribution on the stent fringe (i.e.,on the esophageal mucosa) was compared with that at the center of esophagus without metal stent.Results When a single anterior field was used to irradiate the esophageal carcinoma, the dose enhancement on the anterior and posterior point of the Chinese metal stent was 16.2% and 7.8% by 60Co,15.4% and 6.8% by 4 MV X-ray and 12.8% and 5.8% by 6 MV X-ray. With the same set-up, the dose enhancement of Japanese stent was 13.0% by 6 MV X-ray. When anterioposterior and posterioanterior (AP/PA) opposing fields were used ,the dose enhancement ratio was 11.7%～24.0%. When three fields from three different directions were used ,the dose were increased by 3.2～16.2%.Conclusions When irradiating esophageal carcinoma with intra-cavitary metal stent,we suggest the fraction dose be below 1.7 Gy when one field is used and not exceed 1.5 Gy when AP/PA fields are used. It is advisable to use the three field technique with the diameter of the stent limited to 1.5 cm.