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Objective:Investigate the safety and feasibility of using the new self-designed implanting applicator in vaginal three-dimensional intracavitary brachytherapy after hysterectomy for gynecological cancer, and to explore the clinical value of the self-designed implanting applicator.Methods:Sixty-two gynecological cancer patients who underwent brachytherapy in Sun Yat-sen University Cancer Center were selected in this study. Each patient received three-dimensional intracavitary brachytherapy because of the indication of postoperative radiotherapy. Each patient was treated with different types of self-designed implanting applicators according the condition of postoperative vagina,and the vaginal tube and implant needle were placed in the template according to the preset channnel. Based on the actual CT images, the high-risk clinical target volume (HR-CTV), and organs at risk were defined according to unified target area delineation criteria and then the brachytherapy plan was conducted. The prescription dose of high-risk clinical target volume (HR-CTV) was 5.5 Gy/time. The parameters such as target area, organs at risk volume and irradiated dose were evaluated by DVH diagram.Results:Sixty-two patients successfully completed brachytherapy under the guidance of self-designed implanting applicator. A total of 140 implantation treatments were performed. The total average dose of HR-CTV D90% was (575.48±22.30) cGy, the mean dose D 2cm3 of bladder, rectum and sigmoid colon were (328.69±102.71), (369.14±46.59) and (27.28±71.27) cGy, the small intestine did not drop the target area, so there was no statistics. There was statistical significance between target volume and organs at risk dose ( P<0.05). Conclusions:The new self-designed implanting applicator has obvious clinical advantages in vaginal three-dimensional intracavitary brachytherapy after hysterectomy for gynecological cancer, meets the requirements of the preset planning dose,and it is sample to operate and highly safe,which indicated a bright future of the clinical application.
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Objective:To compare the dosimetric difference between 3D-printed multi-channel applicator and conventional vaginal single-channel applicator for brachytherapy, aiming to provide guidance for patients receiving brachytherapy after cervical cancer surgery.Methods:From January 2019 to November 2020, 25 cervical cancer patients complicated with VAIN Ⅲ receiving 192Ir high-dose-rate brachytherapy after cervical cancer surgery were selected. Each patient was located by CT scanning with 3D-printed multi-channel applicator and conventional vaginal single-channel applicator, and corresponding plan and evaluation were carried out. The dose volume histogram (DVH) was obtained by inverse dose optimization algorithm. The dosimetric differences of high-risk clinical target volume (HRCTV), bladder and rectum during brachytherapy were compared with those of source applicators. The optimal treatment plan was selected. Results:D 90%, D 100%, V 100% and V 150% of the plans designed by 3D-printed individual multi-channel applicator had no significant differences compared with those designed by conventional single-channel applicator (all P>0.05). The bladder and rectal D 2cm 3 designed by 3D-printed multi-channel applicator were significantly lower than those using conventional single-channel applicator, and the differences were statistically significant (both P<0.05). Conclusion:The multi-channel individual applicator target made by 3D-printing technology has good conformal property, properly protects the bladder and rectum and possesses treatment advantages over conventional single-channel applicator.
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Objective:To design a drum-shaped applicator through Monte Carlo simulation for breast intraoperative radiotherapy.Methods:Applicator designing process is as follows: first, determined the shape of the applicator based on the geometric characteristics of the breast tumor bed closed to the chest wall; second, calculated the scattering angle and dose rate of the electron beam after passing through a series of scattering foils of different thicknesses to determine the thickness of the scattering foil; thrid, modeled the layer according to the applicator′s geometric characteristics where modulator located, and designed the modulator through the relationship between the geometric characteristics of the layer and the surface dose of the applicator. EGSnrc/BEAMnrc and EGS4/DOSXYZ were employed to model the head of the Mobetron, the layer, the applicator, and to calculate the dose distributions.Results:The applicator has two components. The upper component is a 3cm-diametre cylindrical collimator with 0.5cm wall made of 0.3cm steel and 0.2cm water equivalent material (WEM), a 0.13cm-foil made of tansgen. The lower component is a 4cm-diametre drum made of 0.2cm WEM and a 0.14cm maximum thickness hill-shaped modulator made of steel. When the energy of electron beam was 12MeV, the dose rate was about 90.44 cGy/min, and the depth of the 50% isodose curve was 1cm.Conclusion:The applicator is successfully designed, and can obtain a drum-shaped dose distribution.
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Objective To explore the feasibility of 3D printed individualized applicator for the intracavitary HDR-brachytherapy for nasopharyngeal carcinoma.Methods CT scan was performed in 1 case of recurrent rT1 nasopharyngeal carcinoma and 1 case of T2 residual nasopharyngeal carcinoma and the obtained images were transmitted to 3D image processing software.The geometric contour parameters of the nasopharyngeal cavity were obtained and a pipeline was designed to make it close to the recurrent gross tumor volume (rGTV).Individualized cavity applicators were created by using 3D printer.The applicator was inserted into the patient's nasopharyngeal cavity through oral cavity.The source tube and false source were inserted into the preset pipe of the applicator.CT scan was performed again and the images were transmitted to the 3D brachytherapy planning system.Mter delineating the target volume and organ at risk,treatment plan was optimized.After completing the first treatment,the applicator was removed.Before second treatment in a few days,CT scan was reviewed to confirm whether the position was correct.Results When the applicator was inserted into the nasopharyngeal cavity,it could be fully aligned with the nasopharyngeal wall and self-fixed without additional fixation measures.Comparing the location of false source in multiple reviews of CT scan,the error was ≤ 1 mm.No significant discomfort was reported throughout the treatment.In optimized three-dimensional treatment,100％ prescription dose curve included the full rGTV,maximum dose of the brain stem and spinal cord was＜30％ prescription dose.Recurrent patients were given with a prescription dose of DT 40Gy/8 fractions/4 weeks and patients with residual tumors were given with 12Gy/2 fractions/1 week.No tumor recurrence was observed at postoperative 3 months in two cases.Conclusions The 3D printed individualized nasopharyngeal intracavitary applicator has the advantages of self-fixation,accurate location,good repeatability and good patient tolerance.The short-term outcome is effective,whereas its long-term clinical effect and adverse reactions need to be further observed.
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Objective To investigate the Offset values of different applicators in afterloading brachytherapy.Methods Six types of applicators were selected in this study which included stainless steel interstitial needle (Part#083.062),proguide round needle (Part#189.608),proguide sharp needle (Part# 189.601),vaginal multi-channel applicator (Part # 110.800),fletcher CT/MR applicator (Part # 189.745)and henschke titanium applicator (Part#110.437).According to the sources imaging in the fluorography film,the distance of applicators between the first dwell position and the top could be measured.Marker was pasted on the surface of applicator corresponding to the first dwell position.And then the applicator was put into the pelvic phantom for a CT scan.During applicator reconstruction in the treatment planning system,the Offset values of all applicators could be acquired through adjusting the value of offset to superimpose the first dwell and the marker images.On account of the density of plastic material applicators were similar to human tissues,it was difficult to reconstruct the top of the applicator.With the help of stopper or simulation source,the value of offset could be acquired for plastic material applicators.Based on the measurement results,the differences were analyzed among different applicators.Results The Offset values significantly differed among various applicators.The Offset value for stainless steel interstitial needle was-11.4 mm,-4.1 mm for proguide round needle,-3.5 mm for proguide sharp needle,0 mm or-5.0 mm for vaginal multi-channel applicator,-6.5 mm for fletcher CT/MR applicator and-7.5 mm for henschke titanium applicator,respectively.Conclusion To adapt to the rapid development of precise radiotherapy,it is necessary to verify the Offset value in afterloading brachytherapy.
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Objective@#To investigate the Offset values of different applicators in afterloading brachytherapy.@*Methods@#Six types of applicators were selected in this study which included stainless steel interstitial needle (Part#083.062), proguide round needle (Part#189.608), proguide sharp needle (Part#189.601), vaginal multi-channel applicator (Part#110.800), fletcher CT/MR applicator (Part#189.745) and henschke titanium applicator (Part#110.437). According to the sources imaging in the fluorography film, the distance of applicators between the first dwell position and the top could be measured. Marker was pasted on the surface of applicator corresponding to the first dwell position. And then the applicator was put into the pelvic phantom for a CT scan. During applicator reconstruction in the treatment planning system, the Offset values of all applicators could be acquired through adjusting the value of offset to superimpose the first dwell and the marker images. On account of the density of plastic material applicators were similar to human tissues, it was difficult to reconstruct the top of the applicator. With the help of stopper or simulation source, the value of offset could be acquired for plastic material applicators. Based on the measurement results, the differences were analyzed among different applicators.@*Results@#The Offset values significantly differed among various applicators. The Offset value for stainless steel interstitial needle was -11.4 mm, -4.1 mm for proguide round needle, -3.5 mm for proguide sharp needle, 0 mm or -5.0 mm for vaginal multi-channel applicator, -6.5 mm for fletcher CT/MR applicator and -7.5 mm for henschke titanium applicator, respectively.@*Conclusion@#To adapt to the rapid development of precise radiotherapy, it is necessary to verify the Offset value in afterloading brachytherapy.
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Aim: The purpose of this study is to measure radiation leakage of Siemens Primus Plus and Siemens Artiste linear accelerators in electron mode and to compare the leakage level with that recommended by the International Electrotechnical Commission (IEC) standard. Materials and Methods: In this assessment, Siemens Primus Plus linear accelerator with 10 cm × 10 cm, 15 cm × 15 cm, and 25 cm × 25 cm applicators was used. The radiation leakage in lateral and vertical directions was measured for Siemens Primus Plus and Siemens Artiste linear accelerators. Results: Data derived from radiation leakage measurement for Siemens Primus Plus and Siemens Artiste linear accelerators in lateral direction from the field edge and in vertical direction from the applicator were reported. The radiation leakage data were then compared with the IEC standard to evaluate in-air field leakage. Conclusion: Comparing the radiation leakage level from fields with the IEC standard for two applicators, the maximum that was occurred for 12 MeV electron beam and applicator size of 10 cm × 10 cm in Siemens Artiste linear accelerator was 2.3%, which is less than the IEC's recommended limit of 10%. It is concluded that the leakage amount is much less than the specified limit and that both of the linear accelerators have high level of safety. Considering the measurement stage, it also needs to be noted that the beam angle affected the radiation leakage level from field edge, and in 25° angle, it is higher than in 0° angle. Comparing radiation leakage from the right side of the field for the two linear accelerators, the amount of leakage for Siemens Primus Plus linear accelerator is more than Siemens Artiste linear accelerator
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Background@#There are only very few reports on clinical outcomes using multi-channel applicators (MCA) for patients with endometrial cancer (EC) in China. We aimed to evaluate the clinical experience of treating intermediate-risk (IR) to high-risk (HR) stage I EC using in-house made multi-channel applicators (IH-MCA) in a single institution.@*Methods@#Three hundred and ninety patients with stage I IR to HR EC were treated with hysterectomy and adjuvant radiotherapy from 2003 to 2015. All patients received post-operative vaginal cuff brachytherapy (VBT) alone or as a boost after external beam radiotherapy (EBRT). The prescriptions were 500 cGy per fraction for a total of 5 to 6 fractions with brachytherapy alone or 400 to 600 cGy per fraction for 2 to 3 fractions if it was combined with EBRT. Two types of applicators including a traditional rigid IH-MCA and a recent model custom-made with 3 dimension printing technology were used for treatment. The Kaplan-Meier method was used to calculate survival rate.@*Results@#Follow-up rate was 92.8% and the median follow-up time was 48 months (range 4–172 months). The 5-year overall survival (OS), progression-free survival, local recurrence, and distant metastasis rates for all patients were 96.3%, 92.1%, 2.9%, and 4.8% respectively. Two patients had isolated relapse in vagina outside the irradiated volume. The univariate and multivariate analysis showed that age and grade were the prognostic factors correlated with OS (hazard ratio: 0.368, 95% confidence interval [CI]: 0.131–1.035, P = 0.048; hazard ratio: 0.576, 95% CI: 0.347–0.958, P = 0.026,).@*Conclusions@#For patients with IR to HR stage I EC, adjuvant VBT alone or in combination with EBRT using IH-MCA led to excellent survival and recurrence rates. Age and grade were the prognostic factors correlated with OS.
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Objective@#To investigate the effect of Utrecht applicator on dosimetrics of targets and OARs in brachytherapy for advanced cervical cancer.@*Methods@#Data of patients with locally advanced cervical cancer who received brachytherapy with Utrecht Source Applicator from 2017 to 2018 in the Department of Radiotherapy, Cangzhou Hospital of Integrated Traditional Chinese and Western Medicine, Hebei province, were collected. The original plan was intracavitary /interstitial brachytherapy (IC/IS-BT). With the original contour and prescription dose unchanged, the implantation was removed and new intracavitary brachytherapy (IC) plan was designed. The dosimetric parameters of IC/IS plan and IC plan were compared and analyzed, and the effect of IS implantation on dose was evaluated.@*Results@#The D90 of HR-CTV was (88.68±1.84) Gy in IC/IS group and (85.54±0.54) Gy in IC group, with significant difference(t=6.200, P<0.05). In addition, conformity index of the IC/IS plan was significantly higher than that of the IC plan (IC/IS: 0.58±0.08, IC: 0.43±0.05; t=1.010, P<0.05). In terms of OAR, there was no significant difference in dosage between the two groups (P>0.05).@*Conclusions@#For the brachytherapy of locally advanced cervical cancer, the use of Utrecht Source Applicator can satisfy the prescription dose coverage. Adding IS insertion needle can improve the optimization space of the plan. Without exceeding the dose limit of OAR, the radiation dose to HR-CTV can be significantly increased, and the uniformity of dose distribution can be improved as well.
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OBJECTIVE@#To compare the accuracy of different methods for image registration in image-guided adaptive brachytherapy (IGABT) for cervical cancer.@*METHODS@#The last treatment planning CT images (CT1) and the first treatment planning CT images (CT2) were acquired from 15 patients with cervical cancer and registered with different match image qualities (retained/removed catheter source in images) and different match regions [target only (S Group)/ interested organ structure (M Group)/body (L Group)] in Velocity3.2 software. The dice similarity coefficient (DSC) between the clinical target volumes (CTV) of the CT1 and CT2 images (CTVCT1 and CTVCT2, respectively) and between the organs-at-risk (OAR) of the two imaging datasets (OARCT1 and OARCT2, respectively) were used to evaluate the image registration accuracy.@*RESULTS@#The auto-segmentation volume of the catheter source using Velocity software based on the CT threshold was the closest to the actual volume within the CT value range of 1700-1800 HU. In the retained group, the DSC for the OARs of was better than or equal to that of the removed group, and the DSC value of the rectum was significantly improved ( < 0.05). For comparison of different match regions, the high-risk target volume (HRCTV) and the low-risk target volume (IRCTV) had the best precision for registration of the target area, which was significantly greater than that of M group and L group ( < 0.05). The M group had better registration accuracy of the target area and the best accuracy for the OARs. The DSC values of the bladder and rectum were significantly better than those of the other two groups ( < 0.05).@*CONCLUSIONS@#The CT value range of 1700-1800 HU is optimal for automatic image segmentation using Velocity software. Automatic segmentation and shielding the volume of the catheter source can improve the image quality. We recommend the use of interested organ structures regions for image registration in image-guided adaptive brachytherapy for cervical cancer.
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Female , Humans , Brachytherapy , Methods , Reference Standards , Organs at Risk , Diagnostic Imaging , Radiotherapy Dosage , Radiotherapy Planning, Computer-Assisted , Methods , Reference Standards , Radiotherapy, Image-Guided , Methods , Reference Standards , Software , Tomography, X-Ray Computed , Methods , Reference Standards , Uterine Cervical Neoplasms , Diagnostic Imaging , RadiotherapyABSTRACT
Precise implantation of applicator is the key step of brachytherapy in cervical cancer patients. The imaging guidance can guarantee the accuracy of applicator placement. At present, the imaging approaches used to guide the applicator placement mainly include ultrasound, CT and X-ray, and MRI and laparoscopy have been applied in certain institutions. There has been no consensus on the standard imaging technique. In this paper, nearly 50 articles and surveys were reviewed to demonstrate that ultrasound-guided placement is of clinical value and guiding significance. Therefore, the application of ultrasound-guided applicator placement in the brachytherapy for cervical cancer was summarized and reviewed.
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Objective To evaluate the effect of stainless steel applicator on dose distribution in GZP 60 Co brachytherapy source and to obtain the dosimetric parameters of the 60 Co source with stainless steel applicator. Methods Geant4 was employed to obtain the mean adsorption dose of the 60 Co brachytherapy source in the range of 0-10 cm, and the dosimetric parameters were calculated according to the formula proposed by AAPM reports TG43 and TG43U1. The 60 Co source was located in the center of a sphere water phantom with a radius of 30 cm. Results For channel 1 and 2 of GZP 60 Co source, the results of Λ with stainless steel applicator were 1. 014 cGyh-1 U-1( with a difference of 0. 5％ compared with non-applicator) , the results of Λ with stainless steel applicator for channel 3 were 0. 998 cGyh-1 U-1 ( with a difference of 0. 1％ compared with non-applicator) . The radial dose function in the range of 0. 5-10. 0 cm in a longitudinal direction was calculated and the fitting formula for the function was obtained. The polynomial function for the radial dose function and the anisotropy function with a of 0°-175° and an r of 0. 5-10. 0 cm were obtained. Conclusion The dosimetric parameters of the 60 Co source with stainless steel applicator are obtained, which provide more accurate reference data for clinical application. In clinical practice, the effect of stainless steel applicator on dose distribution should be considered.
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Objective To report a simple method for determination of dwell position offset of ring applicator using GafchromicTM EBT3 film and ImageJ software. Methods In the dummy plan, this study reconstructed the ring applicator point by point manually according to the MR line marker, the most distal reconstruction point was at the end of marker, set the offset to zero. The first, eleventh, and twenty-third dwell positions were activated with the step length of 2. 5 mm. A setup image was designed to immobilize the ring applicator. The setup image was composed of two perpendicular thin lines and a circular with a diameter of 16 mm. GafchromicTM EBT3 film was fixed behind the setup image by plastic tapes. After irradiation, a ruler was put on the bottom of the irradiated film as a plotting scale. Photos were taken with the help of a vertical camera using a tripod. The file was imported into ImageJ software and the coordinate values were obtained by semi-automatic recognition of the center of exposure area. The test was repeated five times at one week interval to evaluate the uncertainty. For every time, each dwell position was measured five times. Results The angle between the radius of the first dwell position and the x-axis was 43° in the dummy plan, and (46. 8 ± 0. 9)° for actual measurement. The offset was 0. 9 mm for the ring applicator combined with the MR according to calculation. The distances between the first,the eleventh and the twenty-third dwell positions and the center of the ring were ( 12. 9 ± 0. 1 ) mm, ( 12. 5 ± 0. 1 ) mm, (12. 4 ± 0. 1) mm, respectively. Conclusions Using GafchromicTM EBT3 film and the ImageJ software is a simplified method to validate the dwell position offset of the ring applicator.
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Objective To investigate the relationship between the channel design of tandem-andovoid (T&O) applicator and the doses to organs at risk (OARs) and target volume in three-dimensional brachytherapy for advanced cervical carcinoma.Methods The data on 15 patients with advanced cervical carcinoma treated with three-dimensional brachytherapy in our hospital from 2015 to 2016 were collected,and 30 randomly selected high-dose-rate titanium T&O plans were retrospectively studied.CT-guided,conformal brachytherapy plans were generated.To simulate T&O applicator,the tandem applicator was virtually compared with the T&O plans with the target volume and OARs remaining unchanged.The DVH parameters of the rectum,bladder,and sigmoid were compared using the paired t test.Results For T&O plans and tandem applicator plans,the mean D2cc of the rectum was 387.8±96.8 cGy and 340.8±88.1 cGy,respectively;the mean D2cc of the bladder was 443.2± 87.5 cGy and 719.4± 243.0 cGy,respectively;the mean D2cc of the sigmoid was 330.3±88.8 cGy and 383.1±105.6 cGy,respectively.In the T&O plans,the doses to the rectum,bladder,and sigmoid were within the limits (rectum:D2cc ≤ 500 cGy;bladder:D2cc ≤ 550 cGy;sigmoid:D2c ≤ 500 cGy),while D2cc of the bladder and sigmoid was higher or partially higher than the limits.T&O plans showed a significant reduction in bladder D2cc and sigmoid D2cc compared with the tandem applicator plans (all P＜0.05).Conclusions Compared with tandem applicator plans,plans using T&O applicator provide significant sparing of bladder and sigmoid tissues in three-dimensional brachytherapy for cervical carcinoma,but the toxicities require further investigation.
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OBJECTIVE: The aim of this study was to determine the efficacy of 252Californium neutron intracavitary brachytherapy using a two-channel Y applicator combined with external beam radiotherapy for the treatment of endometrial cancer. METHODS: Thirty-one patients with stage I-III endometrial cancer were recruited for this study. The stage I patients received only 252Californium neutron intracavitary brachytherapy with a two-channel applicator. The stage II and III patients received both 252Californium neutron intracavitary brachytherapy using a two-channel applicator and parallel-opposed whole pelvic radiotherapy. RESULTS: The five-year local control rate was 80.6% (25/31), the overall survival rate was 51.6% (16/31), and the disease-free survival rate was 54.8% (17/31). The incidence of serious late complications was 12.9% (4/31). CONCLUSIONS: 252Californium neutron intracavitary brachytherapy using a two-channel applicator combined with external beam radiotherapy was effective for treating endometrial cancer and the incidence of serious late complications related to this combination was within an acceptable range.
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Adult , Aged , Female , Humans , Middle Aged , Adenocarcinoma/radiotherapy , Brachytherapy/methods , Californium/therapeutic use , Endometrial Neoplasms/radiotherapy , Adenocarcinoma/mortality , Adenocarcinoma/pathology , Antineoplastic Combined Chemotherapy Protocols/therapeutic use , Brachytherapy/instrumentation , Combined Modality Therapy , Carmustine/therapeutic use , Cytarabine/therapeutic use , Endometrial Neoplasms/mortality , Endometrial Neoplasms/pathology , Follow-Up Studies , Melphalan/therapeutic use , Podophyllotoxin/therapeutic use , Survival Rate , Treatment OutcomeABSTRACT
Objective To investigate the dosimetric differences between Utrecht applicator and ring applicator in three-dimensional (3D) conformal brachytherapy for locally advanced cervical cancer.Methods Twenty-five patients with locally advanced cervical cancer were treated with magnetic resonance imaging-guided 3D conformal brachytherapy.Utrecht applicator and ring applicator were used interchangeably for 96 cycles.Patients were divided into two groups according to the type of applicator.Each group received 48 cycles of treatment, in which ring applicator was first applied for 26 cycles and Utrecht applicator was first applied for 22 cycles.High-risk clinical target volume ( HR-CTV) , width, thickness, and D90 at the point A level, D2 cm3 of organs at risk (OARs), V7 Gy , W7 Gy,A, V7 Gy ,A, and W/T7 Gy were evaluated and analyzed using paired t-test.Results There were no significant differences in HR-CTV and the width, thickness, and D90 at the point A level between the Utrecht group and the ring group ( P=0.487;P=0.340;P=0.857;P=0.921);there were no significant differences in D2 cm3 values of bladder, rectum, sigmoid, and bowel between the two groups ( P=0.136;P=0.802;P=0.985;P=0.458);there were no significant differences in V7 Gy and T7 Gy,A between the two groups ( P=0.076;P=0.435) .The Utrecht group had a significantly larger W/T7 Gy,A than the ring group ( P=0.002 ) .Conclusions Utrecht applicator is appropriate for patients with relatively large width and width/thickness ratio of HR-CTV at the point A level.
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Objective To investigate the clinical application of Utrecht applicator in three-dimensional image-guided brachytherapy (3D-IGBT) for locally advanced cervical cancer,as well as its application discipline in intracavitary/interstitial (IC/IS) therapy.Methods A retrospective analysis was performed for the clinical data of 45 patients with locally advanced cervical cancer who received radical radiotherapy,and the patients received external beam radiotherapy followed by 3D-IGBT.A total of 130 times (n =45) of IC/IS therapy were performed,and the patients who received such therapy were all enrolled.The patients who met the target dose fractionation defined in the plan were enrolled as group A (n=37,86 times),and the other patients were enrolled as group B (n=22,44 times).Two groups difference was analyzed with Group t-test.Results The frequencies of use of 15-,20-,and 25-mm ovoids by the applicator were 50.0％,20.0％,and 30.0％,respectively,and the 30-mm ovoid was not used.A total of 499 needles were used,and the frequencies of use of 6,7,10,and 11 insertion holes were 23.1％,21.2％,21.2％,and 24.1 ％,respectively.Group A had a significantly lower mean number of the needles than group B (3.7 vs.4.2,P=0.008).Compared with group B,group A had a significantly lower mean high-risk clinical target volume (CTV)(40.71±18.43 cm3 vs.51.81±14.74 cm3,P=0.001),as well significantly lower width and height of high-risk CTV (P=0.011 and 0.006),but the thickness of high-risk CTV was similar between the two groups (P=0.595).The difference between height and insertion depth (DH) was similar between the two groups (P=0.366).Group A had a smaller difference between width and pinhole distance Dw than group B (P=0.007).Conclusions When IC/IS therapy is performed for locally advanced cervical cancer,the 15-,20-,and 25-mm ovoids of Utrecht applicator and 6,7,10,and 11 insertion holes are frequently used.When the number of needles is no less than 4 and the depth is no less than 3 cm,width is the major factor which affects the planned dose.
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Objective To study the impacts of different applicators on dose distribution in 192 Ir brachytherapy. Methods The inner tubes of two cylinder applicators from Nucletron,#101?001 and#084?350, were made of plastic and stainless steel, respectively. The cylinder parts of them were made of plastic, and had four different radiuses:1?00 cm, 1?25 cm, 1?50 cm, and 1?75 cm. EGSnrc program was used to simulate dose distribution when applicators were present in a phantom, and the results calculated by the treatment planning system were compared with the results of EGSnrc. The impacts of applicators on dose distribution were analyzed with different materials, thickness, and numbers of resident source. Results There was no significant relationship between dose deviation and the radius for the two applicators. When an applicator was present, the actual dose delivered to a patient was smaller than the planned dose. The dose deviation of the applicator#101?001 was no more than 1%, while the dose deviation of the applicator#084?350 was close to 3%. The dose deviation remained the same when the number of resident source changed. Conclusions The plastic applicator, if possible, is the best choice for brachytherapy right now. In a long term, in order to promote the accuracy of brachytherapy, current dosimetry algorithm should be improved, and the impacts of the applicator made of metal, such as stainless steel, on dose distribution should be taken into account.
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Objective To explore the influence of age factor on the treatment of cutaneous hemangioma with (90Sr-90Y) applicator.Methods A total of 224 babies and children of different ages with cutaneous hemangioma were treated by using 90Sr-90 Y applicator.Then,the relation between their therapeutic effects and ages were analyzed respectively.Results The differences in the therapeutic effect between group of one month to less than one year and group of one to less than five years,and group of one month to less than one year and group of five to ten years,and between group of one to less than five ages and group of five to ten years (P＜0.05),were statistically significant.With an increase of the age,the recovery rate gradually decreased,but their effective rate,improvement rate and ineffective rate increased.In the 199 well-healed or effective patients,the differences in the distribution of treatment course between group of one month to less than one year and group of one to less than five years,and group of one month to less than one year and group of five to ten years,were statistically significant (P＜0.05); but the difference in the distribution of treatment course between group of one to less than five ages and group of five to ten years was not statistically significant (P＞0.05).The number of treatment course presented an increased tendency with an increase of the age for patients.Conclusions The age of patients is a factor influencing the therapeutic effect on cutaneous hemangioma with 90 Sr-90Y applicator.The younger the patients,the better their therapeutic effects,the shorter their courses of treatment,and the smaller the adverse reaction of beta ray.
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PURPOSE: The aim of this study was to compare the flexural strength of polymethyl methacrylate (PMMA) and bis-acryl composite resin reinforced with polyethylene and glass fibers. MATERIALS AND METHODS: Three groups of rectangular test specimens (n = 15) of each of the two resin/fiber reinforcement were prepared for flexural strength test and unreinforced group served as the control. Specimens were loaded in a universal testing machine until fracture. The mean flexural strengths (MPa) was compared by one way ANOVA test, followed by Scheffe analysis, using a significance level of 0.05. Flexural strength between fiber-reinforced resin groups were compared by independent samples t-test. RESULTS: For control groups, the flexural strength for PMMA (215.53 MPa) was significantly lower than for bis-acryl composite resin (240.09 MPa). Glass fiber reinforcement produced significantly higher flexural strength for both PMMA (267.01 MPa) and bis-acryl composite resin (305.65 MPa), but the polyethylene fibers showed no significant difference (PMMA resin-218.55 MPa and bis-acryl composite resin-241.66 MPa). Among the reinforced groups, silane impregnated glass fibers showed highest flexural strength for bis-acryl composite resin (305.65 MPa). CONCLUSION: Of two fiber reinforcement methods evaluated, glass fiber reinforcement for the PMMA resin and bis-acryl composite resin materials produced highest flexural strength. CLINICAL IMPLICATIONS: On the basis of this in-vitro study, the use of glass and polyethylene fibers may be an effective way to reinforce provisional restorative resins. When esthetics and space are of concern, glass fiber seems to be the most appropriate method for reinforcing provisional restorative resins.