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Objective:To discuss the dosimetric contribution of the ovoid in the cervical cancer brachytherapy through the intracavity combined with interstitial(IC/IS)technique.Methods:The data on 20 patients with FIGO(2009)stageⅡ A, Ⅱ B or Ⅲ Bcervical cancer treated with radical radiotherapy in China-Japan Union Hospital of Jilin University during 2015-2017 was collected. External irradiation treatment was 45 Gy/1.8 Gy× 25 fractions. Brachytherapy was MRI-guided IC/IS brachytherapy with a prescription of 28 Gy/7 Gy× 4 fractions. All of 20 patients developed two kinds of plans, the ovoid group and the non-ovoid group. The original MRI-guided brachytherapy treatment plan was set(80 fractions)to the ovoid group. As contrast model that removed the ovoid and consisted of tandem combined with needles set to the non-ovoid group was built, and the same physicist designed the plan to make the dose of D90% for high-risk clinical target volume(HR-CTV)similar to the ovoid group. The dosimetric differences of the D90% and D98% for HR-CTV, D90% and D98% for intermediate-risk clinical target volume(IR-CTV)and D2 cm 3 for the bladder, rectum, sigmoid colon and small intestines between two groups of plans were analyze by paired t-test. Results:Compared with the ovoid group, the non-ovoid group showed no significant difference on HR-CTV D90%( P>0.05), but the HR-CTV D98%(6.99±0.60 vs. 6.78±0.76), IR-CTV D90%(4.71±0.58 vs. 4.26±0.57) and D98%(3.77±0.58 vs. 3.26±0.59) of the non-ovoid group decreased significantly( t=3.906, 9.860, 8.636, P<0.05). The sigmoid colon showed no significant difference( P>0.05), while the bladder (5.29±0.67 vs. 4.92±0.74), rectum (3.72±0.69 vs. 3.35±0.92) and small intestines (3.05±1.37 vs. 2.98±1.34) D2 cm 3of the non-ovoid group decreased significantly( t=8.758, 7.543, 8.059, P<0.05). Conclusions:Ovoid is very important for IC/IS technique in cervical cancer brachytherapy. Reasonable optimization of the dose weight ratio of the ovoid and the needle can bring better clinical benefits.
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Objective:To summarize the clinical features of children with autosomal dominant hyper-IgE syndrome (AD-HIES) and the differential diagnosis of hyper-IgE syndrome and allergic diseases as well.Methods:All clinical data, including general information, clinical features, and genetic changes, from 7 children with AD-HIES who were diagnosed in Beijing Children′s Hospital Affiliated to Capital Medical University from April 2016 to June 2020 were analyzed retrospectively.The diagnostic criteria are based on the National Institutes of Health′s (NIH)′s hyper-IgE syndrome score and combined with the results of gene detection, shown as follows: (1) NIH score over 40, with signal transducer and activator of transcription 3 gene ( STAT3) pathogenic mutation; (2) NIH score between 20 and 40, with reported STAT3 pathogenic mutation; (3) NIH score less than 20 points was excluded. Results:There were 3 males and 4 females.The onset age of 7 cases was within 2 months after birth, and the mean age at diagnosis was 3 years old.All seven cases had recurrent skin or lung infections, with 4 cases having skin and lung infections, 1 case of skin abscesses at the BCG vaccination site, and 2 cases without skin infection suffering from recurrent pneumonia.The mean onset age of skin abscess in 5 cases was 1.5 years, and pus culture of 3 cases were Staphylococcus aureus.Four cases developed bullae and 6 cases had lung infections.Four cases had otitis media, and oral thrush was seen in 4 cases.One case of skin and lung infection developed liver abscess and sepsis.Seven cases had eczema, which was disco-vered in the neonatal period for 6 cases.Four cases had the symptoms of eczema for the first visit.Two cases had food allergy, and 1 case had recurrent wheezing within 1 year old.The serum IgE level and blood eosinophil count in 7 children were elevated.All children had heterozygous pathogenic mutations in STAT3.Six patients had de novo mutations.There were 6 different mutation sites.The 4 mutation sites were reported: c.1145G>A, c.1144C>T, and c. 1699A>G were missense mutations, and c. 1139+ 5G>A was splicing mutation.Two mutation sites had not been reported: c.1031A>C was missense mutation, and c. 2050G>T was nonsense mutation.The pathogenic grade of them were likely pathogenic, and the NIH score of 2 cases were above 40 score, which was consistent with the clinical diagnosis of hyper-IgE syndrome. Conclusions:Eczema is a common and early clinical manifestation of hyper-IgE syndrome, along with elevated IgE levels and eosinophil counts that need to be differentiated from allergic diseases.On the contrary, it often had recurrent skin abscesses or pneumonia, which was prone to bullae.The clinical manifestations of young children were atypical, and genetic testing was helpful for early diagnosis.
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Objective:To investigate the etiology of pleural effusion in hospitalized children in Beijing Children′s Hospital.Methods:Clinical information of children with pleural effusion admitted to Beijing Children′s Hospital Affiliated to Capital Medical University from January 2016 to December 2018 was retrospectively analyzed.According to the etiology, the children were divided into infection group (parapneumonic pleural effusion, tuberculous pleurisy and empyema) and non infection group.According to the age, the children were further divided into ≤ 3 years old, >3-7 years old and > 7 years old groups.Classification of statistics was performed, and the etiology of pleural effusion were retrospectively analyzed.Results:Among the 1 165 children with pleural effusion, 746 cases(64.0%) were infected with pleural effusion, 697 cases (697/746, 93.4%) of who were parapneumonic effusion.In patients with parapneumonic effusion, 457 cases (61.3%) had Mycoplasma pneumonia (MP) infection.Infectious pleural effusion was more common in children >7 years old(339/479 cases, 70.8%), while non-infectious pleural effusion was prevalent in children under 3 years old(188/324 cases, 58.0%). The difference was statistically significant ( χ2=96.33, P<0.05). Among the patients with non-infectious pleural effusion, 239 cases (239/419 cases, 57.0%) had multi-system diseases and 97 cases (97/419 cases, 23.2%) had malignant pleural effusion.All the 18 deaths were non-infectious pleural effusion. Conclusions:The leading reason for pleural effusion in children is infection.The most prevalent symptom is parapneumonic effusion, which is mainly caused by MP.
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In China, COVID-19 epidemic is currently showing a sporadic state, and the task of epidemic prevention is still arduous. Brachytherapy (BT) plays a critical role in the treatment of cancer. For some cancer receiving radiotherapy, use of BT can not be replaced or excessively delayed. Nevertheless, the recommendations or guidelines regarding the application of BT during COVID-19 epidemic have been rarely reported. In this article, a few recommendations on the application of BT during COVID-19 epidemic were retrieved and the work experience of Department of Radiation Oncology, China-Japan Union Hospital of Jilin University in the early epidemic period was summarized, aiming to provide relevant reference for the use of high-dose-rate BT for malignant tumor patients during COVID-19 epidemic.
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Objective:To explore the application of 3D printing technology-assisted standardized applicator in the image-guided adaptive brachytherapy (IGABT) for cervical cancer.Methods:Twenty-three patients with stage Ⅲ B cervical cancer with extensive paracervical invasion after external irradiation (45 Gy/25f) were treated with IGABT, and the prescription dose was 7 Gy/f×4f. According to the regression of tumor on MRI before and after external irradiation, the range of brachytherapy was determined, and the under dose area of standard intracavitary/interstitial applicator (IC+ IS) was estimated. The virtual transperineal needle channel was inserted in the under dose area, the angle, spacing and depth of implantation were optimized. The auxiliary templates were designed with graphic design software, and 3D printing technology was utilized to print the auxiliary templates. The auxiliary templates were closely combined with the standardized applicator. Under the anesthesia condition, ultrasound-guided applicator was completed, and patients were scanned with MRI image after operation. The MRI images were introduced into treatment planning system (TPS) to delineate the target area and organs at risk, and the treatment plans were optimized to complete the plan evaluation and treatment. Results:The average printing time of templates was (3.5±1.0) h, 382 implant needles were inserted guided by auxiliary templates, (4.2±1.5) template-guided implant needles were used in each fraction and the weight ratio was (16.49±9.50)%. The total dose of HR-CTV D 90% EQD 2Gy, α/ β=10 was (90.45±3.03) Gy, and IR-CTV D 90% EQD 2Gy, α/ β=10 was (66.46±3.68) Gy. The D 2cm 3 EQD 2Gy, α/ β=3 of the bladder, rectum, small intestine and sigmoid colon were (82.69±2.60) Gy, (73.20±2.52) Gy, (69.35±3.32) Gy and (69.39±3.27) Gy, respectively, all of which met the clinical dose requirements. The 1-and 2-year local control rates were 96% and 87%, 87% and 70% for the distant metastasis-free survival rates, and 96% and 78% for thea overall survival rates, respectively. Conclusion:The auxiliary applicators made by 3D printing technology can effectively compensate for the dose insufficiency of the standard applicator in the paracervical and other areas during the clinical brachytherapy in patients with stage Ⅲ B cervical cancer, providing an effective method for the brachytherapy of advanced cervical cancer.
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Objective:To explore the clinical efficacy and adverse reactions of the combination of external beam radiotherapy followed by three-dimensional intracavitary brachytherapy in patients with inoperable locally advanced rectal cancer.Methods:Clinical data of 11 patients with inoperable locally advanced rectal cancer, 7 male and 4 female, admitted to China-Japan Union Hospital of Jilin University from 2013 to 2015 were retrospectively analyzed. All patients received pelvic external irradiation (50 Gy in 25 fractions), followed by a three-dimensional intracavitary brachytherapy boost (15-20 Gy in 3-4 fractions, 1 fraction/week). External beam radiotherapy was used to boost the dose to the perirectal lymph nodes (60-66 Gy in 30-33 fractions). All patients received concurrent chemotherapy with Capecitabine during external beam radiotherapy. Efficacy evaluation was performed using the RECIST standard. Survival and local control rates were calculated using the Kaplan- Meier method. Early and late radiotherapy responses were assessed using the RTOG lesion grading criteria. Results:The CTV D 90% EQD 2 Gy of HDR 3D-ICBT among 11 patients was (21.3±1.60) Gy. The complete response (CR) and partial response (PR) rates were 64% and 27%, respectively, yielding an objective response rate (CR+PR) of 91%. With a median follow-up time of 36 months, the 1-, 2-, and 3-year overall survival rates were 82%, 64% and 46%, respectively. The 1-, 2-, 3-year disease-free survival rates were 64%, 45% and 27%, respectively. The 3-year local control rate was 46%. One patient presented with lung metastases after 8 months, 7 patients experienced grade 1-2 acute intestinal reactions and 5 patients developed grade 1-2 acute bladder reactions, only one patient had grade 2 myelosuppression; long-term grade 1-2 intestinal reactions occurred in 5 patients, and 1 patient had long-term grade 1-2 bladder reaction. All the radiation-induced toxicities were alleviated by medication administration. Conclusions:External beam radiotherapy followed by three-dimensional intracavitary brachytherapy can be a safe and effective surrogate in patients with inoperable locally advanced rectal cancer, which yields reliable clinical efficacy and tolerable adverse reactions.
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Objective:To measure the effect of applicator materials on absorbed dose in water from HDR afterloading 192Ir source by using three-dimensional printed holder (3DPH) and synthetic single-crystal diamond detector (SSCDD). Methods:SSCDD and plastic implants were fixed on the 3DPH in turn. The central axis of SSCDD was perpendicular to that of plastic implant needle on the same plane. The actual residence dwell position measured using source position simulator was 248 mm, which was consistent with the maximum response dwell position measured in a point by point way. The materials for measurement included 304 stainless steel, polyphenylene sulfone resins (PPSU), polymethyl methacrylate (PMMA) and 3-D printed polylactic acid (PLA), respectively. The attenuation of absorbed dose in water with different thickness or filling ratio was measured.Results:The linear fitting formula of relative dose varying with thickness (mm) for 304 stainless steel and PPSU materials were y=-0.029 7 x+ 1.000 3 and y=-0.002 3 x + 1.010 2, respectively. And the goodness-of-fits were 0.925 3 and 0.722 2, respectively. The effect on dose of PMMA materials within 10 mm was less than 1%. The linear fitting formula of relative dose varying with filling ratio (%) for PLA materials with 10 mm thickness was y=-0.000 4 x+ 1.024 6, with a goodness-of-fit of 0.854 5. Conclusions:The effect of applicator materials on the absorbed dose arising from afterloading 192Ir source should attract enough attention of both developers and clinical users, especially with regard to high-density materials like 304 stainless steel and new technology materials such as 3D printed polylactic acid.
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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 application of superficial brachytherapy in the treatment of the upper arm skin invasion of breast cancer. Methods This study was conducted on a female patient with ipsilateral chest wall, axillary, and clavicle recurrence, and circumferential skin and subcutaneous soft tissue invasion in the ipsilateral upper arm after modified radical mastectomy for breast cancer. The upper arm lesions were treated with 192Ir high-dose-rate superficial brachytherapy at a dose of 50 Gy in 25 fractions. Dosimetric parameters were compared between superficial brachytherapy and electron irradiation plan. Treatment outcomes and adverse reactions were observed during and after treatment. Results The heterogeneity index(HI)for target volume was 1.62 and 1.94 in superficial brachytherapy and electron irradiation plan, respectively. The D90,D100, and V150%for clinical target volume were higher in superficial brachytherapy than in electron irradiation plan(205 vs. 189 cGy;163 vs. 110 cGy;6.3% vs. 3.23%). The D0.1,D1, and D2for the humerus were also higher in superficial brachytherapy than in electron irradiation plan(155 vs. 80 cGy;147 vs. 55 cGy;145 vs. 36 cGy)and much lower than the bone tolerance dose in both treatments. The lesions partially subsided after superficial brachytherapy. The main adverse reaction was grade 2 radiation dermatitis. Conclusions Compared with electron irradiation plan, superficial brachytherapy is a simple and effective approach for irradiation of shallow target volume with a large curvature, such as circumferential upper arm skin invasion of breast cancer. Superficial brachytherapy achieves satisfactory homogeneity and dose distribution.
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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 investigate the correlation between ICRU reference point dose and dosevolume parameters of organs at risk (OARs) under different bladder and rectal filling status in threedimensional conformal brachytherapy for locally advanced cervical cancer.Methods A total of 31 patients who received magnetic resonance imaging-guided three-dimensional conformal brachytherapy for cervical cancer in 96 fractions were enrolled.The ICRU rectal and bladder reference points were determined in the treatment planning system,and the doses at these points were recorded and compared with the dose-volume parameters of the rectum and bladder.The paired t-test was used to analyze the differences between them.Results Bladder DICRU was lower than bladder D0.1cm3 and D1 cm3 (P=0.000 and 0.000),higher than bladder D5 cm3 and D10cm3 (P=0.000 and 0.000),and similar to bladder D2 cm3 (P=0.345).Under the bladder filling status,bladder DICRU was lower than D2cm3.Rectal DICRU was lower than rectal D0.1 cm3 and D1cm3 (P =0.000 and 0.002),higher than rectal D5 cm3 and D 10 cm3 (P =0.000 and 0.000),and similar to rectal D2cm3 (P=0.058).The ICRU bladder and rectal reference point doses were positively correlated with corresponding D2 cm3.In the case of bladder volume ≥ 200 cm3,the ICRU bladder reference point dose underestimated bladder D2 cm3.In the case of rectal volume ≥ 37 cm3,the ICRU rectal reference point dose overestimated rectal D2 cm3.Conclusions In three-dimensional conformal brachytherapy,it is generally safe to use D2 cm3 as an index to evaluate OARs,but when the bladder or rectum is in an empty status,the ICRU bladder or rectal reference point doses should be considered.
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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 explore the dosimetric advantages of computed tomography-based and ultrasound-guided three-dimensional image-quided brachytherapy (3D-IGBT) combined with intracavitary/interstitial (IC/IS) brachytherapy for locally advanced cervical cancer.Methods A total of 45 patients with FIGO (2009) stage ⅠB2-ⅣA locally advanced cervical cancer who received radical external beam radiotherapy and 3D-IGBT combined with IC/IS brachytherapy in our hospital from 2013 to 2014 were analyzed.After the treatment with 192Ir-based IC/IS brachytherapy,patients had needles removed from the original images and received treatment only from IC radiation sources.Dosimetric differences in the planning D90 for high-risk clinical target volume (HR-CTV),D90 for intermediate-risk CTV (IR-CTV),and D2 cm3 for the bladder,rectum,sigmoid colon,and small intestines were determined and analyzed by paired t-test.Results A total of 260 after-loading treatment plans,including IC/IS treatment plans for 130 patients and IC treatment plans for 130 patients,were made.The D90 for HR-CTV and D90 for IR-CTV in the IC/IS brachytherapy group were significantly higher than those in the IC brachytherapy group (P =0.000;P =0.000).Moreover,the average D2cm3 values for the bladder and rectum were significantly reduced in the IC/IS brachytherapy group compared with those in the IC brachytherapy group (P =0.000;P =0.006).Conclusions The 3D-IGBT combined with IC/IS brachytherapy not only achieves a higher dose for the target volume,but also reduces the radiation dose to the bladder and rectum in the treatment of locally advanced cervical cancer.
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Objective To evaluate the effect of bladder volume change on the doses to normal tissues in cervical cancer patients undergoing external three-dimensional conformal radiotherapy (3DRT)plus 3D conformal brachytherapy (3DCBT).Methods The study included 56 patients with cervical cancer who were admitted to our hospital from 2012 to 2013 and received radical external 3DRT and 3DCBT.During 3DCBT,the doses to 0.1,1.0,and 2.0 cm3(D0.1 cm3,D1.0cm3,and D2.0cm3,respectively) for the rectum,small intestine,sigmoid colon,and bladder under different bladder filling status (empty,50,100,and 150 ml) were compared and analyzed by paired t-test.Results The rectum D0.1cm3 with bladder volumes of 50and 100 ml were significantly reduced compared with that with an empty bladder (P =0.000,0.000).The D0.1 cm3,D1.0cm3,and D2.0cm3 for the small intestine with bladder volumes of 50,100,and 150 ml were significantly reduced compared with those with an empty bladder (P =0.008,0.000,0.000 and 0.000,0.000,0.000 or 0.000,0.000,0.000).The D0.1 cm3,D1.0cm3,and D2.0cm3 for the bladder with bladder volumes of 100 and 150 ml were significantly increased compared with those with an empty bladder (P =0.000,0.000 and 0.000,0.000 or 0.000,0.000).Conclusions The doses to the bladder and small intestine are influenced by different bladder filling status,but the doses to the rectum and sigmoid colon show no significant variation.The increase in bladder volume is helpful in reducing the dose to the small intestine.Without any change in the bladder dose,the bladder volume of 50 ml is more beneficial to reduce the dose to the small intestine than those of 100 and 150 ml.
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Objective To compare target volume and dosimetry between computed tomography (CT)?and magnetic resonance imaging (MRI)?guided three?dimensional (3D) conformal brachytherapy for locally advanced cervical cancer, and to provide evidence for optimization of the image?guided approach and improvement of treatment regimen. Methods Thirteen patients with locally advanced cervical cancer who were treated with radical radiotherapy in our hospital in 2014 were enrolled as subjects. All patients received MRI?guided 3D conformal intracavitary/ interstitial brachytherapy. All patients received MRI and CT scans for each brachytherapy fraction, based on which the target volume delineation, intracavitary/ interstitial regimen design, and intracavitary?only treatment regimen design were performed. Comparison of data between MRI and CT scans was performed using paired t test. Results The width and volume of the high?risk clinical target volume ( HR?CTV) were significantly smaller in the MRI simulation than in the CT simulation ((38.0±9?? 4) mm vs. (45.1±8?? 7) mm, P= 0?? 000;(34.2±15?? 3) cm3 vs. (42.9±20?? 4) cm3 , P= 0?? 002), and the width, thickness, and volume of the intermediate?risk clinical target volume (IR?CTV) were also significantly smaller in the MRI simulation than in the CT simulation ((58.8±9?? 4) mm vs. (65.4±10?? 3) mm, P= 0?? 000;(34.8±6?? 3) mm vs. (37.5±6?? 3) mm, P= 0?? 001;(90.9±28?? 5) cm3 vs. (109.0±36?? 4) cm3 , P= 0?? 000). The D90 values for HR?CTV and IR?CTV were significantly higher in the MRI simulation than in the CT simulation (87?? 6 Gy vs. 85?? 8 Gy, P= 0?? 013;67?? 7 Gy vs. 66?? 3 Gy, P= 0?? 005), while the average D2 cm3 values for the bladder and rectum were significantly lower in the MRI simulation than in the CT simulation ( 73?? 1 Gy vs . 75?? 5 Gy , P= 0?? 011 ; 61?? 0 Gy vs . 65?? 7 Gy , P= 0?? 000 ) . Conclusions Compared with the MRI simulation, the CT simulation overestimates the width of target volume. MRI has substantial advantages in dosimetry for target volume and normal tissues. The intracavitary/ interstitial treatment can make up the reduced dose for the target volume resulting from the CT simulation.
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Objective To explore the correlation between the dose measured in the rectum and reference dose in three?dimensional brachytherapy ( 3DBT ) for cervical cancer, and to evaluate the significance of the dose measured in the rectum. Methods Fifty patients receiving radiotherapy for cervical cancer were selected, and 3DBT was performed after pelvic external beam radiotherapy. According to the rectal monitoring method recommended in the report ICRU38, in vivo monitoring was applied to obtain the dose measured in the rectum, reference point dose ( DICRU ) , and D2 cm3 , and the planned dose was obtained from the planning system. The differences in these values were determined by the paired t?test and correlation analysis was performed with Pearson test. Results The dose measured in the rectum was higher than the planned dose (3. 48 vs. 3. 25,P=0. 000), and lower than DICRU(3. 48 vs. 3. 71,P=0. 000) and D2 cm3(3. 48 vs. 3. 87,P=0. 002). A linear relationship existed between the dose measured in the rectum and the planned dose, with a deviation percentage of-20% to 40% and an average deviation of 8. 16%;63%of the patients with cervical cancer had a deviation of<± 10%;the maximum deviation was 60%. The dose measured in the rectum had a strong correlation with DICRU(r=0. 722), but a weak correlation with D2 cm3 ( r=0. 284) . Conclusions During 3DBT for cervical cancer, the dose measured in the rectum has certain deviations, but has a linear correlation with the planned dose. Both the dose measured and the planned dose underestimate the dose at the reference point in the rectum, and in vivo rectal monitoring may be an effective method for quality control.