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Radiotherapy is an important treatment of gynecological tumors. Although novel techniques or measures in recemy years have improved the tumor control rate and reduced radiation toxicity, radiation toxicity remains a major problem due to the location of some key organs adjacent to the tumor. A new material-hydrogel, as an organ spacer, provides a new method to reduce the radiotherapy toxicity. In this article, the application of hydrogel as an organ spacer in brachytherapy for gynecological tumors was reviewed from the aspects of hydrogel characteristics, suitable population, mode of injection, interval distance and dose effect, clinical benefits and cost effectiveness, etc.
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Objective:To investigate the impact of carbon based non-conductive sliding rails on intensity-modulated radiation therapy (IMRT) planning for vertebral tumors.Methods:A reconstruction imaging of the couch plate and its rails removed from the EDGE linear accelerator was acquired by helical computed tomography (CT), and pushed into the treatment planning system (TPS). Based on CT images of homogeneous phantom and patients in our database, 6 and 10 MV photon IMRT plans were designed with five fields (180°, 200°, 220°, 160°, 140°), setting a prescribed dose of 3 Gy/F ×10 F to the planning target volume (PTV), and the dose was calculated by AcruosXB. In addition, optimization plans (OP) without rails and with rails symmetrically moving (4-19 cm, step size 1 cm) were created and verification plans(VP) were created by inserting and removing slide rail′s structure from the corresponding OP in VP. The differences in mean dose ( Dmean), homogeneity index (HI), and conformability index (CI) of the PTV, and maximum dose ( Dmax) of the spinal cord were compared and analyzed between the VP and OP. Results:HI of PTV with and without the rails were worse in the 6/10 MV verification plans, with a maximum difference of 2%. In 6 MV plans, with rails Dmean of PTV decreased by (2.07±0.99)%, CI increased by (4.91±3.12)%, and Dmax of spinal cord decreased by (1.83±1.37)%. Without rails, the Dmean of PTV increased by (2.02±0.96)%, but CI decreased by (3.07±1.31)% and Dmax of the spinal cord increased by (2.03±1.44)% in the patient respectively. There were significant statistical differences between groupswith and without rails( F=27.55, 361.32, 13.05, P<0.05). The target volume Dmean and spinal cord Dmax decreased with a sloping " W" with the change of the rail position. The difference appeared to be noticeable in the range of less than 10 cm, but it gradually decreased as the rails slid to the outside until it reached zero, and the Dmean of PTV and Dmax of the spinal cordchanges were less in 10 MV plans, comparing to 6 MV plans. Conclusions:The dose attenuation by the sliding rails of the Qfix kVue should not ignored in the IMRT of spinal metastases and the slide position should be consistent with the planned position.
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Objective:To investigate the sensitivity of the Catalyst HD in monitoring different skin colors, and assess the effect of skin color on the setup uncertainties using this system in radiotherapy.Methods:The standard cards guiding skin color and the cylinder model guiding quality control in radiotherapy were utilized to simulate the patients’ positioning. During the first monitoring, Catalyst HD was employed to acquire the image of the phantom as the reference image after conventional positioning (indoor laser+ phantom marking). When it was not the first monitoring, the couch was moved (-5 to 5 mm, step length of 2 mm) and Catalyst HD was adopted to obtain the surface image after conventional positioning. The bed deviation and corresponding setup errors monitored by Catalyst HD for different skin colors were recorded in the anterior-posterior (AP), superior-inferior (SI) and left-right (LR) direction, respectively.Results:During Catalyst HD monitoring, the integration time and gain were increased with the darker color. The logarithm of integration time and gain was significantly linearly negatively correlated with the same color ( R2>0.9). When the color difference with 1Y01SP was ΔE≤189, there was a significant correlation between the bed deviation and corresponding setup errors monitored by Catalyst HD in the SI and LR directions (R SI>0.5, R LR>0.5, R AP>0.9). The Catalyst HD monitoring was rapid and stable. When 218≤ΔE≤253, the correlation coefficients of them in the LR were R LR<0.3 and the Catalyst HD monitoring was stable. When 254≤ΔE≤285, the Catalyst HD failed to monitor stably. When ΔE>318, it failed to monitor this skin color. Conclusions:Gain, integration time and color have a certain correlation. The Catalyst HD can accurately monitor the setup errors within a specific range of skin color.
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Objective@#To investigate the correlation between skin elasticity and setup error in optical surface image-guided radiotherapy.@*Methods@#The skin elasticity (R7) data of the head, chest and abdomen were extracted and analyzed its correlation with age by systematic literature review. Fifty-four patients diagnosed with nasopharyngeal carcinoma, breast cancer and cervical cancer were recruited in this study. Firstly, the patients were positioned based on the room laser and markers. Subsequently, the patient position was verified by the Varian On-Board Imager, and then C-Rad Catalyst was adopted to obtain surface images in two states (mask or non-mask) as reference images. In the subsequent fraction treatment, after initial positioning, the local calibration was performed by Catalyst, and setup errors in three directions were recorded. Meanwhile, the patient setup was verified by CBCT twice a week. The Pearson correlation analysis was performed to analyze the correlation between setup error and age.@*Results@#The skin elasticity was negatively correlated with aging (P<0.01). The correlation coefficient between random error and age in head-and-neck cancer were 0.645, 0.624 and 0.866 in the AP, SI and LR directions (all P<0.05) for male patients without mask, respectively. The system error was significantly correlated with age in the LR direction (P<0.05) for male patients, and in the AP direction (P<0.05) for female patients with head-and-neck cancer without mask. The setup error had a significant correlation with skin elasticity in male patients with head-and-neck cancer, and the sequence of absolute value of correlation coefficient was LR>SI>AP.@*Conclusion@#In optical surface-guided radiotherapy of head and neck cancer, skin elasticity may be a significant index for assessing the setup errors in male patients.
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Objective:To monitor and evaluate in vivo dose changes of intensity-modulated radiotherapy (IMRT) in patients with cervical cancer in a real-time manner. Methods:Twelve patients with cervical cancer admitted to our hospital were enrolled in this study. The in vivo doses were monitored by PerFRACTION?. Electronic portal imaging device (EPID) were collected in each treatment fraction for two-dimensional in vivo dose verification[γ index and dose difference (DD) index]. Log files were recorded for three-dimensional in vivo dose verification (γ index). The correlation between in vivo dose and treatment duration was analyzed by Pearson correlation analysis. Results:A total of 206 sets of EPID images and corresponding Log files were collected. The three-dimensional in vivo dose verification γ 1%/1mm of all patients was not correlated with treatment fraction ( P>0.05). Among them, the absolute difference of γ 1%/1mm of 94.66% fractions was< 1%. The mean DD 3% of two-dimensional in vivo dose verification of all patients was negatively correlated with treatment fraction ( P<0.05). Among which, the average γ 3%/3mm of 9 patients was>89% in the treatment fractions, and the average γ 3%/3mm of 98.57% fractions of these 9 patients was>93%. The other 3 patients had an average γ 3%/3mm ranged from 38% to 100%. CBCT images showed that the bladder volume of these 3 patients was significantly decreased with the relative changes by 82.08%, 84.41% and 73.59%, respectively, and the target area was retracted significantly with the relative changes by 38.12%, 59.79% and 24.46%, respectively. Conclusion:Combined with γ index and DD index, PerFRACTION? can monitor the mechanical stability of accelerator and MU delivery accuracy during treatment fractions, and monitor the changes of in vivo dose in patients with cervical cancer, which can improve the safety and quality assurance of IMRT for cervical cancer patients and provide guidance for patients with adaptive radiotherapy.
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Objective To investigate the correlation between skin elasticity and setup error in optical surface image-guided radiotherapy.Methods The skin elasticity (R7) data of the head,chest and abdomen were extracted and analyzed its correlation with age by systematic literature review.Fifty-four patients diagnosed with nasopharyngeal carcinoma,breast cancer and cervical cancer were recruited in this study.Firstly,the patients were positioned based on the room laser and markers.Subsequently,the patient position was verified by the Varian On-Board Imager,and then C-Rad Catalyst was adopted to obtain surface images in two states (mask or non-mask) as reference images.In the subsequent fraction treatment,after initial positioning,the local calibration was performed by Catalyst,and setup errors in three directions were recorded.Meanwhile,the patient setup was verified by CBCT twice a week.The Pearson correlation analysis was performed to analyze the correlation between setup error and age.Results The skin elasticity was negatively correlated with aging (P＜0.01).The correlation coefficient between random error and age in headand-neck cancer were 0.645,0.624 and 0.866 in the AP,SI and LR directions (all P＜0.05) for male patients without mask,respectively.The system error was significantly correlated with age in the LR direction (P＜0.05) for male patients,and in the AP direction (P＜ 0.05) for female patients with head-and-neck cancer without mask.The setup error had a significant correlation with skin elasticity in male patients with head-and-neck cancer,and the sequence of absolute value of correlation coefficient was LR ＞ SI ＞ AP.Conclusion In optical surface-guided radiotherapy of head and neck cancer,skin elasticity may be a significant index for assessing the setup errors in male patients.
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Objective To evaluate the clinical application of Catalyst system in positioning patients during cervical cancer radiotherapy,and to analyze its correlation with the bladder volume and body mass index (BMI) of patients.Methods A total of 33 patients diagnosed with cervical cancer from July to December 2017 in our hospital were included in the study.All patients were auxiliary positioned by an optical surface imaging system (C-Pad Catalyst) before each treatment.The CBCT imaging was executed twice a week.The setup errors from Catalyst and CBCT in the anterior-posterior (AP),superior-inferior (SI) and leg-fight (LR) directions were recorded.Each patient's bladder volume and BMI were also recorded.Results The setup errors between Catalyst with masks and CBCT had the significant difference in SI (P＜0.05) and LR (P＜0.05).For Catalyst without masks,the setup errors with the bladder volume of 200-300 ml had the significant association in SI (R=-0.316,P＜0.05).For the bladder volume of＞300 ml,the setup errors for Catalyst with masks had the significant association in AP (R=-0.493,P＜0.05),and that without masks had the significant association in SI and LR (R=0.335,P＜0.05,R=-0.348,P＜0.05).For patients of＜25 kg/m2,setup errors for Catalyst with masks had the significant association with the BMI in LR (R=0.197,P＜0.05);for ≥ 25 kg/m2,that with masks had the significant association in AP and SI (R =0.818,P＜0.05;R=-0.498,P＜0.05),that without masks had the significant association in AP and LR (R=0.652,P＜0.05;R=-0.558,P＜0.05).Conclusion Unlike CBCT system,the patient positioning by Catalyst system was easily affected by the bladder volume and BMI of patients.
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Objective To investigate the dosimetric characteristics between helical tomotherapy ( HT) and intensity-modulated radiotherapy ( IMRT) plans in children receiving craniospinal irradiation and estimate the risk of radiogenic second cancer according to the excess absolute risk ( EAR) model. Methods Computer-tomography scans of 15 children who received craniospinal irradiation between 2012 and 2017 were selected. HT and IMRT plans were designed for each patient after contouring the volumes of tumors and organ at risks ( OARs) and then the homogeneous index ( HI) , conformity index ( CI) , the maximum dose and the mean dose of OAR,V10 and V20 were analyzed to optimize the clinical treatment plan. The second cancer risk was estimated by DVH of each organ and EAR model and statistically compared between HT and IMRT. Results Both two plans met the clinical requirements in target coverage ( 100％ dose≥95％ target volume).The HI in the HT group was significantly superior to that in the IMRT group (P=0. 000) whereas no significant difference was noted in CI between two groups. Compared with the IMRT plan, HT plan possessed absolute advantage in protecting hippocampus and the D2％ and Dmean were significantly lower ( P=0. 000).As for the protection of OAR, the Dmax, Dmean and V20 of thyroid (P=0. 001,0. 002 and 0. 014) and Dmax,V10 of heart ( P=0. 001 and 0. 003) in the HT plan were significantly lower than those in the IMRT plan. In terms of second cancer risk, HT plan yielded a significantly higher second cancer risk for thyroid and lung compared with IMRT the EAR in thyroid was 28. 666 vs. 26. 926 ( P=0. 010 ) and 20. 496 vs. 18.922( P=0. 003) in lung. Both plans yielded a relatively high second cancer risk for stomach ( P=0. 248), whereas a low second cancer risk for liver (P=0. 020). Conclusions HT plan is superior to IMRT plan in the hippocampus-sparing craniospinal irradiation in children. However, HT plan yields a high second cancer risk for thyroid and lung. Consequently, the balance between the carcinogenic risk and the effect on other normal tissues should be assessed in the establishment of therapeutic plan.
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Objective To evaluate the clinical application of Catalyst system in patient positioning during breast cancer radiotherapy,and to analyze its correlation with age and body mass index (BMI).Methods Twenty-four patients with breast cancer who were admitted to our hospital from May to August,2016 were enrolled as subjects.For all patients,auxiliary positioning was made by the optical surface imaging system (CRad Catalyst) before each treatment.The kV-kV imaging was executed weekly to verify positioning.Age,BMI,and setup errors of the two systems in the anterior-posterior (AP),superior-inferior (SI),and left-fight (LR) directions were recorded and analyzed by independent samples t-test and Pearson correlation analysis.Results The C-Rad Catalyst system had a significantly larger setup error in the AP direction than the kV-kV imaging (0.22±0.17 vs.0.18±0.13 cm,P＜0.05).There were no significant differences in setup errors in the SI or LR direction between the two systems (0.23±0.18 vs.0.19±0.15 cm,P＞0.05;0.28±0.28 vs.0.20±0.15 cm,P＞ 0.05).Age and BMI of patients had significant impacts on the C-Rad Catalyst system but the kV-kV imaging (P＞0.05):there were significant differences in setup errors in the AP and SI directions between patients ≤44 years of age and those 45-59 years of age (all P＜0.05);there were significant differences in setup errors in the AP and LR directions between patients ≤44 years of age and those ≥60 years of age (all P＜0.05);there was a significant difference in setup error in the LR direction between patients 45-59 years of age and those ≥ 60 years of age (P＜0.05);there was a significant difference in setup error in the SI direction between patients with BMIs of＜ 25 and ≥ 25 kg/m2 (P＜ 0.05).For patients ≥ 60 years of age,setup error of the C-Rad Catalyst system in the SI direction was correlated with age (r=-0.496,P＜0.05).For patients with BMI of＜25 kg/m2,setup error of the C-Rad Catalyst system in the AP direction was correlated with BMI (r=-0.445,P＜ 0.05).For patients with a BMI of ≥ 25 kg/m2,setup error of the C-Rad Catalyst system in the SI direction was correlated with BMI (r=-0.252,P＜0.05).Conclusions There is significant difference in setup error in the AP direction between the C-Rad Catalyst system and the kV-kV imaging.Age and BMI have impacts on patient positioning by the C-Rad Catalyst system.
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<p><b>OBJECTIVE</b>To evaluate the accuracy of the latest BladderScan BVI9400 on measuring bladder volume.</p><p><b>METHODS</b>Two bladder phantoms were selected for investigating the accuracy of BVI9400. 341 patients with the iU22 ultrasound examinations were followed by BVI 9400. The difference and correlation between BVI9400 and iU22 were contrastively analyzed.</p><p><b>RESULTS</b>The relative difference between results from BVI9400 and phantom volume was 2.5% and 1.36%. There was a strong correlation for patients between BVI9400 and iU22 (R = 0.96, P < 0.001). The relative difference between BVI9400 and iU22 decreased with the increasing of bladder volume and had no significant difference with patient's gender (P > 0.1).</p><p><b>CONCLUSION</b>BladderScan BVI9400 had the ability of high accuracy and good stability of measured data. In view of quick and conveniences, BVI9400 could be as auxiliary equipment on pelvic tumor to evaluate whether the bladder volume during fractional radiotherapy was consistency with that during CT positioning.</p>