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Objective:To explore the clinical application of the electronic portal imaging device (EPID) based on the linear accelerator produced by Shanghai United Imaging Healthcare Co., Ltd. (UIH) to in vivo dose verification. Methods:A total of 68 patients (32 cases with head and neck tumors, 16 cases with chest tumors, and 20 cases with abdomen and pelvis tumors) who were treated with volumetric modulated arc therapy (VMAT) in the Henan Provincial People′s Hospital were selected in this study. Each patient underwent the pre-treatment dose verification using an Arccheck device (Pre Arccheck), the pre-treatment dose verification using an EPID (Pre EPID), and the in vivo dose verification using an EPID (In vivo EPID). Moreover, the position verification based on fan beam computed tomography (FBCT) was also performed for each patient in the first three treatments and then once a week. The patients were treated when the setup error in any direction ( x: left-right, y: head-foot, z: vertical) was less than 3 mm; otherwise, position correction would be conducted. The three-dimensional setup deviation d was calculated according to setup errors x, y, and z. Results:The γ passing rates of dose verifications Pre EPID and In vivo EPID of 68 patients were (99.97±0.1)% and (94.15±3.84)%, respectively, significantly different from that (98.86±1.48)% of the Pre Arccheck dose verification ( t = -6.12, 9.43; P < 0.05). The γ passing rates of the chest, abdomen and pelvis, and head and neck in the In vivo EPID dose verification showed no significant differences ( P > 0.05). The difference in the γ passing rates (5.56±3.72)% between dose verifications Pre EPID and first In vivo EPID was unrelated to the three-dimensional setup deviation d (1.46±1.51 mm) ( P > 0.05). As the treatment proceeded, the γ passing rate of In vivo EPID gradually decreased from (94.15±3.84)% in the first week to (92.15±3.24)% in the fifth week. From the third week to the fifth week, the γ passing rates of In vivo EPID were significantly different from those in the first week ( t = 2.48, 2.75, 3.09, P < 0.05). Conclusions:The setup errors within 3 mm do not affect the γ passing rate of in vivo dose verification. The clinically acceptable threshold for the γ passing rate of in vivo EPID needs to be further determined. In addition, in vivo dose verification can support the clinical application of adaptive radiotherapy to a certain extent.
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Objective:To compare the effects of two methods of marking surface landmarks on the patient’s positional stability when using a multifunctional body board in combination with thermoplastics to fix the abdominal and pelvic areas for radiotherapy patients.Methods:50 subjects who underwent positional fixation using a multifunctional body board in combination with thermoplastics from August 2022 to January 2023. The subjects were divided into two groups, A and B, with 25 cases each, according to the different methods of body surface marking. In group A, landmarks were marked on the body surface on the top edge of the thermoplastics. In group B, three sets of surface landmarks were marked on the patient’s body according to the laser line on the projection of the patient’s body surface when the thermoplastics were completed. Manual registration is performed using L3 to L5 as the main registration targets. The pre-treatment CBCT image is used to analyze the first-time positioning pass rate, setup errors in the x-, y-, and z-axis directions, and the distribution of positive and negative setup errors in both groups of patients. Results:The pass rates of the first-time positioning of patients in Groups A and B were 76.9% and 86.1%, respectively, which met the clinical requirements. Group B had a better first-time positioning pass rate than group A, and the difference between the two groups was statistically significant ( P < 0.05). The pendulum errors of group B were smaller than those of group A in both the x-axis and y-axis (all P < 0.05), and the difference between the two groups in terms of the pendulum errors in the z-axis direction was not statistically significant (all P > 0.05). The difference in the frequency distribution of the pendulum error in the positive and negative directions of the x- and z-axis between the two groups was not statistically significant (all P > 0.05). The difference in the frequency of distribution of the pendulum error in the positive and negative directions of the y-axis between the two groups was statistically significant ( P < 0.05). Conclusions:The proposed two methods of surface landmark marking are generally in line with the positioning requirements for conventional fractionation radiotherapy for abdominal and pelvic patients. Using a laser line on the projection of the patient’s body surface for three sets of surface landmark markings produces smaller setup errors and is better than using the top edge of the thermoplastics for surface landmark markings, improving the positional stability of abdominal and pelvic patients.
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@#<b>Objective</b> To study the setup error under deep inspiration breath hold (DIBH) guided by optical surface monitoring system (OSMS) and free breathing (FB) FB1 and FB2 (without OSMS guidance, directly set up the body marker line by laser lamp) in radiotherapy after radical mastectomy for left breast cancer, and to provide a basis for individualized clinical target volume-planning target volume (CTV-PTV) expansion for the doctor in charge to delineate the target volume. <b>Methods</b> A total of 36 patients with left breast cancer after radical mastectomy were selected and divided into three groups, in which cone beam computed tomography (CBCT) images were taken in three states: DIBH, FB1, and FB2, respectively. CBCT and CT images were analyzed for registration; the absolute error data of linear displacement in the ventro-dorsal, cranio-caudal, and left-right directions were recorded, and the expanding margin was calculated. <b>Results</b> The translation errors in the ventro-dorsal, cranio-caudal, and left-right directions were (0.06 ± 0.22) cm, (0.05 ± 0.23) cm, and (0.01 ± 0.24) cm in the DIBH group, (0.07 ± 0.21) cm, (0.02 ± 0.23) cm, and (0.02 ± 0.21) cm in the FB1 group, and (0.07 ± 0.24) cm, (0.07 ± 0.34) cm, and (0.25 ± 0.09) cm in the FB2 group. The statistical results of the DIBH group and FB1 group in the ventro-dorsal, RTN, and ROLL directions were significantly different (<i>P</i> < 0.05). The statistical results of the FB1 group and FB2 group in the ventro-dorsal direction were significantly different. The relation of three groups in the value of margin of planning target volume was DIBH < FB1 < FB2 in the ventro-dorsal and cranio-caudal directions and FB1 < DIBH < FB2 in the left-right direction. <b>Conclusion</b> OSMS-guided DIBH radiotherapy in patients with left breast cancer after radical mastectomy can reduce the setup error and provide an important basis for individualized CTV-PTV expansion for the doctor in charge to delineate the target volume.
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ObjectiveThis study aimed to analyze the difference in setup error before and after correction of systematic error. To determine the most appropriate image-guided strategy during HT treatment， we use different scanning ranges and image-guidance frequencies in patients with nasopharyngeal carcinoma （NPC） treated with helical tomotherapy （HT）. MethodsFifteen patients with NPC who received HT treatment in Sun Yat-sen University Cancer Center from October 2019 to February 2020 were selected. Megavoltage computed tomography （MVCT） scanning was performed before each treatment. After five times of radiotherapy， system-error correction was performed to adjust the setup center. The setup errors before and after the correction of systematic errors， as well as the setup errors of different scanning ranges and different scanning frequencies， were collected for analysis and comparison. ResultsWhen comparing the setup errors before and after the correction of systematic error， the differences in setup errors in the left–right （LR）， superior–inferior （SI）， and anterior–posterior （AP） directions were statistically significant （P<0.05）.The different scanning ranges of "nasopharynx + neck" and "nasopharynx" were compared， and a statistically significant difference was found in yaw rotational errors （P<0.05）. In the comparison of daily and weekly scan frequency after system-error correction， a significant difference was found in AP direction （P<0.05）. ConclusionDuring radiotherapy for NPC， the systematic error can be corrected according to the first five setup errors， and then small-scale scanning was selected for image-guided radiotherapy every day.
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Objective To investigate the effects of multimedia information technologies on precision radiotherapy of head and neck malignant tumors (HNT). Methods A total of 96 patients with HNT recruited from 2016 to 2019 were randomly assignedto group A and group B with the same planning methodand therapists/technicians. Conventional and multimedia information technologies were respectively used in group A and group B for medical science popularization, individualized education, and doctor-patient communication before radiotherapy planning and positioning. Medical compliance, radiotherapy responses, setup errors, and machine occupancy time were investigated. Results Medical compliance was significantly higher (P < 0.05) in group A (96.5%) than in group B (73.8%). Skin acute radiation reaction was significantly lower (P < 0.05) in group A than in group B. Three-dimensional absolute setup errors were 0.69 ± 0.29 mm, 0.97 ± 0.69 mm, and 0.79 ± 0.47 mm in group A, which were significantly lower than 1.39 ± 0.81 mm, 1.87 ± 1.19 mm, and 2.50 ± 0.99 mm in group B(P < 0.05). Traditional three-dimensional setup errors were 0.73 ± 0.39 mm, 0.51 ± 0.69 mm, and 0.74 ± 0.17 mm in group A, which were significantly lower than 1.32 ± 0.76 mm, 1.89 ± 1.21 mm, and 1.37 ± 0.57 mm in group B (P < 0.05). Planning time was 145.15 ± 28.45 sin group A, which was significantly lower than 240.38 ± 50.45 sin group B (P < 0.05). Positioning time was 115.15 ± 18.45 s in group A, which was significantly lower than 173.38 ± 24.45 sin group B (P < 0.05). Conclusion The application of multimedia information technologies inmedical science popularization, individualized education, and doctor-patient communication forpatients who received precision radiotherapy for HNT can significantly increase patient compliance, alleviate acute radiation reactions, reduce setup errors, and shorten the machine occupancy time of planning and positioning.
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Objective:To compare the setup errors in the supraclavicular regions of two different postures (arms placed on each side of the body, namely the body side group; arms crossed and elbows placed above forehead, namely the uplifted group) using the chest and abdomen flat frame fixation device in lung and esophageal cancer.Methods:Clinical data of patients with stage Ⅰ to Ⅳ lung or esophageal cancer who received three-dimensional radiotherapy with chest and abdomen flat frame fixation device in our institution from November 2020 to April 2021 were retrospectively analyzed. The setup errors of two postures were compared.Results:A total of 56 patients were included, including 31 patients (55%) in the body side group and 25 patients (45%) in the uplifted group. A total of 424 CBCTs were performed in the whole group. The overall setup errors in the X, Y and Z directions were similar in both groups ( P>0.05). The setup errors of sternoclavicular joint in the X and RZ directions in the body side group were significantly smaller than those in the uplifted group [(0.163±0.120) cm vs. (0.209 ±0.152) cm, P=0.033; 0.715°±0.628° vs. 0.910°±0.753°, P=0.011]. The setup errors of acromioclavicular joint in the Y, Z and RZ directions in the body side group were significantly smaller than those in the uplifted group [(0.233±0.135) cm vs. (0.284±0.193) cm, P=0.033; (0.202±0.140) cm vs. (0.252±0.173) cm, P=0.005; 0.671°±0.639° vs. 0.885°±0.822°, P=0.023]. The margins of target volume for setup errors were smaller in the X (0.45 cm vs. 0.54 cm) and Y (0.54 cm vs. 0.65 cm) directions of the sternoclavicular joint, as well as in the Y (0.59 cm vs. 0.78 cm) and Z directions (0.53 cm vs. 0.72 cm) of the acromioclavicular joint in the body side group. Conclusions:For lung and esophageal cancer patients requiring supraclavicular irradiation, the body side group yields smaller setup errors and corresponding margins of target volume than the uplifted group. In clinical practice, it is necessary to take comprehensive consideration of the accuracy of radiotherapy and additional radiation of the limbs to select appropriate posture.
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Objective:To explore the impacts of comprehensive geriatric assessment (CGA) on setup errors during the radiotherapy of elderly patients with rectal cancer.Methods:A total of 45 patients over 70 years of age and receiving radiotherapy were enrolled in the study. A comprehensive geriatric assessment was conducted before the radiotherapy. The enrolled patients had a median age of 77 years, including 28 male and 17 female cases. Meanwhile, 31 patients were determined to be in a good CGA status and 14 were determined to be in a poor CGA status, and 35 patients received radiotherapy in the prone position and 10 in the supine position. Cone beam CT (CBCT) was used for setup correction during radiotherapy. CBCT was performed daily in the first week and once a week from the second week. By fusing and aligning the CBCT images with simulation CT images according to the lumbar vertebra, setup errors in the left-right ( x axis), cranio-caudal ( y axis), and anterior-posterior ( z axis) directions were obtained. A total of 338 CBCT images were obtained. A generalized linear model was used to evaluate the effects of multiple factors on the setup errors. Results:During the radiotherapy, setup errors of all patients were (0.24±0.19) cm in the left-right direction, (0.33±0.25) cm in the cranio-caudal direction, and (0.19±0.15) cm in the anterior-posterior direction. The setup error in the cranio-caudal direction was more than that in the left-right direction and that in the anterior-posterior direction ( Z=-4.86, -7.72, P< 0.001). The setup error in the left-right direction was greater than that in the anterior-posterior direction ( Z=-2.79, P=0.005). The mean setup errors of the good and poor status groups in the left-right direction were (0.21 ± 0.17) and (0.30 ± 0.22) cm, respectively ( Z=2.16, P=0.031). There was no statistically significant difference in the setup errors between cranio-caudal direction and anterior-posterior direction ( P>0.05). The setup errors in the anterior-posterior direction were (0.17 ± 0.13) and (0.27 ± 0.19) cm, respectively for the prone and supine positions during the radiotherapy ( Z=2.85, P=0.004). There was no statistically significant difference in the setup errors between the left-right direction and the cranio-caudal direction ( P>0.05). Conclusion:The status of CGA elderly patients with rectal cancer affects the setup error in the left-right direction. It may be necessary to clinically adjust the PTV margin.
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Objective:To investigate the feasibility of surface-guided hypo-fractionated radiotherapy for intracranial metastasis with open face mask immobilization.Methods:Nineteen patients treated with hypo- fractionated radiotherapy for intracranial metastasis in our hospital were included. Before the start of treatment, each patient underwent simulation with open face mask immobilization. During the treatment, cone-beam CT(CBCT)images were collected for verification each time. Laser-guided positioning was used for the first time in the treatment, and surface images were captured after six-dimensional position correction as the reference images for subsequent treatment. Subsequent treatment was randomly divided into laser-guided positioning group(LG, 85/F)and optical surface-guided positioning group(SG, 101/F). The six-dimensional error data of patients with two positioning methods were compared and expressed as mean ± standard deviation. Meanwhile, the correlation and consistency between the optical surface error data and the gold standard CBCT error data were compared in the laser-guided fraction. GraphPad Prism 6.0 software was used for data processing and mapping, and SPSS 21.software was used for mean analysis and normality test. Pearson correlation analysis was used to analyze the correlation, and Bland-Altman plot analysis was used to test the coincidence between two methods.Results:Compared with the laser-guided positioning, the 3D error of optical surface-guided positioning was reduced from(0.35±0.16)cm to(0.14±0.07)cm. The Pearson coefficient of correlation along all three directions was less than 0.01,R 2 was 0.91,0.70 and 0.78 on Lat, Lng and Vrt, and R 2 was 0.75,0.85 and 0.77 on Pitch, Roll and Rtn(all P<0.01), respectively. The measurement results of two methods were positively correlated. The Bland-Altman plot analysis showed that the 95% limits of agreement were within preset 3 mm tolerance([-0.29 cm, 0.19 cm], [-0.25 cm, 0.25 cm], [-0.27 cm, 0.19 cm]), and the 95% limits of agreement were within preset 3° tolerance(Pitch[-1.76°,1.76°], Roll[-1.54°,1.60°], ROT[-2.18°,1.69°]), indicating agreement between two methods. Conclusions:The optical surface-guided positioning can reduce the setup errors in the hypo-fractionated radiotherapy for intracranial metastasis with open face mask immobilization. The optical surface error and CBCT error have good correlation and agreement.
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Objective:To provide evidence for the selection of fixation devices and CTV to PTV margins (M ptv) in precision radiotherapy for pelvic tumors by analyzing three fixation devices in precision radiotherapy for prostate cancer. Methods:From April 2015 to December 2020, 133 prostate cancer patients treated with pelvic drainage area irradiation in our center were retrospectively analyzed. The patients were fixed with 1.2m vacuum bag (n=39), 1.8m vacuum bag (n=44) and personalized prone plate by our center (n=50). Each patient was asked to complete our bowel and bladder preparation process before positioning and radiotherapy. The registration of CBCT to planned CT before each treatment adopted the same registration box and algorithm. Setup errors in the SI, LR and AP directions under qualified bowel and bladder conditions were recorded. Setup errors in three directions under three fixation devices and corresponding M ptv values were analyzed. The correlation between setup errors with age and body mass index (BMI) was analyzed. Results:Analysis of 3333 setup errors data showed: in the SI and LR directions, the mean setup errors of 1.2m vacuum bag (3.26mm, 2.34mm) were greater than those of 1.8m vacuum bag (2.51mm, P<0.001; 1.90mm, P<0.001), and personalized prone plate (3.07mm, P=0.066; 2.10 mm, P=0.009). In the AP direction, the mean setup errors of 1.2m vacuum bag (supine)(2.20mm) were smaller than those of 1.8m vacuum bag (3.33mm, P<0.001) and personalized prone plate (3.61mm, P<0.001). The setup errors of 1.8m vacuum bag in all directions were smaller than those of personalized prone plate (P≤0.028). According to Van Herk's expansion formula, the M ptv of 1.2m vacuum bag in three directions was approximately 4 mm. The M ptv of 1.8m vacuum bag and personalized prone plate in the SI and LR directions was approximately 3 mm, and more than 5 mm in the AP direction. The setup errors were not correlated with age or BMI. Conclusions:From the setup errors results of three devices, 1.8m vacuum bag is the best, followed by personalized prone plate. And supine position is better than prone position in the AP direction.
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Objective:To investigate the 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 explore the application value of skin lead marker combined with iSCOUT image-guided positioning system in monitoring and correcting the setup error of intensity-modulated radiotherapy (IMRT) for breast cancer and calculate the PTV margin, aiming to provide reference for clinical practice.Methods:25 breast cancer patients treated with IMRT after modified radical mastectomy in Fujian Medical University Union Hospital from April to August 2019 were enrolled in this study. The skin lead marker combined with iSCOUT image-guided positioning system was employed for image-guided positioning based on the gold standard registration algorithm. Initial setup errors on the x (lateral), y (craniocaudal) and z (anteroposterior) axis and residual errors after the position correction were recorded and analyzed. The effect of the errors before and after image-guided correction upon the plan dose was compared and the reasonable PTV margin was calculated.Results:25 patients received 150 times of positioning verification using skin lead marker combined with iSCOUT image-guided positioning system. The absolute residual errors on the x-, y-and z-axis were (1.53±0.96), (1.30±0.99) and (1.34±0.92) mm, significantly smaller than the initial setup errors of (2.63±2.12), (2.41±2.45) and (3.07±2.77) mm (all P<0.001). The percentage of dose deviation due to residual errors was also smaller than that of the initial errors. Significant differences were observed in D 98%, D 2%, D max of PTV, D max of the heart, D max of the healthy breast, and D mean of the affected lung and both lungs. The percentage deviation from the original plan was decreased from 2.18%, 3.19%, 10.66%, 8.75%, 48.21%, 10.50%, and 3.66% to 0.38%, 0.23%, 2.31%, 0.04%, 13.78%, 6.35% and 0.41%, respectively (all P<0.05). PTV margins on the x-, y-and z-axis after correction were calculated as 1.87, 1.75 and 1.69 mm, respectively. Conclusion:It is feasible and valuable to apply the skin lead marker combined with iSCOUT image-guided positioning system in the positioning verification and correction of breast cancer radiotherapy position, providing novel reference for clinical PTV margin.
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Objective:To investigate the setup errors of postoperative radiotherapy immobilized with integrated cervicothoracic board (mask) system in breast cancer patients.Methods:Thirty-two breast cancer patients treated with postoperative radiotherapy immobilized with integrated cervicothoracic board (mask) system were prospectively recruited in this study. Breast/chest wall (cw) and supra/infraclavicular nodal region (sc) were irradiated with intensity-modulated radiotherapy. CBCT location verification in radiotherapy and target areas of the breast/chest wall and upper and lower collarbone were carried out, respectively. The consistency between setup errors and the position of the upper and lower target areas of 239 CBCT images was analyzed.Results:The translational setup errors of the breast/chest wall in the X-cw (left-right), Y-cw (superior-inferior), Z-cw (anterior-posterior) directions were (1.84±2.36) mm, (1.99±2.48) mm, and (1.75±1.86) mm, respectively. The translational setup errors of the supra/infraclavicular nodal region in the X-sc (left-right), Y-sc (superior-inferior), Z-sc (anterior-posterior) directions were (1.98±2.44) mm, (1.98±2.48) mm, and (1.71±1.79) mm, respectively. The differences of translational setup errors between the breast/chest wall and supra/infraclavicular nodal region in the X, Y, Z directions were (0.38±0.66) mm, (0.07±0.41) mm, and (0.45±0.92) mm, respectively. Conclusion:For the breast cancer patients treated with postoperative radiotherapy covering breast/chest wall and supra/infraclavicular nodal region, the integrated cervicothoracic board (mask) immobilization system provides good reproducibility and yields Sfew setup errors.
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Objective:To compare the difference between active breathing coordinator (ABC) technique and free breathing (FB) mode combined with bodyfix stereotactic radiotherapy (SBRT) for chest tumors.Methods:40 thoracic tumor patients receiving SBRT were randomly selected and divided into the ABC technique group and FB model group. After fixation with bodyfix fixing devices in two groups, cone-beam CT (CBCT) scan images before each SBRT were matched with the plan reference images. The setup errors in the left-right (LR), superior-inferior (SI) and anterior-post (AP) directions were obtained. Then, the setup errors were corrected. SBRT was performed and split intra-fraction CBCT was conducted simultaneously, which was repeated until the end of treatment.Results:In the ABC technique group, the setup errors in the LR, SI and AP directions were (0.25±0.21) cm, (0.28±0.21) cm, and (0.21±0.24) cm, significantly less compared with (0.31±0.22) cm, (0.32±0.21) cm and (0.37±0.23) cm in the FB model group (all P<0.05). The V 30Gy of the heart, the V 20Gy and V 30Gy of the lung in the ABC technique group were significantly less than those in the FB model group (0.31%∶7.35%; 24.5%∶32.9%; 19.5%∶25.8%, all P<0.05). Conclusions:ABC technique combined with bodyfix fixation device may be superior to FB mode in SBRT for chest tumors, which remains to be validated by subsequent studies with large samples.
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Objective:To summarize the experience of ELEKTA Unity MR-linac in clinical application in our hospital and analyze the positioning accuracy, process time and other related issues.Methods:A total of 14 patients enrolled in the Unity MR-Linac study were reviewed. All treatment time (including positioning, scanning, replanning, and beam discharge) and setup errors in 3directions were statistically analyzed. 11 patients with conventional accelerators using the multifunctional immobilization system (MIS) were randomly selected to make statistical analysis of the setup errors, and the differences between the Unity group and the conventional accelerators using the MIS were compared using t-test. Results:In the Unity group, the setup errors in X, Y and Z directions were (-0.15±0.30) cm, (0.02±0.57) cm and (-0.10±0.28) cm, respectively. The average treatment time was 36.87minutes. The average positioning time was 5.40minutes. The mean scan time was 7.48minutes, the mean adaptive plan time was 7.46minutes, and the mean beam time was 9.48minutes. In the conventional accelerator group, the setup errors were (0.05±0.25) cm, (-0.01±0.25) cm and (-0.03±0.23) cm, respectively. The results of the setup errors of patients fixed with MIS showed that there were significant differences in the left and right directions ( P<0.001), while there were no significant differences in the Y and Z directions ( P=0.061 and 0.374) between two groups. Conclusions:Except in the X direction, there is no significant difference in setup errors between the Unity and conventional accelerator groups in the condition of laser-free system. Under smooth circumstances, the treatment time by using ATP (adapt to position) workflow will also be within the range of tolerance of the patients. Magnetic-guided radiotherapy has a promising application prospect, whereas the procedure needs to be optimized.
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Objective:To retrospectively analyze the setup errors of thermoplastic head and shoulder molds alone or combined with vacuum pad in hypofractionated stereotactic radiotherapy (HFSRT) for non-small cell lung cancer (NSCLC) with brain metastases.Methods:Fifty-four NSCLC patients with brain metastases who received HFSRT from 2017 to 2019 were enrolled in this study. Twenty-four patients were fixed with thermoplastic head and shoulder molds (group A), and 30 patients were fixed with thermoplastic head and shoulder molds plus vacuum pad (group B). The interfraction and intrafraction setup errors were acquired from cone-beam CT online image registration before and after the HFSRT. Optical surface system was applied in monitoring the intrafraction setup errors. The setup errors in each direction between two groups were analyzed by independent samples t-test. Results:For the interfraction setup errors of the whole group, the proportion of the horizontal setup errors of ≥3mm was 7.0% to 15.4% and 7.0% to 12.6% for the rotation setup errors of ≥2°. In group A, the anteroposterior setup error was (1.035±1.180)mm, significantly less than (1.512±0.955)mm in group B ( P=0.009). In group A, the sagittal rotation setup error was 0.665°±0.582°, significantly less than 0.921°±0.682° in group B ( P=0.021). For the intrafraction setup errors of the whole group, the proportion of horizontal setup errors of ≥1mm was 0% to 0.7%, whereas no rotation setup error of ≥1° were observed. In group B, bilateral, anteroposterior and sagittal rotation setup errors were (0.047±0.212)mm, (0.023±0.152)mm and 0.091°±0.090°, significantly less compared with (0.246±0.474)mm, (0.140±0.350)mm and 0.181°±0.210° in group A ( P=0.004, P=0.020, P=0.001), respectively. Optical surface monitoring data were consistent with the obtained results. Conclusions:Thermoplastic head and shoulder molds (with or without vacuum pad) combined with online image registration and six-dimensional robotic couch correction can be applied in HFSRT for brain metastases from NSCLC. The intrafraction setup errors in group B are smaller than those in group A. Optical surface system has certain value in monitoring the intrafractional movement.
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Objective:To compare the positioning errors of individual head-rest combined with thermoplastic fixation mask versus thermoplastic fixation mask alone in patients with head and neck tumors. Methods:Twenty-eight patients who received irradiation with helical tomotherapy in Cancer Hospital of the University of Chinese Academy of Sciences (Zhejiang Cancer Hospital) between October 2019 and April 2020 were included in this study. They were randomly assigned to receive position fixation with either individual head-rest combined with thermoplastic fixation mask (N1 group, n = 14) or thermoplastic fixation mask alone (N2 group, n = 14). Megavoltage computed tomography (MVCT) scanning registration was used to obtain the positioning errors in translation and rotation (ROLL) in the left-right (X), head-food (Y), and belly-back (Z) directions. There were a total of 841 CT scans, consisting of 425 scans in group N1 and 416 scans in group N2. Results:The positioning errors in X, Y, Z and ROLL directions in the N1 group were (1.37 ± 1.04) mm, (1.38 ± 1.12) mm, (1.47 ± 1.62) mm and (1.47 ± 1.62) ° respectively, and they were (1.57 ± 1.21) mm, (2.10 ± 1.51) mm, (1.61 ± 1.50) mm and (1.40 ± 1.30) ° respectively in the N2 group. There was significant difference in positioning errors in the Y direction between N1 and N2 groups ( P = 0.013). In the N1 group, the outward expansion boundaries in X, Y and Z directions was 4.15 mm, 4.23 mm and 4.81 mm respectively, and it was 4.77, 6.31 and 5.08 mm, respectively in the N2 group. In the X direction, there was significant difference in positioning errors taking 3 mm as the dividing point between N1 and N2 groups ( χ2 = 10.516, P < 0.001). In the Y direction, there was significant difference in positioning errors taking 1, 2 and 3 mm as the dividing points between N1 and N2 groups ( χ2 = 24.889, P < 0.001; χ2 = 42.202, P < 0.001; χ2 = 46.204, P < 0.001). In the Z direction, there was significant difference in positioning errors taking 2 mm as the dividing point between N1 and N2 groups ( χ2 = 7.335, P = 0.007). In the N1 group, the percentage of positioning errors < 3 mm in the X, Y and Z directions was 92%, 90% and 92%, respectively. Conclusion:Compared with thermoplastic fixation mask alone, individual head-rest combined with thermoplastic fixation mask can better effectively improve the positioning stability and reduce positioning errors in patients receiving irradiation with helical tomotherapy for head and neck tumors. The combined method is of certain innovation.
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Objective: To compare setup errors between patients using the customized Klarity AccuCushion® with a thermoplastic fixation mask and patients using a thermoplastic fixation mask or vacuum fixation cushion alone while receiving radiotherapy. Methods: A total of 66 patients with head and neck (H&N) tumors (n=27) or thoracic and abdominal tumors (T&N) tumors (n=39) were included during Jaurnary 2018 to December 2019. 15 H&N cancer patients using only a single head-neck-shoulder mask were categorized into group A; 12 patients using a customized Klarity AccuCushion® and head-neck-shoulder mask were categorized into group B. Among T&A cancer patients, 19 patients using only a vacuum fixation cushion were classified into group A; the remaining 20 patients using a customized Klarity AccuCushion® and thermoplastic fixation mask were classified into group B. Cone-beam computed tomography was performed, and the setup errors were evaluated. The setup errors in the left-right (LR) direction, superior-inferior (SI) direction, anterior-posterior (AP) direction, and for rotation were compared between groups A and B. Results: Among H&N cancer patients, the setup errors in group B in the LR direction, SI direction, and for rotation were 0.06±0.06 cm, 0.08±0.07 cm, and 0.12±0.17°, respectively, which were smaller than those in group A (0.10±0.11 cm, 0.13±0.14 cm, and 0.25±0.47°, respectively). The differences in setup errors in the LR direction, SI direction, and for rotation were significant between the two groups (P0.05). For T&A cancer patients, significant differences were found in setup errors between the two groups (P<0.05) in the LR direction (group B vs. group A: 0.10±0.08 cm vs. 0.14±0.12 cm) and for rotation (group B vs. group A: 0.09 ± 0.18° vs. 0.22 ± 0.39°). No significant differences were observed in the setup errors in the SI and AP directions. Conclusions: Compared with the immobilization techniques using only a thermoplastic mask and only a vacuumed fixation cushion, the technique using a customized Klarity AccuCushion® with a thermoplastic fixation mask can improve repeatability, stability, and setup errors in radiotherapy.
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Objective To evaluate the effect of setup errors upon the target area and the organs at risk (OAR) during radiotherapy for prostate cancer.Methods Twelve prostate cancer patients receiving treatment in the recent 1 year were randomly recruited in this study.The position of each patient was verified by using cone beam CT (CBCT) for 6-10 times during the treatment.In treatment planning system (TPS),the isocenter position was moved along the setup errors with averaging error value (Plan_A) and each CBCT value (Plan_F).The dose distribution was recalculated without changing the beam setting,weight factors and monitor units (MUs).The dose difference was statistically compared between the simulation and original plans (Plan_O).Results For clinical target volume (CTV) D95,there was a significant difference between Plan_A and Plan_O (P =0.008),whereas no significant difference was observed between Plan_F and Plan_O.There were significant differences between Plan_F and Plan_O,Plan_A and Plan_O (P=0.004,and 0.041) for the planned target volume (PTV) D95.For OAR,rectal V60,Dmax,left femoral V20,Dmax and right femoral Dmax significantly differed between Plan_F and Plan_O (P=0.026,0.015,0.041,0.049,0.003).However,only left femoral Dmax significantly differed between Plan_A and Plan_O (P=0.045).The movement in the superior-inferior (SI) direction was significantly correlated with the changes in the rectal V40,V50 and V60 and PTV D95 (r=-0.785,-0.887,-0.833,0.682).The movement in the anterior-posterior (AP) direction was significantly associated with the variations in the bladder V20,V30,V40,V50 and V60(r=-0.945,-0.823,-0.853,-0.818,-0.774).The evaluation indexes of all normal tissues in the re-plan could meet the clinical requirements.However,the volume of target prescription volume had different levels of deficit,and the deficit of Plan_F was greater than that of Plan_A.Conclusions The simulation results of averaging into the TPS underestimates the effect of daily setup errors on the dose distribution.The effect of setup errors on the dose distribution in target area is greater than that of normal tissues.Y-direction errors are more likely to cause the variations of the rectal and PTV dose,and the errors in the z-direction are inclined to cause the changes in the bladder dose.
ABSTRACT
Objective@#To preliminarily investigate the difference of position fixation accuracy between polyurethane styrofoam and vacuum negative pressure pad in intensity-modulated radiation therapy (IMRT) after radical mastectomy for breast cancer.@*Methods@#Forty breast cancer patients, who received breast-conserving surgery followed by hyper-fractionated IMRT of the whole breast (42.56 Gy for 16 times) in our hospital between 2017 and 2018 were recruited and randomly divided into the polyurethane styrofoam group and vacuum negative pressure pad group. Before IMRT treatment, the anterior and lateral films of patients were taken with kilovoltage digital radiographs (KVDRs) by Varian Trilogy machine-borne OBI KV image verification system. The KVDRs images were matched with the DRR images reconstructed by the planned system to obtain the setup errors in the left and right, head and foot, and ventral and back directions between two groups. Each patient was verified for 10 times to obtain 400 sets of data. The independent sample t-test was adopted to analyze the setup errors between two groups. The external expansion value of graded setup errors from clinical target volume (CTV) and planned target volume (PTV) was calculated.@*Results@#The setup errors in the left and right, head and foot, ventral and back directions between the styrofoam fixation and vacuum pad groups were (1.63±1.29) mm and (1.83 ±1.61) mm (P=0.18), (1.46±1.51) mm and (2.26±2.03) mm (P=0.00), and (1.30±1.35) mm and (1.91±1.67) mm (P=0.00), respectively. The external expansion values of setup errors from CTV to PTV were 2.19 mm, 2.51 mm, 1.57 mm and 2.40 mm, 3.97 mm and 2.63 mm, respectively.@*Conclusion@#Both two fixation methods meet the clinical requirements. However, the setup accuracy and reproducibility in the polyurethane styrofoam group are better than those in the vacuum negative pressure pad group.
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Objective@#To compare the setup accuracy between Catalyst HD and skin markers in stereotactic body radiotherapy (SBRT) of lung cancer.@*Methods@#A total of 24 cases treated with SBRT were selected and all patients were fixed with vacuum pad in the supine position. Patients in group A were positioned by Catalyst HD and those in group B were positioned by shin markers. All patients were matched with the CT images after CBCT scan by rigid registration and the setup errors in six directions (x-, y-, z-axis, Rtn, Pitch and Roll) were obtained.@*Results@#The mean±SD in group A and B in the six directions were as follows: (0.13±0.12) cm, (0.25± 0.19) cm; (0.26±0.15) cm, (0.13±0.11) cm; (0.23±0.19) cm, (0.35±0.29) cm; (0.43°±0.40°), (0.80°±0.69°); (0.48°±0.47°), (0.79°±0.64°); (0.62°±0.60°) and (0.88°±0.70°), respectively. Except the x-axis data in group B, all the data in the six directions were not normally distributed. The obtained data significantly differed between two groups (all P<0.05). The out-of-tolerance errors (>0.5 cm/2°) also significantly differed between two groups (P<0.05).@*Conclusions@#The setup errors of Catalyst HD are less than those of the skin markers (except the y-axis). The setup accuracy of Catalyst HD is superior to that of traditional skin markers, which is worthy of application in clinical practice.