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Objective To observe the daily bladder and bowel preparation of patients with prostate cancer by cone-beam computed tomography (CBCT), and analyze its impact on the precise implementation of radiotherapy for prostate cancer and side effects. Methods We retrospectively analyzed 38 patients with prostate cancer who underwent volumetric modulated arc therapy. The number of radiation fractions for each patient ranged from 25 to 35. A CBCT scan was performed before each daily radiation therapy, and the number of scans for each patient ranged from 25 to 40. Setup errors were adjusted to ensure that the tumor was targeted and the rectum wall was not in the high-dose target area of the prostate. There were 93 instances where treatment could not be successfully implemented and re-preparation and re-scanning were required. We calculated the success rate of treatment and setup errors, compared radiotherapist-adjusted error values under different bladder and bowel preparation conditions, and recorded radiotherapy-related side effects. Results The success rate of treatment in the 38 patients was (92.14 ± 5.25)%. Among the 93 instances of seriously inadequate preparation, 48.4% were due to insufficient bladder filling, and 30.1% were due to intestinal bloating. Radiotherapy side effects were negatively correlated with the success rate of treatment (r = −0.393, P = 0.015). When bladder filling was sufficient, there were no significant differences in radiotherapist-adjusted error values in the left-right (LR), superior-inferior (SI), and anterior-posterior (AP) directions between adequate and inadequate bowel preparation (P > 0.05). When the bladder was moderately or insufficiently filled, there were significant differences in radiotherapist-adjusted error values in the LR, SI, and AP directions between adequate and inadequate bowel preparation (P < 0.05). Conclusion Insufficient bladder filling and intestinal bloating are the main factors influencing the successful implementation of radiotherapy for prostate cancer. When the bladder is sufficiently filled, bowel preparation does not affect prostate position change.
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Objective To explore the effects of image registration using various regions of interest(ROI)on the setup error for nasopharyngeal carcinoma(NPC)patients who were immobilized individually.Methods Forty-three NPC patients who required radiotherapy were enrolled.The patients were immobilized with customized plastic foam and thermoplastic mask,and CBCT verification was performed once a week.In CBCT images,ROI was divided into the whole ROI(ROIPTV)and 7 local ROI containing different cervical structures(ROIsphenoid sinus,ROIatlantoaxial,ROIneck3,ROIneck4,ROIneck5,ROIneck6,and ROIneck7),which were then used for registrations with localized CT image.The setup errors in superior-inferior(SI),left-right(LR),anterior-posterior(AP),Pitch,Roll,and Yaw directions were recorded.Results In SI direction,the setup errors within 0.3 cm accounted for 89.74%for ROIneck7,and more than 90%for the other ROI.The proportion of setup errors within 0.3 cm gradually increased with the neck upward in LR direction,and they were 76.78%,81.70%,85.26%,and above 90%for ROIneck7,ROIneck6,ROIneck5,and the other ROI,respectively.In AP direction,the proportions of setup errors within 0.3 cm were less than 90%,except for ROIatlantoaxial and ROIneck3.The setup errors of ROIsphenoid sinus,ROIatlantoaxial,ROIneck3,and ROIneck4 were significantly positively correlated with ROIPTV in SI direction,and the correlation coefficients(R)were 0.94,0.95,0.90,and 0.83,respectively.In LR direction,there were positive correlations between the setup errors of ROIatlantoaxial and ROIsphenoid sinus(R=0.95),ROIneck3 and ROIsphenoid sinus(R=0.91),ROIPTV and ROIneck3(R=0.91).The setup errors of ROIPTV in AP direction were positively correlated with ROIatlantoaxial vertebrae and ROIneck3(R=0.88,0.90).The margins of all ROIs ranged from 0.38 cm to 1.01 cm.The extension of ROIneck6 and ROIneck7 in AP direction exceeded 0.9 cm,and the extension of ROIneck7 reached 0.95 cm in SI direction.Conclusion ROIPTV and ROIsphenoid sinus,ROIatlantoaxial,ROIneck3 are significantly correlated in SI,LR,and AP directions.The setup error of nasopharyngeal carcinoma patients gradually increases with the neck down.The nasopharyngeal and cervical regions need to be expanded in segments when patients are immobilized individually.
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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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@#<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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Objective:To explore the influence of the contours of different parts of the human body on the setup errors of Catalyst HD optical surface imaging (OSI) system-guided radiotherapy.Methods:Using the 3D printing technology, arc- and oval arc-shaped phantoms with base angles of 5°-45° (step length: 5°) were designed to simulate the contours of different body parts of patients. A Catalyst HD system was employed for monitoring, during which the gains and integration time of the system were adjusted. The treatment couches were manually moved (range: -5 mm to 5 mm, with a step length of 2 mm). The ratios of transverse to longitudinal dimensions of all phantoms were recorded. The recorded items also included couch value errors in the anterior-posterior (AP), inferior-superior (SI), and left-right (LR) directions for transversely and longitudinally placed phantoms, as well as the setup errors monitored using the Catalyst HD system. Then, this study presented an analysis of the correlation between phantoms for different body contours and the gains and integration time of the Catalyst HD system. The purpose was to compare the setup errors under the two different placement conditions of phantoms and to analyze the correlation between the monitored values of the Catalyst HD system and couch values.Results:There was a significant linear negative correlation between the gain and the logarithm of integration time required for monitoring using the Catalyst HD system, with a slope of -0.001. There was a certain functional relationship between the intercept and the ratio of the transverse to longitudinal dimensions of the phantoms. Under the same gain, the integration time decreased with an increase in the base angles of phantoms. The Catalyst HD system showed different monitoring accuracy under different placement conditions of the phantoms ( Z = -8.59 to -0.02, P < 0.05), with the monitoring accuracy in the LR and AP directions higher in the transverse position. The correlation between the monitored values of the Catalyst HD system and the actual couch values increased in the LR and SI directions with an increase in the base angle of the phantoms, showing a strong correlation in the case of base angles of ≥ 25°. Furthermore, the correlation was always significant in the AP direction ( R > 0.9). Conclusions:When the best surface images are obtained using the Catalyst HD system, the gains and integration time of the system are correlated with body surface contours. The Catalyst HD system shows high monitoring accuracy in the AP direction. This system shows high accuracy in all directions when the ratios of transverse to longitudinal dimensions are ≤ 2 or the base angles ≥ 25°.
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Objective:To explore the tracking accuracy of the surface optically guided tracking system (OGTS) in radiotherapy.Methods:Phantom verification and clinical trial verification were adopted. Specialized equipment was employed for the phantom verification. Specifically, the displacement of the optical markers as they moved from a predetermined position to the target position on the reflector ball platform was captured using the OGTS, and then the obtained displacement was compared with the fixed distance within the phantom to calculate the accuracy and repeatability of the OGTS. For the clinical trial verification, 45 patients treated with radiotherapy, which consisted of 15 cases with head, breast, and rectal tumors each, were selected to investigate the tracking accuracy and repeatability of the OGTS. For each patient, the values derived from the image-guided positioning system (IGPS) and the OGTS before and after image-guided setup error correction during three times of fractionated radiotherapy were randomly obtained. The translational errors of each error correction were also recorded. Before radiotherapy, patients′ setup errors were corrected and relevant data were obtained using the IGPS. The correction result of translation errors obtained using the IGPS served as a gold standard to verify the accuracy of the OGTS in monitoring the translational motion of patients. Finally, the comprehensive translational deviation of both method was calculated.Results:The phantom measurements showed that the comprehensive translational deviation for tracking accuracy and tracking repeatability of the OGTS had a maximum deviation and a standard deviation of 0.18 mm and 0.03 mm, respectively. The clinical trial result indicated that the tracking accuracy of IGPS and OGTS exhibited statistically significant differences only for the head in the z direction ( t = 2.21, P < 0.05). Conversely, no statistically significant differences were observed for the head in the remaining directions or for the breast and rectum in the three translational directions ( P > 0.05). The analysis showed that comprehensive translational deviations for the head, breast, and rectum derived from OGTS and IGPS were (0.91±0.62), (1.64±1.30), and (1.52±1.29) mm, respectively, satisfying the requirement that the deviations should be below 2 mm. Conclusions:The OGTS, featuring easy operation and high tracking accuracy, can assist the IGPS in real-time respiratory monitoring during radiotherapy.
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Objective:To design a method to introduce random six-dimensional setup error (6D-SE) into the intensity-modulated radiotherapy (IMRT) planning for rectal cancer and evaluate its dosimetric effect.Methods:A total of 21 IMRT plans for patients with rectal cancer were randomly selected as reference plans [2 Gy per fraction for a total of 50 Gy; a 5 mm uniform margin around the clinical target volume (CTV) was taken as the planning target volume (PTV)]. For each fraction of the reference plan, a randomly generated 6D-SE was introduced by adjusting the geometrical parameters of the radiation field, and the dose was recalculated. The overall dose distribution with 6D-SE was obtained by adding up the dose of each fraction. A treatment simulation program that could complete the above workflow was developed using the Varian Eclipse scripting API (ESAPI). 6D-SEs that obey two preset distributions [distribution 1: translational error obey N(0, 4 2), and rotational error obey N(0, 2 2); distribution 2: translational error obey N(0, 2 2), and rotational error obey N(0, 1 2)] were introduced into the reference plans, and the dosimetric effects were assessed. Results:When the reference plans, error distribution 1, and error distribution 2 were applied, the Dmin values of the CTV were (49.4±0.41), (47.56±0.76), and (49.17±0.64) Gy, respectively; the D98% values of the CTV were (50.23±0.07), (49.98±0.10), and (50.27±0.09) Gy, respectively; the D98% values of the primary target area (the kernel part of the target area, excluding the margins) were (50.25±0.08), (50.42±0.13), and (50.33±0.10) Gy, respectively; the D98% values of the marginal area were (50.22±0.10), (49.88±0.11), and (50.26±0.10) Gy, respectively. In addition, compared with the result of the reference plans, the result of errors 1 and 2 showed no significant changes in the mean dose of the bladder and femoral heads ( P>0.05), despite slight decreases in the conformity index of the dose distribution with limited clinical significance. Conclusion:The proposed method and the treatment simulation program developed thereupon can introduce the 6D-SE obeying different distributions into the IMRT plans for rectal cancer on demand and provide overall dosimetric changes.
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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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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 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 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 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 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 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 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 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 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 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 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 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.