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Objective:To investigate the role of cervical core muscle group exercise and massage in the change of cervical spine curvature during radiotherapy for head and neck tumors and the effect on set-up errors.Methods:A total of 40 patients with head and neck tumours receiving radiotherapy in the First Affiliated Hospital of Air Force Military Medical University from March 2020 to July 2021 were prospectively selected, and all of them underwent different degrees of changes in cervical spine curvature during radiotherapy. The cervical core muscle exercise and manual massage were used to do treatment intervention on the change in the cervical spine curvature. Changes in cervical spine curvature at the time of the curvature change of the cervical spine and at 1 d, 3 d and 5 d after the intervention were observed by using cone beam CT, and then data were recorded in 3 dimensions. The set-up error when cervical spine curvature changed was compared with that after the muscle group exercise and manipulation, and Pearson was used to analyze the linear correlation of set-up errors in each direction.Results:There were 23 males and 17 females, with a median age of 41 years (26-62 years). The significant improvement of cervical curvature at 1 d, 3 d and 5 d after the intervention could be found in 2 cases (5.0%), 20 cases (50.0%) and 39 cases (97.5%). Using the cervical 4 vertebrae as the matching standard, the set-up errors at the time of change in cervical spine curvature and at 1 d, 3 d and 5 d after treatment were (1.3±0.9) mm, (1.2±0.8) mm, (1.3±0.7) mm and (1.3±0.7) mm in the left-right direction respectively; (2.0±0.7) mm, (1.7±0.8) mm, (1.8±0.7) mm and (1.9±0.8) mm in the head-foot direction respectively; (4.9±0.7) mm, (4.6±0.7) mm, (3.4±0.7) mm, (1.7±0.6) mm in the anterior-posterior direction respectively. The set-up error in the anterior-posterior directions at 3 d and 5 d after treatment intervention was lower than that at the time of change in cervical spine curvature and at 1 d after treatment intervention (all P < 0.01), and that at 5 d after treatment intervention was lower than that at 3 d after treatment intervention ( P < 0.01). There were no statistically significant differences between the left-right direction and head-foot direction at each time point (all P > 0.05). There was no correlation between left-right direction and head-foot direction ( r = 0.049, P = 0.540), between left-right direction and anterior-posterior direction ( r = 0.041, P = 0.607), and between head-foot direction and anterior-posterior direction ( r = 0.003, P = 0.931) in terms of set-up errors. Conclusions:Core cervical muscle group training and massage could improve the change in cervical spine curvature, increase the repeatability of the set-up, which provides a favourable guarantee for accurate treatment.
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Objective:To evaluate the effect of image-guided with cone-beam computed tomography (CBCT) based on volumetric modulated arc therapy (VMAT)-flattening filter free (FFF) on the setup errors of stereotactic body radiotherapy (SBRT) in patients with spinal metastatic tumors.Methods:The clinical data of 15 patients with spinal metastatic tumors who underwent SBRT in Jilin Cancer Hospital from August 2020 to January 2022 were retrospectively analyzed. The radiotherapy dose of bone metastasis was 32 Gy per 4 times and CBCT scanning was performed before and after radiotherapy. Every patient received radiotherapy 4 times; all 15 patients underwent SBRT 60 times in total and 120 CBCT volume images were finally obtained and analyzed. The systematic error (Σ) and random error (σ) were calculated at different correction threshold levels. The translational setup error and rotational setup error at the left-right (X axis), head-foot (Y axis) and front-back (Z axis) directions before and after radiotherapy were compared, which were expressed as Σ ± σ.Results:The pre-SBRT and post-SBRT translational setup errors were (0.14±0.27) cm and (0.07±0.19) cm, respectively ( P<0.001) in the X direction, (-0.05±0.33) cm and (0.00±0.19) cm, respectively ( P = 0.001) in the Y direction, (-0.13±0.19) cm and (-0.02±0.14) cm, respectively ( P = 0.012) in the Z direction. The pre-SBRT and post-SBRT rotational setup errors were (-0.31±0.76)° and (-0.09±0.34)°, respectively ( P < 0.001) in the X direction, (-0.13±0.88)° and (-0.07±0.36) °, respectively ( P < 0.001) in the Y direction, (0.10±0.51)° and (0.16±0.38)°, respectively ( P < 0.001) in the Z direction. Conclusions:CBCT correction could reduce Σ and σof the translational setup and rotational setup, increase the accuracy of SBRT based on VMAT-FFF for patients with spinal metastatic tumors.
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Objective:To propose a markless patient setup workflow based on the optical surface monitoring system (AlignRT) and open-face mask immobilization for whole-course head tumor radiotherapy, assess the setup time and repositioning frequency of the proposed workflow, and conduct a comparative analysis of the differences, correlation, and consistency of the setup errors of the AlignRT and cone beam CT (CBCT) systems.Methods:A retrospective analysis was conducted for the data on the errors of 132 fractionated setup based on open-face mask immobilization of 33 head tumor patients. AlignRT-guided markless patient setup workflow was applied throughout the radiotherapy. Meanwhile, the body structures automatically generated by the treatment planning system were used as body references. The 6-degree-of-freedom (6DoF) setup errors (lateral, vertical, longitudinal, rotation, pitch, roll, and yaw directions), setup time, and repositioning frequency of the AlignRT and CBCT systems were recorded and analyzed. The Wilcoxon and Spearman analyses were used to statistically assess the differences and correlation of the setup errors of the two systems. Moreover, the Bland-Altman analysis was employed to evaluate the consistency of the two systems.Results:The 6DoF setup errors of CBCT were within the clinical tolerance (linear motions: -0.30 to 0.30 cm; rotational motions: -2.0° to 2.0°). The setup time and repositioning frequency of CBCT were (98 ± 31) s and 1.51% (2/132), respectively. There was no significant difference in setup errors between the two systems except those in x-axis ( Z = -3.11, P= 0.002), y-axis ( Z = -7.40, P<0.001), and Pitch ( Z= -4.48, P<0.001). There was a significant positive correlation between the setup errors along lateral ( rs = 0.47, P<0.001) and vertical ( rs = 0.29, P = 0.001) directions, rotation (Rtn; rs = 0.47, P<0.001), pitch (Pitch; rs = 0.28, P = 0.001) and roll (Roll; rs = 0.45, P<0.001) of the two systems. The 95% limits of agreement (95% LoA) of 6DoF setup errors were -0.12 to 0.09 cm, -0.07 to 0.17 cm, -0.19 to 0.20 cm, -1.0° to 0.9 °, -1.0° to 1.5°, and -0.9° to 1.0°, respectively. The 95% confidence interval (95% CI) of 95% LoA was -0.14 to 0.11 cm, -0.09 to 0.19 cm, -0.23 to 0.23 cm, -1.2° to 1.1°, -1.2° to 1.7°, and-1.0° to 1.1°, respectively, all of which were within the permissible error ranges. The 6DoF setup error difference of 3.41% (27/792< 5%) was beyond the 95% LoA. The maximum absolute differences of 6DoF setup errors within the 95% LoA were 0.12, 0.16, 0.19 cm, 0.9°, 1.5°, and 1.0°, respectively. Conclusions:The proposed markless setup workflow based on AlignRT combined with open-face mask immobilization for whole-course head tumor radiotherapy exhibits reasonable agreement and consistency with the patient setup using CBCT, with acceptable clinical efficiency. It can be applied to the first radiotherapy and the real-time monitoring of therapy to improve the safety and thus is of value in clinical applications.
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Objective:To compare and analyze the differences in the setup accuracy of different immobilization method in breast cancer radiotherapy after breast-conserving surgery.Methods:A retrospective study was conducted on 60 patients who received radiotherapy after breast-conserving surgery from January to August, 2021. These patients were divided into two groups. One group consisted of 30 cases who were immobilized using a modified body thermoplastic membrane combined with a multifunction body board during the breast cancer radiotherapy and was called the modified body thermoplastic membrane group. The other group comprised 30 cases immobilized using a vacuum cushion during breast cancer radiotherapy and was referred to as the vacuum cushion group. The setup errors, 3D vector errors, the proportion of errors of > 5 mm, and the dosimetric differences in the planning target volume (PTV) and the clinical target volume (CTV) before and after simulated treatment bed moving (including the PTV_ V100, PTV_ V95, and CTV_ V95 before simulated treatment bed moving and the PTV_ V100 S, PTV_ V95 S, and CTV_ V95 S after simulated treatment bed moving) were compared between two groups. Moreover, for the modified body thermoplastic membrane group, the changes in the average setup errors at different radiotherapy stages were also analyzed. Results:A total of 369 cone-beam CT scans were conducted for 60 patients, including 195 CT scans for the modified body thermoplastic membrane group and 174 CT scans for the vacuum cushion group. The setup errors in the x, y, and z directions (right-left, anterior-posterior, and superior-inferior, respectively) of the modified body thermoplastic membrane group were (2.59±1.98) mm, (2.38±2.04) mm, and (1.45±1.16) mm, respectively, while those of the other group were (2.24±1.63) mm, (2.78±2.17) mm, and (2.70±1.88) mm, respectively. The 3D vector errors of both groups were (4.32±2.28) mm and (5.13±2.14) mm, respectively. Therefore, the setup error in direction z and the 3D vector error of the modified body thermoplastic membrane group were less than those of the vacuum cushion group ( t = -7.77, -3.41, P<0.05). Moreover, the proportion of setup errors of > 5 mm in the x direction of the vacuum cushion group was lower than that of the modified body thermoplastic membrane group ( χ2 = 7.13, P<0.05), while such proportion in the z direction of the modified body thermoplastic membrane group was lower than that of the vacuum cushion group ( χ2= 5.90, P<0.05). After the simulated treatment bed moving, the PTV_ V100 S of the modified body thermoplastic membrane group was better than that of the vacuum cushion group ( t = 2.47, P < 0.05). Furthermore, for the modified body thermoplastic membrane group, the setup errors in the x direction in the first week were higher than those in the 2-3 weeks and 4-5 weeks ( P<0.05). Conclusions:The modified body thermoplastic membrane combined with a multifunction body board yield better immobilization effects than a vacuum cushion. However, it produces high setup errors in the x direction in the first week of the radiotherapy, to which special attention should be paid.
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Objective:To explore the setup errors of vacuum pad combined with breast bracket in linear accelerator intensity-modulated radiotherapy for breast cancer.Methods:The clinical data of 72 patients who received linear accelerator intensity-modulated radiotherapy after breast conserving surgery in Hai'an Hospital of Traditional Chinese Medicine from July 2017 to March 2022 were retrospectively analyzed. According to the radiotherapy fixation schemes, they were divided into vacuum pad group (24 patients), breast bracket group (27 patients) and vacuum pad combined with breast bracket group (21 patients). Cone-beam CT was used to analyze the setup errors of the fixation, and the mean value of the overall errors and the standard deviation of the system errors were calculated. The relative factors affecting the fixed setup errors were analyzed.Results:There were statistical differences among vacuum pad group, breast bracket group and vacuum pad combined with breast bracket group in the level of forward and backward (Z) direction translation error (2.11±0.41, 2.67±0.26 and 1.79±0.21) and Z direction rotation error (1.14±0.24, 1.05±0.21 and 0.91±0.22) ( F values were 45.86 and 6.21, both P < 0.05). The level of Z direction translation error in vacuum pad group was higher than that in vacuum pad combined with breast bracket group, and the difference was statistically significant ( t = 12.37, P = 0.001). The level of Z direction rotation error in breast bracket group was higher than that in vacuum pad combined with breast bracket group, and the difference was statistically significant ( t = 3.41, P = 0.001). In the breast bracket group, the planning target volume (PTV) extension boundary values in the left and right (X), up and down (Y), and Z directions were 2.02, 2.09 and 1.97; the PTV release boundary values in X, Y and Z directions of the vacuum pad group were 1.81, 2.07 and 2.25; the external boundary values of PTV in X, Y and Z directions of the vacuum pad combined with breast bracket group were 1.13, 1.51 and 1.49. The result of multifactor analysis showed that body mass index (BMI) ( OR = 4.208, 95% CI 1.438-12.312) and breast volume ( OR = 4.023, 95% CI 1.375-11.769) were the independent influencing factors of fixed setup errors (both P < 0.05). Conclusions:The application of vacuum pad combined with breast bracket in the fixed setup of linear accelerator intensity-modulated radiotherapy of breast cancer is helpful to reduce the fixed setup errors, but at the same time, the fixed setup errors is affected by the patient's BMI, breast volume and other factors.
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RESUMEN Introducción: las radiaciones con fines terapéuticos han revolucionado la medicina y en especial, las tecnologías de radiación para el tratamiento del cáncer. Objetivo: determinar el margen de error de la configuración y el movimiento de órganos en la determinación de la posición del Clinical Target Volumen basadas en la tomografía computarizada de haz cónico de kilovoltaje en el tratamiento al cáncer de próstata, así como cuantificar el movimiento de los órganos durante la terapia conformal de la próstata obtenida un margen para la próstata. Métodos: investigación experimental; se asumió el método radioterápico de la adaptación día a día. Se seleccionaron los pacientes registrados de enero a abril del 2017 de Oncología Radioterápica del Hospital Universitario de la Universidad de Verona en Italia, con adenocarcinoma de próstata en estadios T1 a T4; fueron tratados mediante terapia de arco volumétrico modulado. Resultados: se utilizó la fórmula de Van Herk para encontrar el margen de la próstata, se observó que en la dirección cráneo caudal y lateral existen dispersiones pequeñas, y en la anteroposterior el grado de dispersión es más grande, lo que se relacionó con el llenado rectal, movimiento de la vejiga y peristalsis del paciente. Se encontró que los márgenes requeridos para la próstata entre CTV y PTV serían en la dirección cráneo caudal 3,3 mm, lateral 3,7 mm y anteroposterior 4,4mm. Conclusiones: la tomografía computarizada de haz cónico es una herramienta precisa para la guía de imágenes, proporciona un medio equivalente de corrección de la configuración para pacientes de próstata.
ABSTRACT Introduction: radiations with therapeutic aims have revolutionized medicine, particularly radiation technologies for the treatment of cancer. Objective: to determine the margin of errors of the configuration and the movement of organs in determining the position of Clinical Target Volume using kilovoltage cone-beam computed tomography in the treatment of prostate cancer, as well as to quantify the movement of organs during the planned therapy of prostate obtained by a margin for the prostate. Methods: an experimental research, the radio-therapeutic method on a day-to day basis was taken on. Patients registered from January to April 2017 on Cancer Radiotherapy from the University Hospital of Verona University in Italy, with prostate adenocarcinoma stages T1 to T4; and who were treated using volumetric modulated arch therapy. Results: making use of Van Herk's formula to position the margin of prostate, it was observed that in the craniocaudal and lateral direction there are small scatterings, and in the anteroposterior direction the degree of scattering is greater, being related to rectal filling, bladder movement and peristalsis of the patient. Finding the required margins for the prostate between CTV and PTV would be in the craniocaudal direction 3,3 mm, lateral 3,7 mm and anteroposterior 4,4 mm. Conclusions: cone-beam computed tomography is a precise tool to guide the images; it provides an equivalent approach of correction of the configuration for prostate cancer patients.
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Objective The literature study the setup errors of head and neck, thoracic, abdominal and pelvic tumors by megavoltage fan-beam CT based image guidance in TOMO-HD to provide the margin enlarging from clinic target volume (CTV) to planning target volume (PTV) in treatment planning system of TOMO-HD. Methods 103 patients with head and neck (30 patients), thoracic (42 patients), abdominal and pelvic (31 patients) carcinoma were enrolled. Megavoltage fan-beam CT based image guidance in tomotherapy-HD was used to acquire CT scan before every treatment. The left-right (X), superior-inferior (Y), anterior-posterior (Z) and rotation (Fy) setup errors of patients can be obtained from the tomography image automatically restructured by the system. Calculating the systematic error and the random error in the three dimensions and check whether the setup data accord with the normal distribution or not, then acquire the data expand in the three directions. Results According to 2593 fan-beam CT scans, the shift errors (µ ± s) in X, Y, Z and Fy (rotation) of three study group were [(−0.31 ± 2.16) mm、(1.09 ± 3.56) mm、(2.36 ± 2.27) mm, (0.29 ± 0.96)°] (head and neck tumor), [(−0.98 ± 2.95) mm、(0.45 ± 6.86) mm、(3.79 ± 2.47) mm, (0.18 ± 0.60)°] (thoracic cancer) and [(−0.86 ± 2.85) mm、(−1.59 ± 6.91) mm、(5.77 ± 2.40) mm, (0.20 ± 0.68)°](abdominal and pelvic carcinoma). The systematic errors (∑) and random errors (σ) in X, Y, Z dimensions of patients with head and neck, thoracic, abdominal and pelvic tumors were (1.06 mm and 1.84 mm), (1.93 mm and 3.43 mm), (2.41 mm and 2.71 mm), (1.10 mm and 2.56 mm), (3.79 mm and 5.46 mm), (1.38 mm and 1.99 mm) and (1.39 mm and 0.87 mm), (4.98 mm and 5.69 mm), (1.19 mm and 2.05 mm), respectively. Conclusion It is recommended as a reference for image guidance in TOMO-HD according to the frequency distribution of setup errors, for patients with head and neck, chest and abdominal and pelvic tumors, the maximum range of motion in three dimensions are (5.00, 5.00, 5.00) mm, (6.63, 17.25, 16.00) mm and (6.49, 16.24, 13.60) mm.
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Objective To investigate the accuracy and application value of optical surface monitoring system in intensity modulated radiotherapy for thoracic tumors patients.Methods Twenty-eight patients with thoracic tumors were included.During each treatment fraction,the patients were immobilized with body surface markers and laser lamps.The surface images obtained by the optical surface monitoring system were registered with the reference images and recorded during the CBCT scan.The translation and rotation errors of x (left-right),y (craniocaudal) and z (anterior-posterior) axes were recorded.After scanning,the CBCT images were registered with the planned CT images and the translation and rotation errors of x,y and z axes were recorded.The setup errors of these two image systems were analyzed and corrected before each treatment.The correlation between the two sets of setup errors were analyzed with Pearson test,and systematic error (∑) and random error (σy) were also calculated.The consistency of the two image systems was evaluated with the Bland-Altman method and the 95％ limits of agreement were calculated.Results There was a good correlation between these two groups,and the correlation coefficients were 0.79,0.62,and 0.53 in x,y and z axes,respectively.The ∑/σr of the optical surface monitoring system were 0.7 mm/1.5 mm,0.9 mm/1.8 mm and 0.9 mm/1.5 mm in x,y and z axes,respectively.The ∑/σ of CBCT were 0.8 mm/1.6 mm,1.3 mm/1.9 mm and 0.7 mm/1.5 mm in x,y and z axes,respectively.The 95％ limits of agreement of translations direction were (-2.0-2.3),(-3.4-3.6) and (-3.3-2.4) mm,and the 95％ limits of agreement of rotation direction were (-2.0 to 1.6)°,(-2.0 to 1.4)° and (-1.6 to 1.6)° inx,y and z axes,respectively.Conclusions The optical surface monitoring system is an effective image guide tool,which can quickly and accurately verify the patient's position and improve the position accuracy.It can be applied for positioning in the intensity modulated radiation treatments for the thoracic tumor patients.
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Objective To retrospectively analyze the setup error in radiotherapy of somal tumors and body metastases using the ExacTrac X-ray portal image,and to evaluate the feasibility and effectiveness of 6D setup error correction in body radiotherapy.Methods The translational and rotational setup errors were calculated by registering the bony structures on the ExacTrac X-setup images to that of the digitally reconstructed setup images,and the corresponding residual errors were calculated together.Results The translational and rotational setup errors in the x (left-right),y (superior-inferior),z (anterior-posterior) and Rx (sagittal),Ry (transverse),Rz (coronal) directions were(2.27±2.02) mm,(4.49±2.52) mm,(2.27± 1.37) mm and (1.02 ± 0.73) °,(0.67 ± 0.68) °,(0.76 ± 0.84) °,respectively.The residual translational and rotational setup errors in the x(r),y(r),z(r) and Rx(r),Ry(r),Rz(r) directions were(0.27±0.48)mm,(0.37±0.45)mm,(0.22±0.30)mm and (0.17±0.33)°,(0.14±0.34)°,(0.16± 0.28) ° respectively.Conclusions Besides the translational setup errors,a certain amount of rotational setup errors exist in radiotherapy of somal tumors and body metastases.By using the 6D setup error correction of the ExacTrac system,a translational less than 0.4 mm and rotational setup errors less than 0.2° could be achieved.
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Objective@#To study the more safe and accurate guidance scheme of cone beam computed tomography (CBCT) in nasopharyngeal carcinoma.@*Methods@#CBCT was regularly performed on 87 patients with nasopharyngeal carcinoma in Meizhou People's Hospital from November 2014 to August 2015. For each patient, 10 times CBCT scans were obtained pre-treatment. All the setup errors were obtained and analysed on the orientation X (left and right), Y (head and foot) and Z (vertical) axis.@*Results@#With the increase of the number of CBCT scans, there was no statistically significant difference among the mean setup errors of the 10 times scans in X (left and right) and Y (head and foot) directions (all P > 0.05). And there was no statistically significant difference among the mean setup errors of 6 times scans in Z (vertical) direction, but from the beginning of the 7th, the systematic error in Z direction was increasing, the system error of the 7th, 8th, 9th, 10th time was 0.140, 0.292, 0.461, and 0.640 mm. Moreover, the difference of the mean systematic errors among the first 7 times was statistically significant (H = 15.232, P = 0.019), and the differences of the mean systematic errors among the first 8, 9 and 10 times were statistically significant (all P < 0.05).@*Conclusions@#Non-consecutive scans of CBCT could reduce the systematic and random errors. The appropriate frequency of application of CBCT based on the change law of setup errors is an ideal CBCT guidance scheme for nasopharyngeal carcinoma.
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Objective To compare the positioning accuracy between personalized polyurethane foam with wing boards and negative pressure vacuum bag in radiotherapy for lung cancer using kilovoltage cone beam computed tomography(CBCT). Methods Thirty-nine patients with lung cancer who received chest radiotherapy in our hospital from 2015 to 2016 were enrolled as subjects. In those patients, 20 were immobilized by negative pressure vacuum bags(VB group)and the others by personalized polyurethane foam with wing boards(PF group).CBCT images were acquired weekly and registered with planning CT images. Setup errors in the left-right, superior-inferior, and anterior-posterior directions, three-dimensional(3D) displacement vector,and setup time were recorded. The margin of the planning target volume(PTV)was calculated using the Van Herk formula(2.5∑+0.7σ). Between-group comparison was made by paired t test. Results The PF group had a significant smaller setup error in the y-direction than the VB group (2.54±1.79 vs.3.19±2.14 mm,P=0.03),while there were no significant differences in setup errors in the x-or z-direction between the two groups(1.80± 1.48 vs. 1.90± 1.41 mm, P=0.46;2.14± 1.75 vs. 2.25± 1.75 mm,P=0.35). There were no significant differences in rotational setup errors in the Rx-,Ry-,or Rz-direction between the two groups(1.15°±0.76°vs. 1.15°±0.85°, P=0.50;0.71°±0.60°vs. 0.72°±0.43°, P=0.45;0.62°±0.54° vs. 0.46°±0.30°,P=0.06). The PTV margins in the x?,y?,and z?directions were expanded by 5.56, 8.57, and 7.02 mm, respectively, in the PF group, and by 5.62, 9.27, and 7.23 mm,respectively,in the VB group. The proportion of patients with 3D displacement vectors larger than 5 mm was 40% in the PF group and 45% in the VB group.Conclusions For patients undergoing radiotherapy for lung cancer,personalized polyurethane foam with wing boards can,to a certain extent,reduce the setup error in the superior-inferior direction and PTV margin expansion.[Key words] Lung neoplasms/radiotherapy; Polyurethane foam; Vacuum bag; Setup errors;Margin
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PURPOSE: To investigate positional uncertainty and its correlation with clinical parameters in spine stereotactic body radiotherapy (SBRT) using thermoplastic mask (TM) immobilization. MATERIALS AND METHODS: A total of 21 patients who underwent spine SBRT for cervical or upper thoracic spinal lesions were retrospectively analyzed. All patients were treated with image guidance using cone beam computed tomography (CBCT) and 4 degrees-of-freedom (DoF) positional correction. Initial, pre-treatment, and post-treatment CBCTs were analyzed. Setup error (SE), pre-treatment residual error (preRE), post-treatment residual error (postRE), intrafraction motion before treatment (IM1), and intrafraction motion during treatment (IM2) were determined from 6 DoF manual rigid registration. RESULTS: The three-dimensional (3D) magnitudes of translational uncertainties (mean ± 2 standard deviation) were 3.7±3.5 mm (SE), 0.9±0.9 mm (preRE), 1.2±1.5 mm (postRE), 1.4±2.4 mm (IM1), and 0.9±1.0 mm (IM2), and average angular differences were 1.1°±1.2° (SE), 0.9°±1.1° (preRE), 0.9°±1.1° (postRE), 0.6°±0.9° (IM1), and 0.5°±0.5° (IM2). The 3D magnitude of SE, preRE, postRE, IM1, and IM2 exceeded 2 mm in 18, 0, 3, 3, and 1 patients, respectively. No association were found between all positional uncertainties and body mass index, pain score, and treatment location (p > 0.05, Mann-Whitney test). There was a tendency of intrafraction motion to increase with overall treatment time; however, the correlation was not statistically significant (p > 0.05, Spearman rank correlation test). CONCLUSION: In spine SBRT using TM immobilization, CBCT and 4 DoF alignment correction, a minimum residual translational uncertainty was 2 mm. Shortening overall treatment time and 6 DoF positional correction may further reduce positional uncertainties.
Subject(s)
Humans , Body Mass Index , Cone-Beam Computed Tomography , Immobilization , Masks , Neoplasm Metastasis , Radiosurgery , Radiotherapy , Retrospective Studies , Spine , UncertaintyABSTRACT
Objective To evaluate the effect of setup errors on the 2D image projection and image registration, and then propose an improved registration method based on mutual information. Methods An anthropomorphic head phantom was used to simulate the rotational and translational setup errors. The geometric disparities were reflected by the changes of mutual information. Known setup errors were intentionally introduced to twenty cases divided into two groups demarcated by 3 mm translation error and 3° rotation error: ten cases with larger errors and ten with smaller errors. Then the anterior-posterior and lateral portal images were captured by the electronic portal imaging device ( EPID ) , based on which the setup errors were calculated using two mutual information registration method respectively: the vender provided one, and the improved method as proposed. The calculated errors were compared with the actual setup errors to evaluate robustness of the method. Results For the ten cases with smaller setup errors, the average translational registration disparities using the conventional method were 0. 3, 0. 4, and 0. 3 mm in x, y and z directions respectively. The rotational disagreements were 0. 4° in both x and z directions. The average time consumption was 28. 7 s. The corresponding discrepancies analyzed using the improved method were 0. 3, 0. 4, 0. 3 mm, 0. 5° and 0. 4°, respectively. On average, 31. 1 s was needed for registration. For the ten cases with larger setup errors, the mean disparities of the conventional method were 0. 9, 0. 7, 0. 8 mm, 0. 9° and 0. 8°, 29. 9 s taken on average. The corresponding result of the improved method was 0. 5, 0. 4, 0. 5 mm, 0. 6° and 0. 5°, 33. 2 s taken on average. Conclusions Regarding smaller setup errors, the two methods showed little difference and both had good performance in imageregistration accuracy. For larger setup errors, however, the improved mutual information registration method exhibited significantly higher accuracy than the conventional method, at cost of clinically acceptable registration time.
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Objective To evaluate the effect of setup errors on the 2D image projection and image registration, and then propose an improved registration method based on mutual information. Methods An anthropomorphic head phantom was used to simulate the rotational and translational setup errors. The geometric disparities were reflected by the changes of mutual information. Known setup errors were intentionally introduced to twenty cases divided into two groups demarcated by 3 mm translation error and 3° rotation error: ten cases with larger errors and ten with smaller errors. Then the anterior-posterior and lateral portal images were captured by the electronic portal imaging device ( EPID ) , based on which the setup errors were calculated using two mutual information registration method respectively: the vender provided one, and the improved method as proposed. The calculated errors were compared with the actual setup errors to evaluate robustness of the method. Results For the ten cases with smaller setup errors, the average translational registration disparities using the conventional method were 0. 3, 0. 4, and 0. 3 mm in x, y and z directions respectively. The rotational disagreements were 0. 4° in both x and z directions. The average time consumption was 28. 7 s. The corresponding discrepancies analyzed using the improved method were 0. 3, 0. 4, 0. 3 mm, 0. 5° and 0. 4°, respectively. On average, 31. 1 s was needed for registration. For the ten cases with larger setup errors, the mean disparities of the conventional method were 0. 9, 0. 7, 0. 8 mm, 0. 9° and 0. 8°, 29. 9 s taken on average. The corresponding result of the improved method was 0. 5, 0. 4, 0. 5 mm, 0. 6° and 0. 5°, 33. 2 s taken on average. Conclusions Regarding smaller setup errors, the two methods showed little difference and both had good performance in imageregistration accuracy. For larger setup errors, however, the improved mutual information registration method exhibited significantly higher accuracy than the conventional method, at cost of clinically acceptable registration time.
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Objective To investigate the distribution rules of setup errors in different locations for tomotherapy.Methods 151 patients induding 53 head and neck tumors,45 thoracic tumors,20 abdominal tumors,and 33 pelvic tumors,who accepted tomotherapy were retrospectively analyzed in this study.The planning CT images of patients were obtained in simulation,and all patients underwent megavoltage CT (MVCT) scan before radiotherapy.And the setup errors were calculated by rigid registering MVCT images to planning CT images,and setup errors on + x(left),-x(right),+ y(in),-y(out),+z(ventral),-z (dorsal)axes were analyzed respectively.Results A total of 3 281 MVCT scans were performed on 151 patients,The setup errors on +x (left),-x(right),+y(in),-y(out),+z (ventral),-z (dorsal)axes were (1.61 ± 1.21),(1.76 ±2.11),(2.26 ± 1.74),(1.83 ± 1.47),(3.24±1.76) and (1.75 ± 1.61)mm for head and neck tumors;(2.43 ±1.88),(2.55 ± 1.92),(3.06 ±2.64),(3.90 ±2.91),(6.71 ±3.46) and (2.64 ±2.77)mm for thoracic tumors;(3.67±3.06),(2.37±1.77),(3.18±1.96),(3.98±3.01),(6.74±3.25) and (1.92±2.00) mm for abdominal tumors;(2.92 ±2.13),(2.17±1.68),(3.50±2.61),(3.72±2.66),(7.18± 3.43) and (1.92 ± 1.61)mm for pelvic tumors,respectively.The setup errors were different between +z and-z with statistically significant in all tumors (t =-4.119、-5.033、-3.763、-5.057,P ＜ 0.05).The setup errors on + z direction of patients immobilized with thermoplastic mask were smaller than those immobilized with vacuum cushions for thoracic tumors (t =-2.357,P ＜ 0.05).Conclusions The setup errors of head and neck tumors are less than other parts tumor in tomotherapy.The patients immobilized with thermoplastic mask can reduce the setup errors for thoracic tumors.The heterogeneity of setup errors on ventral-dorsal directions for the all parts of tumors should not be ignored.
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Objective To study the feasibility of Brainlab plus 6-degree-of-freedom(6D) couch in the radiotherapy of head and neck by using their setup error.Methods Twenty-four patients with head and neck neoplasms in our hospital during AugustOctober 2016 were taken as the examples.After positioning by technician,each Brainlab was carried out,the setup errors in 3 translation directions of left-to-right(X),head-to-foot(Y) and abdomen to-back(Z) and 3 pivoting directions of Rx,Ry and Rz were obtained after registration of positioned CT image.After adjustment,Brainlab re-scanning was conducted for getting corrected errors.Results The online correction by Brainlab plus 6D obviously reduced the setup errors.The setup errors in all directions approached to 0,in which the difference between Ry and Rz directions had no statistical significance(P＞0.05),while the difference among the X,Y,Z and RX directions was statistically significant(P＜0.05).Conclusion The online corrections of Brainlab combined with 6D considerably reduces the errors in translation and rotation directions in radiotherapy of head and neck neoplasms,thus reduces normal tissue received amount and increases the radiotherapeutic accuracy.
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Objective To investigate the change in body weight over time in rectal cancer patients receiving radiotherapy and the correlation between setup errors and weight loss,and to establish the image-guided radiotherapy regimens in different periods of treatment.Methods A total of 24 postoperative patients with rectal cancer admitted to our hospital in 2016 were selected.Before each fraction of radiotherapy,the body weight was recorded,and the patients underwent cone-beam computed tomography (CBCT) with different frequencies in every week.The planning CT was matched with CBCT to obtain setup errors.The paired t test was used for difference analysis;the Pearson method was used to analyze the correlation between setup errors and weight loss.Results Body weight was measured 456 times in the 24 patients,and these patients underwent CBCT scans and image registration 456 times.Two patients were excluded because of treatment discontinuance.In the first and second weeks,there was no significant change in body weight.In the third week,the mean weight loss was 1.53 kg.In the fourth week,the mean weight loss was 2.48 kg.In the fifth week,the mean weight loss was 3.24 kg.The setup errors obtained by CBCT image registration in the superior-inferior (SI),anterior-posterior (AP),and left-right (LR) directions were 0.19 cm,0.20 cm,and 0.18 cm,respectively,in the first week,0.18 cm,0.17 cm,and 0.15 cm,respectively,in the second week,0.20 cm,0.22 cm,and 0.21 cm,respectively,in the third week,0.19 cm,0.25 cm,0.24 cm,respectively,in the fourth week,and 0.34 cm,0.33 cm,and 0.31 cm,respectively,in the fifth week.The Pearson correlation analysis showed that weight loss increased the setup errors,with P values of 0.140,0.046,and 0.044 in the SI,AP,and LR directions,respectively.Conclusions For rectal cancer patients receiving radiotherapy,the body weight decreases significantly in the late period (especially in the fifth week),which influences the setup errors.Therefore,in the fourth and fifth weeks of radiotherapy for rectal cancer,the weight loss should be closely monitored,and the number of CBCT scans can be increased before the treatment fraction to ensure the accuracy and optimization of treatment.
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Objective: Application of tomotherapy with megavoltage CT (MVCT)image-guided technique into craniospinal radiotherapy to analyzethe fixation effect of whole-body fixation plate.Methods: A retrospective analysis of 10 cases receiving craniospinalradiotherapy was performed. All patients were in supine position and were fixed with a whole-body fixation plate combined with thermoplastic mesh. The MVCTimages acquired before tomography were matched with the kilovoltage CT (KVCT) images, sothat the setup errors in six directions were detected. The tomography was performed if thematching result was satisfactory, otherwise the patient needed to be setup for the secondtime when the matching result was not accepted by the clinical radiation therapists.Results: A total of 159 MVCT scans was conducted in 10 patients. The average setup errorsin left-right (LR), cranial-caudal (CC), anterior-posterior (AP), pitch, roll and yaw directionswere (1.94 ± 1.44) mm, (2.98 ± 2.51) mm, (1.71 ± 1.87) mm, (0.73 ± 0.64) degrees, (0.30 ±0.26) degrees and (0.34 ± 0.31) degrees, respectively. The probability of second setup was3.14% (5/159).Conclusion: MVCT image-guided technique can significantly reduce the setup errors incraniospinal tomography. The fixation effect of the whole-body fixation plate is acceptable.
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Abstract Objective: To evaluate three-dimensional translational setup errors and residual errors in image-guided radiosurgery, comparing frameless and frame-based techniques, using an anthropomorphic phantom. Materials and Methods: We initially used specific phantoms for the calibration and quality control of the image-guided system. For the hidden target test, we used an Alderson Radiation Therapy (ART)-210 anthropomorphic head phantom, into which we inserted four 5mm metal balls to simulate target treatment volumes. Computed tomography images were the taken with the head phantom properly positioned for frameless and frame-based radiosurgery. Results: For the frameless technique, the mean error magnitude was 0.22 ± 0.04 mm for setup errors and 0.14 ± 0.02 mm for residual errors, the combined uncertainty being 0.28 mm and 0.16 mm, respectively. For the frame-based technique, the mean error magnitude was 0.73 ± 0.14 mm for setup errors and 0.31 ± 0.04 mm for residual errors, the combined uncertainty being 1.15 mm and 0.63 mm, respectively. Conclusion: The mean values, standard deviations, and combined uncertainties showed no evidence of a significant differences between the two techniques when the head phantom ART-210 was used.
Resumo Objetivo: Comparar os erros de posicionamento e erros residuais translacionais tridimensionais de uma radiocirurgia guiada por imagem, frame versus frameless, com uso de um objeto simulador antropomórfico. Materiais e Métodos: Para a calibração e qualidade do sistema de imagem foram utilizados objetos simuladores específicos. Para o teste hidden target foi utilizado o crânio do objeto simulador antropomórfico Alderson Radiation Therapy (ART)-210, dentro do qual foram inseridas quatro esferas metálicas de 5 mm de diâmetro como volumes alvos de tratamento. Imagens tomográficas foram realizadas com o ART-210 devidamente posicionado para ambos os métodos de imobilização. Resultados: Para o método frameless, a média foi 0,22 ± 0,04 mm para os erros setup e 0,14 ± 0,02 mm para os erros residuais, apresentando uma incerteza combinada de 0,28 mm e 0,16 mm, respectivamente. Para o método frame, a média foi 0,73 ± 0,14 mm para os erros setup e 0,31 ± 0,04 mm para os erros residuais, apresentando uma incerteza combinada de 1,15 mm e 0,63 mm, respectivamente. Conclusão: Com base nas médias, desvios-padrão e incertezas combinadas, os resultados mostraram não haver evidências de diferença significativa entre as técnicas em questão quando utilizado um objeto simulador antropomórfico craniano ART-210.
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Objective To compare the errors of double-center and single-center setup, and to study the role of both on reducing the rotational setup errors for the patients with esophageal carcinoma depend on rigid registration errors between online kV-cone-beam computed tomography (kV-CBCT) images and plans for CT images. Methods 20 patients with middle esophageal carcinoma received image scanning before treatment every week by using double-center setup and CBCT, and single-center setup images of 20 patients were taken from the X volume image (XVI) system. Then the images of both setup types, registration errors of CT image and rotational setup errors were compared respectively. Every patient received kV-CBCT scanning analysis before treatment every week, and 6 times in total. 240 group of kV-CBCT images from all of the patients were off-line matched with plans for CT images to calculate the errors of X-axis, Y-axis, Z-axis. Then the data of linear errors and rotational setup errors from patients were collected, aiming at putting the error data into the patients treatment program and analyzing the significances. Results The standard registration of double-center setup was as follows: T (X) (0.28 ±0.19) cm, T (Y) (0.27 ±0.19) cm, T (Z) (0.33 ±0.12) cm, R (X) (0.40 ±0.19)° , R (Y) (0.30 ±0.18)° , R (Z) (0.30 ±0.19)° . The standard registration of single-center setup was as follows:T(X) (0.32±0.20) cm, T(Y) (0.29±0.25)cm, T(Z) (0.31±0.16) cm, R(X) (2.2±0.68)°, R(Y) (0.5±0.32)°, R(Z) (2.10±0.60)°. There were statistical differences between linear errors in T(X) and rotational setup errors in R(X), R(Y) or R(Z) (P< 0.05). Conclusion Double-center position can reduce the rotational setup errors, especially in X-axis, Y-axis errors, and may provide more help for the radiation oncology departments without on-board CBCT.