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Objective:To study the inter-fraction setup errors, intra-fraction movement of patients and its influence on dosimetry, position repeatability of the supraclavicular area, and the plastic stability of the vacuum cushion and styrofoam when one of the three fixation method are applied in the clinical radiotherapy of breast cancer. The three fixation method include acuum negative pressure pad (VP), acuum negative pressure pad combined with a breast bracket (VB), and polyurethane styrofoam combined with a breast bracket (PB).Methods:A total of 96 breast cancer patients who received radiotherapy at Jiangsu Cancer Hospital during 2019-2021 were collected prospectively for study. They were randomly divided into three groups (VP, VB, and PB). Cone-Beam CT and a planning system were used to obtain inter-fraction setup errors, intra-fraction movement of patients and its influence on dosimetry, position repeatability of supraclavicular area, and the plastic stability of vacuum pad and polyurethane tyrofoam.Results:In the left-right (LR) direction, there were no statistical differences in the inter-fraction setup errors among the three groups. In the superior-inferior (SI) direction, inter-fraction setup errors of the PB group were smaller than those of the VB group (3.02 ± 2.04, 3.65 ± 2.64, t=2.35, P=0.031). In the anterior-posterior (AP) direction, the inter-fraction setup errors of both the VB and PB groups were smaller than those of the VP group (3.36 ± 2.93, 3.14 ± 0.98, 4.03 ± 2.55, t=2.29, 3.11, P< 0.05). In the AP direction, the intra-fraction movement of patients of the VP and PB groups were less than that of the VB group (1.31 ± 0.95, 1.24 ± 0.89, 1.88 ± 1.33, t=-2.04, -2.31, P< 0.05). Moreover, the intra-fraction movement of patients had no statistical effect on the dosimetric distribution ( P> 0.05), and the breast bracket did not improve the position repeatability of the supraclavicular region ( P>0.05). In addition, the plastic stability of polyurethane styrofoam was significantly better than that of the acuum negative pressure pad ( t=2.43-5.63, P< 0.05). Conclusions:The inter-fraction setup errors and intra-fraction movement of patients with breast cancer can be reduced by using PB. Compared to an acuum negative pressure pad, polyurethane styrofoam can keep plastic stability throughout the treatment of the patients.
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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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Objective:By comparing the positioning errors caused by 3D printed personalized breast bracket and common headrest in intensity-modulated radiation therapy (IMRT), the fixation effect of 3D printed personalized breast bracket in IMRT was analyzed.Methods:Thirty-two breast cancer patients from January to July 2021 were randomly divided into a the 3D printed breast bracket group and common headrest group. All patients in two groups were kept in supine position, head tilted to the healthy side, the affected hand held the grip bar on the same side of the horizontal bar, the healthy hand held the opposite side of the vertical bar, and the chest and mandible were fixed with thermoplastic film. CBCT scan was performed weekly, and gray level registration was carried out according to the three registration regions of interest: breast or chest wall field, supraclavicular and inferior field, and axillary field. The positioning errors in the left and right, head and foot, abdomen and back directions were analyzed between two groups.Results:In the 3D printed breast bracket group, the positioning errors of breast or chest wall field, supraclavicular and inferior field and axillary field in the left and right, head and foot, abdomen and back directions were (1.75±1.26), (1.77±1.11) and (1.70±1.08) mm, (1.75±1.25), (1.72±1.09) and (1.70±1.05) mm,(1.86±1.34), (2.14±2.13) and (1.66±1.19) mm, respectively.In the common headrest group, the positioning errors of breast or chest wall field, supraclavicular and inferior field and axillary field in the left and right, the head and feet, the abdomen and back directions were (2.54±1.84), (2.73±3.62) and (2.18±2.45) mm, (3.25±2.02), (3.52±2.26) and (2.62±2.83) mm, (3.25±2.05), (4.44±2.90) and (3.10±3.18) mm, respectively.The positioning errors significantly differed between two groups (all P<0.05). Conclusions:The positioning error of 3D printed personalized breast bracket fixation is less than that of common headrest fixation. The positioning consistency of 3D printed personalized breast bracket in the three target areas of breast or chest wall field, supraclavicular and inferior field and axillary field is better than that of common headrest.
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Objective To explore the effects of improvements on setup error ( SE ) and clinical target ( CTV ) margin of supraclavicular field ( SCF ) by using moisture-cured resin cushion and breast bracket for lower neck fixation in breast cancer patients who underwent post-mastectomy radiotherapy. Methods Totally 13 patients with breast cancer who underwent post-mastectomy radiotherapy were enrolled. All patients were immobilized by breast bracket and moisture-cured resin cushion. Firstly, each patient′s lower neck and head was fixed well by moisture-cured resin cushion, filling the gap between the neck and breast bracket. Secondly,each patient underwent the cone-beam CT ( CBCT) at the first, tenth and twentieth treatment after positioning. Then these CBCT images were registered to the planning CT to determine setup errors in translational and rotational directions, and SCF CTV margins by the systematic and random errors were evaluated. Results The setup errors in x (left-right), y (superior-inferior), z (anterior-posterior) translational directions were (2. 16 ± 1. 25), (1. 50 ± 1. 28), (1. 94 ± 1. 12) mm and (1. 76 ±1. 87)°, (1. 82 ±1. 12)°, (0. 99 ±0. 58)°, respectively in θ (pitch degree),Ф(roll degree),ψ( yaw degree) rotational directions. Non-parametric rank test ( Mann-Whitney U test) was performed with previous data, the differences of the setup error in y, z,θ directions were statistically significant ( Z =4. 152, 3. 415, 2. 053, P<0. 05). The margins from CTV were 4. 07, 4. 03 and 3. 73 mm in x, y and z directions, respectively. Compared with the previous study on SCF, CTV margin required 8, 8 and 6 mm in x, y and z axis directions, the volume of CTV to PTV were decreased by 32. 73% on average. Conclusions Compared with plastic circular pillow alone, moisture-cured resin cushion with breast bracket locating method could reduce setup errors in SCF target region. The margins from CTV to PTV weredecreased to 4. 07, 4. 03 and 3. 73 mm in x, y and z axis directions at least.
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Objective To explore the effects of improvements on setup error ( SE ) and clinical target ( CTV ) margin of supraclavicular field ( SCF ) by using moisture-cured resin cushion and breast bracket for lower neck fixation in breast cancer patients who underwent post-mastectomy radiotherapy. Methods Totally 13 patients with breast cancer who underwent post-mastectomy radiotherapy were enrolled. All patients were immobilized by breast bracket and moisture-cured resin cushion. Firstly, each patient′s lower neck and head was fixed well by moisture-cured resin cushion, filling the gap between the neck and breast bracket. Secondly,each patient underwent the cone-beam CT ( CBCT) at the first, tenth and twentieth treatment after positioning. Then these CBCT images were registered to the planning CT to determine setup errors in translational and rotational directions, and SCF CTV margins by the systematic and random errors were evaluated. Results The setup errors in x (left-right), y (superior-inferior), z (anterior-posterior) translational directions were (2. 16 ± 1. 25), (1. 50 ± 1. 28), (1. 94 ± 1. 12) mm and (1. 76 ±1. 87)°, (1. 82 ±1. 12)°, (0. 99 ±0. 58)°, respectively in θ (pitch degree),Ф(roll degree),ψ( yaw degree) rotational directions. Non-parametric rank test ( Mann-Whitney U test) was performed with previous data, the differences of the setup error in y, z,θ directions were statistically significant ( Z =4. 152, 3. 415, 2. 053, P<0. 05). The margins from CTV were 4. 07, 4. 03 and 3. 73 mm in x, y and z directions, respectively. Compared with the previous study on SCF, CTV margin required 8, 8 and 6 mm in x, y and z axis directions, the volume of CTV to PTV were decreased by 32. 73% on average. Conclusions Compared with plastic circular pillow alone, moisture-cured resin cushion with breast bracket locating method could reduce setup errors in SCF target region. The margins from CTV to PTV weredecreased to 4. 07, 4. 03 and 3. 73 mm in x, y and z axis directions at least.
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Objective To apply joint fixation with breast bracket and body phantom to breast cancer radiotherapy after breast-conserving operation.Methods Totally 36 patients after breast-conserving operation underwent joint fixation with breast bracket and body phantom, whose cone beam computed tomography (CBCT) images were obtained with on board imager (OBI) before radiotherapy. The errors between the CBCT images and planning CT images were acquired by matching.Results The setup errors in the directions of left-right (X), head-foot (Y) and belly-back (Z) were (2.6±0.783), (3.0± 1.027) and (1.6 ±0.872)mm respectively, and the percentages that the setup errors were more than 5 mm were 16.5%, 20.7% and 9.1% respectively.Conclusion Joint fixation with breast bracket and body phantom may decrease the setup error in radiotherapy after breast-conserving operation, especially in the belly-back direction, and thus has high clinical values.