|
 
 |
| ORIGINAL ARTICLE |
|
| Year : 2022 | Volume
: 8
| Issue : 1 | Page : 25 |
|
Comparison of dosimetric parameters and three-dimensional dosimetric verification of three intensity-modulated radiotherapy plans for thymoma based on the dose–volume histogram and ArcCHECK-3DVH system
Peng Zhou, Jia Luo, He Xiao, Mingying Geng, Xuan He
Department of Cancer Center, Daping Hospital, Army Medical University, Chongqing, China
| Date of Submission | 22-Mar-2022 |
| Date of Decision | 10-Jun-2022 |
| Date of Acceptance | 13-Jun-2022 |
| Date of Web Publication | 21-Oct-2022 |
Correspondence Address:
Mingying Geng
Department of Cancer Center, Daping Hospital, Army Medical University, No. 10 Changjiang Zhilu, Yuzhong District, Chongqing 400042
China
Xuan He
Department of Cancer Center, Daping Hospital, Army Medical University, No. 10 Changjiang Zhilu, Yuzhong District, Chongqing 400042
China
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/digm.digm_11_22
Objective: To compare the dosimetric parameters of step-shoot intensity-modulated radiotherapy (sIMRT), dynamic intensity-modulated radiotherapy (dIMRT), and volume-modulated arc therapy (VMAT) in thymoma and to study the feasibility of the ArcCHECK-3DVH system in three intensity-modulated radiotherapy plans to choose a more appropriate intensity-modulated radiotherapy for thymoma. Materials and Methods: Seventeen patients with thymoma were enrolled in this study. Treatment plans of sIMRT, dIMRT, and VMAT for each patient were based on the Monaco treatment planning system (TPS). Dosimetric verification was performed via the ArcCHECK-3DVH system. We compared and analyzed the 3D γ pass rates of the TPS dose calculation and ArcCHECK-3DVH system dose reconstruction with the three gamma criteria (3 mm/3%, 2 mm/2%, and 1 mm/1%) with a threshold of 10%. Dose–volume histogram analysis was used to compare the dose parameters for target volumes, and organs at risk (OARs), such as D98%, D50%, D2%, Dmax, V20, and V5. Monitor units (MUs) and delivery time were also compared. Results: There were significant differences in the three intensity-modulated radiotherapy plans. For target volume, VMAT showed the highest planning target volume (PTV) D98% and the lowest PTV D50% compared with sIMRT or dIMRT. The PTV D2% of VMAT was lower than that of sIMRT and higher than that of dIMRT, and VAMT demonstrated the highest conformity index and MU, lowest homogeneity index, and shortest treatment delivery time. For the OARs, VMAT is not inferior to sIMRT and dIMRT in OARs protection. For the dosimetric verification, the entire area, PTV, lungs, heart, and spinal cord of VMAT showed the highest γ pass rates than the other two techniques under the gamma 3 mm/3% criteria, which was even more pronounced when the stricter gamma criteria of 2 mm/2% and 1 mm/1% were applied. Conclusion: VMAT can be applied to radiotherapy of thymoma, and the accuracy of treatment plan execution can be guaranteed through the ArcCHECK-3DVH system.
Keywords: ArcCHECK volume-modulated arc therapy, Dosimetric parameters, Dosimetric verification, Intensity-modulated radiotherapy, Thymoma
How to cite this article:
Zhou P, Luo J, Xiao H, Geng M, He X. Comparison of dosimetric parameters and three-dimensional dosimetric verification of three intensity-modulated radiotherapy plans for thymoma based on the dose–volume histogram and ArcCHECK-3DVH system. Digit Med 2022;8:25 |
How to cite this URL:
Zhou P, Luo J, Xiao H, Geng M, He X. Comparison of dosimetric parameters and three-dimensional dosimetric verification of three intensity-modulated radiotherapy plans for thymoma based on the dose–volume histogram and ArcCHECK-3DVH system. Digit Med [serial online] 2022 [cited 2023 Jun 9];8:25. Available from: http://www.digitmedicine.com/text.asp?2022/8/1/25/359354 |
| Introduction | |  |
Thymoma is a common mediastinal tumor that is difficult to diagnose early due to hidden onset. The location of the lesion is adjacent to the great blood vessels of the heart, and the boundary between the tumor and peripheral blood vessels is not clear in advance thymoma, which is difficult to cure completely by surgery alone. Therefore, postoperative adjuvant radiotherapy is essential to reduce local recurrence and distant metastasis.[1],[2],[3],[4],[5]
At present, intensity-modulated radiotherapy (IMRT) is one of the most common radiotherapy techniques for thymoma and can be divided into step-shoot IMRT (sIMRT) and dynamic IMRT (dIMRT). For sIMRT, the beam is delivered with the specific dose rate, while gantry angle and multileaf collimators (MLC) position are fixed. For dIMRT, MLC position and dose rate are all variable during the irradiation process.[6],[7],[8] With the rapid development of radiotherapy techniques, volume-modulated arc therapy (VMAT), as a new modulated radiotherapy technique, can continuously change the gantry angle, MLC position, and dose rate during the irradiation process. VMAT improves the conformity of the dose distribution to the target volume and the irradiation efficiency and can also better protect organs at risk (OARs) from radiation. Therefore, VMAT is widely used in the clinic.[8],[9],[10],[11] However, the dynamic change in multiple parameters and the complex dose distribution in VMAT make the implementation of radiotherapy more uncertain, and patient-specific quality assurance (QA) is necessary. The most frequently used method of QA is to compare the calculated dose of treatment planning system (TPS) and the measured dose of the dosimetric verification phantom.[12],[13] Gamma analysis is usually used to determine if the dose distribution of the measured result is appropriate for the calculated dose distribution. It consists of two concepts: dose difference and distance to agreement (DTA). The American Association of Medical Physics in Medicine recommended that the criteria of a 3% dose difference and 3 mm DTA (3 mm/3%) are commonly used in clinical dosimetric research.[14],[15],[16]
Therefore, VMAT used in postoperative adjuvant therapy of thymoma is rarely reported at home and abroad. To explore the differences in the application of sIMRT, dIMRT, and VMAT in thymoma, we compared the dosimetric parameters, conducted dosimetric verification using the ArcCHECK-3DVH system, and analyzed their dosimetric differences to provide a basis for clinical application.
| Materials and Methods | | |
Patient selection
Seventeen thymoma patients who received postoperative adjuvant radiotherapy in Army Special Medical Center from January 2017 to January 2020 were enrolled in this study, including 11 males and 6 females, aged 24–64 years, with a median age of 45 years. All patients were confirmed by pathological examination to have lesions located in the anterior superior mediastinum, and there were no contraindications to radiotherapy. All patients signed the informed consent form during the experiment.
Computed tomography simulation-based localization
All the patients were supine with their heads in their hands and fixed with thermoplastic body film. After a thermoplastic membrane was formed, lead points were placed in the anterior midline and on both sides of the body under laser beam guidance. Under calm breathing, the coverage of the contrast-enhanced computed tomography (CT) scan was extended from the cricoid cartilage to the bottom of the lung using the Philips 16-slice CT locator (Philips, Eindhoven, Netherlands) and reconstruction with a layer spacing of 5 mm. The obtained CT images were transmitted to the Monaco TPS (Version 5.11.01, Elekta AB, Stockholm, Sweden) and reconstructed 3D images.
Target volume delineation and organs at risk
The gross tumor volume and clinical target volume (CTV) were delineated according to the experience of our hospital and the guidelines of the International Commission on Radiation Units and Measurements. The planning target volume (PTV) was generated by expanding 3 mm outward on the basis of CTV and delineating the lungs, heart, spinal cord, and other OARs. The limits for OARs were as follows: for the left and right lungs, they were V5 ≤ 55%, V10 ≤ 45%, V20 ≤ 30%, and V30 ≤ 20%; for the heart, they were V20 ≤ 50%, V30 ≤ 40%, and V40 ≤ 30%; and for the spinal cord, it was Dmax ≤ 40 Gy.
Treatment plan design
SIMRT, dIMRT, and VMAT treatment plans were designed for each patient using the Monaco TPS (v5.11.01), and all the treatment plans were generated for the Elekta Synergy linear accelerator. The prescription dose was 50 Gy/25 F. For the three techniques' treatment plans, the plan isocenter was placed in the center of the PTV. Five fixed gantry fields were created for the sIMRT and dIMRT plans (300°, 330°, 30°, 60°, and 180°). Two fields were created for VMAT plans (the angle between 2 beams ranged from 120° to 230°). All plans were calculated using the Monaco TPS (v5.11.01), and 8 MV photon energy was used. All plans were optimized under the same objective functions and parameters.
Dose delivery and verification
All plans included irradiation with 8 MV of photon energy generated by an Elekta Axesse (Elekta AB, Stockholm, Sweden) linear accelerator. The ArcCHECK-3DVH system (Sun Nuclear Corporation [SNC], Melbourne, Florida, USA) was used for dosimetric verification of all treatment plans, which uses a phantom for data acquisition and SNC patient software and 3DVH software (version 3.2) for comparative analysis. The length of the ArcCHECK phantom is 21 cm, and it is cylindrical. There are 1386 semiconductor probes in a helical distribution in the phantom, the probe spacing is 1 cm, and the effective detection area is 0.8 mm × 0.8 mm. Calibration of the background, matrix, and absolute dose are necessary prior to acquiring data with the ArcCHECK system. All the treatment plans were uploaded into the ArcCHECK phantom to recalculate doses. The RT plan and RT dose files of the calculated results were imported into the SNC patient software in DICOM format and compared with the results obtained from the phantom measurements. The difference between the calculated dose and the measured dose was analyzed using γ pass rates.[17],[18],[19]
Comparison of dose–volume histogram-based parameters
Comparison of the differences between the sIMRT, dIMRT, and VMAT plans for each patient by dose–volume histogram (DVH). All the treatment plans required more than 95% of the target volume covered by the prescription isodose curve. PTV dose (D98%, D50%, and D2%), lung dose (V30, V20, V10, and V5 and mean dose), heart (V30, V20, and V10), and spinal cord doses (maximum dose) were evaluated. The homogeneity index (HI) and the conformity index (CI) of the target volume were also evaluated. CI = VRX2/(TV × VRI), VRX represents the target volume covered by the 95% prescription isodose curve, TV represents the target volume, VRI represents the volume of all areas covered by the 95% prescription isodose curve, and CI is ideally 1. HI = D5/D95, where D5 represents the dose covering 5% of the target volume and D95 represents the dose covering 95% of the target volume; a lower HI value represents better uniformity of the target.[20],[21] The actual treatment delivery time and the monitor units (MUs) were compared between the three techniques.[22],[23]
Analysis of 3D γ pass rates with 3DVH
In our study, the 3D γ pass rates of each region of interest (ROI) were calculated. The 3D γ pass rates of sIMRT, dIMRT, and VMAT for each patient were compared using three gamma criteria (3 mm/3%, 2 mm/2%, and 1 mm/1%) with a threshold of 10%. The difference was analyzed using the Friedman test.[24]
Statistical methods
The data were represented as medians and interquartile range. The differences in all dosimetry parameters among the three groups were evaluated with the Friedman test. Stepwise comparison between any two groups was performed by the Nemenyi test, and the Bonferroni method was used to correct the P value from multiple comparisons. All statistical analyses were performed with R (version 4.1.1), and P < 0.05 was considered statistically significant.
| Results | | |
Comparison of target volume dose, monitor units, and treatment delivery time
All the treatment plans conformed to the clinical treatment requirements. The dose distribution of the sIMRT, dIMRT, and VMAT plans on the same cross-section and sagittal section is shown in [Figure 1]. The comparison results of the PTV dose parameters (D98%, D50%, and D2%), MUs, and treatment delivery time for the three techniques are shown in [Table 1] and [Figure 2]. The differences in the D98%, D50%, and D2% of the PTV among the three techniques were statistically significant (P < 0.05). VMAT showed the highest PTV D98% and the lowest PTV D50% compared with sIMRT or dIMRT. For the D2% of the PTV, VMAT was lower than sIMRT and higher than dIMRT. There were also statistically significant differences in CI, HI, MUs, and treatment delivery time among the three techniques (P < 0.05). For the other two techniques, VAMT demonstrated the highest CI and MUs, lowest HI, and shortest treatment delivery time. | Figure 1: Dose distribution of sIMRT, dIMRT, and VMAT plans on the same cross-section and sagittal plane. sIMRT: Step-shoot intensity-modulated radiotherapy, dIMRT: Dynamic intensity-modulated radiotherapy, VMAT: Volume-modulated arc therapy.
Click here to view |
 | Figure 2: Dosimetry, MU and treatment delivery time comparison of the target among sIMRT, dIMRT, and VMAT. (a) : PTV D98%; (b) : PTV D50%; (c) : PTV D2%; (d) : HI; (e): CI; (f) : MUs; (g) : Treatment delivery time. sIMRT: Step-shoot intensity-modulated radiotherapy, dIMRT: Dynamic intensity-modulated radiotherapy, VMAT: Volume-modulated arc therapy, MUs: Monitor units, PTV: Planning target volume, CI: Conformity index, HI: Homogeneity index.
Click here to view |
 | Table 1: Dosimetry, monitor units and treatment delivery time comparison of the target among step-shoot intensity-modulated radiotherapy, dynamic intensity-modulated radiotherapy and volume-modulated arc therapy
Click here to view |
Dosimetry comparison of organs at risks
The DVHs of the sIMRT, dIMRT, and VMAT plans are shown in [Figure 3]. | Figure 3: The DVH of sIMRT, dIMRT, and VMAT plans. sIMRT: Step-shoot intensity-modulated radiotherapy, dIMRT: Dynamic intensity-modulated radiotherapy, VMAT: Volume-modulated arc therapy, DVH: Dose–volume histogram, PTV: Planning target volume.
Click here to view |
The dosimetry comparison of OARs between each group of the three techniques is shown in [Table 2] and [Figure 4]. Except for no significant difference in the V10 of the left lung between dIMRT and VMAT (P > 0.05), the Dmean, V40, V30, V20, V10, and V5 of the lungs, the Dmean, V40, V30, and V20 of the heart, and the maximum dose of the spinal cord were all significantly different between each of the three technique groups (P < 0.05). | Figure 4: Dosimetric comparison of OARs among sIMRT, dIMRT, and VMAT. (a–e) represents the Dmean, V30, V20, V10, V5 of R-lung; (f–j) represents the Dmean, V30, V20, V10, V5 of L-lung; (k–n) represents the Dmean, V40, V30, V20 of heart; (o) represent Dmax of spinal cord. sIMRT: Step-shoot intensity-modulated radiotherapy, dIMRT: Dynamic intensity-modulated radiotherapy, VMAT: Volume-modulated arc therapy, OARs: Organs at risk.
Click here to view |
 | Table 2: Dosimetric comparison of organs at risk among step-shoot intensity-modulated radiotherapy, dynamic intensity-modulated radiotherapy and volume-modulated arc therapy
Click here to view |
For the right lung, VMAT showed the lowest V10 and the highest V30 and V20, and the Dmean and V5 were lower than those of sIMRT and higher than those of dIMRT. For the left lung, the V20 and V5 of VMAT were lower than those of the other two techniques, while Dmean and V30 were higher, and the V10 of VMAT was lower than that of sIMRT. For the heart, VMAT demonstrated the lowest Dmean, V30, and V20 and the highest V40. VMAT produced the lowest Dmax of the spinal cord.
Although the difference in dosimetric OARs among the three techniques was statistically significant, it was not clinically significant due to the small differences between each group. Therefore, VMAT is not inferior to sIMRT and dIMRT in OARs protection.
Analysis of 3D γ pass rates with 3DVH
[Table 3] and [Figure 5] show the 3D γ pass rate analysis results for the entire area and each ROI of sIMRT, dIMRT, and VMAT. Except for the fact that the right lung γ pass rate was not significantly different between sIMRT and dIMRT under the gamma criteria of 3 mm/3% and 1 mm/1% (P > 0.05), the differences in γ pass rates between the other groups were statistically significant (P < 0.05). The γ pass rates of VMAT are >95% under the gamma criteria of 3 mm/3% and 2 mm/2%, meeting the clinical demands. For the gamma 3 mm/3% criteria, the entire area, PTV, lungs, heart, and spinal cord of VMAT showed the highest γ pass rates than the other two techniques, which was even more pronounced when the stricter gamma criteria of 2 mm/2% and 1 mm/1% were applied. | Figure 5: γ pass rates of sIMRT, dIMRT, and VMAT. (a–f) represents the γ pass rates of entire area, PTV, R-lung, L-lung, heart, spinal cord under the gamma 3mm/3% criteria; (g–l) represents the γ pass rates under the gamma 2mm/2% criteria; (m–r) represents the γ pass rates under the gamma 1mm/1% criteria. sIMRT: Step-shoot intensity-modulated radiotherapy, dIMRT: Dynamic intensity-modulated radiotherapy, VMAT: Volume-modulated arc therapy, PTV: Planning target volume.
Click here to view |
 | Table 3: Comparison of γ pass rates of step-shoot intensity-modulated radiotherapy, dynamic intensity-modulated radiotherapy and volume-modulated arc therapy
Click here to view |
| Discussion | | |
In recent years, VMAT has been widely used because of its uniform dose distribution and short treatment delivery time, but it also has a shortcomings, as it is difficult to control the dose delivered to the lungs, especially in low-dose areas.[25],[26] Radiopulmonary lesion (RPL) is the main factor affecting the quality of life after thoracic tumor radiotherapy, and the occurrence of severe RPL is closely related to the volume of the low-dose irradiated area of the lungs, especially the V5 of the lungs.[27] Therefore, VMAT is rarely used in the treatment of thoracic tumors. Radiotherapy is one of the comprehensive treatment measures for invasive thymoma, and it is a necessary treatment for thymoma patients with Stage II or III disease diagnosed by pathology.[28–30] Only small clinical studies have reported the use of VMAT in thymoma radiotherapy.[31] In our study, we analyzed and compared the dosimetric parameters and verification results of sIMRT, sIMRT, and VMAT. We provide a reference for the selection of different IMRT for thymoma in the clinic.
The results of this study showed that VMAT was not inferior to sIMRT and dIMRT in thymoma radiotherapy. For the target volume, the dose distribution of VMAT met the clinical requirements and was comparable to those of the other two techniques. VMAT demonstrated the highest CI and the lowest HI than sIMRT and dIMRT, resulting in better conformity and uniformity of target volume. For the OARs, VMAT showed the lowest V20, V10, and V5 of the L-lung, the lowest V30 and V20 of the heart, and the lowest Dmax of the spinal cord compared to sIMRT and dIMRT. For the right lung, VMAT showed the lowest V10, and V5 was lower than sIMRT and higher than dIMRT. VMAT exhibited better protection of the left lung, heart, and spinal cord and had a protective effect on the right lung, especially the low-dose irradiated area. At the same time, VMAT reduced the treatment delivery time, which can reduce the position movement error caused by the discomfort of the patient due to the long treatment time.
Of course, whether a treatment plan can be accurately implemented for treatment is also critical. Multiple variable parameters make the VMAT treatment plan more complex during execution; therefore, the dosimetric verification of VMAT is important. ArcCHECK-3DVH system is a 3D dosimetric verification system that has been used for dosimetric verification in multiple treatment plans.[12],[13] Our study found that VMAT showed the highest γ pass rates than the other two techniques, which was even more pronounced when stricter gamma criteria of 2 mm/2% and 1 mm/1% were applied. From the dose validation results, VMAT outperforms sIMRT and dIMRT.
| Conclusion | | |
VMAT can be applied to radiotherapy of thymoma, and the accuracy of treatment plan execution can be guaranteed through the ArcCHECK-3DVH system.
Financial support and sponsorship
This work was supported by the National Key Research and Development Project (2018YFC0114402).
Conflicts of interest
There are no conflicts of interest.
| References | | |
| 1. | Liu Q, Gu Z, Yang F, Fu J, Shen Y, Wei Y, et al. The role of postoperative radiotherapy for stage I/II/III thymic tumor-results of the ChART retrospective database. J Thorac Dis 2016;8:687-95.  |
| 2. | Lombe DC, Jeremic B. A review of the place and role of radiotherapy in thymoma. Clin Lung Cancer 2015;16:406-12. |
| 3. | Multidisciplinary Committee of Oncology; Chinese Physicians Association. Chinese guideline for clinical diagnosis and treatment of thymic epithelial tumors (2021 Edition). Zhonghua Zhong Liu Za Zhi 2021;43:395-404. |
| 4. | Omasa M, Date H, Sozu T, Sato T, Nagai K, Yokoi K, et al. Postoperative radiotherapy is effective for thymic carcinoma but not for thymoma in stage II and III thymic epithelial tumors: The Japanese Association for Research on the Thymus Database Study. Cancer 2015;121:1008-16. |
| 5. | Zhai Y, Chen D, Gao Y, Hui Z, Xue L, Zhou Z, et al. Role of modern neoadjuvant chemoradiotherapy in locally advanced thymic epithelial neoplasms. Tumori 2021;107:407-15. |
| 6. | Fan C, Feng Q, Chen Y, Zhai Y, Zhou Z, Chen D, et al. Postoperative radiotherapy for completely resected Masaoka stage III thymoma: A retrospective study of 65 cases from a single institution. Radiat Oncol 2013;8:199. |
| 7. | Wang C, Gao L, Fang W. Radiotherapy for stage IVa thymoma-Shanghai Chest experience. Mediastinum 2019;3:7. |
| 8. | Wang CL, Gao LT, Lyu CX, Wang JM, Liu J, Gu HL, et al. Intensity modulated radiation therapy for pleural recurrence of thymoma: A prospective phase 2 study. Int J Radiat Oncol Biol Phys 2021;109:775-82. |
| 9. | Franceschini D, Cozzi L, Loi M, Franzese C, Reggiori G, Mancosu P, et al. Volumetric modulated arc therapy versus intensity-modulated proton therapy in the postoperative irradiation of thymoma. J Cancer Res Clin Oncol 2020;146:2267-76. |
| 10. | Ma Y, Zhou J, Wang H. Dosimetric comparison between Volumetric Modulated Arc Therapy (VMAT) and Intensity-Modulated Radiotherapy (IMRT) for dental structures of head and neck cancer patients. J Healthc Eng 2022;2022:4998997. |
| 11. | Yadav G, Bhushan M, Dewan A, Saxena U, Kumar L, Chauhan D, et al. Dosimetric influence of photon beam energy and number of arcs on volumetric modulated arc therapy in carcinoma cervix: A planning study. Rep Pract Oncol Radiother 2017;22:1-9. |
| 12. | Infusino E, Mameli A, Conti R, Gaudino D, Stimato G, Bellesi L, et al. Initial experience of ArcCHECK and 3DVH software for RapidArc treatment plan verification. Med Dosim 2014;39:276-81. |
| 13. | Saito M, Kadoya N, Sato K, Ito K, Dobashi S, Takeda K, et al. Comparison of DVH-based plan verification methods for VMAT: ArcCHECK-3DVH system and dynalog-based dose reconstruction. J Appl Clin Med Phys 2017;18:206-14. |
| 14. | Ezzell GA, Burmeister JW, Dogan N, LoSasso TJ, Mechalakos JG, Mihailidis D, et al. IMRT commissioning: Multiple institution planning and dosimetry comparisons, a report from AAPM Task Group 119. Med Phys 2009;36:5359-73. |
| 15. | Low DA, Harms WB, Mutic S, Purdy JA. A technique for the quantitative evaluation of dose distributions. Med Phys 1998;25:656-61. |
| 16. | Nelms BE, Simon JA. A survey on planar IMRT QA analysis. J Appl Clin Med Phys 2007;8:76-90. |
| 17. | Cheng S, Shan D, Cao K, Bin S, Zhang J, Tang T. Dosimetric verification of stereotactic body radiotherapy treatment plan via ArcCHECK-3DVH system. Zhong Nan Da Xue Xue Bao Yi Xue Ban 2021;46:475-80. |
| 18. | Jiménez-Melguizo M, Espinosa M, Montes J, Guirado D, Lallena AM. Response of the ArcCHECK® device at 6 MV and 15 MV for VMAT and IMRT quality control. Phys Med 2020;80:373-82. |
| 19. | Song JH, Shin HJ, Kay CS, Son SH. Dosimetric verification by using the ArcCHECK system and 3DVH software for various target sizes. PLoS One 2015;10:e0119937. |
| 20. | Wang L, Qiu G, Yu J, Zhang Q, Man L, Chen L, et al. Effect of auto flash margin on superficial dose in breast conserving radiotherapy for breast cancer. J Appl Clin Med Phys 2021;22:60-70. |
| 21. | Wang Y, Chen L, Zhu F, Guo W, Zhang D, Sun W. A study of minimum segment width parameter on VMAT plan quality, delivery accuracy, and efficiency for cervical cancer using Monaco TPS. J Appl Clin Med Phys 2018;19:609-15. |
| 22. | Poeta S, Jourani Y, De Caluwé A, Van den Begin R, Van Gestel D, Reynaert N. Split-VMAT technique to control the deep inspiration breath hold time for breast cancer radiotherapy. Radiat Oncol 2021;16:77. |
| 23. | Qiao L, Cheng J, Liang N, Xie J, Luo H, Zhang J. A comparative dosimetric study of volumetric-modulated arc therapy vs. fixed field intensity-modulated radiotherapy in postoperative irradiation of stage IB-IIA high-risk cervical cancer. Oncol Lett 2016;11:959-64. |
| 24. | Song JH, Shin HJ, Kay CS, Chae SM, Son SH. Comparison of dose calculations between pencil-beam and Monte Carlo algorithms of the iPlan RT in arc therapy using a homogenous phantom with 3DVH software. Radiat Oncol 2013;8:284. |
| 25. | Akcay M, Etiz D, Duruer K, Bozdogan O, Ozen A. Dosimetric comparison of single-arc/partial-arc volumetric modulated arc therapy and intensity-modulated radiotherapy for peripheral and central lung cancer. J Cancer Res Ther 2021;17:80-7. |
| 26. | Deng X, Han C, Chen S, Xie C, Yi J, Zhou Y, et al. Dosimetric benefits of intensity-modulated radiotherapy and volumetric-modulated arc therapy in the treatment of postoperative cervical cancer patients. J Appl Clin Med Phys 2017;18:25-31. |
| 27. | Rajan Radha R, Chandrasekharan G. Pulmonary injury associated with radiation therapy – Assessment, complications and therapeutic targets. Biomed Pharmacother 2017;89:1092-104. |
| 28. | Basse C, Botticella A, Molina TJ, Falcoz PE, Oulkhouir Y, Kerjouan M, et al. RADIORYTHMIC: Phase III, opened, randomized study of postoperative radiotherapy versus surveillance in Stage IIb/III of masaoka koga thymoma after complete surgical resection. Clin Lung Cancer 2021;22:469-72. |
| 29. | Muslim Z, Baig MZ, Weber JF, Detterbeck FC, Connery CP, Spera JA, et al. Invasive thymoma – Which patients benefit from post-operative radiotherapy? Asian Cardiovasc Thorac Ann 2021;29:935-42. |
| 30. | Zhou D, Liu QX, Zheng H, Lu X, Dai JG. Postoperative radiotherapy for completely resected thymoma: Differing roles in masaoka stage II and stage III disease. Asian J Surg 2022;22:S1015-9584. |
| 31. | Dolera M, Malfassi L, Mazza G, Urso G, Sala M, Marcarini S, et al. Feasibility for using hypofractionated stereotactic volumetric modulated arc radiotherapy (VMAT) with adaptive planning for treatment of thymoma in rabbits: 15 cases. Vet Radiol Ultrasound 2016;57:313-20. |
[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
[Table 1], [Table 2], [Table 3]
|
Search Pubmed for