Dosimetric comparison between biaxially rotational dynamic radiation therapy and volumetric modulated arc therapy for locally advanced non-small cell lung cancer

Introduction

Background

Lung cancer is one of the most commonly diagnosed malignancies each year (1). Approximately 30% of patients with non-small cell lung cancer (NSCLC) are diagnosed with locally advanced NSCLC (LA-NSCLC) (2). The majority of LA-NSCLC cases are considered non-surgical, given the disease extent, making these patients candidates for radiotherapy, with or without chemotherapy.

Rationale and knowledge gap

Although chemoradiotherapy (CRT) is an effective treatment for LA-NSCLC, some patients experience severe adverse events, including cardiopulmonary toxicity (3,4). To minimize these adverse events, CRT treatment planning must optimize several key dose-volume parameters, such as Lung-V20, Heart-V40, and left anterior descending coronary artery (LAD)-V15. Therefore, in recent years, intensity-modulated radiotherapy (IMRT) with involved-field irradiation has been increasingly employed in CRT for managing LA-NSCLC (5,6). However, the risk of adverse events remains even with radiotherapy using IMRT with involved-field irradiation. Therefore, treatment plans are required to mitigate the risk of these adverse events.

A new O-ring-type linear accelerator system was developed recently (OXRAY, Hitachi Ltd., Tokyo, Japan). The O-ring rotates the synchronized gantry and enables non-coplanar volumetric modulated arc therapy (VMAT), which is an advanced IMRT technique that eliminates the need of moving the patient’s couch. In LA-NSCLC planning, this novel OXRAY system also has the potential to improve various dose-volume parameters without worsening the irradiation dose to the target volume. However, the use of this system coupled with biaxially rotational dynamic radiation therapy (BROAD-RT) in the treatment of LA-NSCLC remains to be investigated.

Objective

Therefore, this study aimed to evaluate the impact of BROAD-RT effect using the OXRAY system in optimising dose distribution for LA-NSCLC. We present this article in accordance with the STROBE reporting checklist (available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-952/rc).

Methods

Patients

Data from the treatment planning system of 10 patients with LA-NSCLC who received VMAT at the National Cancer Center Hospital East were analysed (Table 1). Between July 2023 and July 2024, 10 consecutive patients were selected from LA-NSCLC cases whose hearts were included in the irradiated field. The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The study was approved by the Institutional Review Board of the National Cancer Center Hospital East (No. 2018-076 and date of approval: 11 July 2018). Informed consent was not required for the retrospective nature of this study.

All the patients were immobilized with their hands up using a suction brace covering their heads, shoulders, arms, and waist. Computed tomography (CT) simulated datasets were acquired with Aquilion One (Canon Medical Systems, Tochigi, Japan) with an image slice thickness of 2 mm. Simulated CT scans for lower-lobe lung cancer were performed with patients fasting for at least 4 h. All patients underwent four-dimensional CT (4D-CT) imaging to measure the respiratory motion of the target structures.

Delineation of target and organ at risk

All structures were delineated by radiation oncologists and reviewed by additional oncologists. The gross tumour volume (GTV) was defined as the primary tumour and metastatic lymph nodes. The primary tumour was identified using contrast-enhanced CT and [¹⁸F] fluoro-D-glucose positron emission tomography/CT. The clinical target volume (CTV) for the primary tumour was defined as the tumour volume plus 0.5 cm margins in all directions, while the CTV for metastatic lymph nodes was defined as any metastatic lymph node volume. In addition, internal target volume (ITV) was defined as the target volume of the CTV plus the internal margin. The planning target volume (PTV) was defined as the overall ITV plus 0.5 cm margins in all directions.

Organs at risk were defined as the entire heart, LAD region (LADR), lungs, oesophagus, and spinal cord. The structure of the entire heart was delineated using a cardiac atlas for radiotherapy with appropriate window settings (window width =500 Hounsfield units; window level =50 Hounsfield units) (7). Similarly, the structure of the LADR was delineated using the LADR atlas for radiotherapy (8). In addition, the structure of the oesophagus was delineated using the same window settings as those used for the whole-heart delineation. The structure of the lungs which is excluded GTV was delineated using pulmonary windows (window width =1,500 Hounsfield units, window level =−600 Hounsfield units), and the structure of the spinal cord was delineated based on the bony limits of the spinal canal.

Virtual planning and evaluation

Two virtual radiotherapy plans were generated for a prescribed dose of 60 Gy in 30 fractions (D95 = 100%; 95% of the PTV received 100% of the prescribed dose) to PTV. However, if achieving Lungs-V20 <35% was not feasible, a similar dose was prescribed (D95 = 95%; 95% of the PTV receiving 95% of the prescribed dose) to PTV was acceptable. The two virtual radiotherapy plans were as follows: (I) BROAD-RT with OXRAY (two arcs with continuous modulating ring angles at nine modulation points, using a 6 MV photon beam); and (II) conventional coplanar VAMT with TrueBeam (Varian Medical Systems, Palo Alto, CA, USA) (VMAT, two arcs and collimator angles of 345° and 15° with a 6 MV photon beam). All the plans were created by well-trained radiation oncologists and medical physicists.

The prescribed doses were calculated using the Collapsed Cone version 5.8 algorithm of our treatment planning system. The treatment plans were developed using the RayStation Planning System (Raysearch, Stockholm, Sweden). The dose-volume parameters evaluated included: PTV-D50 (%), PTV-D2 (%), PTV-Conformity Index (CI), PTV-Homogeneity Index (HI), Lungs-V40 (%), Lungs-V30 (%), Lungs-V20 (%), Lungs-V5 (%), Lungs-V1 (%), Lungs-Mean (Gy), Heart-V50 (%), Heart-V40 (%), Heart-V30 (%), Heart-V20 (%), Heart-Mean (Gy), LADR-V30 (%), LADR-V15 (%), LADR-V10 (%), Oesophagus-V60 (%), Oesophagus-V50 (%), Oesophagus-V40 (%), Oesophagus-V30 (%), Oesophagus-D_{0.03 mL} (Gy), Oesophagus-Mean (Gy), and SpinalCord-D_{0.03 mL} (Gy). The dose thresholds for optimisation are shown in Table S1. Information on the devices used for treatment planning is summarised in Table S2.

Statistical analysis

Descriptive statistics, such as mean and standard deviation (SD), are used to summarise dose distributions. A paired t-test was used to compare the two radiotherapy plans (BROAD-RT and VMAT). Statistical significance was set at P<0.05. All statistical analyses were performed using SAS (version 9.4; Cary, NC, USA).

Results

PTV dose-volume parameter comparison between BROAD-RT and VMAT

In a case involving two virtual plans, 95% of the PTV delivered 57 Gy because Lungs-V20 <35% could not be met with the 60 Gy prescription. The mean (SD) of PTV-D2 (%), PTV-D50 (%), PTV-HI, and PTV-CI were 110.46 (15.58), 103.06 (0.71), 12.98 (15.10), and 0.90 (0.03) for BROAD-RT and 105.67 (1.86), 103.02 (1.09), 7.87 (4.84), and 0.84 (0.06) for VMAT, respectively. BROAD-RT impacted PTV-CI improvement compared with VMAT (P=0.001; Table 2). However, BROAD-RT did not affect PTV-D2 (%), PTV-D50 (%), and PTV-HI improvement compared to that with VMAT (P=0.35, 0.89, and 0.32, respectively; Table 2). Examples of the BROAD-RT and VMAT dose distributions are presented in Figure 1.

Figure 1 Differences in dose distribution between BROAD-RT and VMAT. (A) CT images displaying dose distribution of radiotherapy for LA-NSCLC (60 Gy in 30 fractions). The red line represents the PTV. Because the size of the PTV was very large to achieve a Lungs-V20 <35% with PTV-D95 =100%, this case was planned with a prescription dose of PTV-D95 =95%. (B) Dose-volume parameters of the PTV, lungs, heart, and LADR. The BROAD-RT plan improved important parameters such as Lungs-V20, Heart-V40, and LADR-V15. However, the low dose area for all organs was lower in the VMAT plan than in the BROAD-RT plan. BROAD-RT, biaxially rotational dynamic radiation therapy; CT, computed tomography; D95, dose receiving 95% of the volume; LA-NSCLC, locally advanced non-small cell lung cancer; LADR, left anterior descending coronary artery region; PTV, planning target volume; V15, volume receiving 15 Gy; V20, volume receiving 20 Gy; V40, volume receiving 40 Gy; VMAT, volumetric modulated arc therapy.

Lung dose-volume parameter comparison between BROAD-RT and VMAT

The mean (SD) of Lungs-V40 (%), Lungs-V30 (%), Lungs-V20 (%), and Lungs-Mean (Gy) was 10.25 (4.99), 14.82 (4.94), 21.64 (5.15), and 13.53 (2.95) for BROAD-RT and 12.41 (5.38), 18.55 (5.11), 26.76 (5.80), and 15.30 (3.32) for VMAT, respectively. BROAD-RT influenced Lungs-V40, Lungs-V30, Lungs-V20, and Lungs-Mean improvement against VMAT (P=0.002, <0.001, 0.001, and 0.001; Table 2). The mean (SD) of Lungs-V5 (%) was 54.67 (9.95) for BROAD-RT and 59.97 (12.40) for VMAT. BROAD-RT did not influence Lungs-V5 improvement compared to that with VMAT (P=0.10; Table 2). Additionally, the mean (SD) of Lungs-V1 (%) was 97.38 (3.98) for BROAD-RT and 90.84 (10.00) for VMAT. BROAD-RT significantly worsened Lungs-V1 outcomes compared to that with VMAT (P=0.01; Table 2).

Heart and LADR dose-volume parameter comparison between BROAD-RT and VMAT

The mean (SD) of Heart-V50 (%), Heart-V40 (%), Heart-V30 (%), and Heart-V20 (%) was 4.44 (2.23), 6.42 (3.00), 9.68 (4.66), and 17.39 (9.31) for BROAD-RT and 5.51 (2.68), 8.56 (4.30), 13.18 (7.15), and 21.88 (13.31) for VMAT, respectively. BROAD-RT influenced the Heart-V50, Heart-V40, Heart-V30, and Heart-V20 improvements compared to that with VMAT (P=0.002, 0.009, 0.01, and 0.03, respectively; Table 2). However, the mean (SD) of Heart-Mean (Gy) was 12.78 (4.65) for BROAD-RT and 13.63 (5.90) for VMAT. BROAD-RT did not influence the mean dose improvement compared to that with VMAT (P=0.21; Table 2).

The mean (SD) of LADR-V10 (%) and LADR-V15 (%) was 36.07 (16.32) and 7.05 (6.02) for BROAD-RT and 21.88 (13.31) and 18.66 (11.46) for VMAT, respectively. BROAD-RT influenced LADR-V10 and LADR-V15 improvement compared to that with VMAT (P=0.02 and 0.006; Table 2). However, the mean (SD) of LADR-V30 (%) was 1.31 (2.60) for BROAD-RT and 3.38 (4.77) for VMAT. BROAD-RT did not influence LADR-V30 improvement compared to that with VMAT (P=0.050, Table 2).

Oesophagus dose-volume parameter comparison between BROAD-RT and VMAT

The mean (SD) of Oesophagus-V60 (%), Oesophagus-V50 (%), Oesophagus-V40 (%), and Oesophagus-V30 (%) was 10.72 (7.37), 20.37 (12.06), 27.01 (15.33), and 33.69 (16.68) for BROAD-RT and 14.64 (9.36), 25.16 (14.78), 30.17 (15.40), and 36.91 (15.24) for VMAT, respectively. BROAD-RT influenced the Oesophagus-V60, Oesophagus-V50, Oesophagus-V40, and Oesophagus-V30 improvements compared to that with VMAT (P=0.005, 0.006, <0.001, and 0.03, respectively; Table 2). However, the mean (SD) of Oesophagus-Mean (Gy) and Oesophagus-D_{0.03 mL} (Gy) were 23.83 (7.65) and 61.34 (5.61) for BROAD-RT and 24.41 (8.43) and 62.30 (4.32) for VMAT. BROAD-RT did not influence the mean dose and D_{0.03 mL} improvement compared to that with VMAT (P=0.22 and 0.11, respectively; Table 2).

Discussion

This study evaluated the usefulness of BROAD-RT with OXRAY for dose distribution in patients with LA-NSCLC. BROAD-RT for LA-NSCLC planning enhanced many key dose-volume parameters, including Lungs-V20, Lungs-V5, Heart-V40, and LADR-V15, without affecting the PTV dose distribution when compared to that with VMAT. However, the volume irradiated with very low doses, such as in Lungs-V1, increased.

Lungs-V20 is recognised as the most important dose-volume parameter for predicting the risk of severe pneumonitis (3,9). Therefore, radiotherapy treatment planning for LA-NSCLC requires strict adherence to Lungs-V20 dose constraints. In this study, although VMAT was optimised to comply with the Lungs-V20 dose constraint, BROAD-RT achieved a more pronounced reduction in Lungs-V20 compared to that with VMAT. The clinical relevance of Lungs-V5 as an indicator of severe pneumonitis risk remains controversial; however, some studies have suggested that Lungs-V5 is an important dose-volume parameter for predicting severe pneumonitis risk (10-12). In this study, although the use of BROAD-RT did not significantly improve Lungs-V5 compared to that with VMAT, the Lungs-V5 of BROAD-RT was slightly better than that of VMAT. These results suggested that BROAD-RT may reduce the risk of severe radiation pneumonitis compared to that with VMAT in radiotherapy treatment for LA-NSCLC.

However, in this study, Lungs-V1, which indicates an extended low-dose irradiation area, was worse in BROAD-RT than in VMAT. This indicates that BROAD-RT disperses very low-dose radiation over a broader area, which is not typically accounted for in standard dose constraints for LA-NSCLC treatment planning due to its incorporation of various beam paths, including non-coplanar beams. Although this very low-dose (Lungs-V1) scattering within normal lungs seemed not to increase radiation pneumonitis, irradiation to normal organs can increase the risk of developing secondary cancers (13,14). This secondary cancer risk is influenced even by very low-dose irradiation. Therefore, careful use of BROAD-RT, especially for younger patients with LA-NSCLC, is warranted.

A low Heart-V40 is associated with better survival (9). Therefore, radiotherapy treatment planning for LA-NSCLC requires adherence to the Heart-V40 dose constraints. Additionally, recent studies have suggested that low LAD-V15 is associated with improved survival in patients with LA-NSCLC (4,15). In this study, these two key dose-volume parameters improved significantly in BROAD-RT plan compared to VMAT plan. Furthermore, in this study, improvements in these important dose-volume parameters were achieved without worsening PTV coverage. Therefore, BROAD-RT is a potentially preferable treatment planning technique for LA-NSCLC compared with VMAT.

In addition, the incidence of severe acute oesophagitis is approximately 10–20% in patients with LA-NSCLC treated with CRT (16,17). Severe acute oesophagitis usually results in poor nutrition status, interruption of RT, and low tolerance of CRT (18-20). Oesophagus-V60 and V50 have significant associations with severe esophagitis in patients treated with CRT (21,22). In this study, BROAD-RT led to a more pronounced reduction in both Oesophagus-V60 and V50 compared to that with VMAT. Therefore, BROAD-RT may reduce the risk of severe acute in patients with LA-NSCLC treated with CRT.

In our study, BROAD-RT did not worsen the important PTV index (PTV-D95, PTV-D50, and PTV-D2) compared to that with VMAT. Furthermore, in PTV-CI, BROAD-RT improved significantly in comparison to VMAT. However, in PTV-HI which is an objective tool to analyse the uniformity of dose distribution in PTV (23), BROAD-RT was slightly worse than VMAT. This suggested that BROAD-RT may cause more hotspots or dose heterogeneity within the PTV compared to that with VMAT. However, recently, spatially fractionated radiotherapy, delivered at a highly heterogeneous dose to target volume, have been reported in some cancer radiotherapy treatments (24-26). This indicates that not all heterogeneous doses within the PTV have a negative impact on treatment outcome. Thus, a slightly poorer HI did not support BROAD-RT being inferior to VMAT.

This study had some limitations. First, generalizability of the findings is restricted by the small sample size. Second, the treatment plan quality may have been influenced by the planner’s optimization skills. Specifically, in BROAD-RT, which allows for a nearly omnidirectional beam selection that does not collide with the patient or couch; therefore, the optimal beam arrangement may not have been fully explored. Nonetheless, this underscores the possibility of further optimising dose distribution by refining planning strategies. Finally, the use of BROAD-RT with the OXRAY system was constrained to cases with field sizes <20 cm, limiting its applicability to all patients with LA-NSCLC in clinical settings. Despite these limitations, BROAD-RT using the OXRAY system demonstrates clinical utility by achieving better dose constraints for critical OARs, while maintaining a PTV coverage comparable to that of VMAT.

Conclusions

BROAD-RT with the OXRAY system for LA-NSCLC treatment planning improved key OAR dose constraints, such as Lungs-V20, Lungs-V5, Heart-V40, and LADR-V15, without worsening the PTV coverage when compared with that of VMAT. BROAD-RT may be effective for treatment planning of LA-NSCLC with large and extensive PTV, which is difficult for VMAT to achieve the OAR dose constraints without worsening PTV coverage.

Acknowledgments

None.

Footnote

Reporting Checklist: The authors have completed the STROBE reporting checklist. Available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-952/rc

Data Sharing Statement: Available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-952/dss

Peer Review File: Available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-952/prf

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-952/coif). K.H. reports honoraria for lectures and support for attending meeting from Hitachi High-Tech Corporation. M.N. reports research grant from Illumina, Inc., and honoraria from AstraZeneca and Sumitomo Heavy Industries, Ltd. T.N. reports honoraria for lectures from Bristol Myers Squibb, Ono Pharmaceutical Co., Boehringer Ingelhaim, Chugai Pharmaceutical Co., AstraZeneca, Eli Lilly, Eisai, and Taiho Pharmaceutical Co. The other authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The study was approved by the Institutional Review Board of the National Cancer Center Hospital East (No. 2018-076 and date of approval: 11 July 2018). Informed consent was not required for the retrospective nature of this study.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

References

1. Bray F, Laversanne M, Sung H, et al. Global cancer statistics 2022: GLOBOCAN estimates of incidence and mortality worldwide for 36 cancers in 185 countries. CA Cancer J Clin 2024;74:229-63. [Crossref] [PubMed]
2. Chen VW, Ruiz BA, Hsieh MC, et al. Analysis of stage and clinical/prognostic factors for lung cancer from SEER registries: AJCC staging and collaborative stage data collection system. Cancer 2014;120:3781-92. [Crossref] [PubMed]
3. Chun SG, Hu C, Choy H, et al. Impact of Intensity-Modulated Radiation Therapy Technique for Locally Advanced Non-Small-Cell Lung Cancer: A Secondary Analysis of the NRG Oncology RTOG 0617 Randomized Clinical Trial. J Clin Oncol 2017;35:56-62. [Crossref] [PubMed]
4. Atkins KM, Chaunzwa TL, Lamba N, et al. Association of Left Anterior Descending Coronary Artery Radiation Dose With Major Adverse Cardiac Events and Mortality in Patients With Non-Small Cell Lung Cancer. JAMA Oncol 2021;7:206-19. [Crossref] [PubMed]
5. Fernandes AT, Shen J, Finlay J, et al. Elective nodal irradiation (ENI) vs. involved field radiotherapy (IFRT) for locally advanced non-small cell lung cancer (NSCLC): A comparative analysis of toxicities and clinical outcomes. Radiother Oncol 2010;95:178-84. [Crossref] [PubMed]
6. Li R, Yu L, Lin S, et al. Involved field radiotherapy (IFRT) versus elective nodal irradiation (ENI) for locally advanced non-small cell lung cancer: a meta-analysis of incidence of elective nodal failure (ENF). Radiat Oncol 2016;11:124. [Crossref] [PubMed]
7. Duane F, Aznar MC, Bartlett F, et al. A cardiac contouring atlas for radiotherapy. Radiother Oncol 2017;122:416-22. [Crossref] [PubMed]
8. Lee J, Hua KL, Hsu SM, et al. Development of delineation for the left anterior descending coronary artery region in left breast cancer radiotherapy: An optimized organ at risk. Radiother Oncol 2017;122:423-30. [Crossref] [PubMed]
9. Chun SG, Hu C, Komaki RU, et al. Long-Term Prospective Outcomes of Intensity Modulated Radiotherapy for Locally Advanced Lung Cancer: A Secondary Analysis of a Randomized Clinical Trial. JAMA Oncol 2024;10:1111-5. [Crossref] [PubMed]
10. Tatsuno S, Doi H, Okada W, et al. Risk factors for radiation pneumonitis after rotating gantry intensity-modulated radiation therapy for lung cancer. Sci Rep 2022;12:590. [Crossref] [PubMed]
11. Tsujino K, Hashimoto T, Shimada T, et al. Combined analysis of V20, VS5, pulmonary fibrosis score on baseline computed tomography, and patient age improves prediction of severe radiation pneumonitis after concurrent chemoradiotherapy for locally advanced non-small-cell lung cancer. J Thorac Oncol 2014;9:983-90. [Crossref] [PubMed]
12. Yom SS, Liao Z, Liu HH, et al. Initial evaluation of treatment-related pneumonitis in advanced-stage non-small-cell lung cancer patients treated with concurrent chemotherapy and intensity-modulated radiotherapy. Int J Radiat Oncol Biol Phys 2007;68:94-102. [Crossref] [PubMed]
13. Inskip PD. Second cancers following radiotherapy. In: Neugut AI, Meadows AT, Robinson E. editors. Multiple Primary Cancers. Philadelphia: Lippincott Williams & Wilkins; 1999:91-135.
14. Tucker MA, D'Angio GJ, Boice JD Jr, et al. Bone sarcomas linked to radiotherapy and chemotherapy in children. N Engl J Med 1987;317:588-93. [Crossref] [PubMed]
15. McKenzie E, Zhang S, Zakariaee R, et al. Left Anterior Descending Coronary Artery Radiation Dose Association With All-Cause Mortality in NRG Oncology Trial RTOG 0617. Int J Radiat Oncol Biol Phys 2023;115:1138-43. [Crossref] [PubMed]
16. Uyterlinde W, Chen C, Kwint M, et al. Prognostic parameters for acute esophagus toxicity in intensity modulated radiotherapy and concurrent chemotherapy for locally advanced non-small cell lung cancer. Radiother Oncol 2013;107:392-7. [Crossref] [PubMed]
17. Wijsman R, Dankers F, Troost EG, et al. Multivariable normal-tissue complication modeling of acute esophageal toxicity in advanced stage non-small cell lung cancer patients treated with intensity-modulated (chemo-)radiotherapy. Radiother Oncol 2015;117:49-54. [Crossref] [PubMed]
18. Cox JD, Pajak TF, Asbell S, et al. Interruptions of high-dose radiation therapy decrease long-term survival of favorable patients with unresectable non-small cell carcinoma of the lung: analysis of 1244 cases from 3 Radiation Therapy Oncology Group (RTOG) trials. Int J Radiat Oncol Biol Phys 1993;27:493-8. [Crossref] [PubMed]
19. Hill A, Kiss N, Hodgson B, et al. Associations between nutritional status, weight loss, radiotherapy treatment toxicity and treatment outcomes in gastrointestinal cancer patients. Clin Nutr 2011;30:92-8. [Crossref] [PubMed]
20. Rowell NP, O'rourke NP. Concurrent chemoradiotherapy in non-small cell lung cancer. Cochrane Database Syst Rev 2004;CD002140. [Crossref] [PubMed]
21. Palma DA, Senan S, Oberije C, et al. Predicting esophagitis after chemoradiation therapy for non-small cell lung cancer: an individual patient data meta-analysis. Int J Radiat Oncol Biol Phys 2013;87:690-6. [Crossref] [PubMed]
22. Rodríguez N, Algara M, Foro P, et al. Predictors of acute esophagitis in lung cancer patients treated with concurrent three-dimensional conformal radiotherapy and chemotherapy. Int J Radiat Oncol Biol Phys 2009;73:810-7. [Crossref] [PubMed]
23. Kataria T, Sharma K, Subramani V, et al. Homogeneity Index: An objective tool for assessment of conformal radiation treatments. J Med Phys 2012;37:207-13. [Crossref] [PubMed]
24. Li H, Mayr NA, Griffin RJ, et al. Overview and Recommendations for Prospective Multi-institutional Spatially Fractionated Radiation Therapy Clinical Trials. Int J Radiat Oncol Biol Phys 2024;119:737-49. [Crossref] [PubMed]
25. Xu P, Wang S, Zhou J, et al. Spatially fractionated radiotherapy (Lattice SFRT) in the palliative treatment of locally advanced bulky unresectable head and neck cancer. Clin Transl Radiat Oncol 2024;48:100830. [Crossref] [PubMed]
26. Lu Q, Yan W, Zhu A, et al. Combining spatially fractionated radiation therapy (SFRT) and immunotherapy opens new rays of hope for enhancing therapeutic ratio. Clin Transl Radiat Oncol 2024;44:100691. [Crossref] [PubMed]