PMC9875284_01
A patient with metastatic Ewing sarcoma with two left lower lobe lesions where two SABR plans resulted in dose overlap within the stomach. Isodose lines: Yellow = 40 Gy, Blue = 33 Gy, Green = 20 Gy, Purple = 10 Gy all over 5 fractions (A). A significant change in stomach anatomy was observed during daily cine imaging between simulation (B) and each treatment fraction (C). Online adaptive replanning was performed to enable the plan of the day to meet dose constraints for the stomach; in this example, the predicted dose on the anatomy of the day would have exposed 5.96 cc of the stomach to >= 32 Gy, while the re-optimized plan improved GTV/PTV coverage and met dose constraints.
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Two metastases were peripherally located, including one in the anterior left lower lobe (LLL) as illustrated in  Figure 1 . This constraint included the dose contribution from SABR to the anterior LLL delivered using VMAT.  Figure 1  illustrates the large magnitude interfraction change observed in the stomach between simulation and the 5th treatment fraction and the resulting dose constraint violation to the stomach based on the anatomy of the day.
PMC9875284_02
A patient with metastatic rhabdomyosarcoma with a solitary liver metastasis who received SABR using MRgRT. Continuous cine imaging and gated delivery during mid-inspiration breath hold enabled treatment with PTV expansion of 3 mm. No ITV was used.
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The patient was treated with SABR to 40 Gy in 5 fractions using MRgRT for margin reduction and improved soft tissue visualization.  Figure 2  illustrates that the 0.35
PMC9875284_03
In a patient with metastatic neuroblastoma involving the mandible, the MR simulation (A) provided superior visualization of the tumor relative to the adjacent masseter and pterygoid muscles compared to CT (B). The patient was treated with a 3D conformal MRgRT plan (C), which provided favorable sparing of the oral cavity and the ipsilateral and contralateral salivary glands with similar plan quality to IMRT.
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The patient underwent MR and CT simulation with a thermoplastic mask and moldcare pillow.  Figure 3  demonstrates that the MR Linac significantly improved soft tissue visualization and permitted differentiation between the tumor and the adjacent masseter and pterygoid muscles.
PMC9875284_04
A patient with Stage IV ALK-rearranged non-small cell lung cancer and a 10 cm primary tumor received 30 Gy in 10 fractions with MRgRT. Continuous cine imaging and gated delivery during mid-inspiration breath hold enabled treatment with PTV expansion of 3mm. No ITV was used.
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Due to pain, she was referred for radiotherapy and received 30 Gy in 10 fractions with MRgRT using step-and-shoot IMRT.  Figure 4  depicts the MRgRT plan, which delivered a mean dose of 7.77 Gy to the heart, 7.92 Gy to the lungs, and 16.78 Gy to the esophagus.