## 2 Materials and Methods  
### Patient Imaging and Manual Contouring  
In this ethics-approved study, 30 cancer patients (10 liver, 10 prostate, and 10 lung) were recruited and scanned between 17 April 2013 and 15 June 2022 using a 3 tesla (T) magnetic resonance imaging (MRI) scanner (Philips Achieva, Eindhoven, the Netherlands) with a 2D balanced steady-state free precession (bSSFP) sequence (field of view = 30 \(\times\) 40 to 40 \(\times\) 40 cm\({}^{2}\), acquisition matrix size = 128 \(\times\) 128, reconstructed matrix size = 256 \(\times\) 256, voxel size = 2.3 \(\times\) 3.1 \(\times\) 10 \(-\) 3.1 \(\times\) 3.1 \(\times\) 15 mm\({}^{3}\), echo time = 1.1 ms, repetition time = 2.2 ms, and imaging time per frame = 275 ms) to acquire \(\sim\) 500 dynamic images per patient (with an approximately 2 min imaging time). Only patients who were undergoing radiotherapy treatment, had no contraindication to MRI nor hip prostheses, and provided signed informed consent were included. Patients with liver, prostate, or lung cancer were included as they have the potential for significant intrafractional tumor motion and represent a large portion of the radiotherapy patient population (\(\sim\)43% of all patients at our institution). Patient characteristics can be found in Table 1. Patients were imaged for research purposes without the use of gadolinium contrast agents. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multicolumn{1}{c}{**Site**} & \multicolumn{1}{c}{**Patient**} & \multicolumn{1}{c}{**Gender**} & \multicolumn{1}{c}{**Age**} & \multicolumn{1}{c}{**Tumor Area**} & \multicolumn{1}{c}{**Overall**} & \multicolumn{1}{c}{**TNM Stage**} & \multicolumn{1}{c}{**Primary Cancer**} \\ \hline \multirow{10}{*}{Liver} & 1 & F & 65 & 36.2 & III & TXNXMI & Rectal adenocarcinoma \\  & 2 & M & 56 & 0.9 & II & N/A & HCC \\  & 3 & M & 70 & 24.2 & IV & pT4 pN2 MX & Sigmoid colon adenocarcinoma \\  & 4 & M & 57 & 2.8 & I & N/A & HCC \\  & 5 & M & 64 & 2.0 & II & N/A & HCC \\  & 6 & M & 63 & 3.7 & IVB & T2N1M1 & Nasopharyngeal carcinoma \\  & 7 & M & 65 & 3.1 & IVA & T3N2M1 & Colorectal carcinoma \\  & 8 & M & 59 & 2.4 & IV & T3N0M1 & Rectal adenocarcinoma \\  & 9 & M & 68 & 1.5 & IIB & TXNXMI & Rectal adenocarcinoma \\  & 10 & F & 82 & 6.0 & IV & T3N2M1 & Colorectal cancer \\ \hline \multirow{10}{*}{Prostate} & 11 & M & 69 & 25.0 & IIA & T1c & Prostatic adenocarcinoma \\  & 12 & M & 69 & 24.4 & IIA & T1c & Prostatic adenocarcinoma \\  & 13 & M & 69 & 8.4 & IIIC & T3 aN0M0 & Prostatic adenocarcinoma \\  & 14 & M & 69 & 8.4 & IIIC & T3 aN0M0 & Prostatic adenocarcinoma \\  & 15 & M & 73 & 14.8 & IIB & N/A & Prostatic adenocarcinoma \\  & 16 & M & 73 & 12.8 & IIB & N/A & Prostatic adenocarcinoma \\  & 17 & M & 69 & 33.1 & IIA & T1c & Prostatic adenocarcinoma \\  & 18 & M & 75 & 26.4 & IIB & T1c & Prostatic adenocarcinoma \\  & 19 & M & 68 & 15.0 & IIB & T1c & Prostatic adenocarcinoma \\  & 20 & M & 77 & 18.9 & IIIA & T1c & Prostatic adenocarcinoma \\ \hline \multirow{10}{*}{Lung} & 21 & M & 81 & 1.3 & I & T1N0M0 & NSCLC \\  & 22 & M & 79 & 3.8 & I & pT2 pN1 pMX & NSCLC \\  & 23 & F & 73 & 6.4 & II & T2N0M0 & NSCLC \\  & 24 & M & 72 & 4.8 & IVA & T1 nN0M1a & NSCLC \\ \cline{1-1}  & 25 & F & 78 & 7.4 & I & T1N0M0 & Lung cancer unspecified \\ \cline{1-1}  & 26 & M & 65 & 1.4 & IA & T1N0M0 & NSCLC \\ \cline{1-1}  & 27 & M & 65 & 5.1 & I & cT1 cN0M0 & NSCLC \\ \cline{1-1}  & 28 & M & 70 & 1.7 & IB & N0M0 & SCLC \\ \cline{1-1}  & 29 & M & 75 & 3.0 & IIA & T2 bN0M0 & NSCLC \\ \cline{1-1}  & 30 & M & 65 & 3.8 & IA & T1 bN0M0 & NSCLC \\ \hline \multicolumn{1}{c}{Mean (SD)} & \multicolumn{1}{c}{} & \multicolumn{1}{c}{} & \multicolumn{1}{c}{} & \multicolumn{1}{c}{} & \multicolumn{1}{c}{} & \multicolumn{1}{c}{} \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Characteristics of the liver, prostate (sagittal: Patient (P) 11–16, axial: P17–18, coronal: P19–20), and lung cancer patients included in the study. If primary cancer site is different from site, it means it metastas to site, which was imaged.