case_images: PMC6757498_01
case_images: Contrast-enhanced CT of the abdomen and pelvis demonstrated a 73 mm x 70 mm x 41 mm hypoattenuating retroperitoneal mass in the right paracaval region medial to the right kidney encasing the inferior vena cava.
case_images: 10.1177_2036361319878518-fig1.jpg
case_images: PMC6757498_01_10.1177_2036361319878518-fig1.jpg
case_images: fig1-2036361319878518
case_images: On further workup, contrast-enhanced computed tomography (CT) of the abdomen and pelvis demonstrated a 73 mm x 70 mm x 41 mm hypoattenuating retroperitoneal mass in the right paracaval region medial to the right kidney with 180  abutment of the inferior vena cava (Figure 1).
case_images: Gadolinium-enhanced MRI demonstrated a multiloculated T2 hyperintense extravertebral chordoma at the level of L2 in the right retroperitoneum that extends medially along the medial aspect of the right psoas muscle.
case_images: 10.1177_2036361319878518-fig2.jpg
case_images: PMC6757498_01_10.1177_2036361319878518-fig2.jpg
case_images: fig2-2036361319878518
case_images: Gadolinium-enhanced magnetic resonance imaging (MRI) demonstrated a multiloculated T2-hyperintense extravertebral chordoma at the level of L2 in the right retroperitoneum that extended medially along the medial aspect of the right psoas muscle (Figure 2).
case_images: Axial view of the proton (above) and IMRT (below) dose distribution in color wash. CTV (red). Organs-at-risk: duodenum (cyan), large bowel (brown), ipsilateral kidney (magenta), spinal cord (yellow), contralateral kidney (dark blue), and small bowel (light green).
case_images: 10.1177_2036361319878518-fig3.jpg
case_images: PMC6757498_01_10.1177_2036361319878518-fig3.jpg
case_images: fig3-2036361319878518
case_images: Given that the CTV was in close proximity to healthy tissue including the duodenum, small bowel, right kidney, spinal cord, and liver, we created comparison plans of spot-scanning PBT versus intensity-modulated radiation therapy (IMRT) (Figure 3). Both kidneys received essentially no radiation with PBT (Table 1 and Figure 3).