A 43 years old male, presented with symptoms like irritability, mood swings and headache in May 2019. Symptoms were of insidious onset and gradually progressive in nature. He was seen by general physician and was later referred for neurosurgical consultation. MRI brain was suggestive of mass in the sellar region.
He underwent left pterional craniotomy and subtotal resection of tumor. He was kept on close follow up. He was free of symptoms for 1 year when he suddenly developed headache, confusion, nausea and loss of memory, for which he presented to our hospital. We did further evaluation with MRI Brain and it was suggestive of post operative changes in sella and suprasellar region, with 20 mm × 14 mm lesion in suprasellar cistern. The lesion was extending to floor of third ventricle, suggestive of recurrent lesion. He was planned for re-excision and neurosurgery consultation was sought. After thorough evaluation, Neurosurgeon termed it as inoperable and was referred back to us for External Beam Radiotherapy. So we discussed different RT techniques like conventional fractionation schedule, stereotactic Radiotherapy and Stereotactic surgery with patient’s attendants. They opted for stereotactic radiosurgery (SRS) treatment. After taking informed written consent, he was treated with SRS on 23 August 2020 with a dose of 14Gy to Gross tumor Volume. After 6 months post SRS, he is completely free of symptoms and MRI in February 2021 is suggestive of significant reduction in size of the lesion.
After obtaining informed written consent, patient was taken for CT simulation. It was done with Siemens Somatom Definition AS+ 4D CT simulator. Patient was made to lie down on CT Couch in head first supine position with slight chin up. For strict immobilization, frameless stereotactic Double Shell Positioning System (DSPS) was used. CT scans with slice thickness of 1 mm were acquired. Images were imported to Eclipse Treatment Planning System (TPS) of Varian True Beam System version 15.6. Recent MRI images were registered and matching was done with planning CT images (T1 Contrast with Contrast CT). Radiation oncologist and neuro-radiologist delineated the gross tumor volume (GTV) on CT images and was reverified with registered MRI images. Organs at risk contoured were Brainstem, Optic Chiasm and Optic nerves. The dose prescribed to Planning Target Volume (1 mm margin to GTV) was 14Gy in single exposure. For Planning, rapid arc inverse treatment technique was used with 6 coplanar arcs (3 partial arcs and 3 full arcs).
The treatment plan was evaluated by radiation oncologist and medical physicist against the single fraction RTOG organs at risk (OARs). Dose Volume Histogram (DVH) is as shown in figure 3. Before delivering dose to patient, patient specific quality assurance (QA) was done to assure prescribed dose would be delivered accurately within acceptable limits. Patient specific QA included collision check, dummy run and dosimetric fluence variation. The plan was delivered to phantom. The measured fluence was evaluated against TPS calculated fluence. QA tests were passed with 100% scores. The patient was positioned on treatment couch; stereotactic frame (DSPS) was fitted on patients head. Isocenters were matched and shifts were applied according to plan made. Reproducibility was assessed KVCT to ensure ±1 mm accuracy and precision of treatment. Treatment was delivered by Varian True Beam with 6 FFF.
On his first follow up at 1 month post SRS, he was completely free of symptoms. MRI Brain was done 6 months post SRS which was suggestive of reduction in size of lesion (10 mm × 10 mm Vs 24 mm × 14 mm). 6 months post treatment; he is completely free of symptoms.