World Journal of Clinical Cancer Research (ISSN 2831-3275) “Evaluation of advanced Dosimetry in Transarterial Radioembolization of Hepatocellular Carcinoma with 90 Y microspheres” Karin Knešaurek,PhD, and Ahmed Abdelrahman,MD. The authors affiliation : Department of Diagnostic, Molecular and Interventional Radiology, lcahn School of Medicine at Mount Sinai, New York,NY,USA. Corresponding author Karin Knešaurek , Department of Diagnostic, Molecular and Interventional Radiology, lcahn School of Medicine at Mount Sinai, New York,NY,USA. Email : karin.knesaurek@mountsinai.org Received Date : April 17, 2024 Accepted Date : April 18, 2024 Published Date : May 18, 2024 ABSTRACT Objective : The aim of our study was to analyze the relationships between tumor (T) and normal tissue (N) absorbed dose in relation to the clinical outcomes in hepatocellular carcinoma (HCC) patients treated with 90 Y microspheres. Materials and methods : After transarterial radioembolization of HCC with 90 Y microspheres, 62 patients (10 females: 52 males, mean age 68.2±8.2 years) were imaged using a four-ring, time-of-flight (TOF), PET/CT system. Low dose, non-diagnostic CT images from PET/CT were utilized for localization of the 90 Y microspheres and attenuation correction of PET images. Response assessment was conducted using mRECIST criteria on MRI one month post treatment and subsequently every three months after 90 Y treatment. Results : Among 62 patients, mean liver, tumor, and normal tissue doses (mean ± SD) were 51.38±23.32 Gy, 682.60±785.19 Gy and 45.54±21.19 Gy, respectively. Out of these patients, 39 exhibited complete response (CR), 11 showed partial response (PR), 2 had stable disease (SD), and 10 showed progression of the disease (PD). For CR+PR patients the mean T was 824.63±833.10 Gy, whereas for PD patients, the mean T was significantly lower at 205.70±183.22 Gy. The mean liver and normal tissue doses were comparable; for CR+PR patients had liver and normal tissue doses of 51.01±22.55 Gy and 45.18±20.68 Gy, respectively, and for PD patients, these values were 54.34±26.73 Gy and 49.10±22.97 Gy, respectively. Conclusion : Despite not considering the partial volume effect and having a limited number of PD cases, our data indicates a statistically significant lower (P = 0.0001) tumor dose in patients with disease progression compared to those with complete and partial response. These results suggest that post-therapy personalized, and image-based dosimetry provides promising predictive outcomes in 90 Y microsphere radiation therapy for liver cancers. Keywords : 90 Y dosimetry; 90 Y microspheres; hepatocellular carcinoma INTRODUCTION Primary liver cancer is the sixth most common cancer worldwide 1 and hepatocellular carcinoma (HCC) accounts for approximately 90% of all liver cancers. 2 Considering the high incidence and poor prognosis of HCC, research on the epidemiology of HCC is an important public health issue. Unfortunately, due to extensive disease or other contraindications only about 20% of patients with HCC are candidates for surgical treatment in the form of resection or transplantation. For the remaining cases of unresectable HCC, there are many alternative treatment options, including thermal radiofrequency (RFA) or microwave ablation, external beam radiation, systematic chemotherapy (e.g., Sorafenib), alcohol injections, transarterial chemoembolization (TACE) 3,4 , and yttrium-90 ( 90 Y) selective internal radiation therapy (SIRT). 5 SIRT with 90 Y microspheres is an effective and safe option for the treatment of HCC. Recently, there has been a growing interest in the use of SIRT, due to its favorable tumor response and safety profile. 6 This treatment is based on the fact that tumor vascularization is mainly arterial, as opposed to hepatic vascularization. In addition, the intraarterial injection of 90 Y microspheres, if properly performed, delivers high radiation absorbed doses to the tumor while sparing liver parenchyma. It has been shown that higher tumor doses usually achieve a better response. 7,8 However, using higher activities to increase the tumor-absorbed dose is limited by the increase in healthy liver or normal tissue absorbed dose. Our aim was to retrospectively study the relationships between tumor (T) Research Article 1 www.directivepublications.org