Liver tolerance of the same radiation activity as measured in Gy , the same absorbed dose, is therefore greater when fewer particles are injected, each with a higher specific activity. The more homogenous distribution of radiation in the high-number-of-microspheres-injected model means that there is a much more limited area of unaffected liver.
QuiremSpheres are in between. The dose thresholds used for treatment planning therefore vary depending on what type of microsphere is used. Interventionalists utilise different imaging modalities for different microspheres. Turning to imaging, Lam explained how, due to differing microsphere characteristics, the imaging modality used for each also varies.
Holmium also emits gamma radiation, that may be used for quantitative SPECT [single photon emission computed tomography] imaging. Lam went on to explain the clinical significance of this characteristic of Ho Typically, ahead of a radioembolization procedure, he explained, the interventionalist will conduct a work-up or scout procedure using Tcm MAA macroaggregated albumin.
The SARAH trial, an open-label, randomised controlled phase 3 trial investigating the efficacy and safety of selective internal radiotherapy SIRT with Y resin microspheres compared with sorafenib in hepatocellular carcinoma HCC patients, found no significant difference in survival between the two treatments.
I believe this is where Holmium steps in, because instead of Tc-MAA, we use the exact same particles for work-up as we use for the treatment procedure. What we gain is control—over the lung-shunt calculation, and also over the intra-hepatic distribution. Looking to the future, Lam enthused about personalised treatment planning.
The presence of collateral arteries not amenable to coil embolization was considered an absolute contraindication to Y therapy. Additionally, patients received Tcmacro-aggregated albumin via the hepatic artery, followed by a whole-body nuclear scan to determine the estimate of body distribution and the percent of lung shunting.
Macro-aggregated albumin was chosen due to its similar physical size to Y microspheres micron. This pre-treatment procedure was done in order to prevent accidental delivery of microspheres to the lung in order to avoid radiation pneumonitis.
The method varies the prescribed activity based upon the size of the patient as well as the proportion of tumor involvement of the liver. Activity delivered was reduced if there was evidence of increased lung shunt. Glass microspheres activity was determined utilizing conventional Medical Internal Radiation Dose MIRD Committee technique adjusted according to the calculated shunt of lung particles 17 , The dose calculation was performed by a medical physicist and a radiation oncologist, and confirmed by an interventional radiologist.
Tumor response was assessed by sonography, CT scanning, or MRI scanning as determined by the treating clinician. Complete response CR was defined as the disappearance of any intratumoral arterial enhancement in all target lesions.
If a patient expired before repeat imaging could be performed, they were considered to have PD. Patients were followed up with visits at regular intervals as determined by the treating physicians. Toxicities were recorded if present at any time during post-follow-up period. Overall survival was the primary endpoint used in this study defined as the time between the date of first treatment and date of death.
Data was analyzed using descriptive methods. Survival curves were generated using Kaplan-Meier modeling. Statistical analysis was performed using the computing environment R version 3.
Demographics and clinical characteristics of the patients included in this study are presented in Table 1. The median age was Twenty-four percent were 75 years of age or older.
The most common etiologies of liver disease were alcoholic liver disease and hepatitis C cirrhosis. Forty-seven percent had no therapy in addition to radioembolization; forty-one percent received sorafenib either before or after radioembolization.
Seventeen patients underwent treatment with Y radioembolization. The median treatment activity delivered was 1. The median treatment dose delivered was Gy range, Gy. The median lung shunt fraction was 2. Toxicities are listed in Table 2. There were no patients who experienced pulmonary toxicity. One patient developed a biopsy-proven, Y90 induced bleeding gastric ulcer several months after Y treatment requiring care in the ICU.
His hospital course was complicated by sepsis which led to death. The ulcer was thought to be due to a collateral vessel off of the proper hepatic artery supplying the stomach. A total of 17 patients underwent Y radioembolization for treatment of HCC with palliative intent. Two subjects are still alive and were therefore excluded from survival analysis.
Table 3 reports outcome data. Partial treatment response from a patient is represented in Figure 1. Patients survived for a median of 8. Median survival from Y treatment was 8. The mean overall survival from the time of diagnosis was Figure 2 displays a Kaplan-Meier curve for survival since radioembolization treatment Figure 2A and survival since diagnosis Figure 2B. The goal of radioembolization is to deliver tumoricidal doses of radiation within the tumor capillary bed, sparing uninvolved liver tissue.
Conventional external beam radiation is limited by the extreme radiosensitivity of liver parenchyma Radioembolization takes advantage of the unique vascular supply of the liver and hepatic solid tumors. Microspheres embedded with Y, when installed through the hepatic artery, concentrate in liver tumors in a to ratio in comparison to normal liver parenchyma.
Our experience adds to the growing body of evidence suggesting that intra-arterial radioembolization is a safe and effective palliative intervention in patients with unresectable HCC. The company has stated that the typical number of particles that are given by QuiremSpheres is approximately 20 to 30 million. The company has a commercial arrangement simple discount patient access scheme , which would have applied if the technology had been recommended.
It is indicated for treating advanced inoperable liver tumours. Each vial contains 40 to 80 million microspheres, ranging from 20 to 60 micrometres in diameter median diameter The maximum range of beta emission in tissue is 11 mm with a mean of 2. Costs may vary in different settings because of negotiated procurement discounts.
It is indicated for treating hepatic neoplasia. TheraSphere is given through a catheter to the hepatic artery. Custom dose sizes are also available in increments of 0.
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