Scattered neutron dose equivalent to a representative point for a fetus is evaluated in an anthropomorphic phantom of the mother undergoing proton radiotherapy. The effect on scattered neutron dose equivalent to the fetus of changing the incident proton beam energy, aperture size, beam location, and air gap between the beam delivery snout and skin was studied for both a small field snout and a large field snout. Measurements of the fetus scattered neutron dose equivalent were made by placing a neutron bubble detector 10 cm below the umbilicus of an anthropomorphic Rando phantom enhanced by a wax bolus to simulate a second trimester pregnancy. The neutron dose equivalent in milliSieverts (mSv) per proton treatment Gray increased with incident proton energy and decreased with aperture size, distance of the fetus representative point from the field edge, and increasing air gap. Neutron dose equivalent to the fetus varied from 0.025 to 0.450 mSv per proton Gray for the small field snout and from 0.097 to 0.871 mSv per proton Gray for the large field snout. There is likely to be no excess risk to the fetus of severe mental retardation for a typical proton treatment of 80 Gray to the mother since the scattered neutron dose to the fetus of 69.7 mSv is well below the lower confidence limit for the threshold of 300 mGy observed for the occurrence of severe mental retardation in prenatally exposed Japanese atomic bomb survivors. However, based on the linear no threshold hypothesis, and this same typical treatment for the mother, the excess risk to the fetus of radiation induced cancer death in the first 10 years of life is 17.4 per 10,000 children.

Journal of Translational Medicine AbstractBackground: Treatment records and follow-up data on 40 patients with primary and metastatic liver malignancies who underwent a single whole-liver treatment with Y-90 resin microspheres (SIR-Spheres ® Sirtex Medical, Lake Forest, IL) were retrospectively reviewed. The objective of the study was to evaluate the anatomic and physiologic determinants of radiation dose distribution, and the dose response of tumor and liver toxicity in patients with liver malignancies who underwent hepatic arterial Y-90 resin microsphere treatment.Methods: Liver and tumor volume calculations were performed on pre-treatment CT scans. Fractional tumor and liver flow characteristics and lung shunt fractions were determined using hepatic arterial Tc-99m MAA imaging. Absorbed dose calculations were performed using the MIRD equations. Liver toxicity was assessed clinically and by liver function tests. Tumor response to therapy was assessed by CT and/or tumor markers.

Background: Accurate determination of the extrahepatic extent and intrahepatic distribution of disease is very important in patients with primary and metastatic liver disease for deciding whether a patient receives potentially curable surgery or palliative treatment. Our objective was to evaluate the efficacy of delayed phase FDG-PET/CT imaging in lesion detection and to define its clinical impact compared to triple-phase contrast enhanced CT (CECT).

14589 Background: Yttrium-90 (Y-90) microsphere selective internal radiation treatment (SIRT) has been studied in patients (pts) with colorectal cancer liver metastases (CRCLM) in combination with FUDR and 5FU-LV with promising results. This is a phase II trial of SIRT and concurrent contemporary chemotherapy in the frontline management of CRCLM. Methods: Pts with metastatic disease limited predominantly to the liver were eligible for the study. Other entry criteria included KPS 70 or >, 3 month life expectancy and adequate marrow and renal reserve. Pre-treatment evaluations included the assessment of liver function, CEA level, 18F-FDG-PET/CT imaging, an angiogram and a 99mTc-MAA (macroagregate albumin) scan. SIRT with Y-90 resin microspheres (Sirtex Medical, Lake Forest, IL) was administered on day 2 of the first chemotherapy (Fol-Fox or Fol-Firi) course in either lobar or whole-liver fashion. Chemotherapy was repeated on a biweekly schedule. CEA levels and 18F-FDG-PET/CT based anatomic and functional volume (Vf) changes were used to determine tumor response at 4, 8, and 12 weeks after therapy. CTC v3 toxicity grades were used to classify adverse events. Results: 6 pts were treated as first-line and 2 pts as second-line. 5 pts received single lobe and 3 pts received whole liver treatment. Administered activity of Y-90 microspheres ranged from 0.9 to 3.1 GBq (mean 2.3 GBq). Mean tumor radiation absorbed dose was 203.6 Gy (Range 91.0–351.4 Gy). Mean liver absorbed dose was 47.8 Gy (Range 7.9–85.9 Gy). 6/8 pts had complete/near-complete metabolic response with a mean tumor Vf decrease in target lobe(s) of 98%). The remaining 2 pts demonstrated > 50% reduction in Vf in target lobe(s). A parallel decrease in CEA level was observed in responding pts. Surgical downstaging was attained in 3/8 pts. 2 pts developed grade III toxicity (one gastric ulcer and one alkaline phosphatase elevation). Conclusion: Chemo-SIRT as first-line therapy has a high level of response in CRCLM as measured by reductions in functional tumor volume and CEA level. Further follow-up of these pts is needed to confirm that this response is of clinical significance in terms of improved surgical downstaging and survival. [Table: see text]

Scattered neutron dose equivalent to a representative point for a fetus is evaluated in an anthropomorphic phantom of the mother undergoing proton radiotherapy. The effect on scattered neutron dose equivalent to the fetus of changing the incident proton beam energy, aperture size, beam location, and air gap between the beam delivery snout and skin was studied for both a small field snout and a large field snout. Measurements of the fetus scattered neutron dose equivalent were made by placing a neutron bubble detector 10 cm below the umbilicus of an anthropomorphic Rando® phantom enhanced by a wax bolus to simulate a second trimester pregnancy. The neutron dose equivalent in milliSieverts per proton treatment Gray increased with incident proton energy and decreased with aperture size, distance of the fetus representative point from the field edge, and increasing air gap. Neutron dose equivalent to the fetus varied from 0.025 to 0.450 mSv per proton Gray for the small field snout and from 0.097 to 0.871 mSv per proton Gray for the large field snout. There is likely to be no excess risk to the fetus of severe mental retardation for a typical proton treatment of 80 Gray to the mother since the scattered neutron dose to the fetus of 69.7 mSv is well below the estimated radiation absorbed dose threshold of 600 mGy observed for the occurrence of severe mental retardation in prenatally exposed Japanese atomic bomb survivors. However based on the linear no threshold hypothesis and this same typical treatment for the mother, the excess risk to the fetus of radiation induced cancer death in the first 10 years of life is 17.4 per 10,000 children.

No abstract