Even though rotational intraperitoneal pressurized aerosol chemotherapy (RIPAC) has been developed to improve the distribution and penetration depth of anti-cancer agents by pressurized intraperitoneal aerosol chemotherapy (PIPAC), the optimal nozzle position and patient’s posture have not been investigated. Thus, we used nine pigs weighing 50–60 kg, and sprayed 150 mL of 1% methylene blue as an aerosol through the nozzle, DreamPen® (Dreampac Corp., Wonju, Republic of Korea), with a flow rate of 0.6 ml/min under a pressure of 140 to 150 psi for RIPAC in six and three pigs with supine and Trendelenburg positions, respectively. When we evaluated its distribution and penetration depth, even distribution among 13 regions of the abdomen was observed in three pigs with Trendelenburg position regardless of the depth of the nozzle. Regarding penetration depth, the numbers of regions with maximal penetration depth were high in the 2 cm depth of the nozzle with supine position (n = 5) and the 4 cm depth with Trendelenburg position (n = 3). Conclusively, even distribution and maximal penetration of anti-cancer agents can be expected during RIPAC in the medium depth (4 cm) between the nozzle inlet and the visceral peritoneum located on the opposite side of it and the Trendelenburg position.
Methods Scans from 20 patients with pelvic recurrence were used, delivering EBRT 45Gy/25 fractions to pelvis followed by SBRT boost. Cumulative dose limits for bowel, bladder, sigmoid, rectum and sciatic nerve were converted to 5 and 10 fraction equivalent constraints. For isotoxic planning, prescription was escalated/de-escalated until any OAR dose constraint was exceeded. Feasible tumour doses (EQD210) with 5 and 10 fractions were compared. Results With conventional VMAT 20 Gy in 10 fractions, median GTV and PTV dose was 20.0Gy (total EQD210 64.2Gy). Using isotoxic SBRT planning for central pelvic disease, median PTV dose (EQD210) was 29.9Gy (total 74.1Gy) with 5 fractions compared to 32.9Gy (77.2Gy) with 10 fractions and GTV 30.8Gy (cumulative 75Gy) versus 33.9Gy (cumulative78.1Gy) (p<0.0001). Similarly, with pelvic sidewall disease isotoxic doses were increased with 10 fractions: PTV 42.2Gy (cumulative 86.4Gy) versus 45.5Gy (cumulative 89.7Gy); GTV 45Gy (cumulative 89.2Gy) versus 48.6Gy (cumulative92.9 Gy) (p<0.0001) Conclusions Longer fractionation can significantly increase deliverable tumour doses. Further investigation is required to determine optimal patient specific regimens.
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