In:
Frontiers in Oncology, Frontiers Media SA, Vol. 10 ( 2020-12-17)
Abstract:
To assess the dosimetric feasibility of a stereotactic body radiotherapy (SBRT) dose escalated protocol, with a simultaneous integrated boost (SIB) and a simultaneous integrated protection (SIP) approach, in patients with locally advanced pancreatic cancer (LAPC). Material and Methods Twenty LAPC lesions, previously treated with SBRT at our Institution, were re-planned. The original prescribed and administered dose was 50/30/25 Gy in five fractions to PTV sib (tumor-vessel interface [TVI])/PTV t (tumor volume)/PTV sip (overlap area between PTV t and planning organs at risk volume [PRV oars ]), respectively. At re-planning, the prescribed dose was escalated up to 60/40/33 Gy in five fractions to PTV sib /PTV t /PTV sip , respectively. All plans were performed using an inspiration breath hold (IBH) technique and generated with volumetric modulated arc therapy (VMAT). Well-established and accepted OAR dose constraints were used (D 0.5cc & lt; 33 Gy for luminal OARs and D 0.5cc & lt; 38 Gy for corresponding PRV oars ). The primary end-point was to achieve a median dose equal to the prescription dose for the PTV sib with D 98 ≥ 95% (95% of prescription dose is the minimum dose), and a coverage for PTV t and PTV sip of D 95 ≥95%, with minor deviations in OAR dose constraints in & lt; 10% of the plans. Results PTV sib median (± SD) dose/D 95 /conformity index (CI) were 60.54 (± 0.85) Gy/58.96 (± 0.86) Gy/0.99 (± 0.01), respectively; whilst PTV t median (± SD) dose/D 95 were 44.51 (± 2.69) Gy/38.44 (± 0.82) Gy, and PTV sip median (± SD) dose/D 95 were 35.18 (± 1.42) Gy/33.01 (± 0.84) Gy, respectively. With regard to OARs, median (± SD) maximum dose (D 0.5cc ) to duodenum/stomach/bowel was 29.31 (± 5.72) Gy/25.29 (± 6.90) Gy/27.03 (± 5.67) Gy, respectively. A minor acceptable deviation was found for a single plan (bowel and duodenum D 0.5cc =34.8 Gy). V38 & lt; 0.5 cc was achieved for all PRV luminal OARs. Conclusions In LAPC patients SBRT, with a SIB/SIP dose escalation approach up to 60/40/33 Gy in five fractions to PTV sib /PTV t /PTV sip , respectively, is dosimetrically feasible with adequate PTVs coverage and respect for OAR dose constraints.
Type of Medium:
Online Resource
ISSN:
2234-943X
DOI:
10.3389/fonc.2020.600940
DOI:
10.3389/fonc.2020.600940.s001
Language:
Unknown
Publisher:
Frontiers Media SA
Publication Date:
2020
detail.hit.zdb_id:
2649216-7
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