In:
Strahlentherapie und Onkologie, Springer Science and Business Media LLC
Abstract:
A simultaneous integrated boost (SIB) may result in increased out-of-field (D OOF ) and photoneutron (H PN ) doses in volumetric modulated arc therapy (VMAT) for prostate cancer (PCA). This work therefore aimed to compare D OOF and H PN in flattened (FLAT) and flattening filter-free (FFF) 6‑MV and 10-MV VMAT treatment plans with and without SIB. Methods Eight groups of 30 VMAT plans for PCA with 6 MV or 10 MV, with or without FF and with uniform (2 Gy) or SIB target dose (2.5/3.0 Gy) prescriptions (CONV, SIB), were generated. All 240 plans were delivered on a slab-phantom and compared with respect to measured D OOF and H PN in 61.8 cm distance from the isocenter. The 6‑ and 10-MV flattened VMAT plans with conventional fractionation (6- and 10-MV FLAT CONV) served as standard reference groups. Doses were analyzed as a function of delivered monitor units (MU) and weighted equivalent square field size A eq . Pearson’s correlation coefficients between the presented quantities were determined. Results The SIB plans resulted in decreased H PN over an entire prostate RT treatment course (10-MV SIB vs. CONV −38.2%). Omission of the flattening filter yielded less H PN (10-MV CONV −17.2%; 10-MV SIB −22.5%). The SIB decreased D OOF likewise by 39% for all given scenarios, while the FFF mode reduced D OOF on average by 60%. A strong Pearson correlation was found between MU and H PN ( r 〉 0.9) as well as D OOF (0.7 〈 r 〈 0.9). Conclusion For a complete treatment, SIB reduces both photoneutron and OOF doses to almost the same extent as FFF deliveries. It is recommended to apply moderately hypofractionated 6‑MV SIB FFF-VMAT when considering photoneutron or OOF doses.
Type of Medium:
Online Resource
ISSN:
0179-7158
,
1439-099X
DOI:
10.1007/s00066-023-02138-x
Language:
English
Publisher:
Springer Science and Business Media LLC
Publication Date:
2023
detail.hit.zdb_id:
2003907-4
detail.hit.zdb_id:
84983-2
