Evaluation of the minimum segment width and fluence smoothing tools for intensity-modulated techniques in Monaco treatment planning system

Jiménez-Puertas, Sara ; González Rodríguez, Andrea ; Lozares Cordero, Sergio (Universidad de Zaragoza) ; González González, Tomás ; Díez Chamarro, Javier ; Hernández Hernández, Mónica ; Castro Moreno, Raquel ; Sánchez Casi, Marta ; Villa Gazulla, David Carlos ; Gandía Martínez, Almudena ; Campos Bonel, Arantxa ; Puertas Valiño, Maria del Mar ; Font Gómez, José Antonio (Universidad de Zaragoza)

Resumen: Purpose:
This study aims to minimize monitor units (MUs) of intensity-modulated treatments in the Monaco treatment planning system while preserving plan quality by optimizing the “Minimum Segment Width” (MSW) and “Fluence Smoothing” parameters.

Materials and Methods:
We retrospectively analyzed 30 prostate, 30 gynecological, 15 breast cancer, 10 head and neck tumor, 11 radiosurgery, and 10 hypo-fractionated plans. Original prostate plans employed “Fluence Smoothing” = Off and were reoptimized with Low, Medium, and High settings. The remaining pathologies initially used MSW = 0.5 cm and were reoptimized with MSW = 1.0 cm. Plan quality, including total MU, delivery time, and dosimetric constraints, was statistically analyzed with a paired t-test.

Results:
Prostate plans exhibited the highest MU variation when changing “Fluence Smoothing” from Off to High (average ΔMU = −5.1%; P < 0.001). However, a High setting may increase overall MU when MSW = 0.5 cm. Gynecological plans changed substantially when MSW increased from 0.5 cm to 1.0 cm (average ΔMU = −29%; P < 0.001). Organs at risk sparing and planning target volumes remained within 1.2% differences. Replanning other pathologies with MSW = 1.0 cm affected breast and head and neck tumor plans (average ΔMU = −168.38, average Δt = −11.74 s, and average ΔMU = −256.56, average Δt = −15.05 s, respectively; all with P < 0.004). Radiosurgery and hypofractioned highly modulated plans did not yield statistically significant results.

Conclusions:
In breast, pelvis, head and neck, and prostate plans, starting with MSW = 1.0 cm optimally reduces MU and treatment time without compromising plan quality. MSW has a greater impact on MU than the “Fluence Smoothing” parameter. Plans with high modulation might present divergent behavior, requiring a case-specific analysis with MSW values higher than 0.5 cm.

Idioma: Inglés

DOI: 10.4103/jmp.jmp_156_23

Año: 2024

Publicado en: Journal of Medical Physics 49, 2 (2024), 250-260
ISSN: 0971-6203

Factor impacto SCIMAGO: 0.256 - Radiology, Nuclear Medicine and Imaging (Q3) - Biophysics (Q4)

Tipo y forma: Article (Published version)

Área (Departamento): Área Radiol. y Medicina Física (Dpto. Microb.Ped.Radio.Sal.Pú.)