Loading
Radiation Therapy and Dosimetry / Advanced Radiotherapy Techniques · Journal article
BMC Cancer · August 13, 2026
Encouraging direction, but not yet definitive.
This two-phase single-centre study demonstrates that ripple filter integration into pencil beam scanning proton therapy for breast cancer improves treatment delivery efficiency by approximately 20% while reducing dose-averaged LET to skin and distal organs. Dosimetric increases in low-dose exposure to lung and heart are small but statistically significant; Phase II retrospective analysis of 37 matched pairs found no difference in acute radiation-induced dermatitis or esophagitis between ripple filter and non-ripple filter groups.
Two-phase investigation: Phase I prospective dosimetric planning study; Phase II retrospective matched cohort analysis. Phase I: 21 patients (11 breast-conserving surgery, 10 modified radical mastectomy). Phase II: 99 breast-conserving surgery patients treated in the specified period, stratified to 37 matched pairs after multivariate matching.. Intervention: Pencil beam scanning proton therapy with ripple filter integration.. Compared with: Pencil beam scanning proton therapy without ripple filter.. Single institution (not named in source text)..
RiFi plans maintained target coverage (V95) while reducing dose-averaged LET by 0.15–0.65 keV/µm to skin and distal organs-at-risk Mean ipsilateral lung dose increased by 0.13 Gy(RBE) in BCS patients (95% CI: 0.08–0.28, p<0.001) and 0.79 Gy(RBE) in MRM patients (95% CI: 0.46–1.10, p=0.002) Mean heart dose increased by 0.04 Gy(RBE) in BCS patients (95% CI: 0.02–0.06, p=0.006) and 0.08 Gy(RBE) in MRM patients (95% CI: 0.04–0.19, p=0.009)
Only acute toxicity assessed; late radiation effects, recurrence, and overall survival are not reported. Phase II sample (37 matched pairs) is modest; adequacy for detecting clinically important differences in toxicity is not discussed.
The 20% delivery time gain and reduced distal LET exposure may justify ripple filter use in synchrotron-based proton therapy, provided the small increases in low-dose exposure to lung and heart are deemed clinically acceptable. Acute toxicity data support safety for breast-conserving surgery patients, but longer-term outcomes and risk-benefit analysis for modified radical mastectomy remain to be established.
A two-phase feasibility and safety study combining dosimetric planning with retrospective clinical validation in a single institution, showing efficiency gain and acceptable acute toxicity, but limited by retrospective design, modest sample size, and surrogate endpoints.
As stated by the source record.
Quoted from the source exactly as published.
The 20% delivery time gain and reduced distal LET exposure may justify ripple filter use in synchrotron-based proton therapy, provided the small increases in low-dose exposure to lung and heart are deemed clinically acceptable. Acute toxicity data support safety for breast-conserving surgery patients, but longer-term outcomes and risk-benefit analysis for modified radical mastectomy remain to be established.
Graded across the dimensions that decide whether you should act, each from what the source actually supports. There is no single score, and where a dimension was not assessed it says so.
Pencil beam scanning (PBS) proton therapy (PT) offers superior dosimetric advantages for breast cancer treatment. However, synchrotron-based facilities frequently encounter throughput limitations due to slow energy layer switching, particularly problematic for superficial targets requiring numerous energy layers. Although ripple filters (RiFis) can mitigate this constraint by broadening the Bragg peak, their application in breast cancer PT remains unexplored. This study comprehensively investigates the feasibility, efficiency gains, linear energy transfer (LET) characteristics, and clinical safety of integrating a RiFi into PBS PT for breast cancer. We conducted a two-phase investigation beginning with a dosimetric planning study and proceeding to clinical validation. In phase Ⅰ, we generated paired treatment plans (RiFi vs. non-RiFi) for 21 patients (11 breast-conserving surgery [BCS] and 10 modified radical mastectomy [MRM]) to compare target coverage, organ-at-risk (OAR) sparing, dose-averaged LET (LETd) distributions, and number of energy layers. In phase Ⅱ, we conducted a retrospective analysis of 99 BCS patients treated between January and December 2025, employing 1:1 multivariate matching to control for treatment volume and prescription dose, resulting in 37 well-balanced pairs. Dose-volume and LETd parameters, Acute toxicities and treatment delivery time were compared between matched groups. In phase Ⅰ dosimetric study, RiFi plans maintained robust target coverage (V95). However, the broadened beam introduced slight but statistically significant increments in doses to OARs. For BCS patients, the mean ipsilateral lung dose and mean heart dose increased by 0.13 Gy(RBE) (95% confidence interval [CI]: 0.08–0.28 Gy(RBE), p <.001) and 0.04 Gy(RBE) (95% CI: 0.02–0.06 Gy(RBE), p =.006), respectively. For MRM patients, the mean ipsilateral lung dose and mean heart dose increased by 0.79 Gy(RBE) (95% CI: 0.46–1.10 Gy(RBE), p =.002) and 0.08 Gy(RBE) (95% CI: 0.04–0.19 Gy(RBE), p =.009), respectively. Conversely, the RiFi significantly decreased LETd by 0.15–0.65 keV/µm to skin and distal OARs. Phase Ⅱ clinical validation demonstrated similar LETd reduction and no significant differences in the incidence or severity of acute radiation-induced dermatitis or esophagitis between groups. RiFi integration significantly enhanced treatment efficiency, reducing actual beam delivery time by approximately 20%. Integrating a RiFi into breast cancer PBS PT effectively improves delivery efficiency and mitigates distal high-LETd exposure, albeit at the cost of slight increments in low-dose exposure to distal OARs. Clinical data confirm this dosimetric change does not compromise acute safety for BCS patients. These findings suggest that the RiFi is a feasible option for improving treatment delivery efficiency in synchrotron-based PT systems.
Taken from the source record, never inferred. Follow any of these and new work involving them reaches your briefing.