Intensity Modulated Therapy for Patients With Breast Cancer. Practical Guidelines and Tips for an Effective Treatment Planning Strategy

Planning Automation for Treatment Techniques Comparison and Robustness Analysis: Tangential Intensity Modulated Radiation Therapy and Volumetric Modulated Arc Therapy for Whole Breast Irradiation

Purpose

This study evaluates the use of the mCycle automated planning system integrated into the Monaco Treatment Planning System for step-and-shoot intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) in whole breast irradiation (WBI). The aim was to assess whether automation can standardize plan quality across a diverse patient cohort and compare dosimetric outcomes and robustness of the 2 techniques against setup errors and anatomical variations.

Methods and Materials

A total of 65 patients with breast cancer who underwent postoperative WBI were selected for the study. Treatment plans were generated using mCycle, which employs multicriteria optimization with no manual intervention. Two automated planning techniques-IMRT and VMAT-were implemented and evaluated based on dosimetric outcomes, physician review, planning time, and plan robustness. The plan deliverability was verified through γ index and point dose measurements.

Results

The mCycle system produced clinically acceptable plans for both IMRT and VMAT across all patient cohorts. VMAT showed superior target coverage (V95% = 97.9%) and better sparing of ipsilateral organs at risks (OARs), whereas IMRT demonstrated enhanced sparing of contralateral OARs and greater robustness to anatomical changes such as breast swelling. Planning times were reduced with VMAT because of complete automation. Plan deliverability was confirmed with high γ passing rates and acceptable point dose deviations.

Conclusions

The use of mCycle in WBI planning successfully standardized plan quality and improved workflow efficiency. VMAT provided superior target coverage and ipsilateral OAR sparing but was more sensitive to anatomical changes. IMRT showed better contralateral OAR sparing and robustness. Both techniques are viable, with advantages depending on clinical scenarios.

Dosimetric Evaluation of Three-dimensional Conformal Radiotherapy, RapidArc, and Hybrid RapidArc Radiotherapy Techniques for Left-sided Breast Cancer

OBJECTIVE

This study aimed to assess the irradiation techniques-three-dimensional conformal radiotherapy (3DCRT), RapidArc (RArc), and hybrid RapidArc (h-RArc)-for left-sided breast cancer patients, focusing on dose distribution in the planning target volume (PTV) and organs at risks (OARs).

MATERIALS AND METHODS

This study enrolled 20 patients diagnosed with early-stage left-sided breast cancer. All patients received a prescribed dose of 40.05 Gy in 15 fractions (2.67 Gy per fraction), optimized to achieve 95% dose coverage to 95% of the PTV. The dosimetric variations across the three treatment plans for the 20 patients were examined using a one-way ANOVA test. P <0.05 was regarded as statistically significant.

RESULTS

In the 3DRCT plan, D95% of the PTV was 37.21 ± 0.51 Gy. This value was significantly increased to 39.43 ± 0.27 Gy in the RArc plan (P = 0.001) and to 38.47 ± 0.19 Gy in the h-RArc plan (P = 0.630). The RArc plans demonstrated a superior homogeneity index of 0.12 ± 0.02 compared to both 3DCRT (0.18 ± 0.02) and h-RArc (0.13 ± 0.02). When comparing the increase in monitor units (MUs), h-RArc showed a 62.82% increase over 3D-CRT, whereas demonstrating a 38.05% decrease compared to RArc (P = 0.000).

CONCLUSIONS

h-RArc treatment plans for breast cancer may be recommended due to their superior and consistent PTV dose coverage and sparing of OARs, in comparison to both 3DRCT and RArc plans. These h-RArc plans are characterized by reduced MU and beam on time, as well as a less low volume dose when compared to RArc plans.