Feasibility of using calibrated cone-beam computed tomography scans to validate the heart dose in left breast
Bin Tang1,2, Jiabao Ma2, Jinghui Xu2
1Key Laboratory of Radiation Physics, Institute of Nuclear Science and Technology, Sichuan University, No. 24, South Section 1, Yihuar, Chengdu, 610065, China.
Objective:
In post-mastectomy radiotherapy, high-conformal techniques are a valid method for determining the dose distribution around a target. However, the proximity of critical structures is a reason for concern. This study aims to evaluate the feasibility of using calibrated cone-beam computed tomography (CBCT) scans as a valid tool for a timely heart dose evaluation.
Methods:
A retrospective analysis was conducted on 170 retrospective CBCT scans of 17 patients who underwent high-conformal post-mastectomy irradiation. The delivered doses that were calculated using personalized calibrated CBCT were compared with the doses planned, using the dose-volume histogram dosimetric parameters.
Results:
The heart volume that was evaluated using CBCT presented a mean increase of 6%; this discrepancy impacted the heart dose in 4 of 17 patients, with an absolute increase of V25 Gy (range, 2.5%-7.6%) and an increase in the mean dose (range, 1.1-3.4 Gy). The dose for the target, ipsilateral lung, and contralateral breast remained unchanged.
Conclusion:
Using CBCT to monitor the dose that is delivered to the heart is feasible, allowing for a timely shift to an adaptive plan if clinically necessary.
