What is the clinical evidence from this study?

Study design: Observational. Population: Left-sided breast cancer (n=15). Intervention: Systolic phase cardiac CT for radiotherapy planning vs. Diastolic phase cardiac CT. Primary outcome: Mean heart dose (Dmean) (p=0.048).

What does this research mean for the field?

Cardiac-phase-dependent dose variations during deep inspiration breath-hold (DIBH) in breast cancer radiotherapy are statistically significant, but current non-ECG-gated DIBH remains adequate for cardiac dose management. Novelty: ClaimNovelty.INCREMENTAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

What question did this study set out to answer?

This evaluation aims to understand how heart doses change between diastolic and systolic phases during radiation therapy for breast cancer.

February 11, 2026Radiological Physics and Technology0 citationsOpen Access

Robustness of heart dose against cardiac cycle in breast cancer radiotherapy with deep inspiration breath-hold

YYYuya Yanagi HMHajime Monzen KAKen Aoki

Key Result

Cardiac-phase-dependent dose variations under deep inspiration breath-hold were statistically significant but clinically minimal, with a mean heart dose of 5.03 Gy in systole versus 5.10 Gy in diastole.

Key Points

This evaluation aims to understand how heart doses change between diastolic and systolic phases during radiation therapy for breast cancer.
Used electrocardiogram-gated cardiac computed tomography images from 15 women
Created radiation therapy plans delivering 50 Gy in 25 fractions
Assessed dose parameters for heart, LADCA, and LMCA across cardiac phases
Mean heart doses during diastole and systole were 5.10 ± 3.04 Gy and 5.03 ± 3.05 Gy, respectively
Significant differences were found in the D mean of the heart
LADCA doses showed no significant difference across phases due to anatomical variations
LMCA doses were significantly higher during systole with a mean of 2.02 ± 0.28 Gy
Overall, small but significant dose variations were observed under DIBH.

Study Design

Type

Observational (n=15)

Multicenter

Structured PICO

Does the cardiac cycle phase significantly affect the radiation dose to the heart and coronary arteries during deep inspiration breath-hold radiotherapy for left-sided breast cancer?

Population

15 women with left-sided breast cancer undergoing deep inspiration breath-hold (DIBH) radiotherapy planning, mean age 63.5 years.

Intervention

Radiation therapy planning (50 Gy in 25 fractions) evaluated during the systolic cardiac phase using ECG-gated CT.

Comparator

Radiation therapy planning evaluated during the diastolic cardiac phase.

Outcome

Dose differences to the heart, left anterior descending coronary artery (LADCA), and left main coronary artery (LMCA) between diastolic and systolic phases (including Dmean, D2%, and volumetric parameters).surrogate

Cardiac-phase-dependent dose variations under deep inspiration breath-hold are statistically significant but clinically minimal, confirming that current non-ECG-gated DIBH is adequate for cardiac dose management in breast cancer radiotherapy.

Main Result

Absolute Event Rate: 5.03% vs 5.1%

p-value: p=0.048

Limitations

Small sample size of 15 patients
Relative uniformity of the treatment plans used (simple tangential fields, 2 Gy per fraction)
Comparison was restricted to the extreme cardiac motion phases (diastole and systole) due to technical inability to reconstruct images during typical free-beating cardiac motion

Abstract

Abstract This study evaluated dose differences to the heart, left anterior descending coronary artery (LADCA), and left main coronary artery (LMCA) between diastolic and systolic heart phases in radiation therapy for left-sided breast cancer using deep inspiration breath-hold (DIBH). Diastolic and systolic doses to the heart, LADCA, and LMCA were analyzed using electrocardiogram-gated cardiac computed tomography images from 15 women. Radiation therapy plans were created for a total dose of 50 Gy in 25 fractions. Parameters assessed included volume, D mean , D 2% , V 5Gy , V 10Gy , V 20Gy , and V 25Gy for the heart; D mean , D 2% , V 5Gy , V 10Gy , and V 20Gy for the LADCA; and D mean and D 2% for the LMCA. The D mean of the heart was 5.10 ± 3.04 Gy and 5.03 ± 3.05 Gy for diastole and systole, respectively (mean ± 1 standard deviation), and D 2% was 37.44 ± 16.03 Gy and 36.15 ± 16.76 Gy. Statistically significant differences were found in the D mean . LADCA doses showed no significant differences, possibly due to anatomical variations. The D mean of the LMCA was 1.88 ± 0.23 Gy and 2.02 ± 0.28 Gy for diastole and systole, and D 2% was 2.05 ± 0.28 Gy and 2.21 ± 0.30 Gy, with both parameters being statistically significantly higher during systole. Although small, cardiac-phase-dependent dose variations under DIBH were statistically significant, confirming that current non-ECG-gated DIBH remains adequate for cardiac dose management.

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