A comparison of conventional and dynamic radiotherapy planning techniques for early-stage breast cancer utilizing deep inspiration breath-hold

Abstract

Background: For breast cancer patients, radiotherapy increases the risk of cardiac disease. Conventional three-dimensional conformal radiotherapy (3D-CRT) in deep inspiration breath-hold (DIBH) has demonstrated substantial reduction in cardiac doses as compared to treatment in free breathing. The purpose of this treatment planning study is to investigate if dynamic techniques in combination with DIBH could improve the quality of the treatment plans and further reduce the doses to the heart and other organs at risk for early-stage breast cancer patients. Material and methods: CT series in DIBH of 16 patients from a previous study were used. For each patient, treatment plans were generated with the following three techniques: 3D-CRT, tangential intensity-modulated radiotherapy (tIMRT) and volumetric modulated arc therapy with partial arcs (pVMAT). The treatment planning was performed focusing on planning target volume (PTV) coverage, V 95% >95%. Dose-volume histograms were calculated and compared. Doses to the heart, left anterior descending (LAD) coronary artery, ipsilateral and contralateral lung as well as the contralateral breast (CB) were assessed. Results: All plans fulfilled the criterion on PTV coverage. Compared to 3D-CRT, the dynamic plans obtained better dose homogeneity and conformity. The mean heart dose was similar for 3D-CRT and tIMRT, 1.3 and 1.1 Gy, respectively, but significantly higher for pVMAT, 1.6 Gy. The median V 25 Gy to the heart was 0% for all techniques. The LAD doses were generally lower with the dynamic techniques. The mean doses to the ipsi-and contralateral lung and CB were similar with tIMRT and 3D-CRT but significantly higher with pVMAT. V 20 Gy to the ipsilateral lung was significantly lower with tIMRT compared to 3D-CRT. Conclusion: tIMRT and 3D-CRT with DIBH are better techniques for sparing heart tissue and other organs at risk without compromising target coverage in early-stage breast cancer irradiation compared to VMAT.

Harmonization of breast cancer radiotherapy treatment planning in the Netherlands

“…In treatment plan comparison studies, often the volume receiving 95% (V95%) or 107% (V107%) of the prescribed dose is used as a criterion to evaluate the RT plan [6], while the dose received by 98% (D98%) and 2% (D2%) of the volume [7] or the dose to 99% and to maximally 2 cc [8] can also be used. Some studies use the homogeneity index (HI) and conformity index (CI) as the main target volume parameters to compare plans [8,9] or a combination of HI, V95% and V107% [10].…”

Dose constraints for whole breast radiation therapy based on the quality assessment of treatment plans in the randomised Danish breast cancer group (DBCG) HYPO trial

“…Furthermore, Aznar et al showed in a systematic review of lung doses from breast cancer RT that tangential fields spared both the ipsilateral and contralateral lung better than IMRT for whole breast RT without nodal irradiation [20]. With breathing adaption, 3D-CRT and tangential IMRT fields also had higher potential for sparing the heart compared to a partial VMAT technique [21]. These conclusions were recently validated in another study showing that the 3D-CRT in many situations is to be preferred [28].…”

Auxiliary Structures-Assisted Radiotherapy Improvement for Advanced Left Breast Cancer

“…For the ipsilateral lung, the average dose was 11.2 Gy in the period of 2010-2015 (14). For radiotherapy of patients with left-sided advanced breast cancer, 3D-CRT can cover the target with the expected dose, but fails to meet the dosimetric constraints for surrounding normal tissues (15)(16)(17)(18). Compared to 3D-CRT, IMRT and VMAT with additional multiple beam directions, can produce better conformity and homogeneity on the target, especially in the lymph node regions, and can drastically reduce the volume of the heart and lung in the radiation field (19,20).…”