The hypothesis is that the daily use of brass mesh bolus achieves a comparable dose to every-other-day use of Superflab bolus (current standard of care) in chest wall post-mastectomy patients treated with rotational 6 MV photon delivery.

Intervention: During a standard-of-care 15 fraction radiotherapy treatment, a brass mesh bolus will be used for a single fraction. Small in-vivo dosimeters will be used for three treatment fractions to measure and compare skin doses for quantification purposes.

Comparator: Superflab and no bolus applied as per the treating physician's practice, typically on alternate days. The intervention and comparator tools are to be utilized on each participant.

Primary outcome

1. To determine the skin dose under brass mesh bolus and compare it with the skin dose under Superflab bolus (current standard of care).
2. To determine the number of fractions for which brass mesh bolus should be used to achieve an acceptable skin dose.

Inclusion Criteria:

Women undergoing rotational chest wall radiotherapy following mastectomy for breast cancer treatment who would utilize Superflab bolus on some, but not all, days of radiotherapy treatment.

Exclusion Criteria:

Patients who require daily bolus due to skin involvement or other high-risk features requiring a high skin dose will not be included.