Breast Cancer Radiation Treatment Techniques

Comprehensive vocabulary flashcards covering simulation setups, target delineations, RTOG nodal boundaries, dose constraints, bolus types, dose modulation techniques, toxicities, and follow-up protocols in breast cancer radiation therapy.

Wiring Borders (Intact Breast)

Radio-opaque wire placement during CT simulation delineating the lumpectomy bed scar, with borders placed $1\text{--}2\, \text{cm}$ superior to palpable breast tissue, $2\, \text{cm}$ inferior to the inframammary fold, medially at the midline, and laterally at the mid post-axillary line.

Arm Angulation Rule (Chest Wall Simulation)

The positioning guideline stating the ipsilateral arm must not exceed $90^{\circ}$ of elevation above the head to avoid causing the axillary lymph nodes to overlap the humeral head anteriorly.

Breast Clinical Target Volume (CTV)

The target delineation defined in the RTOG atlas that includes the apparent CT glandular breast tissue and clinical breast tissue.

Lumpectomy Gross Tumor Volume (GTV)

The delineated volume encompassing the lumpectomy surgical bed cavity, including seroma, architectural distortion of local tissue, and any surgical clips present.

Chest Wall Bolus Protocol

The therapeutic use of a $0.5\text{--}1\, \text{cm}$ bolus applied typically every other day (or daily for inflammatory breast cancer) to deliver sufficient prescription dose to the skin and subcutaneous tissue without covering the supraclavicular field.

bolus is rarely used for… and typically used daily for…every other day for…

intact breast, inflammatory breast, chest wall

what energy is preferred? at what seperation should you include higher energy beams

6, greater than 22cm

dry desquamation occurs at doses above… moist desquamation

20gy, 30

Radiation-Induced Heart Disease (RIHD) Risk

The proportional increase in major coronary events (MI, coronary revascularization, or ischemic death) after breast radiation that increases linearly with mean heart dose by a relative risk of $7.4\%$ per $\text{Gy}$ ($p < 0.001$) without an apparent minimum threshold.

follow up schedule

Every 3-6 months for the first year, every 6-12 months for the second
to the fifth year

typical breast dose

Primary Breast: 50Gy/25 fx
Boost: 10Gy/ 5 fx (since most local recurrences are at or near the primary site)

hypo fractionated breast dose AND its special criteria

Hypofractionated: 42.5Gy / 16 fx
Criteria:
Heart must be blocked fully
Boost: optional (conventional or 10Gy/4fx boost)).

age requirement for hypo breast

at least 50

FiF technique rules for breast

use 106 idl to start blocking, inframammary fold should be less than 104,
MLC’s have to be at least 2cm from calculation point
Has to be at least a grouping of 2cm of MLC width
Try to minimize the number of FiFs (be efficient)
MLCs can only travel so far (14.5cm is a safe distance from jaw edge)