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    • br Table Mean radiation therapy doses

    2020-08-28


    Table 2 Mean radiation therapy doses to coronary arterial structures from left-sided breast cancer radiation therapy regimens used in Sweden (1958-2001) or Denmark (1978-2000)
    Radiation therapy regimen*
    Mean coronary artery doses (Gy)y
    Country Median Medial Border Field arrangementz,x Usual beam Dose
    Left
    Left anterior descending
    Right
    Circumflex
    Year
    Main
    Whole Prox Mid Dist
    Whole Prox Mid Dist Pd
    Whole Prox Dist
    Tangential
    Anterior AR7 or orthovoltage
    Anterior megavoltage
    Cobalt chain**
    Abbreviations: contra Z contralateral; Co60 Z cobalt 60; dist Z distal; IMC Z internal mammary chain; kV Z kilovoltage; lat Z lateral; MeV Z mega electron-volts; MV Z megavoltage; prox Z proximal; pd Z posterior descending; SCF Z supraclavicular fossa
    Bold tangential regimens are wide tangents, others are midline tangents. Bold anterior electron or orthovoltage regimens are oblique electron fields, others include direct fields.
    Practical Radiation Oncology: May-June 2019
    Practical Radiation Oncology: May-June 2019 Cardiac segment radiation doses breast cancer 165 A Midline tangents, 8 MV photons
    Left Right
    Left anterior descending coronary
    artery: distal
    † B Wide tangents, 6 MV photons Left
    Right
    Left anterior
    descending coronary
    artery: mid
    LV: apex
    † C Direct electron IMC, 12 MeV electrons Left
    Right
    Left anterior
    descending coronary
    artery: proximal
    Fig. 2 Spatial distribution of cardiac dose from breast cancer tangential and direct electron radiation therapy regimens used to treat women with breast cancer in Sweden (1958-2001) or Denmark (1978-2000). Left regimens A-C are illustrated in Fig. 1. y The main circumflex coronary artery has only 2 segments: Proximal and distal. Abbreviations: MV Z megavoltage; MeV Z mega electron-volts.
    The mean doses to the coronary artery segments in the left megavoltage tangential radiation therapy varied from 0.4 Gy to 48.0 Gy. For all megavoltage tangents, the LADCA mid- and distal segments received the highest doses of 32.8 Gy (Table 2, Fig. 2). The LADCA proximal received 18.9 Gy from the wide divergent and partially wide megavoltage tangents and 8.6 Gy to 11.0 Gy from the midline megavoltage tangents. The RCA and Cx segments were further from the fields and received 0.4 Gy to 8.2 Gy. 
    For orthovoltage midline tangents, the prescribed dose was only 10.5 Gy, and all cardiac segments received 9 Gy (Tables 1, 2, E3 and E4). For McWhirter ortho-voltage wide-tangential radiation therapy (36.0 Gy pre-scribed dose), whole LV and LADCA doses were similar to those for megavoltage wide tangents, but the RCA and Cx doses were higher owing to scattered radiation from orthovoltage beams.
    Right
    “typical CT-scan”
    Mid Div. Mid Blk. Direct IMC Direct CW Mid Div. Mid Blk. Direct IMC Direct CW Mid Div. Mid Blk. Direct IMC Direct CW Mid Div. Mid Blk. Direct IMC Direct CW
    Wide Div. Pa. Wide Blk Oblq CW
    Wide
    Tangents Anterior electrons Tangents Anterior electrons Tangents Anterior electrons Tangents Anterior electrons
    Tangents
    Anterior electrons
    Tangents
    Anterior electrons
    Tangents
    Anterior electrons
    Tangents
    Anterior electrons Mid Div. Mid Blk. Direct IMC Direct CW Mid Div. Mid Blk. Direct IMC Direct CW Mid Div. Mid Blk. Direct IMC Direct CW Mid Div. Mid Blk. Direct IMC Direct CW
    Wide Div. Pa. Wide Blk Oblq CW
    Wide Div. Pa. Wide Blk Oblq CW
    Wide Div. Pa. Wide Blk Oblq CW
    Wide Div. Pa. Wide Blk Oblq CW
    Tangents Anterior electrons Tangents Anterior electrons Tangents Anterior electrons Tangents Anterior electrons
    Tangents
    Anterior electrons
    Tangents Anterior electrons
    Tangents
    Anterior electrons
    Tangents Anterior electrons
    Direct
    IMC
    Mid Div. Mid Blk.
    Direct CW Mid Div. Mid Blk. Direct IMC Direct CW Mid Div. Mid Blk. Direct IMC Direct CW Mid Div. Mid Blk. Direct IMC Direct CW
    Wide Div. Pa. Wide Blk Oblq CW
    Wide Div. Pa. Wide Blk Oblq CW
    Tangents Anterior electrons Tangents Anterior electrons Tangents Anterior electrons Tangents Anterior electrons
    Radiation therapy technique
    Fig. 3 Patient-to-patient variability in mean radiation dose to the whole heart, and left ventricular and coronary arterial segments in women receiving tangential or anterior electron regimens for breast cancer in Sweden (1958-2001) or Denmark (1978-2000). For further details on regimens 1 through 7, see Table E1. Regimen definitions: Tangents (1) Mid. Div, midline divergent, (50 Gy/25 fractions); (2) Wide Div, wide divergent, medial border 3 cm contralateral, (41 Gy/22 fractions); (3) Mid. Blk, midline, blocked posterior border tapered inferiorly around breast (48 Gy/24 fractions); (4) Pa. Wide Blk., partially wide, medial border 3 cm contralateral, blocked posterior border tapered inferiorly below 5th rib (48 Gy/28 fractions). Anterior electron (5) Direct IMC: direct internal mammary chain (40 Gy/10 fractions); (6) Oblq CW: oblique chest wall (48 Gy/26 fractions); and (7) Direct CW: direct chest wall (52 Gy/24 fractions). Abbreviations: LADCA Z left anterior descending coronary artery; LV Z left ventricle; RCA Z right coronary artery.