Keywords:
Breast, Radioprotection / Radiation dose, Cardiac, CT, CT-High Resolution, Radiation therapy / Oncology, Complications, Radiation effects, Cancer, Dosimetric comparison, Image guided radiotherapy
Authors:
A. Parasuramar, M. Borg, A. DeSmit; SA/AU
DOI:
10.1594/ranzcr2017/R-0124
Methods and materials
Selection criteria involved women who were 70 years old or less,
of performance status 0 or 1,
with left sided breast cancer.
Patients with poor function were excluded.
They had to be fluent in English,
had no hearing impairments and must be able to fit through the planning CT scan (size dependent).
20 patients in total were selected,
10 assigned to ABC and 10 assigned to VBH.
Of the ABC cohort patients were able to receive adjuvant left breast or chest wall irradiation,
and where indicated: supraclavicular,
axillary,
or internal mammary nodal (IMC) irradiation.
VBH patients were only able to receive left breast or chest wall radiotherapy as we were unable to ensure an accurate setup in those patients that were recommended nodal irradiation.
Two comparable techniques were introduced - Active Breathing Coordinator (using specialised Elekta equipment) and Voluntary Breath Hold (without equipment following the Bartlett et al.
protocol) (15).
The Elekta ABC device is a mouthpiece attached to a spirometer,
the patient’s nose is pegged to prevent nasal respiration.
The radiotherapist is then able to monitor the patient’s inspiration volume and when it has reached a predetermined threshold pinch-valves activate to prevent the patient from exhaling or inhaling and the radiation dose is administered.
Refer to Figures 1-3.
VBH was performed following the Bartlett et al.
Protocol using tattoos,
reference markers and light fields.
All twenty patients underwent two CT simulation scans one in ‘Free Breathing (FB)’ and the other in ‘Breath-Hold’ (ABC or VBH).
Treatment plans were generated using a tangential radiation therapy technique.
A dosimetric comparison was made between the two plans for the heart,
left lung and contralateral breast as per EviQ guidelines (16,17).
Measurements were collected for Lung V20 (%),
Ipsilateral Lung Maximum Depth (cm),
Heart V25 (%),
Heart (Gy),
and Contralateral Breast V3 (%).
9 patients had LAD mean values measured.
Comparison was made,
firstly,
for FB against DIBH and then for ABC against VBH.