Increase in Superficial Dose in Whole-Breast Irradiation With Halcyon Straight-Through Linac Compared With Traditional C-arm Linac With Flattening Filter: In vivo Dosimetry and Planning Study
| Autor: | Lei Dong, Andrew R. Barsky, James M. Metz, Sasa Mutic, Gary M. Freedman, Neil K. Taunk, Shibu Anamalayil, Bin Cai, C. Kennedy, Eric Laugeman, Taoran Li, Fionnbarr O'Grady, Geoffrey D. Hugo |
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| Rok vydání: | 2020 |
| Předmět: |
lcsh:Medical physics. Medical radiology. Nuclear medicine
Dosimeter Optically stimulated luminescence business.industry lcsh:R895-920 medicine.medical_treatment lcsh:Neoplasms. Tumors. Oncology. Including cancer and carcinogens lcsh:RC254-282 Linear particle accelerator Imaging phantom 030218 nuclear medicine & medical imaging Radiation therapy 03 medical and health sciences 0302 clinical medicine Oncology Whole Breast Irradiation 030220 oncology & carcinogenesis medicine Radiology Nuclear Medicine and imaging Physics Contribution Radiation treatment planning Nuclear medicine business Bolus (radiation therapy) |
| Zdroj: | Advances in Radiation Oncology Advances in Radiation Oncology, Vol 5, Iss 1, Pp 120-126 (2020) |
| ISSN: | 2452-1094 |
| Popis: | Purpose Superficial dose is an important parameter in breast cancer radiation therapy. When treated with conventional linacs, bolus is commonly applied to improve target coverage near the surface while also managing the risk of severe skin reactions and negative cosmesis. With the introduction of modern linacs with 6X flattening filter free (FFF) photon beams, the effect on superficial dose and the need for bolus must be evaluated. Methods and Materials In vivo measurements of superficial dose were made with optically stimulated luminescence dosimeters on 11 breast cancer patients treated with the Halcyon 6X FFF linac (Varian Medical Systems, Palo Alto, CA). Additionally, measurements were made with the Halycon 6X FFF beam and a 6X beam with flattening filter (FF) delivered to an anthropomorphic phantom. A planning study was carried out in which 14 patients treated on the Halcyon were replanned with a conventional linac to determine the difference in superficial dose predicted by the treatment planning system. Measures were taken to increase the accuracy of the treatment planning system superficial dose. Results The use of the Halcyon 6X FFF beam led to higher superficial dose compared with 6X FF beams. The in vivo measurements show an average superficial dose of 83.8% ± 0.6%, which is an increase of approximately 10% compared with published measurements for a 6X FF linac. Comparison of superficial dose for 6X FF and 6X FFF beams in the phantom measurements show an increase from 70% ± 1.3% to 84% ± 1.3%, which is consistent with the in vivo measurements. The planning comparison shows an increase in V70%Rx from 62% ± 4.4% to 81% ± 2.2% for the superficial breast tissue for the Halcyon 6X FFF beam compared with a standard C-arm linac with FF. Conclusions The use of the Halcyon 6X FFF beam was associated with higher superficial dose which may obviate the use of bolus. |
| Databáze: | OpenAIRE |
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