Flattening filter‐free linac improves treatment delivery efficiency in stereotactic body radiation therapy. (6th May 2013)

• Record Type: Journal Article
• Authors: Prendergast, Brendan M.; Fiveash, John B.; Popple, Richard A.; Clark, Grant M.; Thomas, Evan M.; Minnich, Douglas J.; Jacob, Rojymon; Spencer, Sharon A.; Bonner, James A.; Dobelbower, Michael C.
• Is Part Of: Journal of applied clinical medical physics. Volume 14:Number 3(2013)
• Page Start: 64
• Page End: 71
• Publication Date: 2013-05-06
• Subjects: lung SBRT -- liver SBRT -- flattening filter‐free -- treatment efficiency -- treatment time; Medical physics -- Periodicals; Clinical medicine -- Periodicals; Health Physics; Clinical Medicine; Electronic journals; Periodicals; Periodicals; Fulltext; Internet Resources; 610.153
• DOI: 10.1120/jacmp.v14i3.4126
• Languages: English
• ISSNs: 1526-9914

Abstract

Abstract : Stereotactic body radiation therapy (SBRT) employs precision target tracking and image‐guidance techniques to deliver ablative doses of radiation to localized malignancies; however, treatment with conventional photon beams requires lengthy treatment and immobilization times. The use of flattening filter‐free (FFF) beams operating at higher dose rates can shorten beam‐on time, and we hypothesize that it will shorten overall treatment delivery time. A total of 111 lung and liver SBRT cases treated at our institution from July 2008 to July 2011 were reviewed and 99 cases with complete data were identified. Treatment delivery times for cases treated with a FFF linac versus a conventional dose rate linac were compared. The frequency and type of intrafraction image guidance was also collected and compared between groups. Three hundred and ninety‐one individual SBRT fractions from 99 treatment plans were examined; 36 plans were treated with a FFF linac. In the FFF cohort, the mean ( ± s t a n d a r d d e v i a t i o n ) treatment time (time elapsed from beam‐on until treatment end) and patient's immobilization time (time from first alignment image until treatment end) was 11.44 ( ± 6.3 ) and 21.08 ( ± 6.8 ) minutes compared to 32.94 ( ± 14.8 ) and 47.05 ( ± 17.6 ) minutes for the conventional cohort ( p < 0.01 for all values). Intrafraction‐computed tomography (CT) was used more often in the conventional cohort (84% vs. 25%; p < 0.05 ), but use of orthogonal X‐ray imaging remained the same (16% vs. 19%). For lung and liver SBRT, a FFF linac reduces treatment and immobilization time by more than 50% compared to a conventional linac. In addition, treatment with a FFF linac is associated with less physician‐ordered image guidance, which contributes to further improvement in treatment delivery efficiency. PACS number: 87.55.‐x