Abstract:
:Breast treatments are becoming increasingly complex as the use of modulated and partial breast therapies becomes more prevalent. These methods are predicated on accurate and precise positioning for treatment. However, the ability to quantify intrafraction motion has been limited by the excessive dose that would result from continuous X-ray imaging throughout treatment. Recently, surface imaging has offered the opportunity to obtain 3D measurements of patient position throughout breast treatments without radiation exposure. Thirty free-breathing breast patients were monitored with surface imaging for 831 monitoring sessions. Mean translations and rotations were calculated over each minute, each session, and over all sessions combined. The percentage of each session that the root mean squares (RMS) of the linear translations were outside of defined tolerances was determined for each patient. Correlations between mean translations per minute and time, and between standard deviation per minute and time, were evaluated using Pearson's r value. The mean RMS translation averaged over all patients was 2.39 mm ± 1.88 mm. The patients spent an average of 34%, 17%, 9%, and 5% of the monitoring time outside of 2 mm, 3 mm, 4 mm, and 5 mm RMS tolerances, respectively. The RMS values averaged over all patients were 2.71 mm ± 1.83 mm, 2.76 ± 2.27, and 2.98 mm ± 2.30 mm over the 5th, 10th, and 15th minutes of monitoring, respectively. The RMS values (r = 0.73, p = 0) and standard deviations (r = 0.88, p = 0) over all patients showed strong significant correlations with time. We see that the majority of patients' treatment time is spent within 5 mm of the isocenter and that patient position drifts with increasing treatment time. Treatment length should be consid- ered in the planning process. An 8 mm margin on a target volume would account for 2 SDs of motion for a treatment up to 15 minutes in length.
journal_name
J Appl Clin Med Physjournal_title
Journal of applied clinical medical physicsauthors
Wiant DB,Wentworth S,Maurer JM,Vanderstraeten CL,Terrell JA,Sintay BJdoi
10.1120/jacmp.v15i6.4957subject
Has Abstractpub_date
2014-11-08 00:00:00pages
4957issue
6issn
1526-9914journal_volume
15pub_type
杂志文章abstract::We report on initial patient studies to evaluate the performance of a commercial respiratory gating radiotherapy system. The system uses a breathing monitor, consisting of a video camera and passive infrared reflective markers placed on the patient's thorax, to synchronize radiation from a linear accelerator with the ...
journal_title:Journal of applied clinical medical physics
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journal_title:Journal of applied clinical medical physics
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