Three-Dimensional Intrafractional Motion of Breast During Tangential Breast Irradiation Monitored With High-Sampling Frequency Using a Real-Time Tumor-Tracking Radiotherapy System

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 2.39.15emmm±1.88.15emmm. 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 2.71.15emmm±1.83.15emmm, 2.76±2.27, and 2.98.15emmm±2.30.15emmm 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 considered 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.PACS numbers: 87.53.Jw, 87.53.Kn, 87.56.Da, 87.63.L‐

“…This is in good agreement with the mean RMS displacement from isocenter of

2.39 mm \pm 1.88 mm

Section: Discussionsupporting

confidence: 89%

~ 3 mm

of intrafraction motion (25) . This is in good agreement with the mean RMS displacement from isocenter of

2.39 mm \pm 1.88 mm

found in this work.…”

Section: Discussionsupporting

confidence: 82%

Surface imaging‐based analysis of intrafraction motion for breast radiotherapy patients

Wiant

Wentworth

Mäurer

et al. 2014

“…However, plan II uses full IMRT without considering the effect of target movement caused by respiration on dose distribution. Research has shown a maximum front–back error totaling 0.2–0.3 cm 7, 34. This value is related to breast attachment to external chest walls, large body movement, and significant changes in irradiation positions caused by different rising degrees of the arms.…”

Section: Discussionmentioning

confidence: 99%

“…The common clinical two‐side tangent field radiotherapy exhibits an uneven irradiation dose in the target region and high irradiation doses to key organs, such as the heart and lungs. Fixed‐field intensity‐modulated radiation therapy (IMRT) shows significant advantages in improving irradiation dose distribution in the target region and reducing irradiation dose in surrounding normal tissues 6, 7, 8. However, IMRT expands low‐volume irradiation region of normal tissues and increases irradiation doses to the lungs and breasts at the healthy side 9, 10, 11, 12.…”

Section: Introductionmentioning

confidence: 99%

Dosimetric comparison of three intensity‐modulated radiation therapies for left breast cancer after breast‐conserving surgery

Zhang

Xie

et al. 2018

PurposeThis study aimed to evaluate dosimetric differences of intensity‐modulated radiation therapy (IMRT) in target and normal tissues after breast‐conserving surgery.MethodsIMRT five‐field plan I, IMRT six‐field plan II, and field‐in‐field–direct machine parameter optimization–IMRT plan III were designed for each of the 50 patients. One‐way analysis of variance was performed to compare differences, and P < 0.05 was considered statistically significant.ResultsHomogeneity index of plan III is lower than those of plans I and II. No difference was identified in conformity index of targets. Plan I exhibited difference in mean dose (D mean) for the heart (P < 0.05). Plan I featured smaller irradiation dose volumes in V 5, V 20 (P < 0.05) of the left lung than II. Plan I exhibited significantly higher V 5 in the right lung than plans II and III (P < 0.05). Under plan I, irradiation dose at V 5 in the right breast is higher than that in plans II and III. Patients in plan III presented less total monitor unit and total treatment time than those in plans I and II (P < 0.05).ConclusionIMRT six‐field plans II, and field‐in‐field–direct machine parameter optimization–IMRT plans III can reduce doses and volumes to the lungs and heart better while maintaining satisfying conformity index and homogeneity index of target. Nevertheless, plan II neglects target movements caused by respiration. In the same manner, plan III can substantially reduce MU and shorten patient treatment time. Therefore, plan III, which considers target movement caused by respiration, is a more practical radiation mode.

“…Anzai (Anzai Medical, Tokyo, Japan) has recently released a near‐field laser sensor but no data or studies have yet been published 8. There have also been reports on several other systems for DIBH treatments like cine electronic imaging, infrared reflector systems, leveling marks, voluntary DIBH, breathing stick, magnets and stretching belts 9, 10, 11, 12, 13…”

Section: Introductionmentioning

confidence: 99%

Development of a deep inspiration breath‐hold system for radiotherapy utilizing a laser distance measurer

Jensen

Skottner

Frengen

et al. 2016

Deep inspiration breath‐hold (DIBH) is a technique for treating left‐sided breast cancer (LSBC). In modern radiotherapy, one of the main aims is to exclude the heart from the beam aperture with an individualized beam design for LSBC. A deep inhalation will raise the chest wall while the volume of the lungs increase, this will again push the heart away from the breast to be treated. There are a few commercial DIBH systems, both invasive and noninvasive. We present an alternative noninvasive DIBH system based upon an industrial laser distance measurer. This system can be installed in a treatment room at a low cost; it is very easy to use and requires limited amount of training for the personnel and the patient. The system is capable of measuring the position of the chest wall with high frequency and precision in real time. The patient views its breathing curve through video glasses, and gets instructions during the treatment session. The system is well tolerated by test subjects due to its noninvasiveness.