Assessment of Planning Target Volume Margins for Intensity-Modulated Radiotherapy of the Prostate Gland: Role of Daily Inter- and Intrafraction Motion

Tanyi, James A.; He, T.; Summers, P.; Mburu, Ruth G.; Kato, Catherine; Rhodes, S.; Hung, Arthur; Fuß, Martin

doi:10.1016/j.ijrobp.2010.02.001

Cited by 76 publications

(64 citation statements)

References 29 publications

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“…Interfraction motion will not cause blurring in a given fraction; rather, the total accumulated dose distribution will be blurred. To characterize and minimize the interfraction motion, various daily localization techniques have been developed, such as surface fiducial or 3-point surface alignment, implanted fiducial, or bony landmark with on board imaging, ultrasound, and kV/mV CBCT (3)(4)(5). Meanwhile, the daily intrafraction motion also plays an essential role in determining treatment planning margin (6), and may be a function of how frequent the prostate motion is sampled during a course of treatment (7).…”

Section: Introductionmentioning

confidence: 99%

The Non-Gaussian Nature of Prostate Motion Based on Real-Time Intrafraction Tracking

Lin

Liu

Yang

et al. 2013

International Journal of Radiation Oncology*Biology*Physics

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Purpose-The objective of this work is to test the validity of the Gaussian approximation for prostate motion through characterization of its spatial distribution.Methods and Materials-Real-time intrafraction prostate motion was observed using Calypso 4-dimensional (4D) nonradioactive electromagnetic tracking system. We report the results from a total of 1024 fractions from 31 prostate cancer patients. First, the correlation of prostate motion in right/left (RL), anteroposterior (AP), and superoinferior (SI) direction were determined using Pearson's correlation of coefficient. Then the spatial distribution of prostate motion was analyzed for individual fraction, individual patient including all fractions, and all patients including all fractions. The displacement in RL, AP, SI, oblique, or total direction is fitted into a Gaussian distribution, and a Lilliefors test was used to evaluate the validity of the hypothesis that the displacement is normally distributed.Results-There is high correlation in AP/SI direction (61% of fractions with medium or strong correlation). This is consistent with the longitudinal oblique motion of the prostate, and likely the effect from respiration on an organ confined within the genitourinary diaphragm with the rectum sitting posteriorly and bladder sitting superiorly. In all directions, the non-Gaussian distribution is more common for individual fraction, individual patient including all fractions, and all patients including all fractions. The spatial distribution of prostate motion shows an elongated shape in oblique direction, indicating a higher range of motion in the AP and SI directions.Conclusions-Our results showed that the prostate motion is highly correlated in AP and SI direction, indicating an oblique motion preference. In addition, the spatial distribution of prostate motion is elongated in an oblique direction, indicating that the organ motion dosimetric modeling

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Section: Introductionmentioning

confidence: 99%

The Non-Gaussian Nature of Prostate Motion Based on Real-Time Intrafraction Tracking

Lin

Liu

Yang

et al. 2013

International Journal of Radiation Oncology*Biology*Physics

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“…Utilizing the no threshold localization, target margins were 3.4, 3.2, and 3.2 mm in the ML, CC, and AP dimensions, respectively [14]. A series of 14 patients receiving prostate IMRT with on-line CBCT correction based on three implanted transponders found that margins required were 1.4, 2.6, and 2.3 mm in the ML, CC, and AP dimensions, respectively, Abbreviations: M p populations mean, σ p populations standard deviation, M μ mean of all patient means, Σ μ standard deviation of the patient means, Σ σ standard deviation of the standard deviation for each patient, RMS (σ) root mean square of σ with traditional dose per fractions utilized [15]. Further, as mentioned previously, analysis of 47 patients receiving hypofractionated prostate radiation therapy with implanted fiducials found target margins of 1.4, 1.9, and 2.0 mm in the ML, AP, and CC dimensions, respectively, using portal imaging [16].…”

Section: Discussionmentioning

confidence: 99%

Determinants of intrafraction variation during image-guided hypofractionated radiotherapy of the prostate

et al. 2012

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Purpose The purpose of this study is to examine intrafraction variation and residual error (IFV+RE) during conebeam CT (CBCT)-guided hypofractionated prostate radiotherapy and evaluate factors associated along with target margins. Materials and methods Forty-six patients underwent hypofractionated prostate radiotherapy receiving 64 Gy in 20 fractions with on-line CBCT correction. Analysis of factors associated with IFV+RE including patient characteristics, treatment characteristics, and organ volumes was performed using univariate and multivariate analyses. Results The mean IFV+RE were 0.10±1.1, −1.1±2.5, and −1.5 ±2.7 mm in the mediolateral (ML), anteroposterior (AP), and craniocaudad (CC) dimensions, respectively. The IFV+RE vector was 3.5±2.5 mm. It was found that 1, 22, and 31 % of fractions had an IFV+RE greater than 3 mm in the ML, AP, and CC dimensions, respectively. Multivariate analysis found that age and rectal volumes are associated with increased IFV+RE. When evaluating IFV+RE greater than 3 mm, age, treatment time, and rectal volumes were associated. A treatment time of greater than 16.5 min was found to be a cut point for increased IFV+RE. Conclusions IFV may represent a significant component of target margins utilized in hypofractionated prostate radiotherapy with target margins exceeding 3 mm in the CC and AP dimensions. Rectal volumes, treatment time, and age are associated with IFV+RE.

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“…In addition, there are well‐established systematic (

\sum_{setup}

) and random (

σ_{setup}

) errors in patient setup and prostate motion that must be accounted for during planning and treatment delivery. Values for

\sum_{setup}

and

σ_{setup}

have been previously published using similar daily image guidance (without an endorectal balloon) 20 , 24 , 25 . Taking an average of these studies,

\sum_{setup}

was 0.82 mm, 0.97 mm, and 1.19 mm in the LR, AP, and SI directions, respectively, and

σ_{setup}

was 1.46 mm, 2.14 mm, and 1.74 mm in the LR, AP, and SI directions, respectively.…”

Section: Methodsmentioning

confidence: 99%

Quantification of the margin required for treating intraprostatic lesions

Studenski

Valenciaga

Abramowitz

et al. 2016

J Applied Clin Med Phys

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Advances in magnetic resonance imaging (MRI) sequences allow physicians to define the dominant intraprostatic lesion (IPL) in prostate radiation therapy treatments allowing for dose escalation and potentially increased tumor control. This work quantifies the margin required around the MRI‐defined IPL accounting for both prostate motion and deformation. Ten patients treated with a simultaneous integrated intraprostatic boost (SIIB) were retrospectively selected and replanned with incremental 1 mm margins from 0‐5 mm around the IPL to determine if there were any significant differences in dosimetric parameters. Sensitivity analysis was then performed accounting for random and systematic uncertainties in both prostate motion and deformation to ensure adequate dose was delivered to the IPL. Prostate deformation was assessed using daily CBCT imaging and implanted fiducial markers. The average IPL volume without margin was 2.3% of the PTV volume and increased to 11.8% with a 5 mm margin. Despite these changes in volume, the only statistically significant dosimetric difference was found for the PTV maximum dose, which increased with increasing margin. The sensitivity analysis demonstrated that a 3.0 mm margin ensures >95% IPL coverage accounting for both motion and deformation. We found that a margin of 3.0 mm around the MRI defined IPL is sufficient to account for random and systematic errors in IPL position for the majority of cases.PACS number(s): 87.55.de

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Assessment of Planning Target Volume Margins for Intensity-Modulated Radiotherapy of the Prostate Gland: Role of Daily Inter- and Intrafraction Motion

Cited by 76 publications

References 29 publications

The Non-Gaussian Nature of Prostate Motion Based on Real-Time Intrafraction Tracking

The Non-Gaussian Nature of Prostate Motion Based on Real-Time Intrafraction Tracking

Determinants of intrafraction variation during image-guided hypofractionated radiotherapy of the prostate

Quantification of the margin required for treating intraprostatic lesions

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