Influence of intrafraction motion on margins for prostate radiotherapy

Litzenberg, Dale W.; Balter, James M.; Hadley, Scott; Sandler, Howard M.; Willoughby, Twyla R.; Kupelian, Patrick A.; Levine, L.

doi:10.1016/j.ijrobp.2005.12.033

Cited by 198 publications

(163 citation statements)

References 34 publications

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“…The first reported clinical investigations of FFF referred to radiosurgery1 and aimed for shorter treatment times. A reduction of the treatment time reduces the probability of intrafraction motion of the target and organs at risk, which has been demonstrated to be not negligible for the treatment of prostate cancer 2, 3, 4, 5, 6, 7, 8. Another property of FFF is the diminution of head scatter, as the flattening filter is one of its main sources 9, 10.…”

Section: Introductionmentioning

confidence: 99%

Volumetric‐modulated arc therapy and intensity‐modulated radiation therapy treatment planning for prostate cancer with flattened beam and flattening filter free linear accelerators

Treutwein¹,

Hipp

Koelbl³

et al. 2017

J Applied Clin Med Phys

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This study on patients with localized prostate cancer was set up to investigate valuable differences using flattened beam (FB) and flattening filter free (FFF) mode in the application of intensity‐modulated radiotherapy (IMRT) and volumetric‐modulated arc therapy (VMAT). For ten patients, four different plans were calculated with Oncentra planning system of Elekta, using Synergy machines: IMRT and VMAT, with and without flattening filter. Homogeneity and conformity indexes, dose to the organs at risk, and measurements of peripheral dose and dosimetric plan verification including record of the delivery times were analyzed and statistically evaluated. The indexes for homogeneity and conformity (CTV and PTV) are either advantageous or not significantly different for FFF compared to FB with one minor exception. Regarding the doses to the organs at risk and the measured peripheral dose, equivalent or lower doses were delivered for FFF than with FB. Furthermore, the delivery times were significantly shorter for FFF. VMAT compared to IMRT reveals benefits or at least equivalent values. VMAT‐FFF combines the most advantageous plan quality parameters with the shortest delivery times and reduced peripheral dose and is therefore recommended for the given equipment and cancer localization.

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Section: Introductionmentioning

confidence: 99%

Volumetric‐modulated arc therapy and intensity‐modulated radiation therapy treatment planning for prostate cancer with flattened beam and flattening filter free linear accelerators

Treutwein¹,

Hipp

Koelbl³

et al. 2017

J Applied Clin Med Phys

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“…Langen et al found that for individual patients, the maximal value of displacements > 3 mm at 5 and 10 min after initial positioning were 43% and 75%, respectively (10). Litzenberg et al reported that for skin-based setup with inclusion of an intra-fraction motion, prostate treatments required average margins of 10.2, 12.5 and 8.2 mm in the anterior-posterior, cranial-caudal and left-right directions, respectively (11). They suggested that positioning by prostate electromagnetic markers at the start of the treatment fraction reduced these values to 1.8, 5.8, and 7.1 mm, respectively.…”

Section: Introductionmentioning

confidence: 99%

“…Most strikingly, they suggested that "interport adjustment" would further reduce margins to an average of 1.4, 2.3, and 1.8 mm. (11).…”

Section: Introductionmentioning

confidence: 99%

Use of Implanted Markers and Interportal Adjustment With Real-Time Tracking Radiotherapy System to Reduce Intrafraction Prostate Motion

Shimizu

Osaka

Shinohara

et al. 2011

International Journal of Radiation Oncology*Biology*Physics

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Purpose: Interportal adjustment was applied to patients with prostate cancer using three fiducial markers and two sets of fluoroscopy in a real-time tumor-tracking radiotherapy (RTRT) system. The incidence of table position adjustment required to keep intrafractional uncertainty within 2.0 mm was investigated in this study. Methods and Materials:The coordinates of the center of gravity of the three fiducial markers were measured at the start of every portal irradiation in intensity-modulated radiotherapy (IMRT) with seven ports. The table position was adjusted to the planned position if the discrepancy was larger than 2.0 mm in the anterior-posterior (AP), cranio-caudal (CC), or left-right (LR) directions. In total, we analyzed 4541 observations in 20 patients who received 70 Gy in 30 fractions (7.6 times a day in average). Results:The incidence of table position adjustment at 10 minutes from the initial set-up of each treatment was 14.2%, 12.3%, and 5.0% of the observations in the AP, CC, and LR directions, respectively. The accumulated incidence of the table position adjustment was significantly higher at 10 minutes compared to that at 2 minutes for AP (p=0.0033) and CC (p=0.0110) but not LR (p=0.4296). An adjustment greater than 5 mm was required at least once in the treatment period in 11 (55%) patients. Conclusions:Interportal adjustment of table position was required in more than 10% of portal irradiations during the 10-minute period after initial set-up to maintain treatment accuracy within 2.0 mm.

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“…Other studies have looked at inter‐ and intrafraction motion of the prostate, but all of them assume that the interfraction deformation is minimal or dosimetrically irrelevant 15 , 16 , 17 , 21 , 28 . For standard cases, this assumption holds true, but when a particular area of the prostate is receiving an escalated dose, interfraction deformation can influence the tumor control and the normal tissue complications.…”

Section: Discussionmentioning

confidence: 99%

“…Standard prostate radiotherapy accounts for these inter‐ and intrafraction motions by including a 3‐8 mm margin around the prostate to create the planning target volume (PTV). These margins are well established, and account for the random and systematic errors involved in setting up the patient and prostate motion on a daily basis 17 , 19 , 20 , 21 …”

Section: Introductionmentioning

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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Influence of intrafraction motion on margins for prostate radiotherapy

Cited by 198 publications

References 34 publications

Volumetric‐modulated arc therapy and intensity‐modulated radiation therapy treatment planning for prostate cancer with flattened beam and flattening filter free linear accelerators

Volumetric‐modulated arc therapy and intensity‐modulated radiation therapy treatment planning for prostate cancer with flattened beam and flattening filter free linear accelerators

Use of Implanted Markers and Interportal Adjustment With Real-Time Tracking Radiotherapy System to Reduce Intrafraction Prostate Motion

Quantification of the margin required for treating intraprostatic lesions

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