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Variable dose interplay effects across radiosurgical apparatus in treating multiple brain metastases.

Ma L, Nichol A, Hossain S, Wang B, Petti P, Vellani R, Higby C, Ahmad S, Barani I, Shrieve DC, Larson DA, Sahgal A - Int J Comput Assist Radiol Surg (2014)

Bottom Line: All treatment plans were developed at individual centers, and the results were centrally analyzed.We found that dose-volume constraints were satisfied by each apparatus with some differences noted in certain structures such as the lens.Treatment times were shortest with TrueBeam FFF.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiation Oncology, University of California, San Francisco, 505 Parnassus Avenue, Room L-08, San Francisco, CA , 94143, USA, lijunma@radonc.ucsf.edu.

ABSTRACT

Purpose: Normal brain tissue doses have been shown to be strongly apparatus dependent for multi-target stereotactic radiosurgery. In this study, we investigated whether inter-target dose interplay effects across contemporary radiosurgical treatment platforms are responsible for such an observation.

Methods: For the study, subsets ([Formula: see text] and 12) of a total of 12 targets were planned at six institutions. Treatment platforms included the (1) Gamma Knife Perfexion (PFX), (2) CyberKnife, (3) Novalis linear accelerator equipped with a 3.0-mm multi-leaf collimator (MLC), and the (4) Varian Truebeam flattening-filter-free (FFF) linear accelerator also equipped with a 2.5 mm MLC. Identical dose-volume constraints for the targets and critical structures were applied for each apparatus. All treatment plans were developed at individual centers, and the results were centrally analyzed.

Results: We found that dose-volume constraints were satisfied by each apparatus with some differences noted in certain structures such as the lens. The peripheral normal brain tissue doses were lowest for the PFX and highest for TrueBeam FFF and CyberKnife treatment plans. Comparing the volumes of normal brain receiving 12 Gy, TrueBeam FFF, Novalis, and CyberKnife were 180-290 % higher than PFX. The mean volume of normal brain-per target receiving 4-Gy increased by approximately 3.0 cc per target for TrueBeam, 2.7 cc per target for CyberKnife, 2.0 cc per target for Novalis, and 0.82 cc per target for PFX. The beam-on time was shortest with the TrueBeam FFF (e.g., 6-9 min at a machine output rate of 1,200 MU/min) and longest for the PFX (e.g., 50-150 mins at a machine output rate of 350 cGy/min).

Conclusion: The volumes of normal brain receiving 4 and 12 Gy were higher, and increased more swiftly per target, for Linac-based SRS platforms than for PFX. Treatment times were shortest with TrueBeam FFF.

No MeSH data available.


Comparison of the normal beam-on time for treatment plans with , and 12 targets respectively. The four SRS modalities are denoted as:  Gamma Knife Perfexion,  CyberKnife,  Novalis,  flattening filter free Truebeam
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Fig4: Comparison of the normal beam-on time for treatment plans with , and 12 targets respectively. The four SRS modalities are denoted as: Gamma Knife Perfexion, CyberKnife, Novalis, flattening filter free Truebeam

Mentions: The treatment beam-on time for each modality is also plotted in Fig. 4. From the results of Fig. 4, Gamma Knife PFX produced the longest beam-on time, while Truebeam FFF produced the shortest beam-on time. Physically, Gamma Knife PFX delivered treatment at the lowest machine output of 350 cGy/min, while the Truebeam FFF delivery ran at the highest machine output of 1,200 MU/min. Note that the machine output for the Gamma Knife PFX also decreases by approximately 1.1 % per month due to the decay, and the reference dose rate for Cyberknife and Novalis was 800 MU/min in Fig. 4. For the 12-target treatment time as shown in Fig. 4, the treatment time for Cyberknife was found to reach the same level as that of Gamma Knife PFX. This is largely due to the a large number of beam angles required for the Cyberknife cover all the targets simultaneously which in effect lower its dose rate to be comparable to that of Gamma Knife PFX in the clinical version of the planning software [5, 8].Fig. 4


Variable dose interplay effects across radiosurgical apparatus in treating multiple brain metastases.

Ma L, Nichol A, Hossain S, Wang B, Petti P, Vellani R, Higby C, Ahmad S, Barani I, Shrieve DC, Larson DA, Sahgal A - Int J Comput Assist Radiol Surg (2014)

Comparison of the normal beam-on time for treatment plans with , and 12 targets respectively. The four SRS modalities are denoted as:  Gamma Knife Perfexion,  CyberKnife,  Novalis,  flattening filter free Truebeam
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4215114&req=5

Fig4: Comparison of the normal beam-on time for treatment plans with , and 12 targets respectively. The four SRS modalities are denoted as: Gamma Knife Perfexion, CyberKnife, Novalis, flattening filter free Truebeam
Mentions: The treatment beam-on time for each modality is also plotted in Fig. 4. From the results of Fig. 4, Gamma Knife PFX produced the longest beam-on time, while Truebeam FFF produced the shortest beam-on time. Physically, Gamma Knife PFX delivered treatment at the lowest machine output of 350 cGy/min, while the Truebeam FFF delivery ran at the highest machine output of 1,200 MU/min. Note that the machine output for the Gamma Knife PFX also decreases by approximately 1.1 % per month due to the decay, and the reference dose rate for Cyberknife and Novalis was 800 MU/min in Fig. 4. For the 12-target treatment time as shown in Fig. 4, the treatment time for Cyberknife was found to reach the same level as that of Gamma Knife PFX. This is largely due to the a large number of beam angles required for the Cyberknife cover all the targets simultaneously which in effect lower its dose rate to be comparable to that of Gamma Knife PFX in the clinical version of the planning software [5, 8].Fig. 4

Bottom Line: All treatment plans were developed at individual centers, and the results were centrally analyzed.We found that dose-volume constraints were satisfied by each apparatus with some differences noted in certain structures such as the lens.Treatment times were shortest with TrueBeam FFF.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiation Oncology, University of California, San Francisco, 505 Parnassus Avenue, Room L-08, San Francisco, CA , 94143, USA, lijunma@radonc.ucsf.edu.

ABSTRACT

Purpose: Normal brain tissue doses have been shown to be strongly apparatus dependent for multi-target stereotactic radiosurgery. In this study, we investigated whether inter-target dose interplay effects across contemporary radiosurgical treatment platforms are responsible for such an observation.

Methods: For the study, subsets ([Formula: see text] and 12) of a total of 12 targets were planned at six institutions. Treatment platforms included the (1) Gamma Knife Perfexion (PFX), (2) CyberKnife, (3) Novalis linear accelerator equipped with a 3.0-mm multi-leaf collimator (MLC), and the (4) Varian Truebeam flattening-filter-free (FFF) linear accelerator also equipped with a 2.5 mm MLC. Identical dose-volume constraints for the targets and critical structures were applied for each apparatus. All treatment plans were developed at individual centers, and the results were centrally analyzed.

Results: We found that dose-volume constraints were satisfied by each apparatus with some differences noted in certain structures such as the lens. The peripheral normal brain tissue doses were lowest for the PFX and highest for TrueBeam FFF and CyberKnife treatment plans. Comparing the volumes of normal brain receiving 12 Gy, TrueBeam FFF, Novalis, and CyberKnife were 180-290 % higher than PFX. The mean volume of normal brain-per target receiving 4-Gy increased by approximately 3.0 cc per target for TrueBeam, 2.7 cc per target for CyberKnife, 2.0 cc per target for Novalis, and 0.82 cc per target for PFX. The beam-on time was shortest with the TrueBeam FFF (e.g., 6-9 min at a machine output rate of 1,200 MU/min) and longest for the PFX (e.g., 50-150 mins at a machine output rate of 350 cGy/min).

Conclusion: The volumes of normal brain receiving 4 and 12 Gy were higher, and increased more swiftly per target, for Linac-based SRS platforms than for PFX. Treatment times were shortest with TrueBeam FFF.

No MeSH data available.