The first clinical treatment with kilovoltage intrafraction monitoring (KIM): A real‐time image guidance method

Keall, Paul J.; Ng, Jin Aun; O’Brien, Ricky; Colvill, Emma; Huang, Chen-Yu; Poulsen, Per Rugaard; Fledelius, Walther; Juneja, Prabhjot; Simpson, Emma; Bell, Linda; Alfieri, Florencia; Eade, Thomas; Kneebone, Andrew; Booth, Jeremy

doi:10.1118/1.4904023

Cited by 71 publications

(75 citation statements)

References 24 publications

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“…The geometrical accuracy of KIM has been established, and the software has successfully been used to measure prostate displacement during treatment in noninterventional17 and interventional studies 18…”

Section: Introductionmentioning

confidence: 99%

Real‐time intrafraction prostate motion during linac based stereotactic radiotherapy with rectal displacement

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Nguyen

et al. 2017

J Applied Clin Med Phys

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BackgroundKilovoltage Intrafraction Monitoring (KIM) is a method which determines the three‐dimensional position of the prostate from two‐dimensional kilovoltage (kV) projections taken during linac based radiotherapy treatment with real‐time feedback. Rectal displacement devices (RDDs) allow for improved rectal dosimetry during prostate cancer treatment. This study used KIM to perform a preliminary investigation of prostate intrafraction motion observed in patients with an RDD in place.MethodsTen patients with intermediate to high‐risk prostate cancer were treated with a Rectafix RDD in place during two boost fractions of 9.5–10 Gy delivered using volumetric modulated arc therapy (VMAT) on Clinac iX and Truebeam linacs. Two‐dimensional kV projections were acquired during treatment. KIM software was used following treatment to determine the displacement of the prostate over time. The displacement results were analyzed to determine the percentage of treatment time the prostate spent within 1 mm, between 1 and 2 mm, between 2 and 3 mm and greater than 3 mm from its initial position.Results KIM successfully measured displacement for 19 prostate stereotactic boost fractions. The prostate was within 1 mm of its initial position for 84.8%, 1–2 mm for 14%, 2–3 mm 1.2% and ≥3 mm only 0.4% of the treatment time.ConclusionsIn this preliminary study using KIM, KIM was successfully used to measure prostate intrafraction motion, which was found to be small in the presence of a rectal displacement device.Trial registrationThe Hunter New England Human Research Ethics Committee reference number is 14/08/20/3.01.

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Section: Introductionmentioning

confidence: 99%

Real‐time intrafraction prostate motion during linac based stereotactic radiotherapy with rectal displacement

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Nguyen

et al. 2017

J Applied Clin Med Phys

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“…KIM determines the position of the prostate in three dimensions from 2D kV projections using a probability density function 9, 10. KIM has successfully been used to measure prostate displacement during treatment in retrospective11 and interventional studies 12…”

Section: Introductionmentioning

confidence: 99%

Technical note: TROG 15.01 SPARK trial multi‐institutional imaging dose measurement

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Greer

Keall

et al. 2017

J Applied Clin Med Phys

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PurposeThe Trans‐Tasman Radiation Oncology Group (TROG) 15.01 Stereotactic Prostate Adaptive Radiotherapy utilizing Kilovoltage intrafraction monitoring (SPARK) trial is a multicenter trial using Kilovoltage Intrafraction Monitoring (KIM) to monitor prostate position during the delivery of prostate radiation therapy. KIM increases the accuracy of prostate radiation therapy treatments and allows for hypofractionation. However, an additional imaging dose is delivered to the patient. A standardized procedure to determine the imaging dose per frame delivered using KIM was developed and applied at four radiation therapy centers on three different types of linear accelerator.MethodsDose per frame for kilovoltage imaging in fluoroscopy mode was measured in air at isocenter using an ion chamber. Beam quality and dose were determined for a Varian Clinac iX linear accelerator, a Varian Trilogy, four Varian Truebeams and one Elekta Synergy at four different radiation therapy centers. The imaging parameters used on the Varian machines were 125 kV, 80 mA, and 13 ms. The Elekta machine was measured at 120 kV, 80 mA, and 12 ms. Absorbed doses to the skin and the prostate for a typical SBRT prostate treatment length were estimated according to the IPEMB protocol.ResultsThe average dose per kV frame to the skin was 0.24 ± 0.03 mGy. The average estimated absorbed dose to the prostate for all five treatment fractions across all machines measured was 39.9 ± 2.6 mGy for 1 Hz imaging, 199.7 ± 13.2 mGy for 5 Hz imaging and 439.3 ± 29.0 mGy for 11 Hz imaging.ConclusionsAll machines measured agreed to within 20%. Additional dose to the prostate from using KIM is at most 1.3% of the prescribed dose of 36.25 Gy in five fractions delivered during the trial.

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“…Each patient had three implanted markers. Both the KIM [9,15] and Calypso® [19] systems have been reported to have sub-millimetre accuracy. In both trials, the motion of the centroid of the implanted markers, with no corrections, was used as a surrogate for intrafraction prostate motion.…”

Section: Patient Cohortmentioning

confidence: 99%

“…The KIM technology uses kV fluoroscopy to monitor, in real-time, the 3D position of three radio-opaque markers implanted into the prostate target [9,15]. It uses 2D X-ray images to accurately estimate the 3D target position at 5-10 Hz during the treatment delivery [18].…”

Section: Patient Cohortmentioning

confidence: 99%

Quantification of intrafraction prostate motion and its dosimetric effect on VMAT

Juneja

Colvill

Kneebone

et al. 2017

Australas Phys Eng Sci Med

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Compliance with ethical standards Conflict of interestRoyal North Shore Hospital has a collaborative research agreement with Varian Medical Systems to support Calypso® and Kilovoltage intrafraction monitoring (KIM) clinical trials. PK holds part ownership of the patent, between Stanford University and Varian Medical Systems, on KIM technology. Ethical approvalAll procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.Intrafraction prostate motion degrades the accuracy of radiation therapy (RT) delivery. Whilst a number of metrics in the literature have been used to quantify intrafraction prostate motion, it has not been established whether these metrics reflect the effect of motion on the RT dose delivered to the patients. In this study, prostate motion during volumetric modulated arc therapy (VMAT) treatment of 18 patients and a total of 294 fractions was quantified through novel metrics as well as those available in the literature. The impact of the motion on VMAT dosimetry was evaluated using these metrics and dose reconstructions based on a previously validated and published method. The dosimetric impact of the motion on planning target volume (PTV) and clinical target volume (CTV) coverage and organs at risk (OARs) was correlated with the motion metrics, using the coefficient of determination (R 2 ), to evaluate their utility. Action level threshold for the prostate motion metric that best described the dosimetric impact on the PTV D95% was investigated through iterative regression analysis. The average (range) of the mean motion for the patient cohort was 1.5 mm (0.3-9.9 mm). A number of motion metrics were found to be strongly correlated with PTV D95%, the range of R 2 was 0.43-0.81. For all the motion measures, correlations with CTV D99% (range of R 2 was 0.12-0.62), rectum V65% (range of R 2 was 0.33-0.58) and bladder V65% (range of R 2 was 0.51-0.69) were not as strong as for PTV D95%. The mean of the highest 50% of motion metric was one of the best indicator of dosimetric impact on PTV D95%. Action level threshold value for this metric was found to be 3.0 mm. For an individual fraction, when the metric value was greater than 3.0 mm then the PTV D95% was reduced on average by 6.2%. This study demonstrated that several motion metrics are well correlated with the dosimetric impact (PTV D95%) of individual fraction prostate motion on VMAT delivery and could be used for treatment course adaptation.

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The first clinical treatment with kilovoltage intrafraction monitoring (KIM): A real‐time image guidance method

Cited by 71 publications

References 24 publications

Real‐time intrafraction prostate motion during linac based stereotactic radiotherapy with rectal displacement

Real‐time intrafraction prostate motion during linac based stereotactic radiotherapy with rectal displacement

Technical note: TROG 15.01 SPARK trial multi‐institutional imaging dose measurement

Quantification of intrafraction prostate motion and its dosimetric effect on VMAT

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