Highlights
- •RayPilot transmitters may migrate within the prostate between treatment fractions.
- •Localization accuracy of the RayPilot suffers from instability of the transmitters.
- •Localization accuracy of Calypso is comparable to kV imaging of fiducials.
Abstract
The aim of this study was to evaluate the localization accuracy of electromagnetic
(EM) tracking systems RayPilot (Micropos Medical AB) and Calypso (Varian Medical Systems)
in prostate cancer radiotherapy. The accuracy was assessed by comparing couch shifts
obtained with the EM methods to the couch shifts determined by simultaneous fiducial
marker (FM) based orthogonal kilovoltage (kV) imaging. Agreement between the methods
was compared using Bland-Altman analysis. Interfractional positional stability of
the FMs, RayPilot transmitters and Calypso transponders was investigated. 582 fractions
from 22 RayPilot patients and 335 fractions from 26 Calypso patients were analyzed.
Mean (± standard deviation (SD)) differences between RayPilot and kV imaging were
0.3 ± 2.2, −2.2 ± 2.4 and −0.0 ± 1.0 mm in anterior-posterior (AP), superior-inferior
(SI) and left-right (LR) directions, respectively. Corresponding 95% limits of agreement
(LOA) were ±4.3, ±4.7 and ±2.1 mm around the mean. Mean (±SD) differences between
Calypso and kV imaging were −0.2 ± 0.6, 0.1 ± 0.5 and −0.1 ± 0.4 mm in AP, SI and
LR directions, respectively, and corresponding LOAs were ±1.3, ±1.0 and ±0.8 mm around
the mean. FMs and transponders were stable: SD of intermarker and intertransponder
distances was 0.5 mm. Transmitters were unstable: mean caudal transmitter shift of
1.8 ± 2.0 mm was observed. Results indicate that the localization accuracy of the
Calypso is comparable to kV imaging of fiducials and the methods could be used interchangeably.
The localization accuracy of the RayPilot is affected by transmitter instability and
the positioning of the patient should be verified by other setup techniques. The study
is part of clinical trial NCT02319239.
Keywords
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References
- Measurement of prostate movement over the course of routine radiotherapy using implanted markers.Int J Radiat Oncol Biol Phys. 1995; 31: 113-118
- Prostate motion during standard radiotherapy as assessed by fiducial markers.Radiother Oncol. 1995; 37: 35-42
- Evaluating the effect of rectal distension and rectal movement on prostate gland position using cine MRI.Int J Radiat Oncol Biol Phys. 1999; 44: 525-533
- Multi-institutional clinical experience with the Calypso system in localization and continuous, real-time monitoring of the prostate gland during external radiotherapy.Int J Radiat Oncol Biol Phys. 2007; 67: 1088-1098
- Observations on real-time prostate gland motion using electromagnetic tracking.Int J Radiat Oncol Biol Phys. 2008; 71: 1084-1090
- Intrafractional prostate motion during external beam radiotherapy monitored by a real-time target localization system.J Appl Clin Med Phys. 2015; 16: 51-61
- Organ motion and its management.Int J Radiat Oncol Biol Phys. 2001; 50: 265-278
- Image guidance in clinical practice – influence of positioning inaccuracy on the dose distribution for prostate cancer.Phys Med. 2018; 46: 81-88
- Predicting toxicity in radiotherapy for prostate cancer.Phys Med. 2016; 32: 521-532
- Bladder spatial-dose descriptors correlate with acute urinary toxicity after radiation therapy for prostate cancer.Phys Med. 2016; 32: 1681-1689
- Comparison of daily megavoltage electronic portal imaging with marker seeds to ultrasound imaging or skin marks for prostate localization and treatment positioning in patients with prostate cancer.Int J Radiat Oncol Biol Phys. 2006; 65: 1585-1592
- An evaluation of the Clarity 3D ultrasound system for prostate localization.J Appl Clin Med Phys. 2012; 13: 100-112
- Evaluation of possible prostate displacement induced by pressure applied during transabdominal ultrasound image acquisition.Strahlenther Oncol. 2006; 182: 240-246
- Prefraction displacement and intrafraction drift of the prostate due to perineal ultrasound probe pressure.Strahlenther Oncol. 2017; 193: 459-465
- Independent verification of ultrasound based image-guided radiation treatment, using electronic portal imaging and implanted gold markers.Med Phys. 2003; 30: 2878-2887
- Comparison of ultrasound and implanted seed marker prostate localization methods: implications for image-guided radiotherapy.Int J Radiat Oncol Biol Phys. 2006; 65: 378-387
- Technical aspects of daily online positioning of the prostate for three-dimensional conformal radiotherapy using and electronic portal imaging device.Int J Radiat Oncol Biol Phys. 2003; 57: 1131-1140
- Analysis of fiducial marker-based position verification in the external beam radiotherapy of patients with prostate cancer.Radiother Oncol. 2007; 82: 38-45
- Fiducial-based translational localization accuracy of electromagnetic tracking system and on-board kilovoltage imaging system.Int J Radiat Oncol Biol Phys. 2008; 70: 892-899
- A comparison of the use of bony anatomy and internal markers for offline verification and an evaluation of the potential benefit of online and offline verification protocols for prostate radiotherapy.Int J Radiat Oncol Biol Phys. 2008; 71: 41-50
- Prostate position relative to pelvic bony anatomy based on intraprostatic gold markers and electronic portal imaging.Int J Radiat Oncol Biol Phys. 2005; 63: 800-811
- Intensity-modulated radiotherapy using implanted fiducial markers with daily portal imaging: assessment of prostate organ motion.Int J Radiat Oncol Biol Phys. 2007; 68: 912-919
- Fiducial marker guided prostate radiotherapy: a review.Br J Radiol. 2016; 89: 20160296
- A new system to perform continuous target tracking for radiation and surgery using non-ionizing alternating current electromagnetics.Int J Comput Assisted Radiol Surg. 2004; 1268 (CARS 2004—Proc. of the 18th Int. Congress and Exhibition (Chicago, USA, 23–26 June 2004)): 425-430
- Accuracy of a wireless localization system for radiotherapy.Int J Radiat Oncol Biol Phys. 2005; 61: 933-937
- High precision transponder localization using a novel electromagnetic positioning system in patients with localized prostate cancer.Radiother Oncol. 2009; 90: 307-311
- The effect of transponder motion on the accuracy of the Calypso electromagnetic localization system.Int J Radiat Oncol Biol Phys. 2008; 72: 295-299
- Standardized accuracy assessment of the calypso wireless transponder tracking system.Phys Med Biol. 2014; 59: 6797-6810
- Comparison between electromagnetic transponders and radiographic imaging for prostate localization: a pelvic phantom study with rotations and translations.J Appl Clin Med Phys. 2017; 18: 43-53
- Performance evaluation of Calypso 4D localization and kilovoltage imagine guidance systems for interfraction motion management of prostate patients.Sci World J. 2009; 9: 449-458
- Target localization and real-time tracking using the Calypso 4D localization system in patients with localized prostate cancer.Int J Radiat Oncol Biol Phys. 2006; 65: 528-534
- A comparison of radiographic techniques and electromagnetic transponders for localization of the prostate.Radiat Oncol. 2012; 7: 101
- Initial experience with intra-fraction motion monitoring using Calypso guided volumetric modulated arc therapy for definitive prostate cancer treatment.J Med Radiat Sci. 2017; 64: 25-34
- The effect of rectal retractor on intrafraction motion of the prostate.Biomed Phys Eng Express. 2016; 2035021
- Positional stability of electromagnetic transponders used for prostate localization and continuous, real-time tracking.Int J Radiat Oncol Biol Phys. 2007; 68: 1199-1206
- Conventional versus hypofractionated high-dose intensity-modulated radiotherapy for prostate cancer: preliminary safety results from the CHHiP randomized controlled trial.Lancet Oncol. 2012; 13: 43-54
- Statistical methods for assessing agreement between two methods of clinical measurement.Lancet. 1986; 327: 307-310
- Measuring agreement in method comparison studies.Stat Methods Med Res. 1999; 8: 135-160
- (Non)-migration of radiopaque markers used for on-line localization of the prostate with an electronic portal imaging device.Int J Radiat Oncol Biol Phys. 2003; 56: 862-866
- A quality assurance program for the on-board imager.Med Phys. 2006; 33: 4431-4447
- Daily prostate targeting using implanted radiopaque markers.Int J Radiat Oncol Biol Phys. 2002; 52: 699-703
- Marker seed migration in prostate localization.Int J Radiat Oncol Biol Phys. 2003; 56: 1248-1251
- Intraprostatic fiducials for localization of the prostate gland: monitoring intermarker distances during radiation therapy to test for marker stability.Int J Radiat Oncol Biol Phys. 2005; 62: 1291-1296
- Clinical feasibility and positional stability of an implanted wired transmitter in a novel electromagnetic positioning system for prostate radiotherapy.Radiother Oncol. 2018; 128: 336-342
- Effectiveness of using fewer implanted fiducial markers for prostate target alignment.Int J Radiat Oncol Biol Phys. 2009; 74: 1283-1289
- Normality tests for statistical analysis: a guide for non-statisticians.Int J Endocrinol Metab. 2012; 10: 486-489
- Statistical notes for clinical researches: assessing normal distribution (2) using skewness and kurtosis.Restor Dent Endod. 2013; 38: 52-54
Article info
Publication history
Accepted:
November 10,
2018
Received in revised form:
October 2,
2018
Received:
August 18,
2018
Identification
Copyright
© 2018 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.
