Calypso^® 4D Localization System: a review

Abstract

PurposeCalypso® 4D Localization System is a system based on electromagnetic transponders detection enabling precise 3D localisation and continuous tracking of tumour target. This review intended to provide information in order to (1) show how Calypso® 4D Localization System works, (2) to present advantages and disadvantages of this system, (3) to gather information from several clinical studies and, finally, (4) to refer Calypso® System as a tool in dynamic multileaf collimator studies for target motion compensation.MethodsA structured search was carried out on B-On platform. The key words used in this research were ‘Calypso’, ‘Transponder’, ‘Electromagnetic Localization’, ‘Electromagnetic Tracking’, ‘Target Localization’, ‘Intrafraction Motion’ and ‘DMLC’.ReviewTreatment the implanted transponders are excited by an electromagnetic field and resonate back. These frequencies are detected and Calypso® software calculates the position of the transponders. If the movement detected is larger than the limits previously defined, irradiation can be stopped. The system has been proven to be submillimetre accurate.DiscussionCalypso® System has been presented as an accurate tool in prostate radiotherapy treatments. The application of this system to other clinical sites is being developed.ConclusionThe Calypso® System allows real-time localisation and monitoring of the target, without additional ionising radiation administration. It has been a very useful tool in prostate cancer treatment.

First online real‐time evaluation of motion‐induced 4D dose errors during radiotherapy delivery

“…This study helps in bringing independent plan QA into the real-time era by exploiting the growing possibilities of real-time motion monitoring [3][4][5][6][7][8][9]28,[31][32][33] to follow the dose as it gradually builds up during the treatment delivery. The real-time dose reconstruction by DoseTracker provides a seamless form of QA similar to the time-consuming QA presently being used for tumor tracking in the clinic 20 and could help pave the way for broader clinical use of tumor tracking.…”

“…The reasons are of historical nature; the reasons being lack of access to reliable real‐time motion information and a lack of methods for evaluating and acting on such information in a swift and seamless manner. Today, however, motion monitoring on conventional linear accelerators is on the verge of a new real‐time era with systems based on electromagnetic monitoring of implanted transponders, x‐ray imaging of implanted fiducial markers, or bony anatomy . Yet, real‐time evaluation of the dosimetric consequences of the motion is still lacking.…”

Online adaptive planning methods for intensity-modulated radiotherapy

“…The NAL protocol estimates the setup error by the average setup error over the first few fractions (de Boer and Heijmen 2007). monitor target localization in real-time; this has been marketed as the Calypso® 4-D Localization System (Willoughby et al 2006, Silva et al 2014. Real-time localization and tracking can also be achieved with MR imaging on an MRI-linac (Fast et al 2019).…”

Technical aspects of real time positron emission tracking for gated radiotherapy

“…25 The Calypso System (Varian Medical Systems, Palo Alto, CA) uses an external magnetic source and receiver coil array to track the location of implanted wireless coils in the patient. 26 The main drawback of this technique is the large size of the transponders (8.7 × 1.85 mm), which increases patient risk during implantation. They may also cause artifacts on MRI or CT images.…”