Prostate cancer radiation therapy with reduced planning target volume (PTV) margins.

124 Background: Electromagnetic tracking of the prostate during radiation therapy for prostate cancer allows decreased PTV margins which may reduce dose to nearby tissues. Sandler, et al. reported a reduction in patient-reported acute morbidity with this strategy (Sandler HM, et al. Urology, 2010 May;75 (5):1004-8). We conducted a similar prospective study and compare our results with Sandler’s Assessing Impact of Margin Reduction (AIM) study and with a group treated with radiation therapy without reduced PTV margins from the Sanda, et al. PROST-QA cohort (Sanda MG, et al. NEJM, 2008 Mar 20;358 (12):1250-61). Methods: 25 patients with low-to-intermediate risk prostate cancer were treated on a prospective study with definitive intensity-modulated radiation therapy with 3 mm circumferential PTV margins and daily electromagnetic localization. An EPIC quality of life questionnaire was completed prior to treatment and at the last treatment. Using data from the referenced publications, we performed a two-tailed t-test to compare EPIC scores from our cohort with the AIM and PROST-QA cohorts treated with external beam radiation therapy alone. Results: Table lists mean pre- and post-treatment EPIC scores and the differences between them. Conclusions: Our patients fared similarly to the PROST-QA cohort, but had a significantly greater mean decrement in the urinary irritation and sexual domains in comparison to the AIM cohort. Clinical trial information: NCT01589939. [Table: see text]

Calypso® 4D Localization System: a review

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.