To retrospectively determine the proportion of
prostate cancer patients who are appropriate candidates for prostate localization with
Calypso (
Calypso Medical, Seattle, WA); to assess the accuracy of surface anatomy in predicting prostate depth; and to describe a simple clinical algorithm predicting patient's appropriateness for
Calypso localization. Medical records and archived CT scans of all patients treated for localized
prostate cancer at our institution between 2006 and 2007 were reviewed. Association between the feasibility of
Calypso use, the depth of the prostate from the anterior torso, and a variety of anatomic factors were assessed (ANOVA, linear regression, and ROC). Patients were appropriate for the
Calypso system in 91% of cases (localize and track, 52%; localize only, 39%). Strong correlation between greater trochanter location and the posterior prostate was seen (r 2 = 0.91, mean difference 0.6 cm). The negative predictive value of the greater trochanter measurements was 31%. Thirty-one out of forty-five patients (69%) who were deemed inappropriate for
Calypso based on greater trochanter to anterior torso measurements were eligible on the basis of CT-based measurements of prostate depth. Weight, BMI, waist circumference, and hip circumference correlated with distance from the prostate to the anterior torso and were predictive of
Calypso appropriateness. All patients with weight <or= 100 kg, BMI <or= 30, or waist/hip circumference <or= 100 cm, were eligible for
Calypso. Most
prostate cancer patients are candidates for
Calypso localization +/- tracking. The greater trochanter to anterior torso distance underestimates the number of eligible patients. Weight, BMI and waist/hip circumference are good predictors for
Calypso appropriateness.