Standardization of prostate brachytherapy treatment plans

Limitations in learning: How treatment verifications fail and what to do about it?

PURPOSE

The purposes of this study were: to provide dialog on why classic incident learning systems have been insufficient for patient safety improvements, discuss failures in treatment verification, and to provide context to the reasons and lessons that can be learned from these failures.

METHODS AND MATERIALS

Historically, incident learning in brachytherapy is performed via database mining which might include reading of event reports and incidents followed by incorporating verification procedures to prevent similar incidents. A description of both classic event reporting databases and current incident learning and reporting systems is given. Real examples of treatment failures based on firsthand knowledge are presented to evaluate the effectiveness of verification. These failures will be described and analyzed by outlining potential pitfalls and problems based on firsthand knowledge.

RESULTS

Databases and incident learning systems can be limited in value and fail to provide enough detail for physicists seeking process improvement. Four examples of treatment verification failures experienced firsthand by experienced brachytherapy physicists are described. These include both underverification and oververification of various treatment processes.

CONCLUSIONS

Database mining is an insufficient method to affect substantial improvements in the practice of brachytherapy. New incident learning systems are still immature and being tested. Instead, a new method of shared learning and implementation of changes must be created.

Tumour and target volumes in permanent prostate brachytherapy: A supplement to the ESTRO/EAU/EORTC recommendations on prostate brachytherapy

The aim of this paper is to supplement the GEC/ESTRO/EAU recommendations for permanent seed implantations in prostate cancer to develop consistency in target and volume definition for permanent seed prostate brachytherapy. Recommendations on target and organ at risk (OAR) definitions and dosimetry parameters to be reported on post implant planning are given.

Parametric shape modeling using deformable superellipses for prostate segmentation

Automatic prostate segmentation in ultrasound images is a challenging task due to speckle noise, missing boundary segments, and complex prostate anatomy. One popular approach has been the use of deformable models. For such techniques, prior knowledge of the prostate shape plays an important role in automating model initialization and constraining model evolution. In this paper, we have modeled the prostate shape using deformable superellipses. This model was fitted to 594 manual prostate contours outlined by five experts. We found that the superellipse with simple parametric deformations can efficiently model the prostate shape with the Hausdorff distance error (model versus manual outline) of 1.32 +/- 0.62 mm and mean absolute distance error of 0.54 +/- 0.20 mm. The variability between the manual outlinings and their corresponding fitted deformable superellipses was significantly less than the variability between human experts with p-value being less than 0.0001. Based on this deformable superellipse model, we have developed an efficient and robust Bayesian segmentation algorithm. This algorithm was applied to 125 prostate ultrasound images collected from 16 patients. The mean error between the computer-generated boundaries and the manual outlinings was 1.36 +/- 0.58 mm, which is significantly less than the manual interobserver distances. The algorithm was also shown to be fairly insensitive to the choice of the initial curve.

Transperineal TRUS-guided prostate brachytherapy using loose seeds versus RAPIDStrand: A dosimetric analysis

PURPOSE

An analysis of the effect of stranded (125)I and loose (predominantly (103)Pd) sources on dosimetric outcomes of brachytherapy of the prostate.

METHODS AND MATERIALS

Between September 1998 and December 2003, 473 patients were treated with brachytherapy for biopsy-proven carcinoma of the prostate. Of these, 337 (71%) procedures were performed using free seeds placed with a Mick applicator. Beginning in April 2002, a program of stranded (125)I sources (RAPIDStrand) was implemented; 136 (29%) patients were treated via this approach. Dosimetric variables were collected, as were events of urinary retention.

RESULTS

Mean V100 values for the stranded (125)I approach were greater than those for free seeds (p < 0.0005), whether (125)I or (103)Pd (p < 0.005). Use of the strand was the most significant determinant of V100 of all variables examined. The stranded (125)I approach was also associated with higher mean D90 values and lower V150-urethral doses.

CONCLUSIONS

Use of stranded (125)I was associated with superior dosimetric outcomes in this group of patients.