Room: ePoster Forums
Purpose: Hydrogel spacer (SpaceOAR) has been used to reduce rectal toxicity in prostate radiotherapy. The present study aims to develop a Hydrogel-Implant-Quality-Score (HIQS) system to assist clinicians in tracking proficiency and to support quality improvement; and design a matched-pair study for LDR patients to investigate the benefit of SpaceOAR in rectal dose reduction.
Methods: 55 patients (IMRT and/or LDR) were respectively selected. Each patient had SpaceOAR implantation under manufacturer supervision. Post-procedure CT and T2-MRI were acquired for planning. A novel scoring system was proposed to evaluate the hydrogel placement quality with criteria including implanted hydrogel volume, left-right symmetry, cranio-caudal symmetry and mid-prostate spacing. Hydrogel implantation was done immediately after LDR seed placement. For each LDR patient (total of 35 patients), a non-SpaceOAR patient was matched based upon intra-operative plan rectal dose (D2cc and D0.1cc) and prostate coverage (V100, V150 and V200). The rectal dose reduction of intra-operative and post-operative were compared between spaceOAR and non-spaceOAR groups using the Student’s t-test.
Results: The average hydrogel volume and mid-prostate spacing were 13.5±2.3cc and 14.6±3.4mm. The mean HIQS were 77.5±13.0. Rectal anatomical distortions, including disruption of serosal and/or submucosal layers, were seen in 14 cases. HIQS was higher in patients without rectal distortion compared with patients with rectal distortion: 79.7±9.3 vs. 71.0±19.4. Over the duration of the practice HIQS improved with a linear trend from 74 to 82 suggesting improved quality with experience. Significant rectal dose reductions between intra-operative and post-operative plans were found for SpaceOAR patients compared to non-SpaceOAR patients (D2cc: 24.1±13.6Gy vs. -6.2±19.1Gy; D0.1cc: 59.2±26.9Gy vs. 13.3±25.1Gy).
Conclusion: HIQS quantifies hydrogel placement quality and provides insights into clinician’s learning and DVH outcome. Larger samples will be needed for validation of HIQS. This study will contribute to a safety culture around quality in SpaceOAR implantation to reduce the likelihood of severe complications.
Not Applicable / None Entered.
Not Applicable / None Entered.