Role of image-guided patient repositioning and online planning in localized prostate cancer IMRT
Autor: | Pradip Amin, Z Wang, Cedric X. Yu, Byong Yong Yi, Sandy Liu, F Lerma, Yuanming Feng, Bei Liu |
---|---|
Rok vydání: | 2009 |
Předmět: |
Male
medicine.medical_specialty Imrt plan medicine.medical_treatment Rectum Online Systems Patient Positioning Prostate cancer Risk Factors Prostate Prone Position Supine Position medicine Humans Radiology Nuclear Medicine and imaging Radiation Injuries Radiation treatment planning Neoplasm Staging business.industry Radiotherapy Planning Computer-Assisted Prostatic Neoplasms Radiotherapy Dosage Hematology Bladder sparing medicine.disease Radiation therapy Prone position Treatment Outcome medicine.anatomical_structure Oncology Radiographic Image Interpretation Computer-Assisted Radiotherapy Intensity-Modulated Radiology business |
Zdroj: | Radiotherapy and Oncology. 93:18-24 |
ISSN: | 0167-8140 |
Popis: | Purpose To determine the expected benefit of image-guided online replanning over image-guided repositioning of localized prostate cancer intensity-modulated radiotherapy (IMRT). Materials and methods On 10 to 11 CT scans of each of 10 early-stage prostate cancer patients, the prostate, bladder and rectum are manually segmented. Using a 3-mm PTV margin expansion from the CTV, an IMRT plan is made on the first CT scan of each patient. Online repositioning is simulated by recalculating the IMRT plan from the initial CT scan on the subsequent CT scans of each patient. For online replanning, IMRT is replanned twice on all CT scans, using 0-mm and 3-mm margins. The doses from subsequent CT images of each patient are then deformed to the initial CT anatomy using a mesh-based thin-plate B-spline deformation method and are accumulated for DVH and isodose review. Results Paired t -tests show that online replanning with 3-mm margins significantly increases the prostate volume receiving the prescribed dose over replanning with 0-mm margins ( p -value 0.004); gives marginally better target coverage than repositioning with 3-mm margins( p -value 0.06–0.343), and reduces variations in target coverage over repositioning. Fractional volumes of rectum and bladder receiving 75%, 80%, 85%, 90%, and 95% (V75, V80, V85, V90, and V95) of the prescription dose are evaluated. V90 and V95 values for the rectum are 1.6% and 0.7 % for 3-mm margin replanning and 1% and 0.4 % for 0-mm margin replanning, with p -values of 0.010–0.011. No significant differences between repositioning and replanning with 3-mm margins are found for both the rectum and the bladder. Conclusions Image-guided replanning using 3-mm margins reduces target coverage variations, and maintains comparable rectum and bladder sparing to patient repositioning in localized prostate cancer IMRT. Marginal reductions in doses to rectum and bladder are possible when planning margins are eliminated in the online replanning scenario. However, further reduction in treatment planning margins is not recommended. |
Databáze: | OpenAIRE |
Externí odkaz: |