Assessing prostate, bladder and rectal doses during image guided radiation therapy — need for plan adaptation?

Varadhan, R; Song, Hui; Way, S; Nisi, Kurt

doi:10.1120/jacmp.v10i3.2883

Cited by 34 publications

(28 citation statements)

References 52 publications

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“…[37][38][39][40][41] While adaptive replanning may become the standard, it will only do so if/when is benefits outweigh the drawbacks of the daily reimaging, daily replanning time, and added resources required compared with current practice or other competing methods.…”

Section: Discussionmentioning

confidence: 99%

Coverage‐based treatment planning to accommodate deformable organ variations in prostate cancer treatment

Vile

Sharma

et al. 2014

Medical Physics

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Purpose: To compare two coverage-based planning (CP) techniques with standard fixed marginbased planning (FM), considering the dosimetric impact of interfraction deformable organ motion exclusively for high-risk prostate treatments. Methods: Nineteen prostate cancer patients with 8-13 prostate CT images of each patient were used to model patient-specific interfraction deformable organ changes. The model was based on the principal component analysis (PCA) method and was used to predict the patient geometries for virtual treatment course simulation. For each patient, an IMRT plan using zero margin on target structures, prostate (CTV prostate ) and seminal vesicles (CTV SV ), were created, then evaluated by simulating 1000 30-fraction virtual treatment courses. Each fraction was prostate centroid aligned. Patients whose D 98 failed to achieve 95% coverage probability objective D 98,95 ≥ 78 Gy (CTV prostate ) or D 98,95 ≥ 66 Gy (CTV SV ) were replanned using planning techniques: (1) FM (PTV prostate = CTV prostate + 5 mm, PTV SV = CTV SV + 8 mm), (2) CP OM which optimized uniform PTV margins for CTV prostate and CTV SV to meet the coverage probability objective, and (3) CP COP which directly optimized coverage probability objectives for all structures of interest. These plans were intercompared by computing probabilistic metrics, including 5% and 95% percentile DVHs (pDVH) and TCP/NTCP distributions. Results: All patients were replanned using FM and two CP techniques. The selected margins used in FM failed to ensure target coverage for 8/19 patients. Twelve CP OM plans and seven CP COP plans were favored over the other plans by achieving desirable D 98,95 while sparing more normal tissues. Conclusions: Coverage-based treatment planning techniques can produce better plans than FM, while relative advantages of CP OM and CP COP are patient-specific. C 2014 American Association of Physicists in Medicine. [http://dx

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Section: Discussionmentioning

confidence: 99%

Coverage‐based treatment planning to accommodate deformable organ variations in prostate cancer treatment

Vile

Sharma

et al. 2014

Medical Physics

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“…13 Although significant variations in bladder volume were observed for three out of five patients, the planned bladder constraints were seldom violated for any patient. The observation that the bladder volume can potentially decrease to the order of 50% of the planned volume has also been reported in the literature.…”

Section: Discussionmentioning

confidence: 85%

Quantifying daily variation in volume and dose to the prostate, rectum and bladder using cone-beam computerised tomography

et al. 2013

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Introduction: In the era of dose escalation for localised prostate cancer, the dose-volume histogram (DVH) is integral to the assessment of rectum and bladder dose constraints. However, reliance on a single planning computerised tomography-based (P-CT) dose distribution may not account for variations in delivered dose that results from deformation of the prostate, bladder and rectum. This study uses conebeam CT (CBCT) datasets from five patients to investigate the concordance between the dose prediction from the initial treatment plan and the dose delivered during treatment.Methods: The intensity-modulated radiation therapy distribution used for treatment was superimposed on alternate day CBCT images for each patient. Dose metrics and absolute volumes for the prostate, rectum and bladder were extracted from the CBCT-based DVH. Differences in dose and volumes were compared with the P-CT values, and significance was tested using the Wilcoxon signed-rank test.Results: For all five case studies, the prostate dose coverage on CBCT plans was lower than predicted with an average reduction of 3% in mean dose. Significant differences in rectal volumes and dose were observed in two out of five and four out of five patients, respectively. Reductions in bladder volume and subsequent increases in dose were observed for three out of five patients. Conclusion:The DVH from P-CT was unable to consistently predict the dose delivered to the bladder and rectum. The current bowel and bladder preparation protocols used at our institution did not eliminate variation in bladder and rectum volumes for the five patients included in this study.

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“…The treatment involves strategies which maximize the dose on the tumour while minimize it on the normal surrounding tissue [7]. Although the accuracy and precision of the dose have improved considerably due to technological advances [8], these are still limiting factors for a total success in radiotherapy [9,10]. Various studies have evaluated the effects of the non-uniformity of the dose deposition and heterogeneity of cancer cells in the same tumour [8,11].…”

Section: −1mentioning

confidence: 99%

ROC Analysis in Radiotherapy: A TCP Model-Based Test

Santos

Neves²

2013

OJAppS

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Several mathematical models have been proposed to describe the dynamics of irradiated cancer cells and to evaluate the tumour control probability (TCP). In this article, we propose a TCP model-based statistical test for predicting the outcome of a radiation treatment. We determine the foresight capability of prostate tumour erradication (cure) from Monte Carlo simulations of the Dawson-Hillen TCP model. We construct the receiver operating characteristic (ROC) curves of the test from the probability distributions of the fraction of remaining tumour cells for simulated experiments that evolve either to cure or non-cure. Simulations show that a similar procedure may be applicable to clinical data. Results suggest that the evaluation of tumour sizes after the treatment has started may be used for short-term prognosis.

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Assessing prostate, bladder and rectal doses during image guided radiation therapy — need for plan adaptation?

Cited by 34 publications

References 52 publications

Coverage‐based treatment planning to accommodate deformable organ variations in prostate cancer treatment

Coverage‐based treatment planning to accommodate deformable organ variations in prostate cancer treatment

Quantifying daily variation in volume and dose to the prostate, rectum and bladder using cone-beam computerised tomography

ROC Analysis in Radiotherapy: A TCP Model-Based Test

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