Assessment of i-125 prostate implants by tumor bioeffect

Haworth, Annette; Ebert, Martin A.; Waterhouse, David; Joseph, David; Duchesne, Gillian

doi:10.1016/j.ijrobp.2004.01.047

Cited by 26 publications

(30 citation statements)

References 27 publications

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“…The linear-quadratic formalism does not account for cell death pathways death beyond reproductive cell death, e.g., apoptosis. Our model also does not account for clonogen distribution heterogeneity (36). Differential clonogen hypoxia and radiosensitivity (37) within and between patients could also contribute to differential outcomes.…”

Section: Discussionmentioning

confidence: 99%

Deriving Prostate Alpha-Beta Ratio Using Carefully Matched Groups, Long Follow-Up and the Phoenix Definition of Biochemical Failure

Shaffer

Pickles

Lee

et al. 2011

International Journal of Radiation Oncology*Biology*Physics

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Section: Discussionmentioning

confidence: 99%

Deriving Prostate Alpha-Beta Ratio Using Carefully Matched Groups, Long Follow-Up and the Phoenix Definition of Biochemical Failure

Shaffer

Pickles

Lee

et al. 2011

International Journal of Radiation Oncology*Biology*Physics

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“…Biological parameters are the subject of some uncertainty due to intra-patient radiosensitivity variations [20–23]. The response probability ( P ) for each voxel was then determined using equation (6) [24–26]. …”

Section: Methodsmentioning

confidence: 99%

Clinical Investigations Radiobiologically based treatment plan evaluation for prostate seed implants

Knaup

Mavroidis

Esquivel

et al. 2011

jcb

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PurposeAccurate prostate low dose-rate brachytherapy treatment plan evaluation is important for future care decisions. Presently, an evaluation is based on dosimetric quantifiers for the tumor and organs at risk. However, these do not account for effects of varying dose-rate, tumor repopulation and other biological effects. In this work, incorporation of the biological response is used to obtain more clinically relevant treatment plan evaluation.Material and methodsEleven patients were evaluated. Each patient received a 145 Gy implant. Iodine-125 seeds were used and the treatment plans were created on the Prowess system. Based on CT images the post-implant plan was created. In the post-plan, the tumor, urethra, bladder and rectum were contoured. The biologically effective dose was used to determine the tumor control probability and the normal tissue complication probabilities for the urethra, bladder, rectum and surrounding tissue.ResultsThe average tumor control probability and complication probabilities for the urethra, bladder, rectum and surrounding tissue were 99%, 29%, 0%, 12% and 6%, respectively. These measures provide a simpler means for evaluation and since they include radiobiological factors, they provide more reliable estimation of the treatment outcome. ConclusionsThe goal of this work was to create more clinically relevant prostate seed-implant evaluation by incorporating radiobiological measures. This resulted in a simpler descriptor of treatment plan quality and was consistent with patient outcomes.

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“…EUBED has been supported by TG-137 4 and implemented by several investigators. [13][14][15][16][17] Biologically effective dose (and EUBED) are often used to calculate TCP from binomial (specifically, Poisson) statistics. If n cells are exposed to a dose D, then a fraction S(D) will survive.…”

Section: A Radiobiological Modelsmentioning

confidence: 99%

Coupling I‐125 permanent implant prostate brachytherapy Monte Carlo dose calculations with radiobiological models

et al. 2017

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Purpose: To investigate the coupling of radiobiological models with patient-specific Monte Carlo (MC) dose calculations for permanent implant prostate brachytherapy (PIPB). To compare radiobiological indices evaluated with different radiobiological models using MC and simulated AAPM TG-43 dose calculations. Methods: Three-dimensional dose distributions previously computed using MC techniques with two types of patient models, TG43sim (AAPM TG-43 water-based conditions) and MCDmm (realistic tissues and interseed effects), for 613 PIPB patients are coupled with biological dose and tumour control probability (TCP) models. Two approaches and their extensions are considered to evaluate biological doses, biologically effective dose (BED) and isoeffective dose (IED), as well as two methods to evaluate TCP. Three novel extensions of equivalent uniform biologically effective dose (EUBED) are suggested which consider the spatial distribution of doses within the target volume. Adopted radiobiological model parameter values (a, b, etc) are those suggested by AAPM TG-137, and sensitivity to parameter choice is discussed. Results: MCDmm dose calculations can reveal low doses in the prostate target volume, due to tissue heterogeneities or inter-seed effects; considering these low doses in EUBED calculations can lower TCP estimates by up to 70%, with largest differences in patients with calcifications. There are large variations in biological doses and TCPs evaluated over the 613 patient cohort for each radiobiological model considered, reflecting the spectrum of physical doses calculated for these patients with either MCDmm or TG43sim. Depending on the model details, BED, IED and EUBED are, on average, 6.0-9.8%, 7.4-9.2% and 1.8-15% higher, respectively, with TG43sim than MCDmm. TCP estimates computed using MCDmm dose distributions are much lower than expected based on past treatment outcome studies, suggesting a need to re-assess model parameters when evaluating radiobiological indices coupled with heterogeneous tissue model-based dose calculations. Conclusions: Cohort average differences in biological dose and TCP estimates between radiobiological models are generally larger than differences for any one radiobiological model evaluated with TG43sim or MCDmm dose calculations. However, heterogeneous tissue dose calculations, like MCDmm, can identify clinically-relevant low dose volumes, e.g., in patients with calcifications, which would otherwise be missed with TG-43. In addition to affecting physical dose distributions, these low dose volumes can largely impact radiobiological dose and TCP estimates, which further motivates the clinical implementation of model-based dose calculations for PIPB.

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Assessment of i-125 prostate implants by tumor bioeffect

Cited by 26 publications

References 27 publications

Deriving Prostate Alpha-Beta Ratio Using Carefully Matched Groups, Long Follow-Up and the Phoenix Definition of Biochemical Failure

Deriving Prostate Alpha-Beta Ratio Using Carefully Matched Groups, Long Follow-Up and the Phoenix Definition of Biochemical Failure

Clinical Investigations Radiobiologically based treatment plan evaluation for prostate seed implants

Coupling I‐125 permanent implant prostate brachytherapy Monte Carlo dose calculations with radiobiological models

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