PSOR12 Presentation Time: 5:25 PM: Comparison of HDR Brachytherapy MCO Planning Using Dosimetrical versus Radiobiological Criteria for the Treatment of Prostate Cancer.
In: Brachytherapy, Jg. 22 (2023-09-02), Heft 5, S. S32- (2S.)
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Zugriff:
Radiobiological indices provide an estimate of the biological effect of treatment instead of tracking only dosimetric surrogate such as dose-volume histograms (DVH) and related dosimetric parameters. The purpose of this work is to evaluate the use of radiobiological criteria as a mean to generate high-dose-rate (HDR) brachytherapy plans for the treatment of prostate cancer within a multi-criteria optimization (MCO) algorithm and to compare them with current plans selected solely based on physical dose criteria. A MCO algorithm on graphics processing units (gMCO) is used to create 2000 Pareto optimal treatment plans covering various compromises between tumor doses and organs at risk from 110 randomly selected patients previously treated in our institution. The prescription was to deliver 15 Gy in a single fraction as a boost to EBRT. For each gMCO plan, the concurring Poisson tumor control probability (TCP) and LKB normal tissue complications probability (NTCP) indices were calculated and used to predict the biological response of the patients. The AAPM TG-137 recommended radiobiological parameters were used in these models. The uncomplicated tumor control probability index, UTCP (UTCP=TCP Π (1-NTCP i)) was also computed. In addition to TCP, NTCP and UTCP, the quality of the treatment plans was evaluated using our institutional (INST) criteria, which are based on RTOG-0924, ABS, and GEC-ESTRO ACROP guidelines. Three (3) plan selection scenarios (i- maximizing target coverage, ii-maximizing UTCP and, iii- meeting all INST criteria and maximizing UTCP) were implemented and compared (see figure 1). Plans that maximize UTCP correspond to a wide range of target dose coverage V100%, covering from 65% to 91%, (figure 1), mainly because UTCP appears to favour plans that are very protective towards normal tissue. For example, the median urethra D10% is under 16 Gy while bladder and rectum V75% are about 0 cm3. None of the plans that maximize UTCP respect the INST dosimetric criteria. Combining INST criteria with UTCP criterion enforces a high tumor coverage (TV100 ≥ 95%)while allowing plan selection favouring normal tissue criteria. Plans respecting INST criteria and maximizing UTCP have a median TV100% of about 95% a bit lower than plans selected solely based on maximizing target coverage. However, the median BV75% and RV75% are much lower, ranging from 0 cm3 to about 0.3 cm3 as opposed to 0.4 cm3 to 0.9 cm3 for plans ignoring UTCP. The median UD10% is also lower, around 16.3 Gy instead of 17 Gy. The p-values of those two distributions are of the order of 10-14 when performing the Wilcoxon test which indicates that the results of the two plan selection techniques are significantly different. Results showed that solely using radiobiological indices can lead to unacceptable target coverage in most cases versus current clinical guidelines. However, adding UTCP to dosimetric guidelines allows for an efficient selection of a Pareto optimal plan meeting all dosimetric requirements while maximizing UTCP. The next step of the project will be to investigate the robustness of the method on the radiobiological model parameters. [ABSTRACT FROM AUTHOR]
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PSOR12 Presentation Time: 5:25 PM: Comparison of HDR Brachytherapy MCO Planning Using Dosimetrical versus Radiobiological Criteria for the Treatment of Prostate Cancer.
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Autor/in / Beteiligte Person: | Iorio-Duval, Charles ; Bélanger, Cédric ; Beaulieu, Luc |
Zeitschrift: | Brachytherapy, Jg. 22 (2023-09-02), Heft 5, S. S32- (2S.) |
Veröffentlichung: | 2023 |
Medientyp: | academicJournal |
ISSN: | 1538-4721 (print) |
DOI: | 10.1016/j.brachy.2023.06.042 |
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