Implementation of an optimization method for parotid gland sparing during inverse planning for head and neck cancer radiotherapy

Delaby, N.; Martin, S; Barateau, A.; Henry, Olivier; Périchon, N.; Crevoisier, R. de; Chajon, É.; Castelli, J.; Lafond, C.

doi:10.1016/j.canrad.2019.09.006

Cited by 1 publication

(3 citation statements)

References 32 publications

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“…With their customized AMD model, the rectum mean dose was significantly decreased from 41.6 to 36 Gy, for a prescribed dose of 74 Gy to the prostate. Delaby et al (18) showed a dose reduction of 6.1 Gy to the parotid glands using their own adaptation of AMD model for H&N. In our study, the dosimetric benefit on rectal mean dose was 4.1 Gy ( Table 1, STD pl minus AMD_RECT pl ) for a prescribed dose of 78 Gy to the prostate.…”

Section: Discussionsupporting

confidence: 50%

“…Their results showed a significant reduction to the mean dose for both rectum and parotid glands, compared to a standard planning approach. However, the application of the AMD model requires a customization to each clinical center and to each tumor location, as shown by Powis et al (24) and Delaby et al (18). Powis et al (24) improved plan quality for prostate cancer.…”

Section: Discussionmentioning

confidence: 99%

“…This model was created from 17 H&N patients (overlap between parotid glands and PTV) and 8 prostate patients (overlap between rectum and prostate) static IMRT plans, with A = 0.2, B = 0.8, C = 1, D = 3. For our study, an adapted Moore's model was fitted based on 15 prostate standard treatment plans from our institution, following the same method as we already published for the H&N case (18). The ratio of the OAR D mean to the prescription dose to PTV (D prescribed ) was plotted against the ratio of the overlap volume between PTV and OAR (V overlap ) to the OAR volume (V OAR ), for each patient.…”

Section: Moore's Model and Optimization Of Achievable Mean Dose Modelmentioning

confidence: 99%

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Planning With Patient-Specific Rectal Sub-Region Constraints Decreases Probability of Toxicity in Prostate Cancer Radiotherapy

et al. 2020

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Background: A rectal sub-region (SRR) has been previously identified by voxel-wise analysis in the inferior-anterior part of the rectum as highly predictive of rectal bleeding (RB) in prostate cancer radiotherapy. Translating the SRR to patient-specific radiotherapy planning is challenging as new constraints have to be defined. A recent geometry-based model proposed to optimize the planning by determining the achievable mean doses (AMDs) to the organs at risk (OARs), taking into account the overlap between the planning target volume (PTV) and OAR. The aim of this study was to quantify the SRR dose sparing by using the AMD model in the planning, while preserving the dose to the prostate. Material and Methods: Three-dimensional volumetric modulated arc therapy (VMAT) planning dose distributions for 60 patients were computed following four different strategies, delivering 78 Gy to the prostate, while meeting the genitourinary group dose constraints to the OAR: (i) a standard plan corresponding to the standard practice for rectum sparing (STD pl), (ii) a plan adding constraints to SRR (SRR pl), (iii) a plan using the AMD model applied to the rectum only (AMD_RECT pl), and (iv) a final plan using the AMD model applied to both the rectum and the SRR (AMD_RECT_SRR pl). After PTV dose normalization, plans were compared with regard to dose distributions, quality, and estimated risk of RB using a normal tissue complication probability model. Results: AMD_RECT_SRR pl showed the largest SRR dose sparing, with significant mean dose reductions of 7.7, 3, and 2.3 Gy, with respect to the STD pl , SRR pl , and AMD_RECT pl , respectively. AMD_RECT_SRR pl also decreased the mean rectal dose by 3.6 Gy relative to STD pl and by 3.3 Gy relative to SRR pl. The absolute risk of grade ≥1 RB decreased from 22.8% using STD pl planning to 17.6% using AMD_RECT_SRR pl considering SRR volume. AMD_RECT_SRR pl plans, however, showed slightly less dose homogeneity and significant increase of the number of monitor units, compared to the three other strategies. Conclusion: Compared to a standard prostate planning, applying dose constraints to a patient-specific SRR by using the achievable mean dose model decreased the mean dose by 7.7 Gy to the SRR and may decrease the relative risk of RB by 22%.

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Section: Discussionsupporting

confidence: 50%

Section: Discussionmentioning

confidence: 99%

Section: Moore's Model and Optimization Of Achievable Mean Dose Modelmentioning

confidence: 99%

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Planning With Patient-Specific Rectal Sub-Region Constraints Decreases Probability of Toxicity in Prostate Cancer Radiotherapy

et al. 2020

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show abstract

Implementation of an optimization method for parotid gland sparing during inverse planning for head and neck cancer radiotherapy

Cited by 1 publication

References 32 publications

Planning With Patient-Specific Rectal Sub-Region Constraints Decreases Probability of Toxicity in Prostate Cancer Radiotherapy

Planning With Patient-Specific Rectal Sub-Region Constraints Decreases Probability of Toxicity in Prostate Cancer Radiotherapy

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