Optimal adaptive IMRT strategy to spare the parotid glands in oropharyngeal cancer

Zhang, Pengcheng; Simon, Antoine; Rigaud, B.; Castelli, J.; Arango, Juan David Ospina; Nassef, Mohamed; Henry, Olivier; Zhu, Jian; Haigron, Pascal; Li, Baosheng; Hu, Shu; Crevoisier, R. de

doi:10.1016/j.radonc.2016.05.028

Cited by 53 publications

(52 citation statements)

References 42 publications

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“…For OAR, a significant difference was only seen between mean planned and delivered dose to the larynx (p = 0.007) and mandible (p = 0.001), although the median differences were small and presumably of no clinical consequence. Changes in dose to the mandible are more likely be due to rotational errors than to true anatomical changes [21,22]. For the other OAR, including the parotids, no difference in mean dose was found.…”

Section: Discussionmentioning

confidence: 89%

“…1 also shows large incidental individual differences between planned and delivered dose to targets, which could very well justify ART. Meaningful use of ART improves quality of life and seems most effective early in treatment, as most anatomical changes occur then [5,6,22,24,25], which is especially true for centers where ART efforts are labor intensive and time consuming.…”

Section: Discussionmentioning

confidence: 99%

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Differences between planned and delivered dose for head and neck cancer, and their consequences for normal tissue complication probability and treatment adaptation

Heukelom

Kantor

Mohamed

et al. 2020

Radiotherapy and Oncology

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Background and purpose: Anatomical changes induce differences between planned and delivered dose. Adaptive radiotherapy (ART) may reduce these differences but the optimal implementation is insufficiently clear. The aims of this study were to quantify the difference between planned and delivered dose in HNC patients, assess the consequential difference in normal tissue complication probability (DNTCP) and to explore the value of DNTCP as an objective selection strategy for ART. Materials and methods: For 52 patients, daily doses were accumulated to estimate the delivered dose. The difference from planned dose was analyzed for CTVs and 9 organs-at-risk (OAR). DNTCP was calculated for xerostomia, dysphagia, parotid gland dysfunction and tube feeding dependency at 6 months. ART was deemed necessary if DNTCP was >5%. The positive predicted value (PPV) was calculated for identification of ART-patients by clinical judgement, and DNTCP at fraction 10 and 15. Results: DNTCP >5% was seen five times for dysphagia and twice for the other toxicities. Only 5/9 patients with any DNTCP >5% clinically received ART, although ART had been done for 13/52 patients (PPV: 0.38). PPV was 0.86 and 0.75 for accumulated dose at fraction 10 and 15, respectively, using a DNTCP cutoff for the allocation of ART of 5%. Using other DNTCP cutoffs did not substantially improve PPV. With this cutoff the negative predictive value was 0.93 for DNTCP method of fraction 10 and fraction 15, and 0.90 for clinical judgement. Conclusion: To identify patients accurately for ART, NTCP calculations based on the dose differences between planned and delivered dose at fraction 10 are superior to clinical judgement.

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Section: Discussionmentioning

confidence: 89%

Section: Discussionmentioning

confidence: 99%

Differences between planned and delivered dose for head and neck cancer, and their consequences for normal tissue complication probability and treatment adaptation

Heukelom

Kantor

Mohamed

et al. 2020

Radiotherapy and Oncology

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“…The replanning strategies, timing, and optimal number of treatments remain unclear so far. Many researchers are investigating these issues, and some have made new progress 15, 37. We firmly believe that it will lead us to new important discoveries if these studies can be performed using CBCT.…”

Section: Discussionmentioning

confidence: 99%

Parotid gland radiation dose‐xerostomia relationships based on actual delivered dose for nasopharyngeal carcinoma

Lou

Huang

et al. 2018

J Applied Clin Med Phys

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Xerostomia induced by radiotherapy is a common toxicity for head and neck carcinoma patients. In this study, the deformable image registration of planning computed tomography (CT) and weekly cone‐beam CT (CBCT) was used to override the Hounsfield unit value of CBCT, and the modified CBCT was introduced to estimate the radiation dose delivered during the course of treatment. Herein, the beams from each patient's treatment plan were applied to the modified CBCT to construct the weekly delivered dose. Then, weekly doses were summed together to obtain the accumulated dose. A total of 42 parotid glands (PGs) of 21 nasopharyngeal carcinoma patients were analyzed. Doses delivered to the parotid glands significantly increased compared with the planning doses. V20, V30, V40, Dmean, and D50 increased by 11.3%, 28.6%, 44.4%, 9.5%, and 8.4% respectively. Of the 21 patients included in the study, eight developed xerostomia and the remaining 13 did not. Both planning and delivered PG Dmean for all patients exceeded tolerance (26 Gy). Among the 21 patients, the planning dose and delivered dose of Dmean were 30.6 Gy and 33.6 Gy, respectively, for patients with xerostomia, and 26.3 Gy and 28.0 Gy, respectively, for patients without xerostomia. The D50 of the planning and delivered dose for patients was below tolerance (30 Gy). The results demonstrated that the p‐value of V20, V30, D50, and Dmean difference of the delivery dose between patients with xerostomia and patients without xerostomia was less than 0.05. However, for the planning dose, the significant dosimetric difference between the two groups only existed in D50 and Dmean. Xerostomia is closely related to V20, V30, D50, and Dmean.

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“…A recent in silico study by Castelli et al found a parotid gland mean dose decrease of 3.6 Gy compared to cumulative dose with six weekly replannings in 15 oropharyngeal cancer patients [24]. From the same group, a study by Zhang et al showed that 95% of this benefit could be achieved by three weekly replannings at the first, second and fifth week of treatment, however they still found a mean benefit of 2.2 Gy with a single adaptive replan [25]. One possible explanation for these differences could be a higher degree of patient selection in these studies, which focused on locally advanced oropharyngeal cancer.…”

Section: Discussionmentioning

confidence: 99%

Cone-beam computed tomography (CBCT) for adaptive image guided head and neck radiation therapy

et al. 2017

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The tested dose surveillance algorithm resulted in a minimal dose reduction ( ≤1 Gy) to parotid glands for three of 40 patients. The proposed algorithm and workflow is thus not sustainable. Mid-course dose verification did not provide added benefit and can be safely omitted in the presence of closely monitored daily IGRT. Daily image guidance and match protocol is a safe and efficient method for identifying patients requiring adaptive replanning.

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Optimal adaptive IMRT strategy to spare the parotid glands in oropharyngeal cancer

Abstract: Early replannings proved the most beneficial for PG sparing, three replannings (weeks 1-2-5), representing an attractive combination for ART in oropharyngeal cancer.

Cited by 53 publications

References 42 publications

Differences between planned and delivered dose for head and neck cancer, and their consequences for normal tissue complication probability and treatment adaptation

Differences between planned and delivered dose for head and neck cancer, and their consequences for normal tissue complication probability and treatment adaptation

Parotid gland radiation dose‐xerostomia relationships based on actual delivered dose for nasopharyngeal carcinoma

Cone-beam computed tomography (CBCT) for adaptive image guided head and neck radiation therapy

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