Radiation Dose–Volume Effects in the Larynx and Pharynx

Rancati, T.; Schwarz, Marco; Allen, Aaron M.; Feng, Felix Y.; Popovtzer, Aron; Mittal, Bharat B.; Eisbruch, Avraham

doi:10.1016/j.ijrobp.2009.03.079

Cited by 200 publications

(134 citation statements)

References 26 publications

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“…They were defined prior to commencement of the AP evaluation. The OAR score values are based on biological endpoints 20 , 21 , 22 , 23 and attempt to capture the physician's perception of the relative importance of different dose goals. Taking the parotid gland as an example, the maximum available score is 15, relative to the target coverage maximum score of 25.…”

Section: Methodsmentioning

confidence: 99%

Initial evaluation of automated treatment planning software

Gintz

Latifi

Caudell

et al. 2016

J Applied Clin Med Phys

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Even with advanced inverse‐planning techniques, radiation treatment plan optimization remains a very time‐consuming task with great output variability, which prompted the development of more automated approaches. One commercially available technique mimics the actions of experienced human operators to progressively guide the traditional optimization process with automatically created regions of interest and associated dose‐volume objectives. We report on the initial evaluation of this algorithm on 10 challenging cases of locoreginally advanced head and neck cancer. All patients were treated with VMAT to 70 Gy to the gross disease and 56 Gy to the elective bilateral nodes. The results of post‐treatment autoplanning (AP) were compared to the original human‐driven plans (HDP). We used an objective scoring system based on defining a collection of specific dosimetric metrics and corresponding numeric score functions for each. Five AP techniques with different input dose goals were applied to all patients. The best of them averaged the composite score 8% lower than the HDP, across the patient population. The difference in median values was statistically significant at the 95% confidence level (Wilcoxon paired signed‐rank test p=0.027). This result reflects the premium the institution places on dose homogeneity, which was consistently higher with the HDPs. The OAR sparing was consistently better with the APs, the differences reaching statistical significance for the mean doses to the parotid glands (p<0.001) and the inferior pharyngeal constrictor (p=0.016), as well as for the maximum doses to the spinal cord (p=0.018) and brainstem (p=0.040). If one is prepared to accept less stringent dose homogeneity criteria from the RTOG 1016 protocol, nine APs would comply with the protocol, while providing lower OAR doses than the HDPs. Overall, AP is a promising clinical tool, but it could benefit from a better process for shifting the balance between the target dose coverage/homogeneity and OAR sparing.PACS number(s): 87.55.D

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Section: Methodsmentioning

confidence: 99%

Initial evaluation of automated treatment planning software

Gintz

Latifi

Caudell

et al. 2016

J Applied Clin Med Phys

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“…For the OARs, the population-averaged mean doses (AE standard deviation) and the maximal doses to the spinal cord and carotid arteries were reported. It has been recommended to keep the dose in the larynx less than $66 Gy for vocal function preservation (2). Therefore, the volume of the CL vocal cord that received $95% of the prescribed dose or more was also reported.…”

Section: Treatment Plansmentioning

confidence: 99%

Imrt in Image-Guided Single Vocal Cord Irradiation

Osman¹,

Astreinidou²,

Keskin-Cambay³

et al. 2009

Radiotherapy and Oncology

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Purpose: We have been developing an image-guided single vocal cord irradiation technique to treat patients with stage T1a glottic carcinoma. In the present study, we compared the dose coverage to the affected vocal cord and the dose delivered to the organs at risk using conventional, intensity-modulated radiotherapy (IMRT) coplanar, and IMRT non-coplanar techniques. Methods and Materials: For 10 patients, conventional treatment plans using two laterally opposed wedged 6-MV photon beams were calculated in XiO (Elekta-CMS treatment planning system). An in-house IMRT/beam angle optimization algorithm was used to obtain the coplanar and non-coplanar optimized beam angles. Using these angles, the IMRT plans were generated in Monaco (IMRT treatment planning system, Elekta-CMS) with the implemented Monte Carlo dose calculation algorithm. The organs at risk included the contralateral vocal cord, arytenoids, swallowing muscles, carotid arteries, and spinal cord. The prescription dose was 66 Gy in 33 fractions. Results: For the conventional plans and coplanar and non-coplanar IMRT plans, the population-averaged mean dose ± standard deviation to the planning target volume was 67 ± 1 Gy. The contralateral vocal cord dose was reduced from 66 ± 1 Gy in the conventional plans to 39 ± 8 Gy and 36 ± 6 Gy in the coplanar and non-coplanar IMRT plans, respectively. IMRT consistently reduced the doses to the other organs at risk. Conclusions: Single vocal cord irradiation with IMRT resulted in good target coverage and provided significant sparing of the critical structures. This has the potential to improve the quality-of-life outcomes after RT and maintain the same local control rates.

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“…One major area of concern for head and neck treatments is the dosimetric sparing of a patient's salivary glands, pharyngeal constrictors, and larynx. High doses of radiation to these organs can cause dry mouth (xerostomia) and difficulty swallowing (dysphagia) 2, 3, 4, 5, 6. Sparing a patient's salivary glands and larynx has been shown to reduce symptoms and increase patient quality of life 2, 7, 8, 9.…”

Section: Introductionmentioning

confidence: 99%

“…The QUANTEC review of dose–volume effects on salivary function by Deasy et al concluded that for IMRT plans the mean dose to each parotid gland should be kept as low as possible 3. It also states that, “a lower mean dose to the parotid gland usually results in better function, even for relatively low mean doses (<1000 cGy).”3 The same review examining larynx and pharynx dose–volume effects had a similar conclusion stating that planners should minimize the volume of pharyngeal constrictors and larynx receiving 6000 cGy, and when, possible 5000 cGy 6. Both publications emphasize the concept of minimizing the dose to these structures beyond the published/accepted benchmarks (i.e., as low as achievable).…”

Section: Introductionmentioning

confidence: 99%

Assessment of PlanIQ Feasibility DVH for head and neck treatment planning

Fried

Chera

Das

2017

J Applied Clin Med Phys

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IntroductionDesigning a radiation plan that optimally delivers both target coverage and normal tissue sparing is challenging. There are limited tools to determine what is dosimetrically achievable and frequently the experience of the planner/physician is relied upon to make these determinations. PlanIQ software provides a tool that uses target and organ at risk (OAR) geometry to indicate the difficulty of achieving different points for organ dose–volume histograms (DVH). We hypothesized that PlanIQ Feasibility DVH may aid planners in reducing dose to OARs.Methods and materialsClinically delivered head and neck treatments (clinical plan) were re‐planned (re‐plan) putting high emphasis on maximally sparing the contralateral parotid gland, contralateral submandibular gland, and larynx while maintaining routine clinical dosimetric objectives. The planner was blinded to the results of the clinically delivered plan as well as the Feasibility DVHs from PlanIQ. The re‐plan treatments were designed using 3‐arc VMAT in Raystation (RaySearch Laboratories, Sweden). The planner was then given the results from the PlanIQ Feasibility DVH analysis and developed an additional plan incorporating this information using 4‐arc VMAT (IQ plan). The DVHs across the three treatment plans were compared with what was deemed “impossible” by PlanIQ's Feasibility DVH (Impossible DVH). The impossible DVH (red) is defined as the DVH generated using the minimal dose that any voxel outside the targets must receive given 100% target coverage.ResultsThe re‐plans performed blinded to PlanIQ Feasibilty DVH achieved superior sparing of aforementioned OARs compared to the clinically delivered plans and resulted in discrepancies from the impossible DVHs by an average of 200–700 cGy. Using the PlanIQ Feasibility DVH led to additional OAR sparing compared to both the re‐plans and clinical plans and reduced the discrepancies from the impossible DVHs to an average of approximately 100 cGy. The dose reduction from clinical to re‐plan and re‐plan to IQ plan were significantly different even when taking into account multiple hypothesis testing for both the contralateral parotid and the larynx (P < 0.004 for all comparisons). No significant differences were observed between the three plans for the contralateral parotid when considering multiple hypothesis testing.ConclusionsClinical treatment plans and blinded re‐plans were found to suboptimally spare OARs. PlanIQ could aid planners in generating treatment plans that push the limits of OAR sparing while maintaining routine clinical target coverage goals.

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Radiation Dose–Volume Effects in the Larynx and Pharynx

Cited by 200 publications

References 26 publications

Initial evaluation of automated treatment planning software

Initial evaluation of automated treatment planning software

Imrt in Image-Guided Single Vocal Cord Irradiation

Assessment of PlanIQ Feasibility DVH for head and neck treatment planning

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