A Novel TPS Toolkit to Assess Correlation Between Transit Fluence Dosimetry and DVH Metrics for Adaptive Head and Neck Radiotherapy

Mapping Intimacies ◽

10.21203/rs.3.rs-541098/v1 ◽

2021 ◽

Author(s):

George Antoniou ◽

Scott Penfold

Keyword(s):

Spinal Cord ◽

Head And Neck Cancer ◽

Head And Neck ◽

Cancer Patients ◽

Neck Cancer ◽

Treatment Plan ◽

Royal Adelaide Hospital ◽

Data Set ◽

Imaging Device ◽

In Transit

Abstract Inter-fractional anatomical variations in head and neck (H&N) cancer patients can lead to clinically significant dosimetric changes. Adaptive re-planning should thus commence to negate any potential over-dosage to organs-at-risk (OAR), as well as potential under-dosage to target lesions. The aim of this study is to explore the correlation between transit fluence, as measured at an electronic portal imaging device (EPID), and dose volume histogram (DVH) metrics to target and OAR structures in a simulated environment. Planning data of 8 patients that have previously undergone adaptive radiotherapy for head and neck cancer using volumetric modulated arc therapy (VMAT) at the Royal Adelaide Hospital were selected for this study. Through delivering the original treatment plan to both the planning and rescan CTs of these 8 patients, predicted electronic portal images (EPIs) and DVH metrics corresponding to each data set were extracted using a novel RayStation script. A weighted projection mask was developed for target and OAR structures through considering the intra-angle overlap between fluence and structure contours projected onto the EPIs. The correlation between change in transit fluence and planning target volume (PTV) D98 and spinal cord D0.03cc with and without the weighting mask applied was investigated. PTV D98 was strongly correlated with mean fluence percentage difference both with and without the weighting mask applied (RMask = 0.69, RNo Mask = 0.79, N = 14, p < 0.05), where spinal cord D0.03cc exhibited a weak correlation (RMask = 0.35, RNo Mask = 0.53, N = 7, p > 0.05) however this result was not statistically significant. The simulation toolkit developed in this work provided a useful means to investigate the relationship between change in transit fluence and change in key dosimetric parameters for head and neck cancer patients.

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The effect of radiotheraphy technique on the spinal cord in head and neck cancer patients

International Journal of Radiation Oncology*Biology*Physics ◽

10.1016/0360-3016(78)90676-4 ◽

1978 ◽

Vol 4 ◽

pp. 77

Author(s):

J.C. Paradello ◽

H.W. Mower ◽

A. Ucmakli

Keyword(s):

Spinal Cord ◽

Head And Neck Cancer ◽

Head And Neck ◽

Cancer Patients ◽

Neck Cancer

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Validation of the relative insensitivity of volumetric-modulated arc therapy (VMAT) plan quality to gantry space resolution

Journal of Radiation Research ◽

10.1093/jrr/rrw114 ◽

2016 ◽

Vol 58 (4) ◽

pp. 579-590 ◽

Cited By ~ 2

Author(s):

Ghulam Murtaza ◽

Stefania Cora ◽

Ehsan Ullah Khan

Keyword(s):

Head And Neck Cancer ◽

Head And Neck ◽

Cancer Patients ◽

Neck Cancer ◽

Treatment Plan ◽

Volumetric Modulated Arc Therapy ◽

Optimization Techniques ◽

Plan Quality ◽

Arc Therapy ◽

Single Arc

Abstract Volumetric-modulated arc therapy (VMAT) is an efficient form of radiotherapy used to deliver intensity-modulated radiotherapy beams. The aim of this study was to investigate the relative insensitivity of VMAT plan quality to gantry angle spacing (GS). Most previous VMAT planning and dosimetric work for GS resolution has been conducted for single arc VMAT. In this work, a quantitative comparison of dose–volume indices (DIs) was made for partial-, single- and double-arc VMAT plans optimized at 2°, 3° and 4° GS, representing a large variation in deliverable multileaf collimator segments. VMAT plans of six prostate cancer and six head-and-neck cancer patients were simulated for an Elekta SynergyS® Linac (Elekta Ltd, Crawley, UK), using the SmartArc™ module of Pinnacle³ TPS, (version 9.2, Philips Healthcare). All optimization techniques generated clinically acceptable VMAT plans, except for the single-arc for the head-and-neck cancer patients. Plan quality was assessed by comparing the DIs for the planning target volume, organs at risk and normal tissue. A GS of 2°, with finest resolution and consequently highest intensity modulation, was considered to be the reference, and this was compared with GS 3° and 4°. The differences between the majority of reference DIs and compared DIs were <2%. The metrics, such as treatment plan optimization time and pretreatment (phantom) dosimetric calculation time, supported the use of a GS of 4°. The ArcCHECK™ phantom–measured dosimetric agreement verifications resulted in a >95.0% passing rate, using the criteria for γ (3%, 3 mm). In conclusion, a GS of 4° is an optimal choice for minimal usage of planning resources without compromise of plan quality.

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Incidence of osteoradionecrosis of the jaws: A retrospective study of 620 head and neck cancer patients treated by radiotherapy

10.21203/rs.3.rs-29543/v1 ◽

2020 ◽

Author(s):

Ryma Kabir ◽

Robert Durand ◽

David Roberge ◽

Eric Dufresne ◽

Phuc Félix Nguyen-Tân ◽

...

Keyword(s):

Head And Neck Cancer ◽

Head And Neck ◽

Cancer Patients ◽

Neck Cancer ◽

Treatment Plan ◽

Comprehensive Treatment ◽

Dental Examination ◽

Factors Influencing ◽

Local Risk ◽

Edentulous Patients

Abstract Background This study aims to assess systemic and local risk factors influencing the development of osteoradionecrosis of the jaws (ORN) and its incidence in head and neck cancer patients undergoing radiotherapy.Methods This was a retrospective cohort study of 620 adult patients following radiation for a head and neck cancer in 2011 or 2012. Results Of the 181 patients who did not require any extraction, the incidence of ORN was 0.5%. Of the 266 patients with 1491 dental extractions (mean 5.5 teeth per patient) performed before radiotherapy, the incidence of ORN was 3.7%. ORN was always observed in extraction sites located in the field of radiation. No dental extractions were done during radiotherapy. Of the 20 patients with 53 dental extractions (mean 2.7 teeth per patient) performed after radiotherapy, 15 teeth were located in the field of radiation. No case of ORN was reported in that group. For edentulous patients, ORN incidence was 1.7%. Conclusion Within the limitations of this study, the incidence of ORN can be minimized with a meticulous pre-radiotherapy dental examination, a comprehensive treatment plan and diligent post-radiotherapy follow-ups conducted by an experienced multidisciplinary team.

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