Dose–volume analysis of locoregional recurrences in head and neck IMRT, as determined by deformable registration: A prospective multi-institutional trial

Co-registration of radiotherapy planning and recurrence scans with different imaging modalities in head and neck cancer

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Head and neck magnetic resonance imaging and computed tomography co-registration.

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Validation of planning and recurrence scan co-registration separated in time.

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Mean distances to agreement for regions of interest/normal tissue were tolerable.

MRI (magnetic resonance imaging) scans are frequently used in follow-up after radiotherapy for head and neck cancer. With the overall aim of enabling MRI-based pattern of failure analysis, this study evaluated the accuracy of recurrence MRI (rMRI) deformable co-registration with planning CT (computed tomography)-scans (pCT). Uncertainty of anatomical changes between pCT and rMRI was assessed by similarity metric analyses of co-registered image structures from 19 patients. Average mean distance to agreement and Dice similarity coefficient performed adequately. Our findings provide proof of concept for reliable co-registration of pCT and rMRI months to years apart for MRI-based pattern of failure analysis.

Target coverage and local recurrences after radiotherapy for sinonasal cancer in Denmark 2008-2015. A DAHANCA study

PURPOSE

The study aimed to investigate the pattern of failure and describe compromises in the definition and coverage of the target for patients treated with curatively intended radiotherapy (RT) for sinonasal cancer (SNC).

METHODS AND MATERIAL

Patients treated with curatively intended RT in 2008-2015 in Denmark for SNC were eligible for the retrospective cohort study. Information regarding diagnosis and treatment was retrieved from the national database of the Danish Head and Neck Cancer Group (DAHANCA). Imaging from the diagnosis of recurrences was collected, and the point of origin (PO) of the recurrent tumour was estimated. All treatment plans were collected and reviewed with the focus on target coverage, manual modifications of target volumes, and dose to organs at risk (OARs) above defined constraints.

RESULTS

A total of 184 patients were included in the analysis, and 76 (41%) relapsed. The majority of recurrences involved T-site (76%). Recurrence imaging of 39 patients was evaluated, and PO was established. Twenty-nine POs (74%) were located within the CTV, and the minimum dose to the PO was median 64.1 Gy (3.1-70.7). The criteria for target coverage (V95%) was not met in 89/184 (48%) of the CTV and 131/184 (71%) of the PTV. A total of 24% of CTVs had been manually modified to spare OARs of high-dose irradiation. No difference in target volume modifications was observed between patients who suffered recurrence and patients with lasting remission.

CONCLUSION

The majority of relapses after radical treatment of SNC were located in the T-site (the primary tumour site). Multiple compromises with regards to target coverage and tolerance levels for OARs in the sinonasal region, as defined from RT guidelines, were taken. No common practice in this respect could be derived from the study.

Recurrence Patterns After IMRT/VMAT in Head and Neck Cancer

Purpose

Intensity-modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT), two advanced modes of high-precision radiotherapy (RT), have become standard of care in the treatment of head and neck cancer. The development in RT techniques has markedly increased the complexity of target volume definition and accurate treatment delivery. The aim of this study was to indirectly investigate the quality of current TV delineation and RT delivery by analyzing the patterns of treatment failure for head and neck cancer patients in our high-volume RT center.

Methods

Between 2004 and 2014, 385 patients with pharyngeal, laryngeal, and oral cavity tumors were curatively treated with primary RT (IMRT/VMAT). We retrospectively investigated locoregional recurrences (LRR), distant metastases (DM), and overall survival (OS).

Results

Median follow-up was 6.4 years (IQR 4.7–8.3 years) during which time 122 patients (31.7%) developed LRR (22.1%) and DM (17.7%). The estimated 2- and 5-year locoregional control was 78.2% (95% CI 73.3, 82.3) and 74.2% (95% CI 69.0, 78.8). One patient developed a local recurrence outside the high-dose volume and five patients developed a regional recurrence outside the high-dose volume. Four patients (1.0%) suffered a recurrence in the electively irradiated neck and two patients had a recurrence outside the electively irradiated neck. No marginal failures were observed. The estimated 2- and 5-year DM-free survival rates were 83.3% (95% CI 78.9, 86.9) and 80.0% (95% CI 75.2, 84.0). The estimated 2- and 5-year OS rates were 73.6% (95% CI 68.9, 77.8) and 52. 6% (95% CI 47.3, 57.6). Median OS was 5.5 years (95% CI 4.5, 6.7).

Conclusion

Target volume definition and treatment delivery were performed accurately, as only few recurrences occurred outside the high-dose regions and no marginal failures were observed. Research on dose intensification and identification of high-risk subvolumes might decrease the risk of locoregional relapses. The results of this study may serve as reference data for comparison with future studies, such as dose escalation or proton therapy trials.

Impact of the method chosen for the analysis of recurrences after radiotherapy for head and neck cancers: volume-based, point-based and combined methods

Intensity modulated radiation therapy for head and neck is a complex technique. Inappropriate delineation and/or dose distribution can lead to recurrences. Analysis of these recurrences should lead to improve clinical practice. For several years, different methods of analysis have been described. The purpose of this review is to describe these different methods and to discuss their advantages and limitations. The first published methods used a volume-based approach studying the entire volume of recurrence according to initial target volumes, or dose distribution. The main limitation of these methods was that the volume of recurrence studied was dependent on the delay in diagnosis of that recurrence. Subsequently, other methods used point-based approaches, conceptualizing recurrence either as a spherical expansion from a core of radioresistant cells (center of mass of recurrence volume) or using a more clinical approach, taking into account tumor expansion pathways. More recently, more precise combined methods have been described, combining the different approaches. The choice of method is decisive for conclusions on the origin of recurrence.

Dose accumulation to assess the validity of treatment plans with reduced margins in radiotherapy of head and neck cancer

BACKGROUND AND PURPOSE

Literature has reported reduced treatment toxicity in head-and-neck radiotherapy (HNRT) when reducing the planning target volume (PTV) margin from 5 to 3 mm but loco-regional control was not always preserved. This study used deformable image registration (DIR)-facilitated dose accumulation to assess clinical target volume (CTV) coverage in the presence of anatomical changes.

MATERIALS AND METHODS

VMAT plans for 12 patients were optimized using 3 or 5 mm PTV and planning risk volume (PRV) margins. The planning computed tomography (pCT) scan was registered to each daily cone beam CT (CBCT) using DIR. The inverse registration was used to reconstruct and accumulate dose (D acc ). CTV coverage was assessed using the dose-volume histogram (DVH) metric D 99 % acc and by individual voxel analysis. Both approaches included an uncertainty estimate using the 95% level of confidence.

RESULTS

D 99 % acc was less than 95% of the prescribed doseD presc for three cases including only one case where this was at the 95% level of confidence. However for many patients, the accumulated dose included a substantial volume of voxels receiving less than 95%D presc independent of margin expansion, which predominantly occurred in the subdermal region. Loss in target coverage was very patient specific but tightness of target volume coverage at planning was a common factor leading to underdosage.

CONCLUSION

This study agrees with previous literature that PTV/PRV margin reduction did not significantly reduce CTV coverage during treatment, but also highlighted that tight coverage of target volumes at planning increases the risk of clinically unacceptable dose delivery. Patient-specific verification of dose delivery to assess the dose delivered to each voxel is recommended.

Head and Neck Cancer Adaptive Radiation Therapy (ART): Conceptual Considerations for the Informed Clinician

For nearly 2 decades, adaptive radiation therapy (ART) has been proposed as a method to account for changes in head and neck tumor and normal tissue to enhance therapeutic ratios. While technical advances in imaging, planning and delivery have allowed greater capacity for ART delivery, and a series of dosimetric explorations have consistently shown capacity for improvement, there remains a paucity of clinical trials demonstrating the utility of ART. Furthermore, while ad hoc implementation of head and neck ART is reported, systematic full-scale head and neck ART remains an as yet unreached reality. To some degree, this lack of scalability may be related to not only the complexity of ART, but also variability in the nomenclature and descriptions of what is encompassed by ART. Consequently, we present an overview of the history, current status, and recommendations for the future of ART, with an eye toward improving the clarity and description of head and neck ART for interested clinicians, noting practical considerations for implementation of an ART program or clinical trial. Process level considerations for ART are noted, reminding the reader that, paraphrasing the writer Elbert Hubbard, "Art is not a thing, it is a way."

Local Failure Rate in Oropharyngeal Carcinoma Patients Treated with Intensity-modulated Radiotherapy Without High-dose Clinical Target Volume

Purpose: Our purpose was to evaluate whether omitting high-dose clinical target volume radiation (CTV-HD) around the gross tumor volume (GTV) in patients with oropharyngeal squamous cell carcinoma (OSCC) treated with intensity-modulated radiotherapy (IMRT) was associated with increased local failure.

Methods and materials: Patients diagnosed with stage I to stage IV OSCC between December 2004 and April 2017 were retrospectively reviewed. All patients were treated with radical radiotherapy using IMRT, with or without neoadjuvant or concurrent chemotherapy. In accordance with institution guidelines, CTV-HD was not used. Local failure was defined as disease persistence or reappearance at the primary tumor site. When primary failure was documented, the computed tomography/positron emission tomography (CT/PET) scan that showed primary failure was fused with the original treatment scan. Each recurrent tumor was contoured to evaluate the pattern of recurrence. Recurrences were categorized as in-field, marginal, or out-of-field if >95%, 20%-95%, or <20% of the recurrent tumor volume, respectively, was encompassed by the 95% high-dose prescription isodose line of the original treatment plan. We then determined whether omitting CTV-HD was associated with increased locoregional failure.

Results: A total of 272 patients with OSCC were assessed. The median follow-up from initial treatment was 43 months (range: 3-194 months). Seven patients were lost to follow-up. The overall five-year survival rate was 87%. The three- and five-year disease-free survival rates were 86% and 83%, respectively. Forty-one patients had 53 treatment failures (16 were local, eight were regional, and 29 were distant; some patients had treatment failures in multiple locations). Fourteen (87.5%) of the local recurrences were in-field, one (6.25%) was marginal, and one (6.25%) was out-of-field.

Conclusion: Our analysis of patients with oropharyngeal cancer suggests that local failure is mostly in-field and potentially due to radioresistance, rather than a marginal miss of the tumor. It suggests that omitting CTV-HD is feasible and safe.

Use of baseline 18F-FDG PET scan to identify initial sub-volumes with local failure after concomitant radio-chemotherapy in head and neck cancer

Introduction

Head and neck squamous cell carcinoma (HNSCC) treated by radio-chemotherapy have a significant local recurrence rate. It has been previously suggested that 18F-FDG PET could identify the high uptake areas that can be potential targets for dose boosting. The purpose of this study was to compare the location of initial hypermetabolic regions on baseline scans with the metabolic relapse sites after radio-chemotherapy in HNSCC.

Results

The initial functional tumor volume was significantly higher for patients with proven local recurrence or residual disease (23.5 cc vs. 8.9 cc; p = 0.0005). The overlap between baseline and follow-up sub-volumes were moderate with an overlap fraction ranging from 0.52 to 0.39 between R40 and I30 to I60.

Conclusion

In our study the overlap between baseline and post-therapeutic metabolic tumor sub-volumes was only moderate. These results need to be investigated in a larger cohort acquired with a more standardized patient repositioning protocol for sequential PET imaging.

Methods

Pre and post treatment PET/CT scans of ninety four HNSCC patients treated with radio-chemotherapy were retrospectively reviewed. Follow-up 18F-FDG PET/CT images were registered to baseline scans using a rigid body transformation. Seven metabolic tumor sub-volumes were obtained on the baseline scans using a fixed percentage of SUV_max (I30, I40, I50, I60, I70, I80, and I90) and were subsequently compared with two post-treatment sub-volumes (R40, R90) in 38 cases of local recurrence or residual metabolic disease. Overlap fraction, Dice and Jaccard indices, common volume/baseline volume and common volume/recurrent volume were used to determine the overlap of the different estimated sub-volumes.

Analysis of CT-verified loco-regional recurrences after definitive IMRT for HNSCC using site of origin estimation methods

INTRODUCTION

A significant part of patients with head and neck squamous cell carcinoma (HNSCC) develop recurrent disease after curative radiotherapy. We aimed to analyze loco-regional recurrence pattern by identifying possible points of recurrence origin by three different methods in relation to treatment volumes.

MATERIAL AND METHODS

A total of 455 patients completed IMRT-based treatment for HNSCC from 2006 to 2012. A total of 159 patients had remaining cancer after IMRT, developed loco-regional recurrence or distant disease during follow-up. Among those, 69 patients with loco-regional recurrences had affirmative CT or PET/CT scan. Possible points of origin (POs) of the recurrences were identified on scans by two independent observers, estimated as center of mass and as maximum surface distance. The recurrence position was analyzed in relation to high-dose treatment volume (CTV1) and 95% of prescription dose.

RESULTS

In total, 104 loco-regional recurrences (54 in T-site and 50 in N-site) were identified in 69 patients. Median time to recurrence for the 69 patients was 10 months. No clinically relevant difference was found between the four POs, with standard deviation between POs in x, y and z axes of 3, 3 and 6 mm. For recurrences inside CTV1, 0-5 mm and 5-10 mm outside CTV1 the standard deviation of dose differences between the POs were 1, 1.4 and 1 Gy, respectively. 56% and 25% of T-site and N-site recurrences were inside CTV1, respectively. Coverage by 95% prescription dose to high-dose treatment volume was achieved in 78% of T-site and 39% of N-site recurrences.

CONCLUSIONS

For recurrences identified by possible points of recurrence origin, no significant difference between observer-based or mathematically estimated methods was found. More than half of T-site recurrences were inside high-dose treatment volume, whereas N-site recurrences were mainly outside.

Recurrent oropharyngeal cancer after organ preserving treatment: pattern of failure and survival

The objectives is to thoroughly analyze the pattern of failure and oncologic outcome in recurrent oropharyngeal cancer (OPC) after (chemo)radiotherapy and correlate the site of failure to the planned radiation dose. Between January 2010 and April 2014, 57 patients with recurrent OPC after (chemo)radiotherapy were analyzed. Endpoints were pattern of failure and overall survival (OS). Local (LF) and regional failure (RF) were classified as in-field [>50% within gross tumor volume (GTV)], marginal [<50% within GTV but >50% within clinical target volume (CTV)], or out-of-field (>50% outside CTV) recurrences. In the whole group, 70 recurrences were reported. Of the 31 LF, 29 (93.5%) were in-field and 2 (6.5%) were marginal. No out-field LF was reported. Of the 21 RF, 13 RF (62%) were in-field, 6 (28.5%) marginal, and 2 (9.5%) out-of-field recurrences. Forty-three percent of RF was developed in an electively treated neck level, and 2 of them were contralateral. OS at 2 years in recurrent HPV positive, compared to HPV-negative OPC, were 66 and 18%, respectively (p = 0.011). OS was also significantly better in patients that were salvage treatment which was possible (70 vs. 6%, p < 0.001). Median survival after distant failure was 3.6 months. The great majority of LFs were located within the GTV and 43% of RFs developed in an electively treated neck level. The currently used margins and dose recipe and the indication for bilateral nodal irradiation need to be reevaluated. OS was significantly better in recurrent HPV-positive OPC and in patients, where salvage treatment was possible.

DARS: a phase III randomised multicentre study of dysphagia- optimised intensity- modulated radiotherapy (Do-IMRT) versus standard intensity- modulated radiotherapy (S-IMRT) in head and neck cancer

BACKGROUND

Persistent dysphagia following primary chemoradiation (CRT) for head and neck cancers can have a devastating impact on patients' quality of life. Single arm studies have shown that the dosimetric sparing of critical swallowing structures such as the pharyngeal constrictor muscle and supraglottic larynx can translate to better functional outcomes. However, there are no current randomised studies to confirm the benefits of such swallow sparing strategies. The aim of Dysphagia/Aspiration at risk structures (DARS) trial is to determine whether reducing the dose to the pharyngeal constrictors with dysphagia-optimised intensity- modulated radiotherapy (Do-IMRT) will lead to an improvement in long- term swallowing function without having any detrimental impact on disease-specific survival outcomes.

METHODS/DESIGN

The DARS trial (CRUK/14/014) is a phase III multicentre randomised controlled trial (RCT) for patients undergoing primary (chemo) radiotherapy for T1-4, N0-3, M0 pharyngeal cancers. Patients will be randomised (1:1 ratio) to either standard IMRT (S-IMRT) or Do-IMRT. Radiotherapy doses will be the same in both groups; however in patients allocated to Do-IMRT, irradiation of the pharyngeal musculature will be reduced by delivering IMRT identifying the pharyngeal muscles as organs at risk. The primary endpoint of the trial is the difference in the mean MD Anderson Dysphagia Inventory (MDADI) composite score, a patient-reported outcome, measured at 12 months post radiotherapy. Secondary endpoints include prospective and longitudinal evaluation of swallow outcomes incorporating a range of subjective and objective assessments, quality of life measures, loco-regional control and overall survival. Patients and speech and language therapists (SLTs) will both be blinded to treatment allocation arm to minimise outcome-reporting bias.

DISCUSSION

DARS is the first RCT investigating the effect of swallow sparing strategies on improving long-term swallowing outcomes in pharyngeal cancers. An integral part of the study is the multidimensional approach to swallowing assessment, providing robust data for the standardisation of future swallow outcome measures. A translational sub- study, which may lead to the development of future predictive and prognostic biomarkers, is also planned.

TRIAL REGISTRATION

This study is registered with the International Standard Randomised Controlled Trial register, ISRCTN25458988 (04/01/2016).

Methodology for analysis and reporting patterns of failure in the Era of IMRT: head and neck cancer applications

Background

The aim of this study is to develop a methodology to standardize the analysis and reporting of the patterns of loco-regional failure after IMRT of head and neck cancer.

Material and Methods

Twenty-one patients with evidence of local and/or regional failure following IMRT for head-and-neck cancer were retrospectively reviewed under approved IRB protocol. Manually delineated recurrent gross disease (rGTV) on the diagnostic CT documenting recurrence (rCT) was co-registered with the original planning CT (pCT) using both deformable (DIR) and rigid (RIR) image registration software. Subsequently, mapped rGTVs were compared relative to original planning target volumes (TVs) and dose using a centroid-based approaches. Failures were then classified into five types based on combined spatial and dosimetric criteria; A (central high dose), B (peripheral high dose), C (central elective dose), D (peripheral elective dose), and E (extraneous dose).

Results

A total of 26 recurrences were identified. Using DIR, recurrences were assigned to more central TVs compared to RIR as detected using the spatial centroid-based method (p = 0.0002). rGTVs mapped using DIR had statistically significant higher mean doses when compared to rGTVs mapped rigidly (mean dose 70 vs. 69 Gy, p = 0.03). According to the proposed classification 22 out of 26 failures were of type A (central high dose) as assessed by DIR method compared to 18 out of 26 for the RIR because of the tendencey of RIR to assign failures more peripherally.

Conclusions

RIR tends to assigns failures more peripherally. DIR-based methods showed that the vast majority of failures originated in the high dose target volumes and received full prescribed doses suggesting biological rather than technology-related causes of failure. Validated DIR-based registration is recommended for accurate failure characterization and a novel typology-indicative taxonomy is recommended for failure reporting in the IMRT era.

Electronic supplementary material

The online version of this article (doi:10.1186/s13014-016-0678-7) contains supplementary material, which is available to authorized users.

Open source deformable image registration system for treatment planning and recurrence CT scans : Validation in the head and neck region

BACKGROUND

Clinical application of deformable registration (DIR) of medical images remains limited due to sparse validation of DIR methods in specific situations, e. g. in case of cancer recurrences. In this study the accuracy of DIR for registration of planning CT (pCT) and recurrence CT (rCT) images of head and neck squamous cell carcinoma (HNSCC) patients was evaluated.

PATIENTS AND MATERIALS

Twenty patients treated with definitive IMRT for HNSCC in 2010-2012 were included. For each patient, a pCT and an rCT scan were used. Median interval between the scans was 8.5 months. One observer manually contoured eight anatomical regions-of-interest (ROI) twice on pCT and once on rCT.

METHODS

pCT and rCT images were deformably registered using the open source software elastix. Mean surface distance (MSD) and Dice similarity coefficient (DSC) between contours were used for validation of DIR. A measure for delineation uncertainty was estimated by assessing MSD from the re-delineations of the same ROI on pCT. DIR and manual contouring uncertainties were correlated with tissue volume and rigidity.

RESULTS

MSD varied 1-3 mm for different ROIs for DIR and 1-1.5 mm for re-delineated ROIs performed on pCT. DSC for DIR varied between 0.58 and 0.79 for soft tissues and was 0.79 or higher for bony structures, and correlated with the volumes of ROIs (r = 0.5, p < 0.001) and tissue rigidity (r = 0.54, p < 0.001).

CONCLUSION

DIR using elastix in HNSCC on planning and recurrence CT scans is feasible; an uncertainty of the method is close to the voxel size length of the planning CT images.

Assessment and topographic characterization of locoregional recurrences in head and neck tumours

Purpose

To evaluate the differences between three methods of classification of recurrences in patients with head and neck tumours treated with Radiation Therapy (RT).

Materials and methods

367 patients with head and neck tumours were included in the study. Tumour recurrences were delineated in the CT images taken during patient follow-up and deformable registration was used to transfer this volume into the planning CT. The methods used to classify recurrences were: method CTV quantified the intersection volume between the recurrence and the Clinical Target Volume (CTV); method TV quantified the intersection between the Treated Volume and the recurrence (for method CTV and TV, recurrences were classified in-field if more than 95% of their volume were inside the volume of interest, marginal if the intersection was between 20-95% and outfield otherwise); and method COM was based on the position of the Centre Of Mass of the recurrence. A dose assessment in the recurrence volume was also made.

Results

The 2-year Kaplan-Meier locoregional recurrence incidence was 10%. Tumour recurrences occurred in 22 patients in a mean time of 16.5 ± 9.4 months resulting in 28 recurrence volumes. The percentage of in-field recurrences for methods CTV, TV and COM was 7%, 43% and 50%, respectively. Agreement between the three methods in characterizing individually in-field and marginal recurrences was found only in six cases. Methods CTV and COM agreed in 14. The percentage of outfield recurrences was 29% using all methods. For local recurrences (in-field or marginal to gross disease) the average difference between the prescribed dose and D_98% in the recurrence volume was -5.2 ± 3.5% (range: -10.1%-0.9%).

Conclusions

The classification of in-field and marginal recurrences is very dependent on the method used to characterize recurrences. Using methods TV and COM the largest percentage of tumour recurrences occurred in-field in tissues irradiated with high doses.

Electronic supplementary material

The online version of this article (doi:10.1186/s13014-015-0345-4) contains supplementary material, which is available to authorized users.

Locoregional recurrences after post-operative volumetric modulated arc radiotherapy (VMAT) in oral cavity cancers in a resource constrained setting: experience and lessons learned

OBJECTIVE

The conformal nature of dose distribution produced by volumetric modulated arc radiotherapy (VMAT) increases the risk of geographic miss. Data regarding patterns of failure after VMAT in oral cavity cancers in resource-constrained settings are scarce. The aim of the present study was to ascertain the patterns of failure in patients receiving adjuvant VMAT intensity-modulated radiotherapy (IMRT) for oral cavity cancer in Malabar Cancer Center, Kerala, India.

METHODS

Data of patients with oral cavity cancer receiving adjuvant VMAT IMRT between April 2012 and March 2014 were collected. Recurrent volumes were delineated on the treatment planning images and classified as defined by Dawson et al (Dawson LA, Anzai Y, Marsh L, Martel MK, Paulino A, Ship JA, et al. Patterns of local-regional recurrence following parotid-sparing conformal and segmental intensity-modulated radiotherapy for head and neck cancer. Int J Radiat Oncol Biol Phys 2000; 46: 1117-26).

RESULTS

75 patients with a median follow-up of 24 months were analysed. 41 (55%) patients had oral tongue cancers and 52 (69%) of the patients had Stage IVA cancers. The 2-year locoregional recurrence-free survival, disease-free survival and overall survival were 88.9%, 82.1% and 80.5%, respectively. With a median time to failure of 6.5 months, five infield and three outfield failures were identified.

CONCLUSION

A relatively low rate of outfield failure and lack of marginal failure attests to the efficacy of VMAT in such patients. Modifications to our existing target delineation policy have been proposed.

ADVANCES IN KNOWLEDGE

The use of standardized target delineation methods allows safe use of VMAT IMRT even in resource-constrained settings.

Quality assurance assessment of diagnostic and radiation therapy-simulation CT image registration for head and neck radiation therapy: anatomic region of interest-based comparison of rigid and deformable algorithms

PURPOSE

To develop a quality assurance (QA) workflow by using a robust, curated, manually segmented anatomic region-of-interest (ROI) library as a benchmark for quantitative assessment of different image registration techniques used for head and neck radiation therapy-simulation computed tomography (CT) with diagnostic CT coregistration.

MATERIALS AND METHODS

Radiation therapy-simulation CT images and diagnostic CT images in 20 patients with head and neck squamous cell carcinoma treated with curative-intent intensity-modulated radiation therapy between August 2011 and May 2012 were retrospectively retrieved with institutional review board approval. Sixty-eight reference anatomic ROIs with gross tumor and nodal targets were then manually contoured on images from each examination. Diagnostic CT images were registered with simulation CT images rigidly and by using four deformable image registration (DIR) algorithms: atlas based, B-spline, demons, and optical flow. The resultant deformed ROIs were compared with manually contoured reference ROIs by using similarity coefficient metrics (ie, Dice similarity coefficient) and surface distance metrics (ie, 95% maximum Hausdorff distance). The nonparametric Steel test with control was used to compare different DIR algorithms with rigid image registration (RIR) by using the post hoc Wilcoxon signed-rank test for stratified metric comparison.

RESULTS

A total of 2720 anatomic and 50 tumor and nodal ROIs were delineated. All DIR algorithms showed improved performance over RIR for anatomic and target ROI conformance, as shown for most comparison metrics (Steel test, P < .008 after Bonferroni correction). The performance of different algorithms varied substantially with stratification by specific anatomic structures or category and simulation CT section thickness.

CONCLUSION

Development of a formal ROI-based QA workflow for registration assessment demonstrated improved performance with DIR techniques over RIR. After QA, DIR implementation should be the standard for head and neck diagnostic CT and simulation CT allineation, especially for target delineation.

Adjuvant simultaneous integrated boost IMRT for patients with intermediate- and high-risk head and neck cancer: outcome, toxicities and patterns of failure

OBJECTIVES

To evaluate loco-regional control, survival, toxicities and patterns of failure of adjuvant intensity-modulated radiotherapy (IMRT) with a simultaneous integrated boost (SIB) for head and neck cancer (HNC) patients according to risk features.

MATERIALS AND METHODS

129 HNC patients who were treated between January 2001 and June 2010 at our institute with adjuvant SIB-IMRT with or without concurrent chemotherapy (CTX-SIB-IMRT) were included. High-risk (HR) patients with extracapsular tumor extension (ECE) and/or close resection margins had CTX-SIB-IMRT to 54/63.9 Gy and intermediate-risk (IR) patients had SIB-IMRT to 50/56 Gy. The primary endpoints were local (LC) and regional control (RC). Secondary endpoints included distant control rate (DC), overall survival (OS), acute and late toxicities and patterns of failure.

RESULTS

79/129 Patients were HR. 50/129 patients IR. 5-year LC was 87% and 89%, RC was 97% and 86%, DC was 95% and 77% and the OS 73% and 67% for IR and HR respectively. 43 deaths occurred. Acute toxicity CTCAE⩾grade 3 was observed in 55% and 56% and late toxicities in 10% and 15% of the IR and HR-group respectively. Fifteen patients developed loco-regional failure.

CONCLUSION

We observed significantly more patients with distant metastases in the HR group and no difference in LC, RC or OS between the two groups. The majority of the analyzed recurrences were in-field, in the high dose volume. Acute and late toxicity was moderate.

Patterns of failure after intensity-modulated radiotherapy in head and neck squamous cell carcinoma using compartmental clinical target volume delineation

AIMS

To determine the pattern of disease recurrence in non-nasopharyngeal head and neck squamous cell carcinoma (HNSCC) patients treated with radical intensity-modulated radiotherapy (IMRT) with or without chemotherapy, and to correlate the sites of locoregional recurrence with radiotherapy target volumes.

MATERIALS AND METHODS

In total, 136 patients treated with radical IMRT with or without chemotherapy between 2008 and 2011 for non-nasopharyngeal HNSCC were retrospectively identified. A compartmental approach to clinical target volume (CTV) delineation was routinely utilised during this period and IMRT was delivered using a 5-7 angle step and shoot technique. Locoregional recurrences were reconstructed on the planning computed tomography scan by both deformable image coregistration and by visual assessment, and were analysed in relation to target volumes and dosimetry.

RESULTS

The median follow-up was 31 (range 3-53) months. Two year local control, regional control, disease-free survival, distant metastasis-free survival and overall survival were 86, 93, 78, 89 and 79%, respectively. One hundred and twenty of 136 (88%) patients achieved a complete response to treatment and 7/120 (6%) have subsequently had a locoregional recurrence. Analysis of these recurrences revealed five to be infield; one to be marginal to the high-dose CTV; one to be out-of-field. Overall the marginal/out-of-field recurrence rate was 2/136 (1.5%).

CONCLUSIONS

IMRT utilising a compartmental approach to CTV delineation was associated with a low rate of marginal/out-of-field recurrence.

Marginal miss or radioresistance? The pattern of local recurrence after operation and 3D planned radiation treatment in soft tissue sarcoma of the extremities and the limb girdles; an analysis based on image fusion

BACKGROUND

Most local recurrences have developed in the clinical target volume in previously published series after combined modality treatment for soft tissue sarcoma. However, marginal misses were seen in almost 20% of the patients. The aim of the present study was to determine the location of the recurrence and the total dose at the centre point of the local recurrence for future radiation therapy planning.

MATERIAL AND METHODS

We included only patients with images in digital form, during 1999-2006 (n = 17), treated for soft tissue sarcoma with combined surgical therapy and radiotherapy at Helsinki University Central Hospital. Image fusion was used to determine the location of the recurrence in relation to radiation therapy target.

RESULTS

In the present study utilising digital image fusion, in patients with 3D CT-based radiation treatment planning the risk of marginal miss was low as only one patient of 17 relapsed outside the target. Estimated mean radiation dose at the site of local recurrence was 49.1 Gy in patients with positive margins and 48.1 Gy in patients with negative margins.

CONCLUSION

The risk of marginal miss in soft tissue sarcoma is low after modern 3D planned radiation treatment combined with surgery. More generous use of boost might improve in-target local control.

Preventive sparing of spinal cord and brain stem in the initial irradiation of locally advanced head and neck cancers

Since reirradiation in recurrent head and neck patients is limited by previous treatment, a marked reduction of maximum doses to spinal cord and brain stem was investigated in the initial irradiation of stage III/IV head and neck cancers. Eighteen patients were planned by simultaneous integrated boost, prescribing 69.3 Gy to PTV1 and 56.1 Gy to PTV2. Nine 6 MV coplanar photon beams at equispaced gantry angles were chosen for each patient. Step‐and‐shoot IMRT was calculated by direct machine parameter optimization, with the maximum number of segments limited to 80. In the standard plan, optimization considered organs at risk (OAR), dose conformity, maximum dose <45 Gy to spinal cord and <50 Gy to brain stem. In the sparing plans, a marked reduction to spinal cord and brain stem were investigated, with/without changes in dose conformity. In the sparing plans, the maximum doses to spinal cord and brain stem were reduced from the initial values (43.5±2.2 Gy and 36.7±14.0 Gy), without significant changes on the other OARs. A marked difference (−15.9±1.9 Gy and −10.1±5.7 Gy) was obtained at the expense of a small difference (−1.3%±0.9%) from initial PTV195% coverage (96.6%±0.9%). Similar difference (−15.7±2.2 Gy and −10.2±6.1 Gy) was obtained compromising dose conformity, but unaffecting PTV195% and with negligible decrease in PTV295% (−0.3%±0.3% from the initial 98.3%±0.8%). A marked spinal cord and brain stem preventive sparing was feasible at the expense of a decrease in dose conformity or slightly compromising target coverage. A sparing should be recommended in highly recurrent tumors, to make potential reirradiation safer.

PACS number: 87.55.D

Target delineation in stereotactic body radiation therapy for recurrent head and neck cancer: a retrospective analysis of the impact of margins and automated PET-CT segmentation

BACKGROUND

Few guidelines exist on stereotactic body radiation therapy (SBRT) treatment planning for recurrent head and neck cancer. We assessed the impact of retrospectively adding margins/automated PET volumes to the gross tumor volume (GTV) in patients with post-SBRT recurrences.

MATERIALS AND METHODS

We reviewed 89 patients with recurrent head and neck cancer treated with SBRT using no margin around the GTV. GTVs were recontoured with 1-5mm margins. PET-CT planned GTVs were also recontoured by adding PET-standardized uptake value (SUV)(3.5), SUV(4.5), SUV(40% max), and signal/background ratio (SBR) to the original GTV. We deformably registered recontoured GTVs to post-SBRT scans and assessed fraction of recurrence volume (RV) falling within the GTV, the "RV-GTV overlap."

RESULTS

With non-PET-CT planning, median RV-GTV overlap increased from 11.7% to 48.2% using 5mm margins, and median GTV size increased by 41.8 cc (156%). With PET-CT planning, RV-GTV overlap increased from 45% to 93.6% using 5mm margins, and GTV size increased by 34.8 cc (140%). Adding SUV(3.5) and SBR increased RV-GTV overlap from 45% to 73.3% and 73.6%, with GTV size increases of 0.8 (3%) and 3.1 cc (11%), respectively.

CONCLUSIONS

Recontouring increased recurrence coverage and also GTV size. Margins up to 5mm may reduce failures but could possibly increase toxicities. Automated PET contours may reduce near-miss failures with smaller increases in GTV size.

PET/CT of cancer patients: part 2, deformable registration imaging before and after chemotherapy for radiation treatment planning in head and neck cancer

OBJECTIVE

The purpose of this perspective is to discuss the use of deformable registration as a tool for image fusion to integrate information from PET/CT scans obtained before and after chemotherapy to assist definition of radiation targets in the management of head and neck cancer.

CONCLUSION

The consistent method for target delineation described capitalizes on the capability of deformable registration to compensate for changes in position and accurately represent evolving spatial relationships between normal anatomy and areas at risk of disease.

[Intensity modulated radiotherapy for head and neck cancers: ethics and patients selection]

PURPOSE

Intensity modulated radiotherapy (IMRT) allows a better coverage of the target volume and a better saving of organs at risk with a decrease of toxicity in head and neck cancers. It requires more human labor and materials compared to conformational radiotherapy. If they are insufficient, a selection of the patients receiving IMRT may be necessary, raising an ethical problem.

MATERIAL AND METHODS

We collected the motives guiding the choice of the technique of radiotherapy for head and neck cancers during a month of physicists' shortage.

RESULTS

Nineteen patients received IMRT and eight conformational radiotherapy. Conformational irradiation was chosen in palliative and postsurgery treatments, to reduce delay, in laryngeal tumors and re-irradiation. IMRT was preferred for complex target volumes and the localizations at risk of important xerostomia following conformational radiotherapy. These choices were confronted with the bioethics criteria of Beauchamp and Childress. The beneficence justified the use of IMRT or conformational radiotherapy depending on the circumstances. The non-maleficence attempted to decrease the toxicity with IMRT. Justice was questioned by the selection. The autonomy of patients was not totally respected in the choice.

CONCLUSION

To help in the choice of the patients receiving an IMRT in a crisis situation, we proposed a hierarchical organization of selection criteria: complex volumes close to critical organs at risk, localization with high risk of xerostomia, long life expectancy and postoperative delay constraints.