Neck Cases Research Articles

Use of Single Chimeric Free Flaps or Double Free Flaps for Complex Head and Neck Reconstruction.

Free flaps have become the preferred reconstructive approach to restore form and function for patients presenting with complex head and neck defects. For composite, complex defects for which a regular free flap might not meet all reconstructive demands, adequate coverage can be achieved with either a single chimeric free flap or a double free flap. We performed a single-center retrospective chart review of patients who underwent either single chimeric free flap or double free flap reconstruction. Indications for reconstruction included defects resultant from head and neck tumor or osteoradionecrosis resections. We extracted the following variables: tumor location, defect, flap(s) performed, and postoperative complications. Unpaired t-tests were performed to evaluate for statistically significant differences in complications encountered between the single chimeric versus the double free flap patient groups. In our series of 44 patients, a total of 55 single chimeric and double free flaps were performed. We found no significant difference in overall complications (p = 0.41) or flap/skin paddle loss (p = 0.45) between the groups. There were three total flap losses; two patients underwent successful salvage procedures and one patient died. The anterolateral thigh (ALT) was the most common free flap (70%) used in our series, and 98% of our patients completed successful reconstruction. As the initial reconstructive effort is critical for achieving favorable long-term outcomes in complex head and neck cases, effective and safe techniques should be employed to ensure optimal delivery of care. We believe that single chimeric and double free flap techniques should be appropriately utilized as part of the armamentarium of head and neck reconstructive microsurgeons.

Epithelioid sarcoma: A clinicopathological study of 12 head and neck cases.

To determine the clinicopathological features of epithelioid sarcoma presenting in head and neck region (HNES) and elucidate diagnostic key points and treatment options for HNES. A total of 12 HNES cases were collected in our department from 2010 to 2020. Their clinical information and pathological features were documented, and relevant follow-up was performed. Immunohistochemistry was carried to analyze the protein markers of HNES. Of the 12 HNES cases, 10 were primary tumors and 2 were metastasized from foot and shoulder, respectively. The patients with primary tumors were significantly younger than those with metastasized ones (22.7 vs 41.5, p=.0157), and male patients outnumbered female patients (3:1). Of all HNES cases, 9 were classic subtype, and 3 were proximal subtype. HNES patients had a poor prognosis, with 5-year overall survival of 41.5% and 5-year relapse-free survival of 22.5%. A loss of INI1 was identified as the hallmark of HNES with 83.3% (10/12) of HNES cases presenting as EZH2 positive. HNES is more prevalent at younger ages and in males, has a poor prognosis, and exhibits a greater proportion of classic subtype than proximal subtype. EZH2 inhibitor has therapeutic potential in HNES.

An improved predictive model for postoperative pulmonary complications after free flap reconstructions in the head and neck.

Commonly used predictive models for postoperative pulmonary complications (PPCs) do not perform when applied to head and neck cases. A head and neck-specific risk prediction tool is needed. Data on 794 free flap head and neck surgery cases at a single center were abstracted from the electronic medical record. Each case was reviewed for the development of PPCs. A predictive model was developed and was then compared to existing predictive models for PPCs. The least absolute shrinkage and selection operator procedure identified age, alcohol use, history of congestive heart failure, preoperative packed cell volume, preoperative oxygen saturation, and preoperative metabolic equivalents as predictors of PPCs in the head and neck population. The model demonstrated an area under the receiving operating characteristic curve of 0.75 (0.69-0.80) with moderately good calibration. Comparisons to the performance of existing models demonstrate superior performance. The model for the development of PPCs developed in this article displays superior performance to existing models.

A self-adaptive prescription dose optimization algorithm for radiotherapy

Abstract Purpose The aim of this study is to investigate an implementation method and the results of a voxel-based self-adaptive prescription dose optimization algorithm for intensity-modulated radiotherapy. Materials and methods The self-adaptive prescription dose optimization algorithm used a quadratic objective function, and the optimization engine was implemented using the molecular dynamics. In the iterative optimization process, the optimization prescription dose changed with the relationship between the initial prescription dose and the calculated dose. If the calculated dose satisfied the initial prescription dose, the optimization prescription dose was equal to the calculated dose; otherwise, the optimization prescription dose was equal to the initial prescription dose. We assessed the performance of the self-adaptive prescription dose optimization algorithm with two cases: a mock head and neck case and a breast case. Isodose lines, dose–volume histogram, and dosimetric parameters were compared between the conventional molecular dynamics optimization algorithm and the self-adaptive prescription dose optimization algorithm. Results The self-adaptive prescription dose optimization algorithm produces the different optimization results compared with the conventional molecular dynamics optimization algorithm. For the mock head and neck case, the planning target volume (PTV) dose uniformity improves, and the dose to organs at risk is reduced, ranging from 1 to 4%. For the breast case, the use of self-adaptive prescription dose optimization algorithm also leads to improvements in the dose distribution, with the dose to organs at risk almost unchanged. Conclusion The self-adaptive prescription dose optimization algorithm can generate an ideal clinical plan more effectively, and it could be integrated into a treatment planning system after more cases are studied.

Sudden neck swelling with rash as late manifestation of COVID-19: a case report

BackgroundAlthough there are reports of otolaryngological symptoms and manifestations of CoronaVirus Disease 19 (COVID-19), there have been no documented cases of sudden neck swelling with rash in patients with Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection described in literature.Case presentationWe report a case of a sudden neck swelling and rash likely due to late SARS-CoV-2 in a 64-year-old woman. The patient reported COVID-19 symptoms over the previous three weeks. Computed Tomography (CT) revealed a diffuse soft-tissue swelling and edema of subcutaneous tissue, hypodermis, and muscular and deep fascial planes. All the differential diagnoses were ruled out. Both the anamnestic history of the patient’s husband who had died of COVID-19 with and the collateral findings of pneumonia and esophageal wall edema suggested the association with COVID-19. This was confirmed by nasopharyngeal swab polymerase chain reaction. The patient was treated with lopinavir/ritonavir, hydroxychloroquine and piperacillin/tazobactam for 7 days. The neck swelling resolved in less than 24 h, while the erythema was still present up to two days later. The patient was discharged after seven days in good clinical condition and with a negative swab.ConclusionSudden neck swelling with rash may be a coincidental presentation, but, in the pandemic context, it is most likely a direct or indirect complication of COVID-19.

Association of Chiropractic Colleges Research Agenda Conference 2021 Abstracts of Proceedings.

Association of Chiropractic Colleges Research Agenda Conference 2021 Abstracts of Proceedings.

Preparations with catastrophic side effects: A case of neck of femur fracture due to secondary osteoporosis with underlying hip osteonecrosis resulting from chronic jamu consumption

Jamu is commonly used to treat a variety of health conditions in South East Asia due to its efficacy, affordability and ease of access. Despite its effectiveness, little is known regarding its contents and adverse effects. Recent studies have found evidence of steroids within jamu preparations. Chronic jamu consumption may inadvertently manifest with adverse effects associated with long-term steroid intake. We describe a case of neck of femur fracture due to secondary osteoporosis with underlying hip osteonecrosis resulting from chronic jamu consumption hoping to increase awareness regarding the devastating effects of these preparations.

The retromandibular transparotid approach vs. retromandibular retroparotid approach for the mandibular condyle

Aim: The mandible is regarded as a frequently fractured bone in patients who present with maxillofacial trauma accounting for almost 15.5% to 59% of all facial fractures. Managing condylar trauma has remained to be a point of contention amongst experts, regardless of the advances in surgical modalities and methodologies, and the treatment plan is often determined by the preference and the experience of the surgeon. There exist various approaches in the literature, each with its own specific benefits and drawbacks. With this study, we aimed to evaluate the prevalence of post-operative complications in patients who experienced ORIF by means of the retromandibular approach, by comparing the outcomes of one group having undergone transparotid surgery, with another that underwent retroparotid surgery. Methods: An experimental trial was undertaken. Convenience sampling was done from among the cases of condylar neck and base fracture visiting the department of OMFS, Dow University of Health Sciences from January 2017 to December 2019. An overall 26 patients were divided into 2 groups of 13 members each; one was managed using Open Reduction Internal Fixation (ORIF) by means of a retromandibular transparotid approach while the other group was treated with ORIF by means of a retromandibular retroparotid approach. A 6 month follow-up was done to assess range of active motion, occlusion, and complications such as deviation/deflection, neural injury, infections, sialocele, salivary fistulae and Frey’s syndrome in both groups. Results: There was no statistically significant difference between the two groups in terms of inter-incisal opening, right and left lateral movements, or protrusion. One patient in the retroparotid group had deviation on mouth opening (7.69%), while one in the transparotid group reported with infection (7.69%), and 2 developed post operative seromas (15.38%). None had persisting facial nerve palsy at 6 months. Conclusion: We find no significant disparity between the 2 approaches at a follow-up of 6 months; therefore, the primary determining factor for selection of either technique is surgeon preference and appropriate case selection.

Comparison of Air-Gaps Effect in a Small Cavity on Dose Calculation for 6 MV Linac.

Background: Many authors stated that cavities or air-gaps were the main challenge of dose calculation for head and neck with flattening filter medical linear accelerator (Linac) irradiation.Objective: The study aimed to evaluate the effect of air-gap dose calculation on flattening-filter-free (FFF) small field irradiation.Material and Methods: In this comparative study, we did the experimental and Monte Carlo (MC) simulation to evaluate the presence of heterogeneities in radiotherapy. We simulated the dose distribution on virtual phantom and the patient’s CT image to determine the air-gap effect of open small field and modulated photon beam, respectively. The dose ratio of air-gaps to tissue-equivalent was calculated both in Analytical Anisotropic Algorithm (AAA) and MC.Results: We found that the dose ratio of air to tissue-equivalent tends to decrease with a larger field size. This correlation was linear with a slope of -0.198±0.001 and -0.161±0.014 for both AAA and MC, respectively. On the other hand, the dose ratio below the air-gap was field size-dependent. The AAA to MC dose calculation as the impact of air-gap thickness and field size varied from 1.57% to 5.35% after the gap. Besides, patient’s skin and oral cavity on head and neck case received a large dose discrepancy according to this study. Conclusion: The dose air to tissue-equivalent ratio decreased with smaller air gaps and larger field sizes. Dose correction for AAA calculation of open small field size should be considered after small air-gaps. However, delivered beam from others gantry angle reduced this effect on clinical case.

Analysis of compression injuries over neck: One-year prospective study

In compression of neck cases with faint or absent ligature mark on the neck and with minimal internal findings it may be difficult to opine about the cause and manner of death. Many times, in forensic practice, cases occur where there is allegation from maternal side of married woman particularly in cases of dowry deaths, where relatives claim that it is a case of post-mortem hanging. In such cases there is importance of clubbing the gross findings. These findings may be helpful in arriving at conclusions in such unsolved and doubtful cases. The present study was conducted in Department of Forensic Medicine and Toxicology of a Government Medical College and Hospital in year 2017. Total 2781 postmortem examinations were conducted in 2017. Out of that total 2781 cases, 176 compression of neck cases came for postmortem and amongst these 105 cases were studied in detail as per inclusion criteria. Out of 105 cases of compression around neck, which were studied, there were 93 cases of hanging, 10 cases of ligature strangulation, 01 case of manual strangulation and 01 case of accidental strangulation studied. Out of total 105 cases, 66 were males and 39 were females. In this study maximum cases of neck compression were observed in 21 to 30 years age group (30 cases). Intimal tear of carotid artery was observed in 11 cases of hanging and no carotid artery intimal tear was found in case of strangulation. In the present study, fracture of hyoid bone alone was found in total 11 cases of which 06 cases were in hanging, 05 cases were in strangulation. Fracture of thyroid cartilage was found in 03 cases of which 02 cases were of strangulation and 01 case of throttling. No case of cricoid cartilage fracture either alone or in combination to fracture of throat skeleton was observed in the present study.

A cluster-randomized trial of workplace ergonomics and neck-specific exercise versus ergonomics and health promotion for office workers to manage neck pain \u2013 a secondary outcome analysis

BackgroundNeck pain is prevalent among office workers. This study evaluated the impact of an ergonomic and exercise training (EET) intervention and an ergonomic and health promotion (EHP) intervention on neck pain intensity among the All Workers and a subgroup of Neck Pain cases at baseline.MethodsA 12-month cluster-randomized trial was conducted in 14 public and private organisations. Office workers aged ≥18 years working ≥30 h per week (n = 740) received an individualised workstation ergonomic intervention, followed by 1:1 allocation to the EET group (neck-specific exercise training), or the EHP group (health promotion) for 12 weeks. Neck pain intensity (scale: 0–9) was recorded at baseline, 12 weeks, and 12 months. Participants with data at these three time points were included for analysis (n = 367). Intervention group differences were analysed using generalized estimating equation models on an intention-to-treat basis and adjusted for potential confounders. Subgroup analysis was performed on neck cases reporting pain ≥3 at baseline (n = 96).ResultsThe EET group demonstrated significantly greater reductions in neck pain intensity at 12 weeks compared to the EHP group for All Workers (EET: β = − 0.53 points 95% CI: − 0.84– − 0.22 [36%] and EHP: β = − 0.17 points 95% CI: − 0.47–0.13 [10.5%], p-value = 0.02) and the Neck Cases (EET: β = − 2.32 points 95% CI: − 3.09– − 1.56 [53%] and EHP: β = − 1.75 points 95% CI: − 2.35– − 1.16 [36%], p = 0.04). Reductions in pain intensity were not maintained at 12 months with no between-group differences observed in All Workers (EET: β = − 0.18, 95% CI: − 0.53–0.16 and EHP: β = − 0.14 points 95% CI: − 0.49–0.21, p = 0.53) or Neck Cases, although in both groups an overall reduction was found (EET: β = − 1.61 points 95% CI: − 2.36– − 0.89 and EHP: β = − 1.9 points 95% CI: − 2.59– − 1.20, p = 0.26).ConclusionEET was more effective than EHP in reducing neck pain intensity in All Workers and Neck Cases immediately following the intervention period (12 weeks) but not at 12 months, with changes at 12 weeks reaching clinically meaningful thresholds for the Neck Cases. Findings suggest the need for continuation of exercise to maintain benefits in the longer term.Clinical trial registrationhACTRN12612001154897 Date of Registration: 31/10/2012.

Association of Surrogate Objective Measures With Work Relative Value Units.

Background: The determination of accurate measures of evaluating surgeon work for reimbursement is poorly characterized. This study defines the correlation of surgical work relative value units (work RVUs) with several surrogate objective measures for otolaryngologic work. The defined surrogate objective measures evaluated in this study are length of hospital stay (LOS), operative time, 30-day mortality, 30-day unplanned readmission, 30-day reoperation, and 30-day morbidity.Methods: We collected data on otolaryngologic cases from 2016 to 2018 from the American College of Surgeons National Surgical Quality Improvement Program. Pearson correlation coefficient was used to associate work RVUs with objective measures of surgeon work. Linear regressions were used to identify predictors of work RVUs from the surrogate objective measures. Studentized residuals were used to identify outlying procedures.Results: Work RVUs correlated strongly with operative time (R=0.6775), 30-day readmission (R=0.6100), and LOS (R=0.6083); moderately with 30-day reoperation (R=0.5257) and 30-day morbidity (R=0.4842); and very weakly with 30-day mortality (R=0.1383). The best predictors for work RVUs based on multivariable linear regression analysis were morbidity, reoperation, and operative time. Analysis revealed that the projected work RVU is 12.23 units higher than the current value for excision of bone, mandible (Current Procedural Terminology [CPT] code 21025) and 19.48 units lower than the current value for resection/excision of lesion infratemporal fossa space apex extradural (CPT code 61605).Conclusion: Using objective surrogate measures for time and intensity of physician work in head and neck cases may improve work RVU assignment accuracy compared to the current system of physician survey. Future investigation with additional objective parameters may be beneficial to make work RVU assignments less subjective.

Intensity-modulated proton therapy (IMPT) versus intensity-modulated radiation therapy (IMRT) for the treatment of head and neck cancer: A dosimetric comparison.

It is the goal of this study to compare the dosimetric advantages of IMPT when compared to IMRT. From January 2019 to August 2020, 25 patients were treated with intensity modulated proton therapy (IMPT) at our institution for either recurrent, metastatic, benign, or primary tumors in the head and neck region. Twenty-one patients met criteria for dosimetric analysis. Histology of disease included squamous cell carcinoma, acinic cell carcinoma, sarcomatoid sinonasal carcinoma, paraganglioma, adenoid cystic carcinoma, salivary high grade carcinoma, and papillary thyroid carcinoma. For IMRT planning, gross tumor volume (GTV) and clinical target volume (CTV) were contoured with the expansion of 3-5 mm to create the planning target volume (PTV) and dose was prescribed to the PTV. For the IMPT planning, dose was prescribed to CTV and robust optimization was utilized which accounted for a 5 mm setup and range uncertainty. The minimum, mean and maximum target doses for IMRT and IMPT plans as well as mean and maximum normal tissue doses are reported for the 21 patients meeting criteria. Mean doses for IMRT and IMPT were 6278.2 cGy and 6449.8 cGyRBE respectively with p-value of 0.0001. Maximum doses for IMRT and IMPT were 6579.5 cGy and 6772.1 cGyRBE respectively with p-value of 0.0014. Minimum doses for IMRT and IMPT were 5440.6 cGy and 5617.9 cGyRBE respectively with p-value of 0.3576. IMPT had an overall advantage in OAR doses in the brain stem, spinal cord, optic structures, cochlea, larynx, contralateral parotid, and oral cavity with only a few exceptions. Our study thus demonstrates a dosimetric advantage for IMPT in treating head and neck tumors in mean and max dose delivered as well as dose to OARs. Given that our patient cohort were mainly unilateral head and neck cases, our study supports the treatment of this specific subset of patients regardless of histology with IMPT. This may aid in appropriate patient selection for IMPT treatment. Further studies will need to determine if this dosimetric advantage translates to a therapeutic advantage for patients.

Evaluation of treatment of fracture neck femur with uncemented HA coated modular bipolar prosthesis

Background: Background: Fracture of the femoral neck has been reported with increasing incidence in recent times due to prevalence of osteoporosis. Uncemented HA coated modular bipolar hemiarthroplasty systems provide a customised press fit solution which improve the patient outcome with respect to limb length discreptancy. We report our series of 15 cases of fracture neck of femur operated over years with modular cementless HA bipolar hemiarthroplasty. Methods: 15 patients (age=50 to 70 years) with displaced femoral neck fractures were operated between January 2019 to December 2019. Cementless HA coated modular bipolar hemiarthroplasty using hydroxyapatite coated stem was done by single surgeon using same implant in all the patients through Moores approach. Clinical and radiological follow-up was done. Results: Total 15 cases with fracture neck femur were operated. The average follow up was 48 months. No intraoperative mortality was seen. 1 patient had calcar fracture of femur during canal preparation. 1 patient had delayed transient sciatic nerve palsy, and 1 patient had insignificant limb length discripency (0.5 cm). 12 patients reached to pre-injury status with average harris hip score of 88 at final follow up. Conclusions: Cementless bipolar hemiarthroplasty with hydroxyapatite coated stem is a good option for femoral neck fractures in elderly patients.

Management of fibrous dysplasia of the femur neck in a child by PHILOS Stabilization, curettage, and bone grafting: A case report

Fibrous dysplasia has a considerable risk of pathological fractures particularly in proximal femur in younger age group. These are challenging to treat, especially in pediatric population. Several treatment modalities have been proposed, each having its own pros and cons. Attention should be given in pediatric population in choosing technique and selection of implants to preserve growth of the limb and to prevent implant prominence and soft tissue irritation. We are reporting a case of pathological neck of femur fracture secondary to fibrous dysplasia, in an 11-year-old obese boy, managed with curettage, iliac crest bone grafting and osteosynthesis with PHILOS plate (a plate routinely used in adults for humerus neck fractures). At 6 months follow-up, he shows a good consolidation of iliac crest graft at fracture site with stable implant and an excellent functional outcome in terms of pain and range of motion, without any radiological sign of recurrence.

Kinect Validation of Ergonomics in Human Pick and Place Activities Through Lateral Automatic Posture Detection

In this paper we evaluate a system based on the Microsoft Kinect™ sensor, aimed at the automatic detection of risk postures during human work activities. We first introduce a pick and place task, where three different lateral standing subjects move light cardboard boxes from the various levels of a bookcase to its top, and then putting them back to their original places. They repeat the task over several work cycles and we capture all their natural movements in a continuous way using Kinect, storing the joint positions and the color images. Secondly, from the joint positions, our system detects specific risk postures following the definitions of the Rapid Upper Limb Assessment (RULA) method. Finally, we compare the posture detections by our system with the baseline detections made by a panel of five experts who used the captured color images. In our study we find that the experts have problems to distinguish among some RULA postures during a work cycle because of the narrow detection margin and the difficulty to perceive if a limb reached a certain position; which is particularly true for the cases of wrist and neck. This leads to a larger false positive rate and to a lower general accuracy, with our system detecting postures that experts do not. After applying a ±1° of relaxation to our system, which in negligible for human perception, we are able to reach an accuracy of 0.93 in the comparison with the baseline. Our results show the suitability of Kinect for lateral risk posture detection in pick and place activities.

Partial fetotomy: technique to resolve wry neck dystocia in mare

Foaling is a process of giving birth to foal which is prompt and forceful event in equine breeding. Dystocia is declared when 2nd stage of parturition exceeds from 20 min without fetal movements in mare. Dystocia is very challenging situation for both mare and veterinarian. Survivability of mare and foal, and subsequent fertility of mare depends on efficient management. Therefore, the current report described a rare case of wry neck (torticollis or unilateral bent neck) resulted in dystocia, that was efficiently resolved by partial fetotomy and repulsion technique in mare under field conditions. Intensive post operative care was performed to avoid infection and to achieve fertility subsequently.

Tissue-specific deformable image registration using a spatial-contextual filter.

Intensity-based deformable registration with spatial-invariant regularization generally fails when distinct motion exists across different types of tissues. The purpose of this work was to develop and validate a new regularization approach for deformable image registration that is tissue-specific and able to handle motion discontinuities. Our approach was built upon a Demons registration framework, and used the image context supplementing the original spatial constraint to regularize displacement vector fields in iterative image registration process. The new regularization was implemented as a spatial-contextual filter, which favors the motion vectors within the same tissue type but penalizes the motion vectors from different tissues. This approach was validated using five public lung cancer patients, each with 300 landmark pairs identified by a thoracic radiation oncologist. The mean and standard deviation of the landmark registration errors were 1.3 ± 0.8 mm, compared with those of 2.3 ± 2.9 mm using the original Demons algorithm. Particularly, for the case with the largest initial landmark displacement of 15 ± 9 mm, the modified Demons algorithm had a registration error of 1.3 ± 1.1 mm, while the original Demons algorithm had a registration error of 3.6 ± 5.9 mm. We also qualitatively evaluated the modified Demons algorithm using two difficult cases in our routine clinic: one lung case with large sliding motion and one head and neck case with large anatomical changes in air cavity. Visual evaluation on the deformed image created by the deformable image registration showed that the modified Demons algorithm achieved reasonable registration accuracy, but the original Demons algorithm produced distinct registration errors.

Development of generalized time-dependent TCP model and the investigation of the effect of repopulation and weekend breaks in fractionated external beam therapy

We developed a tumor control probability (TCP) model that incorporates variable time intervals between fractions and a kick-off time (Tk) for radiation-induced accelerated tumor proliferation. The resulting Lee-Rosen model, TCPLR, was used to compute TCPs for treatment courses with and without weekend treatment for tumors with different proliferation rates – slow (prostate), moderate (breast), and rapid (head and neck). TCPs were computed using ideal uniform dose distributions and actual patient plans. The doses for the uniform plans were the mean doses for the prostate and breast cases and the minimum tumor dose for the head and neck case. The TCPLR model predictions agreed with expectations that TCP increases with increasing Tk in all cases. For standard fractionation, as Tk increased from 0 to 4 weeks, TCP increased for the patient distributions by 74.7% for the head and neck cancer, by 6.2% for the breast cancer, and by 2.4% for the prostate cancers. For the uniform dose distributions, the increases were 79.2%, 5.7%, and 2.3%, respectively. TCP increased as the number of weekend breaks decreased. The effect of weekend breaks decreased as the tumor proliferation rate decreased. For the head and neck tumor, notable decreases in TCP of 6.0% (uniform dose distribution) and 6.8% (actual plan dose distribution) were observed with Friday starts compared to Monday starts for the standard 5 fx/wk schedule (Tk = 4 wk). The 7 fx/wk schedule produced increases in TCP of 17.0% and 20.5% for the uniform and patient dose distributions, respectively, compared to the standard schedule. For the breast cancer, starting the 5 fx/wk schedule on Friday decreased the TCP by 0.2% (Tk = 4 wk) compared to a Monday start. The 7 fx/wk schedule produced increases of 0.3% and 0.4% in TCP compared to the standard schedule for the uniform and patient dose distributions, respectively (Tk = 4 wk). For the prostate cancer, the change in TCP for 5 fx/wk schedules starting on different days was 0.1%. The 7 fx/wk schedule increased TCP by 0.8% compared to the standard schedule (Tk = 4 wk). TCP values for the uniform dose distributions for the standard schedule (Tk = 4 wk) agreed with the TCP values for the actual dose distributions within 4.5% for the head and neck tumor and within 0.2% for the breast and prostate tumors. This good agreement suggests that the doses chosen for the uniform dose distributions were good approximations to the clinical doses. The results for head and neck tumors support, in part, the current practice of hyperfractionated/accelerated radiotherapy. They also suggest that shortening the overall treatment time for conventional fractions by eliminating weekend breaks might be beneficial. The predicted effect on TCP of the various schedules studied was insignificant for prostate and breast tumors, suggesting that a weekend treatment might not be necessary for patients starting radiotherapy on a Friday. There is significant uncertainty in the values of the model parameters chosen for these calculations, and no consideration was given to the potential effects of these various schedules on normal tissues.

Optimal treatment plan adaptation using mid-treatment imaging biomarkers

Previous studies on personalized radiotherapy (RT) have mostly focused on baseline patient stratification, adapting the treatment plan according to mid-treatment anatomical changes, or dose boosting to selected tumor subregions using mid-treatment radiological findings. However, the question of how to find the optimal adapted plan has not been properly tackled. Moreover, the effect of information uncertainty on the resulting adaptation has not been explored.In this paper, we present a framework to optimally adapt radiation therapy treatments to early radiation treatment response estimates derived from pre- and mid-treatment imaging data while considering the information uncertainty. The framework is based on the optimal stopping in radiation therapy (OSRT) framework. Biological response is quantified using tumor control probability (TCP) and normal tissue complication probability (NTCP) models, and these are directly optimized for in the adaptation step. Two adaptation strategies are discussed: (1) uniform dose adaptation and (2) continuous dose adaptation. In the first strategy, the original fluence-map is simply scaled upwards or downwards, depending on whether dose escalation or de-escalation is deemed appropriate based on the mid-treatment response observed from the radiological images. In the second strategy, a full NTCP-TCP-based fluence map re-optimization is performed to achieve the optimal adapted plans.We retrospectively tested the performance of these strategies on 14 canine head and neck cases treated with tomotherapy, using as response biomarker the change in the 3’-deoxy-3’[(18)F]-fluorothymidine (FLT)-PET signals between the pre- and mid-treatment images, and accounting for information uncertainty. Using a 10% uncertainty level, the two adaptation strategies both yield a noteworthy average improvement in guaranteed (worst-case) TCP.