Immediate psychological effects of COVID-2019 in people sheltered in place living in New York state

Introduction

The epidemic caused by the SARS-CoV-2, which began in Wuhan city in December 2019, quickly spread to various countries around the world. The first case in New York State was confirmed on March 1; three weeks later (on March 22, 8 p.m.) the entire population was sheltered in place (SIP). By March 27, the USA had already become the first country in the world for the number of infections. 56% of known domestic cases were confined to New York State.

Objectives

The study aims to evaluate the immediate psychological effects on sheltered in place persons aged between 18 and 70 years old and living in New York State (USA).

Methods

This study is based on a cross-sectional online survey conducted anonymously in the period between the tenth and twenty-third day of SIP. Zung Anxiety Self-Assessment Scale (ZAS scale), Insomnia Severity Index (ISI) and Perceived Stress Scale 4 (PSS4) were used to evaluate anxiety, insomnia and stress respectively.

Results

We collected data on 354 individuals (189 females, 34.9 years). MANOVA evidenced that anxiety was significantly related to marital status (higher for divorced/widow participants as compared to married/civil partnership and single), it decreased significantly with age, it was higher for females and for persons having an history of psychiatric disorders and sleeping problems.

Conclusions

Our results could be used as a “psychological baseline” meanwhile the outbreak of COVID-19 is still ongoing. Despite the few days of shelter in place, we found the presence of a significant incidence and pervasive prevalence of psychological distress.

Disclosure

No significant relationships.

Bayesian models to explain autistic traits in psychiatric population

Introduction

Studies on psychiatric patients have shown that the presence of autistic traits affects the effectiveness of the treatment, decreasing the likelihood of positive clinical outcomes.

Objectives

The aim of the present study is to investigate which are the areas of overlap between psychiatric symptoms and the traits of the autism spectrum using a bayesian approach.

Methods

A sample of 190 adult psychiatric patients, diagnosed with schizophrenia, bipolar disorder, major depression, and personality disorder participated in the study. The RAADS-R questionnaire was used to assess the presence of autistic traits. The severity of psychiatric symptoms was measured with the BPRS and PANSS scales, the perceived well-being and disability using the Whodas and Whoqol scales, the TOL and STROOP for the measurement of executive functions, the attentional matrices for visual-spatial attention, the Raven for general cognitive skills.

Results

No difference emerged between the diagnoses regarding the presence of symptoms of the autism spectrum, which affects 64% of subjects. Logistic regression showed that the severity of symptoms measured as BPRS and PANSS predicted the probability of having autistic traits. Bayesian regression showed that specific autistic traits are indicative of executive functions deficits. Namely, motor impairment severity measured at RAADS is strongly predicted by rule violation with number of correct moves measured at TOL. The other executive functions seemed to be only moderately linked to autistic traits.

Conclusions

These results provide new information about the expression of comorbidity with autism in psychiatric patients.

Eye-movements deficits in schizophrenia: A metanalysis of evidence

Introduction

Although eye-movement disorders are one of the most replicated deficits in the psychiatric literature, the strong heterogeneity of results is still an unexplained issue that could be effectively addressed with a quantitative review of evidence.

Objectives

For this reason, a large-scale metanalytic study comprising more than 200 studies was conducted to analyse the presence of eye-movement deficits in schizophrenia patients, as compared to healthy controls.

Methods

To this aim, saccadic eye movements were grouped based on the type of task required (e.g., standard, predictive) and the quantification method used (e.g., number, duration, amplitude). For each sub-group separate meta-analysis were computed. Cohen’s d was used as measure of effect size. Risk of bias within and between studies and heterogeneity were also analysed.

Results

indicated low Cohen’s d with the exception of the number of correct antisaccades – where schizophrenia patients reportedless correct anti-saccadesthan healthy controls - and antisaccades error rate – where schizophrenia patients reported a higher number of errors than healthy controls.

Conclusions

Antisaccades emerged as better suited to differentiate between patients and healthy controls, thus making them the most promising candidate as a possible biomarker for schizophrenia.

Neuropsychological profile and correlation with outcomes in patients admitted to spdc

Introduction

Literature showed that patients suffering from disorders belonging to the schizophrenic (SZ) and bipolar (DB) spectrum have a qualitatively similar but quantitatively different neurocognitive impairment that correlates with the outcomes. However, the majority of former studies are conducted on patients in remission phase.

Objectives

This study aims to compare cognitive functions between SZ and DB in the acute phase and their possible correlations with treatment outcomes.

Methods

In a prospective longitudinal study conducted at the SPDC Ausl unit of Romagna - Cesena, 57 SZ and 82 DB took part in the study. The diagnosis was based on the SCID5 CV and SCID5 DP. Symptom severity was assessed with BPRS and HONOS both at the beginning and at the end of hospitalization. Executive functions were measured with Tower of London (ToL) and Modified Wisconsin Card Sorting Test (MCST), attention with Attentive Matrices (MA) and Stroop Test (ST), non-verbal logic skills with Colored Matrices by Raven (PM47). The statistical analyzes applied are ANOVA and logistic regression.

Results

The cognitive tests did not reveal significant differences between SZ and DB. The logistic regression analysis showed that the scores obtained at the MCST and MA positively correlate with the efficacy of the treatment for both groups.

Conclusions

Cognition in DB and SZ patients was similarly impaired, supporting recent theories that placed diagnoses on a continuum of severity. Moreover, the results indicated that also in the acute phase the best predictors of the outcome were flexibility in problem solving strategies and visuospatial attention.

Disclosure

No significant relationships.

Phase space dynamics of eye-movement deficits in psychiatric patients

Introduction

Eye movement deficits in psychiatric patients have often been investigated with linear models, which fail to fully capture the complex dynamics characterizing eye movements.

Objectives

The present work aims to investigate the deficits in fixational eye movements in psychiatric patients according as non-linear chaotic dynamic.

Methods

We recruited 191 patients (91 males, average age 45 years) diagnosed with schizophrenia, bipolar disorder, depression and personality disorder. The control sample consisted of 22 healthy subjects (12 males, mean age 41 years). Fixational eye movements were recorded with the Eytribe infrared system and off-line analyzed using Matlab. The dynamics of fixation eye movements were investigated using a phase space graph, which refers to chaotic system analysis. This analysis allows to evaluate how the changes in space during fixation as a function of their speed.

Results

A major difference emerged: psychiatric patients showed larger and faster eye movements gravitating around a single point of density, while control subjects exhibited slower and smaller eye movements with multiple drifts and microtremors.

Conclusions

In conclusion, the dynamics of fixational eye movements in psychiatric patients seemed to be characterized by poorer efficiency in space exploration. These differences could be attributed to a worse coordination between the perceptual and the oculomotor system.

Disclosure

No significant relationships.

Two-step Cluster Analysis Application to a Sample of Psychiatric Inpatients at Psychiatric Service of Diagnosis and Care

Introduction

Recent findings demonstrated significant overlaps among major psychiatric disorders on multiple neurocognitive domains. However, it is not clear which are the cognitive functions that contribute to this phenomenon.

Objectives

To find the optimal clustering solution using the two-step cluster analysis on a sample of psychiatric patients.

Aims

To classify into subgroups a cross-diagnostic sample of psychiatric inpatients on the basis of their neurocognitive profiles.

Methods

Seventy-one patients with psychotic, bipolar, depressive and personality disorders hospitalised at Psychiatric Diagnosis and Care Service of Bufalini Hospital of Cesena participated in the study. The symptomatology was assessed using Health of the Nation Outcome Scales-Roma and Brief Psychiatric Rating Scale. Cognitive functions were evaluated using Tower of London, Modified Wisconsin Card Sorting Test, Judgment and Verbal Abstract Tasks test, Raven matrices, Attentional Matrices, Stroop Test and Mini Mental State Examination. Two-step cluster analysis was conducted using the standardized scores of each neurocognitive test.

Results

Two groups were obtained:– group 1, with good cognitive performances;– group 2, with almost all subjects having impaired cognitive performances.

Executive functions and attention are the major determinants of the cluster solution. The clusters did not differ on socio-demographic correlates. Different diagnoses were equally distributed amongst the clusters.

Conclusions

Two-step cluster analysis was useful in identifying subgroups of psychiatric inpatients with different cognitive functioning, overcoming other cluster techniques limitations. According to former literature, these results confirm a continuum of severity in cognitive impairment across different psychiatric disorders.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

The lost ability to distinguish between self and other voice following a brain lesion

Mechanisms underlying the self/other distinction have been mainly investigated focusing on visual, tactile or proprioceptive cues, whereas very little is known about the contribution of acoustical information. Here the ability to distinguish between self and others' voice is investigated by using a neuropsychological approach. Right (RBD) and left brain damaged (LBD) patients and healthy controls were submitted to a voice discrimination and a voice recognition task. Stimuli were paired words/pseudowords pronounced by the participant, by a familiar or unfamiliar person. In the voice discrimination task, participants had to judge whether two voices were same or different, whereas in the voice recognition task participants had to judge whether their own voice was or was not present. Crucially, differences between patient groups were found. In the discrimination task, only RBD patients were selectively impaired when their own voice was present. By contrast, in the recognition task, both RBD and LBD patients were impaired and showed two different biases: RBD patients misattributed the other's voice to themselves, while LBD patients denied the ownership of their own voice. Thus, two kinds of bias can affect self-voice recognition: we can refuse self-stimuli (voice disownership), or we can misidentify others' stimuli as our own (embodiment of others' voice). Overall, these findings reflect different impairments in self/other distinction both at behavioral and anatomical level, the right hemisphere being involved in voice discrimination and both hemispheres in the voice identity explicit recognition. The finding of selective brain networks dedicated to processing one's own voice demonstrates the relevance of self-related acoustic information in bodily self-representation.

Radiobiological Optimization in Lung Stereotactic Body Radiation Therapy: Are We Ready to Apply Radiobiological Models?

Lung tumors are often associated with a poor prognosis although different schedules and treatment modalities have been extensively tested in the clinical practice. The complexity of this disease and the use of combined therapeutic approaches have been investigated and the use of high dose-rates is emerging as effective strategy. Technological improvements of clinical linear accelerators allow combining high dose-rate and a more conformal dose delivery with accurate imaging modalities pre- and during therapy. This paper aims at reporting the state of the art and future direction in the use of radiobiological models and radiobiological-based optimizations in the clinical practice for the treatment of lung cancer. To address this issue, a search was carried out on PubMed database to identify potential papers reporting tumor control probability and normal tissue complication probability for lung tumors. Full articles were retrieved when the abstract was considered relevant, and only papers published in English language were considered. The bibliographies of retrieved papers were also searched and relevant articles included. At the state of the art, dose–response relationships have been reported in literature for local tumor control and survival in stage III non-small cell lung cancer. Due to the lack of published radiobiological models for SBRT, several authors used dose constraints and models derived for conventional fractionation schemes. Recently, several radiobiological models and parameters for SBRT have been published and could be used in prospective trials although external validations are recommended to improve the robustness of model predictive capability. Moreover, radiobiological-based functions have been used within treatment planning systems for plan optimization but the advantages of using this strategy in the clinical practice are still under discussion. Future research should be directed toward combined regimens, in order to potentially improve both local tumor control and survival. Indeed, accurate knowledge of the relevant parameters describing tumor biology and normal tissue response is mandatory to correctly address this issue. In this context, the role of medical physicists and the AAPM in the development of radiobiological models is crucial for the progress of developing specific tool for radiobiological-based optimization treatment planning.

Visual perception skills: a comparison between patients with Noonan syndrome and 22q11.2 deletion syndrome

Ventral and dorsal streams are visual pathways deputed to transmit information from the photoreceptors of the retina to the lateral geniculate nucleus and then to the primary visual cortex (V1). Several studies investigated whether one pathway is more vulnerable than the other during development, and whether these streams develop at different rates. The results are still discordant. The aim of the present study was to understand the functionality of the dorsal and the ventral streams in two populations affected by different genetic disorders, Noonan syndrome (NS) and 22q11.2 deletion syndrome (22q11.2DS), and explore the possible genotype-phenotype relationships. 'Form coherence' abilities for the ventral stream and 'motion coherence' abilities for the dorsal stream were evaluated in 19 participants with NS and 20 participants with 22q11.2DS. Collected data were compared with 55 age-matched controls. Participants with NS and 22q11.2DS did not differ in the form coherence task, and their performance was significantly lower than that of controls. However, in the motion coherence task, the group with NS and controls did not differ, and both obtained significantly higher scores than the group with 22q11.2DS. Our findings indicate that deficits in the dorsal stream are related to the specific genotype, and that in our syndromic groups the ventral stream is more vulnerable than the dorsal stream.

Smooth pursuit eye movements in psychiatric inpatients

Introduction

Eye movements are used in several studies as a biomarker in order to evaluate cortical alterations in psychiatric disorders. Pursuit eye movements’ deficits were found both in schizophrenia and in affective disorder patients. Nevertheless, these findings are still controversial.

Objectives

Set up a system to record and evaluate the eye movements in psychiatric patients.

Aims

To verify the applicability of a smooth pursuit task in a sample of psychiatric inpatients and to prove its efficiency in discriminating patient and control group performance.

Methods

A sample of psychiatric inpatients was tested at psychiatric service of diagnosis and care of AUSL Romagna-Cesena. Eye movement measures were collected at a sampling rate of 60 Hz using the eye tribe tracker, a bar plugged into a PC, placed below the screen and containing both webcam and infrared illumination. Subjects underwent to a smooth pursuit eye movement task. They had to visually follow a white dot target moving horizontally on a black background with a sinusoidal velocity. At the end of the task, a chart of the eye movements done is shown on the screen. Data are off-line analyzed to calculate several eye movement parameters: gain, eye movement delay with respect to the movement of the target, maximum speed and number of saccades exhibited during pursuit.

Results

Patients compared to controls showed higher delay and lower gain values.

Conclusions

Findings confirm the adequacy of this method in order to detect eye movement differences between psychiatric patients and controls in a smooth pursuit task.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

Zero field PDD and TMR data for unflattened beams in conventional linacs: A tool for independent dose calculations

PURPOSE

To investigate the applicability of the formalism described in BJR supplement n.25 for Flattening Filter Free (FFF) beams in determining the zero-field tissue maximum ratio (TMR) for an independent calculation method of Percentage Depth Doses (PDDs) and relative dose factors (RDFs) at different experimental setups.

METHODS

Experimental PDDs for field size from 40×40cm² to 2×2cm² with Source Surface Distance (SSD) 100cm were acquired. The normalized peak scatter factor for each square field was obtained by fitting experimental RDFs in water and collimator factors (CFs) in air. Maximum log-likelihood methods were used to extract fit parameters in competing models and the Bayesian Information Criterion was used to select the best one. In different experimental setups additional RDFs and TPR₁₀²⁰s for field sizes other than reference field were measured and Monte Carlo simulations of PDDs at SSD 80cm were carried out to validate the results. PDD agreements were evaluated by gamma analysis.

RESULTS

The BJR formalism allowed to predict the PDDs obtained with MC within 2%/2mm at SSD 80cm from 100% down to 50% of the maximum dose. The agreement between experimental TPR₁₀²⁰s and RDFs values at SSD=90cm and BJR calculations were within 1% for field sizes greater than 5×5cm² while it was within 3% for fields down to 2×2cm².

CONCLUSIONS

BJR formalism can be used for FFF beams to predict PDD and RDF at different SSDs and can be used for independent MU calculations.

Brainstem Astrocytomas: The Radiosurgical Approach

Between 1987 and 1998, radiosurgery was performed on 20 cases of brainstem gliomas in patients of ages varying from eight months to 56 years, 11 of whom had low grade tumours and nine malignant growths. Six of the cases were children (ranging from eight months to 16 years). Six of the patients had undergone histological examinations. In fourteen cases, diagnosis of infiltrating brainstem tumour, and the distinction between high and low grade gliomas, was determined clinically and in particular through neuroradiology. In the histologically determined cases there was a pylocytic astrocytoma, a fibrillary astrocytoma, an astrocytoma II, two anaplastic astrocytomas and an angioglioma. The mean 25 mm target dose was 15 Gy in low grade tumours and 36 Gy in malignant gliomas. Of the 11 low grade tumour cases, nine patients are in an excellent state of health after follow-ups of between eight and 17 years. The average survival rate for high grade tumour cases was slightly more than 12 months (with a range of four to 25 months). In two cases of low grade glial tumour, the patients had previously undergone unsuccessful fractionated irradiation. The results presented lead to the conclusion that: 1) in cases of diffuse glioma, radiosurgery vs neurosurgery or even fractionated irradiation does not even appear to be an option, but merely a simple decision to use a new form of treatment; 2) neurosurgery may perhaps be an alternative in selected focal or exophytic tumours; 3) neuroradiology techniques, which are also classic methods for distinguishing the specific nature of glial tumours, ‘naturally’ relegate routine brainstem tumour biopsy to the pages of neurosurgical history.

Efficacy and mucosal toxicity of concomitant chemo-radiotherapy in patients with locally-advanced squamous cell carcinoma of the head-and-neck in the light of a novel mathematical model

BACKGROUND

In the last several decades, combined radiotherapy (RT) and chemotherapy (CT) have been recognized as feasible in locally-advanced-squamous-cell-carcinoma of the head-and-neck (LA-HNSCC). Several meta-analyses identified concurrent RT+CT (CRT) most likely effective approach respect to RT-alone. However, radiobiological models comparing different chemotherapeutic schedules against delivered RT fractionation schedule for overall survival and toxicity are still needed.

METHODS AND MATERIALS

Based on 9 randomized trials (2785 patients), radiobiological models and multivariate logistic regression model were used to derive dose-response curves and estimate the 5-year-overall survival (OS) and ≥G3 acute mucositis rate of CRT or RT-alone.

RESULTS

Equivalent dose at 2 Gy/fraction (EQD2) was calculated using the linear quadratic model. The effect of CRT schedules, considering the CT type and its administration schedule and the HPV status of tumors were estimated using the univariate/multivariate logistic regression. The multivariate logistic regression model for 5y-OS indicated EQD2 and the type of CT, the chemo-sensitization fraction and the HPV status significant prognostic factors, while for toxicity both EQD2 and the concomitant administration of 5-fluorouracil (5Fu) resulted as significant prognostic factors. Combined schedules cisplatin (DDP)+/-5Fu+RT produced the higher OS compared with combined carboplatin+/-5Fu+RT or RT-alone. The concomitant administration of Fu and schedule with high EQD2 increase the rate of observed ≥G3 acute mucositis.

CONCLUSION

Multivariate logistic regression models can be used to predict CRT effect in terms of OS and ≥G3-mucositis, contributing to the identification of novel treatment schedules.

Preliminary Retrospective Analysis of Daily Tomotherapy Output Constancy Checks Using Statistical Process Control

The purpose of this study was to retrospectively evaluate the results from a Helical TomoTherapy Hi-Art treatment system relating to quality controls based on daily static and dynamic output checks using statistical process control methods. Individual value X-charts, exponentially weighted moving average charts, and process capability and acceptability indices were used to monitor the treatment system performance. Daily output values measured from January 2014 to January 2015 were considered. The results obtained showed that, although the process was in control, there was an out-of-control situation in the principal maintenance intervention for the treatment system. In particular, process capability indices showed a decreasing percentage of points in control which was, however, acceptable according to AAPM TG148 guidelines. Our findings underline the importance of restricting the acceptable range of daily output checks and suggest a future line of investigation for a detailed process control of daily output checks for the Helical TomoTherapy Hi-Art treatment system.

Potential third-party radiation exposure from patients undergoing therapy with 131I for thyroid cancer or metastases

The purpose of this work is to evaluate the potential third-party radiation exposure from patients undergoing therapy with 131I for ablation of residual thyroid tumor or metastases, based in part on serial measurements of exposure rates. Exposure rate measurements were performed at 1 m and 5 cm from the surface of each treated patient until patient release. Dose estimates based on measured exposure rates were compared with those based on analytic point-source (PSM) and line-source (LSM) models. Effective doses D(∞) to travelers, co-workers and sleeping partners were estimated by using the standard gamma factor (Γ) and the physical half-life or the values derived from measured data. Seven hundred ten patients were studied until the exposure at 1 m was below the constraints of 0.010 mSv. The 131I activities administered ranged from 1.85 to 11.0 GBq (median: 3.7 GBq), according to the therapeutic requirements. Based on the PSM and an experimental Γ, the mean/maximum estimated D(∞) to sleeping partners, partners, travelers, and co-workers were 2.60/20.65, 0.32/2.53, 0.96/7.59, and 0.57/4.50 mSv, respectively. Using the LSM and an experimental Γ, the D(∞) values were 2.41/19.15, 0.32/2.50, 0.83/6.62, and 0.57/4.42 mSv, respectively, while they were almost double using the theoretical Γ. The results presented, based on measured data in a large cohort of 131I-treated thyroid cancer patients, will allow more accurate estimation of potential third-party D(∞) following patient release and thus may be used to better inform physicians and hospital staff on recommendations for patient release and post-release precautions following radioiodine therapies.

Twenty years of radiobiology in clinical practice: the Italian contribution

AIMS AND BACKGROUND

To present the Italian state-of-the-art contribution to radiobiology of external beam radiotherapy, brachytherapy, and radionuclide radiotherapy.

METHODS AND STUDY DESIGN

A survey of the literature was carried out, using PubMed, by some independent researchers of the Italian group of radiobiology. Each paper was reviewed by researchers of centers not comprising its authors. The survey was limited to papers in English published over the last 20 years, written by Italian investigators or in Italian institutions, excluding review articles.

RESULTS

A total of 135 papers have been published in journals with an impact factor, with an increase in the number of published papers over time, for external beam radiotherapy rather than radionuclide radiotherapy. The quantity and quality of the papers researched constitutes a proof of the enduring interest in clinical radiobiology among Italian investigators.

CONCLUSIONS

The survey could be useful to individuate expert partners for an Italian network on clinical radiobiology, addressing future collaborative investigations.

Abscopal effect of radiation therapy: Interplay between radiation dose and p53 status

PURPOSE

This study investigates whether the abscopal effect induced by radiation-therapy (RT) is able to sterilize non-irradiated tumour cells through bystander signals.

MATERIAL AND METHODS

Wild-type (wt)-p53 or p53-null HCT116 human colon cancer cells were xenografted into both flanks of athymic female nude mice. When tumours reached a volume of 0.2 cm(3), irradiation was performed, under strict dose monitoring, with a dedicated mobile accelerator designed for intra-Operative-RT (IORT). A dose of 10 or 20 Gy (IR groups), delivered by a 10 MeV electron beam, was delivered to a tumour established in one side flank, leaving the other non-irradiated (NIR groups). A subset of mice were sacrificed early on to carry out short-term molecular analyses.

RESULTS

All directly-irradiated tumours, showed a dose-dependent delayed and reduced regrowth, independent of the p53 status. Importantly, a significant effect on tumour-growth inhibition was also demonstrated in NIR wt-p53 tumours in the 20 Gy-irradiation group, with a moderate effect also evident after 10 Gy-irradiation. In contrast, no significant difference was observed in the NIR p53-null tumours, independent of the dose delivered. Molecular analyses indicate that p53-dependent signals might be responsible for the abscopal effect in our model system, via a pro-apoptotic pathway.

CONCLUSIONS

We suggest that the interplay between delivered dose and p53 status might help to sterilize out-of-field tumour cells.

Critical dose and toxicity index of organs at risk in radiotherapy: analyzing the calculated effects of modified dose fractionation in non-small cell lung cancer

To increase the efficacy of radiotherapy for non-small cell lung cancer (NSCLC), many schemes of dose fractionation were assessed by a new "toxicity index" (I), which allows one to choose the fractionation schedules that produce less toxic treatments. Thirty-two patients affected by non resectable NSCLC were treated by standard 3-dimensional conformal radiotherapy (3DCRT) with a strategy of limited treated volume. Computed tomography datasets were employed to re plan by simultaneous integrated boost intensity-modulated radiotherapy (IMRT). The dose distributions from plans were used to test various schemes of dose fractionation, in 3DCRT as well as in IMRT, by transforming the dose-volume histogram (DVH) into a biological equivalent DVH (BDVH) and by varying the overall treatment time. The BDVHs were obtained through the toxicity index, which was defined for each of the organs at risk (OAR) by a linear quadratic model keeping an equivalent radiobiological effect on the target volume. The less toxic fractionation consisted in a severe/moderate hyper fractionation for the volume including the primary tumor and lymph nodes, followed by a hypofractionation for the reduced volume of the primary tumor. The 3DCRT and IMRT resulted, respectively, in 4.7% and 4.3% of dose sparing for the spinal cord, without significant changes for the combined-lungs toxicity (p < 0.001). Schedules with reduced overall treatment time (accelerated fractionations) led to a 12.5% dose sparing for the spinal cord (7.5% in IMRT), 8.3% dose sparing for V20 in the combined lungs (5.5% in IMRT), and also significant dose sparing for all the other OARs (p < 0.001). The toxicity index allows to choose fractionation schedules with reduced toxicity for all the OARs and equivalent radiobiological effect for the tumor in 3DCRT, as well as in IMRT, treatments of NSCLC.

Local tumor control probability to evaluate an applicator-guided volumetric-modulated arc therapy solution as alternative of 3D brachytherapy for the treatment of the vaginal vault in patients affected by gynecological cancer

The purpose of this study was to evaluate the applicator‐guided volumetric‐modulated arc therapy (AGVMAT) solution as an alternative to high‐dose‐rate brachytherapy (HDR‐BRT) treatment of the vaginal vault in patients with gynecological cancer (GC). AGVMAT plans for 51 women were developed. The volumetric scans used for plans were obtained with an implanted CT‐compatible vaginal cylinder which provides spatial registration and immobilization of the gynecologic organs. Dosimetric and radiobiological comparisons for planning target volume (PTV) and organs at risk (OARs) were performed by means of a dose‐volume histogram (DVH), equivalent uniform dose (EUD), and local tumor control probability (LTCP). In addition, the integral dose and the overall delivery time, were evaluated. The HDR‐BRT averages of EUD and minimum LTCP were significantly higher than those of AGVMAT. Doses for the OARs were comparable for the bladder and sigmoid, while, although HDR‐BRT was able to better spare the bowel, AGVMAT provided a significant reduction of d2cc, d1cc, and dmax (p<0.01) for the rectum. AGVMAT integral doses were higher than HDR‐BRT with low values in both cases. Delivery times were about two or three times higher for HDR‐BRT with respect to the single arc technique (AGVMAT1) and dual arc technique (AGVMAT2), respectively. The applicator‐guided volumetric‐modulated arc therapy seems to have the potential of improving rectum avoidance. However, brachytherapy improves performance in terms of PTV coverage, as demonstrated by a greater EUD and better LTCP curves.

PACS number: 87

Development and optimization of a beam shaper device for a mobile dedicated IOERT accelerator

PURPOSE

The aim of this study was to design and build a prototype beam shaper to be used on a dedicated mobile accelerator that protects organs at risk within the radiation field and conforms the beam to the target geometry during intraoperative electron radiotherapy (IOERT). A dosimetric characterization of the beam shaper device was performed based on Monte Carlo (MC) simulations, as well as experimental data, at different energies, field sizes, and source to skin distances.

METHODS

A mobile light intraoperative accelerator (LIAC(®), Sordina, Italy) was used. The design of the beam shaper prototype was based on MC simulations (BEAMnrc∕OMEGA and DOSXYZnrc code) for a selection of materials and thicknesses, as well as for dosimetric characterization. Percentage depth dose (PDD) and profile measurements were performed using a p-type silicon diode and a commercial water phantom, while output factors were measured using a PinPoint ion chamber in a PMMA phantom. Planar doses in planes of interest were carried out using radiochromic films (Gafchromic(TM) EBT and EBT2) in PMMA and in a Solid Water(®) phantom. Several experimental set-ups were investigated with the beam shaper device fixed on the top of the phantom, varying both the short side of the rectangular field and the air gap between the device and the phantom surface, simulating the clinical situation. The output factors (OFs) were determined using different geometrical set-ups and energies.

RESULTS

The beam shaper prototype consists of four blades sliding alongside each other and mounted on a special support at the end of the 10 cm diameter PMMA circular applicator. Each blade is made of an upper layer of 2.6 cm of Teflon(®) and a lower layer of 8 mm of stainless steel. All rectangles inscribed in a 5 cm diameter can be achieved in addition to any "squircle-shaped" field. When one side of the rectangular field is held constant and the second side is reduced, both R(50) and R(max) move towards the phantom surface. Comparing the PDDs obtained with the 5 cm circular applicator and with a 4.4 × 4.4 cm(2) square field (that is the equivalent square of the 5 cm circular field) obtained with the beam shaper, a different behavior was observed in the region extending from the surface to a depth of 50% of the maximum dose. Isodoses measured for rectangular fields used for clinical cases (i.e., 4 × 9 cm(2) 8 MeV) are shown, with different air gaps. For each energy investigated, the normalized OFs slowly increase, when the length of the side decreases down to about 4 cm, and then rapidly decreases for smaller field widths. MC simulation showed an excellent agreement with experimental data (<2%).

CONCLUSIONS

The beam shaper device is able to provide square∕rectangular∕squircle fields with adequate dose homogeneity for mobile dedicated accelerators, thus allowing conformal treatment with IOERT. Monte Carlo simulation can be a very useful tool to simulate any clinical set up and can be used to create a data set to calculate MUs, thereby increasing the accuracy of the delivered dose during IOERT procedures.

Correlation between EGFr expression and accelerated proliferation during radiotherapy of head and neck squamous cell carcinoma

Purpose

To investigate the correlation between the expression of Epidermal Growth Factor receptor (EGFr) and the reduction of the effective doubling time (T_D) during radiotherapy treatment and also to determine the dose per fraction to be taken into account when the overall treatment time (OTT) is reduced in accelerated radiotherapy of head and neck squamous cell carcinoma (HNSCC).

Methods

A survey of the published papers comparing 3-years of local regional control rate (LCR) for a total of 2162 patients treated with conventional and accelerated radiotherapy and with a pretreatment assessment of EGFr expression, was made. Different values of T_D were obtained by a model incorporating the overall time corrected biologically effective dose (BED) and a 3-year clinical LCR for high and low EGFr groups of patients (H_EGFr and L_EGFr), respectively. By obtaining the T_D from the above analysis and the sub-sites’ potential doubling time (T_pot) from flow cytometry and immunohistochemical methods, we were able to estimate the average T_D for each sub-site included in the analysis. Moreover, the dose that would be required to offset the modified proliferation occurring in one day (D_prolif), was estimated.

Results

The averages of T_D were 77 (27-90)_95% days in L_EGFr and 8.8 (7.3-11.0)_95% days in H_EGFr, if an onset of accelerated proliferation T_K at day 21 was assumed. The correspondent H_EGFr sub-sites’ T_D were 5.9 (6.6), 5.9 (6.6), 4.6 (6.1), 14.3 (12.9) days, with respect to literature immunohistochemical (flow cytometry) data of T_pot for Oral-Cavity, Oro-pharynx, Hypo-pharynx, and Larynx respectively. The D_prolif for the H_EGFr groups were 0.33 (0.29), 0.33 (0.29), 0.42 (0.31), 0.14 (0.15) Gy/day if α = 0.3 Gy^-1 and α/β = 10 Gy were assumed.

Conclusions

A higher expression of the EGFr leads to enhanced proliferation. This study allowed to quantify the extent of the effect which EGFr expression has in terms of reduced T_D and D_prolif for each head and neck sub-site.

Modelling the correlation between EGFr expression and tumour cell radiosensitivity, and combined treatments of radiation and monoclonal antibody EGFr inhibitors

Purpose

To estimate the effects of heterogeneity on tumour cell sensitivity to radiotherapy combined with radiosensitizing agents attributable to differences in expression levels of Epidermal Growth Factor Receptor (EGFr).

Materials and methods

Differences in radiosensitivity are not limited to cells of different cancer histotypes but also occur within the same cancer, or appear during radiotherapy if radiosensitizing drugs are combined with ionizing radiation. A modified biologically effective dose (MBED), has been introduced to account for changes in radiosensitivity parameters (α and α/β) rather than changes in dose/fraction or total dose as normally done with standard biologically effective dose (BED). The MBED approach was applied to cases of EGFr over-expression and cases where EGFr inhibitors were combined with radiation. Representative examples in clinical practice were considered.

Results

Assuming membrane EGFr over-expression corresponds to reduced radiosensitivity (α_H = 0.15 Gy^-1 and α_H/β_H = 7.5 Gy) relative to normal radiosensitivity (α = 0.2 Gy^-1 and α/β = 10 Gy), an increased dose per fraction of 2.42 Gy was obtained through the application of MBED, which is equivalent to the effect of a reference schedule with 30 fractions of 2 Gy. An equivalent hypo-fractionated regime with a dose per fraction of 2.80 Gy is obtained if 25 fractions are set. Dose fractionations modulated according to drug pharmacokinetics are estimated for combined treatments with biological drugs. Soft and strong modulated equivalent hypo-fractionations result from subtraction of 5 or 10 fractions, respectively.

Conclusions

During this computational study, a new radiobiological tool has been introduced. The MBED allows the required dose per fraction to be estimated when tumour radiosensitivity is reduced because EGFr is over-expressed. If radiotherapy treatment is combined with EGFr inhibitors, MBED suggests new treatment strategies, with schedules modulated according to drug pharmacokinetics.

Comparative dosimetric and radiobiological assessment among a nonstandard RapidArc, standard RapidArc, classical intensity-modulated radiotherapy, and 3D brachytherapy for the treatment of the vaginal vault in patients affected by gynecologic cancer

To evaluate a nonstandard RapidArc (RA) modality as alternative to high-dose-rate brachytherapy (HDR-BRT) or IMRT treatments of the vaginal vault in patients with gynecological cancer (GC). Nonstandard (with vaginal applicator) and standard (without vaginal applicator) RapidArc plans for 27 women with GC were developed to compare with HDR-BRT and IMRT. Dosimetric and radiobiological comparison were performed by means of dose-volume histogram and equivalent uniform dose (EUD) for planning target volume (PTV) and organs at risk (OARs). In addition, the integral dose and the overall treatment times were evaluated. RA, as well as IMRT, results in a high uniform dose on PTV compared with HDR-BRT. However, the average of EUD for HDR-BRT was significantly higher than those with RA and IMRT. With respect to the OARs, standard RA was equivalent of IMRT but inferior to HDR-BRT. Furthermore, nonstandard RA was comparable with IMRT for bladder and sigmoid and better than HDR-BRT for the rectum because of a significant reduction of d(2cc), d(1cc), and d(max) (p < 0.01). Integral doses were always higher than HDR-BRT, although the values were very low. Delivery times were about the same and more than double for HDR-BRT compared with IMRT and RA, respectively. In conclusion, the boost of dose on vaginal vault in patients affected by GC delivered by a nonstandard RA technique was a reasonable alternative to the conventional HDR-BRT because of a reduction of delivery time and rectal dose at substantial comparable doses for the bladder and sigmoid. However HDR-BRT provides better performance in terms of PTV coverage as evidenced by a greater EUD.

Preliminary experience of a predictive model to define rectal volume and rectal dose during the treatment of prostate cancer

OBJECTIVES

The aim of this study was to define a method to evaluate the total dose delivered to the rectum during the whole treatment course in six patients undergoing irradiation for prostate cancer using an offline definition of organ motion with images from a cone beam CT (CBCT) scanner available on a commercial linear accelerator.

METHODS

Patient set-up was verified using a volumetric three-dimensional CBCT scanner; 9-14 CBCT scans were obtained for each patient. Images were transferred to a commercial treatment planning system for offline organ motion analysis. The shape of the rectums were used to obtain a mean dose-volume histogram (<DVH>), which was the average of the DVHs of the rectums as they appeared in each verification CBCT. A geometric model of an average rectum (AR) was produced using the rectal contours delineated on the CBCT scans (DVH(AR)). To check whether the first week of treatment was representative of the whole treatment course, we evaluated the DVHs related to only the first five CBCT scans (<DVH5> and DVH(AR5)). Finally, the influence of a dietary protocol on the goodness of our results was considered.

RESULTS

In all six patients the original rectal DVH for the planning CT scan showed higher values than all DVHs.

CONCLUSION

Although the application of the model to a larger set of patients is necessary to confirm this trend, reconstruction of a representative volume of the rectum throughout the entire treatment course seems feasible.

IsoBED: a tool for automatic calculation of biologically equivalent fractionation schedules in radiotherapy using IMRT with a simultaneous integrated boost (SIB) technique

Background

An advantage of the Intensity Modulated Radiotherapy (IMRT) technique is the feasibility to deliver different therapeutic dose levels to PTVs in a single treatment session using the Simultaneous Integrated Boost (SIB) technique. The paper aims to describe an automated tool to calculate the dose to be delivered with the SIB-IMRT technique in different anatomical regions that have the same Biological Equivalent Dose (BED), i.e. IsoBED, compared to the standard fractionation.

Methods

Based on the Linear Quadratic Model (LQM), we developed software that allows treatment schedules, biologically equivalent to standard fractionations, to be calculated. The main radiobiological parameters from literature are included in a database inside the software, which can be updated according to the clinical experience of each Institute. In particular, the BED to each target volume will be computed based on the alpha/beta ratio, total dose and the dose per fraction (generally 2 Gy for a standard fractionation). Then, after selecting the reference target, i.e. the PTV that controls the fractionation, a new total dose and dose per fraction providing the same isoBED will be calculated for each target volume.

Results

The IsoBED Software developed allows: 1) the calculation of new IsoBED treatment schedules derived from standard prescriptions and based on LQM, 2) the conversion of the dose-volume histograms (DVHs) for each Target and OAR to a nominal standard dose at 2Gy per fraction in order to be shown together with the DV-constraints from literature, based on the LQM and radiobiological parameters, and 3) the calculation of Tumor Control Probability (TCP) and Normal Tissue Complication Probability (NTCP) curve versus the prescribed dose to the reference target.

Dosimetry in nuclear medicine therapy: radiobiology application and results

The linear quadratic model (LQM) has largely been used to assess the radiobiological damage to tissue by external beam fractionated radiotherapy and more recently has been extended to encompass a general continuous time varying dose rate protocol such as targeted radionuclide therapy (TRT). In this review, we provide the basic aspects of radiobiology, from a theoretical point of view, starting from the "four Rs" of radiobiology and introducing the biologically effective doses, which may be used to quantify the impact of a treatment on both tumors and normal tissues. We also present the main parameters required in the LQM, and illustrate the main models of tumor control probability and normal tissue complication probability and summarize the main dose-effect responses, reported in literature, which demonstrate the tentative link between targeted radiotherapy doses and those used in conventional radiotherapy. A better understanding of the radiobiology and mechanisms of action of TRT could contribute to describe the clinical data and guide the development of future compounds and the designing of prospective clinical trials.