Simplifying two-vector mechanics calculations for challenging tooth movements

The purpose of this article was to describe a simple graphical driven method for determining the necessary two-vector mechanics (TVM) as an alternative solution to the ideal or single force. In orthodontics, some tooth movements are difficult to achieve, mainly because of the impossibility of getting the point of application for the necessary force system. Given two points in biomechanically accessible areas, adding together two vectors applied to those points will result in an equivalent force system. The method was developed based on previous research, 3,880 hypothetical cases were analyzed to determine the trends between the resulting forces and their relative locations. A graphical driven TVM method (GTVM) for establishing the necessary TVM is presented in a manner that combine different procedures from the traditional method that simplify the analysis and may allow the user to perform more complex orthodontic cases making easier to compare systems of force equivalents.

Antibiotic resistance genes in the subgingival microbiome and implications for periodontitis therapy

BACKGROUND

Antibiotic resistance is emerging as a global public threat. However, it remains poorly investigated in the context of periodontal therapy. The aim of the study was to investigate the complete diversity of antibiotic resistance genes in a German population.

METHODS

Thirty-nine volunteers with periodontitis contributed to the present study with one to four periodontal pockets for a total of 124 subgingival samples. Samples were analyzed using shotgun metagenomics.

RESULTS

A total of 19 antibiotic resistance genes from six antibiotic classes were detected in subgingival biofilm. Two thirds of the volunteers (n = 26/39) showed antibiotic resistance genes for at least one of the antibiotic classes used for periodontal treatment in dental practice or research: beta-lactam, lincosamide, macrolide, nitroimidazole, and tetracycline. Macrolide was the most abundant class detected (21/39 patients).

CONCLUSIONS

Findings from our study suggest a high prevalence of antibiotic resistance genes in periodontal pockets from German volunteers. We recommend the development and broader use of molecular diagnostic tests for antibiotic resistance in dental practice to ensure treatment success and to minimize antibiotic resistance.

A Systematic Review of LET-Guided Treatment Plan Optimisation in Proton Therapy: Identifying the Current State and Future Needs

The well-known clinical benefits of proton therapy are achieved through higher target-conformality and normal tissue sparing than conventional radiotherapy. However, there is an increased sensitivity to uncertainties in patient motion/setup, proton range and radiobiological effect. Although recent efforts have mitigated some uncertainties, radiobiological effect remains unresolved due to a lack of clinical data for relevant endpoints. Therefore, RBE optimisations may be currently unsuitable for clinical treatment planning. LET optimisation is a novel method that substitutes RBE with LET, shifting LET hotspots outside critical structures. This review outlines the current status of LET optimisation in proton therapy, highlighting knowledge gaps and possible future research. Following the PRISMA 2020 guidelines, a search of the MEDLINE® and Scopus databases was performed in July 2023, identifying 70 relevant articles. Generally, LET optimisation methods achieved their treatment objectives; however, clinical benefit is patient-dependent. Inconsistencies in the reported data suggest further testing is required to identify therapeutically favourable methods. We discuss the methods which are suitable for near-future clinical deployment, with fast computation times and compatibility with existing treatment protocols. Although there is some clinical evidence of a correlation between high LET and adverse effects, further developments are needed to inform future patient selection protocols for widespread application of LET optimisation in proton therapy.

Comparison of 116 Radiosurgery Treatment Plans for Multi-Leaf and Cone Collimator on a Varian Edge Linac: Are Cones Superior in the Daily Routine?

Delivering focused radiation doses via linear accelerators is a crucial component of stereotactic radiosurgery (SRS) for brain metastases. The Varian Edge linear accelerator provides highly conformal radiation therapy through a high-definition multi-leaf collimator (HD120 MLC) and conical collimator (CC). HD120 MLC adapts to the shape of the target volume using movable tungsten leaves, while CC has a block of conical shape (cones). CC in SRS treatments of small brain metastases is preferred due to its mechanical stability and steeper dose fall-off, potentially sparing organs at risk (OARs) and the brain better than HD120 MLC. This study aims to determine if CC offers significant advantages over HD120 MLC for SRS treatments. For 116 metastatic lesions, CC and HD120 MLC treatment plans were created in Varian Eclipse TPS and compared based on various dose parameters, robustness tests, and QA measurements. The results indicate that CC provides no significant advantages over HD120 MLC, except for slight, clinically insignificant benefits in brain sparing and dose fall-off for the smallest lesions. HD120 MLC outperforms CC in almost every aspect, making it a better choice for irradiating brain metastases with 0.1 cm³ or higher volumes.

Evaluating diagnostic performance of three cephalometric vertical parameters

Objectives

The goal of this research was to see how reliable and valid three selected parameters from different analysis were in detecting the vertical skeletal pattern.

Methods

There were 94 cephalometric x-rays used in all. The vertical skeletal pattern was assessed using the mandibular plane angle by Steiner, Frankfort mandibular angle by Tweed, and facial axis angle by McNamara. According to the diagnostic results of the majority of the measures, the samples were classified as normo-divergent, hypodivergent, or hyperdivergent. Kappa statistics, positive predictive value, and sensitivity were employed to verify the validity and reliability of the analyses.

Results

A statistically significant weak negative correlation was found between Frankfort mandibular angle and facial axis angle in female group (p value < 0.01). A good agreement was found between mandibular plane angle with final diagnosis (K = 0.726). The mandibular plane angle showed highest sensitivity and positive predictive value in hypodivergent group (0.939, 0.816) and normo-divergent group (0.795, 0.833), respectively.

Conclusion

For determining the facial vertical growth pattern the most accurate indicators were identified to be mandibular plane angle (SN-GoGn) and Frankfort mandibular angle.

Prediction of cardiovascular adverse events in newly diagnosed multiple myeloma: Development and validation of a risk score prognostic model

Background

Multiple myeloma (MM) is the second most common hematological malignancy, and the treatments markedly elevate the survival rate of the patients in recent years. However, the prevalence of cardiovascular adverse events (CVAEs) in MM had been increasing recently. CVAEs in MM patients are an important problem that we should focus on. Clinical tools for prognostication and risk-stratification are needed.

Patients and methods

This is a retrospective study that included patients who were newly diagnosed with multiple myeloma (NDMM) in Shanghai Changzheng Hospital and Affiliated Jinhua Hospital, Zhejiang University School of Medicine from June 2018 to July 2020. A total of 253 patients from two medical centers were divided into training cohort and validation cohort randomly. Univariable analysis of the baseline factors was performed using CVAEs endpoints. Multivariable analysis identified three factors for a prognostic model that was validated in internal validation cohorts.

Results

Factors independently associated with CVAEs in NDMM were as follows: age>61 years old, high level of baseline office blood pressure, and left ventricular hypertrophy (LVH). Age contributed 2 points, and the other two factors contributed 1 point to a prognostic model. The model distinguished the patients into three groups: 3-4 points, high risk; 2 points, intermediate risk; 0-1 point, low risk. These groups had significant difference in CVAEs during follow-up days in both training cohort (p<0.0001) and validation cohort (p=0.0018). In addition, the model had good calibration. The C-indexes for the prediction of overall survival of CVAEs in the training and validation cohorts were 0.73 (95% CI, 0.67-0.79) and 0.66 (95% CI, 0.51-0.81), respectively. The areas under the receiver operating characteristic curve (AUROCs) of the 1-year CVAEs probability in the training and validation cohorts were 0.738 and 0.673, respectively. The AUROCs of the 2-year CVAE probability in the training and validation cohorts were 0.722 and 0.742, respectively. The decision-curve analysis indicated that the prediction model provided greater net benefit than the default strategies of providing assessment or not providing assessment for all patients.

Conclusion

A prognostic risk prediction model for predicting CVAEs risk of NDMM patients was developed and internally validated. Patients at increased risk of CVAEs can be identified at treatment initiation and be more focused on cardiovascular protection in the treatment plan.

Periodontal diagnosis and treatment planning - An assessment of the understanding of the new classification system

OBJECTIVES

Substantial variations are seen among clinicians in the diagnosis and treatment planning of periodontal diseases. Accurate diagnosis and treatment planning are fundamental requirements for effective outcome-based patient care. The aim of this study was to evaluate the understanding of the American Academy of Periodontology and the European Federation of Periodontology 2017 periodontal disease classifications in diagnoses and treatment plans across four study groups.

METHODS

The study recruited at least 20 participants in each of the four study groups. These included 1) Periodontal faculty and residents at Indiana University School of Dentistry (IUSD-PF) 2) IUSD general practice faculty (IUSD-GPF), 3) private practice periodontists (PPP), and 4) general practitioners (GP). The participants were provided with 10 HIPPA de-identified case records and a link to a survey. The survey comprised five demographic questions and two questions on diagnosis and treatment plan for each case along with a fixed list of responses. The responses were then compared against gold standards that were determined by a group of three board-certified periodontists.

RESULTS

Overall, for diagnostic questions, GP (69%) were correct significantly less often than IUSD-PF (86%, p < 0.001), IUSD-GPF (79%, p = 0.002), and PPP (80%, p = 0.001). No significant differences (p > 0.05) in the overall correct treatment plan responses were found among the four groups (IUSD-PF: 69%, IUSD-GPF: 62%, PPP: 68%, and GP: 60%). The multi-rater kappas for with-in-group agreement on overall diagnosis ranged from 0.36 (GP) to 0.55 (IUSD-PF) and on overall treatment plan ranged from 0.32 (IUSD-GPF) to 0.42 (IUSD-PF). Overall agreement for diagnosis and treatment plans among the four groups was relatively low and none of the groups were statistically different from each other (p > 0.05).

CONCLUSION

Regular participation in calibration sessions may lead to more accurate adoption of the 2017 periodontal classification and thereby help provide consistent diagnosis and treatment.

Development and evaluation of a teleoncology system for breast cancer during the COVID-19 pandemic

Background: The present study describes the steps of developing a hybrid teleoncology system to provide treatment plans for breast cancer patients. Materials & methods: This research was conducted in four stages, including developing a proposal for experts, identifying and analyzing system requirements, designing a prototype and implementing and evaluating the final version of the hybrid teleoncology system. Results: The results of the usability evaluation showed that the users evaluated the system at a good level and, in practice, the implemented system was perceived to be useful by specialists in providing treatment plans for cancer patients. Conclusion: The hybrid teleoncology system is a practical alternative to traditional methods for providing treatment plans to breast cancer patients.

Managing intoxications with nicotine-containing e-liquids

INTRODUCTION

Nicotine is an addictive and poisonous agent. The recent development of e-cigarettes has caused a new demand for highly concentrated nicotine-containing solutions. These concentrated nicotine solutions have also increased the risk of nicotine overdoses.

AREAS COVERED

Essential factors for nicotine exposure are the concentration of the nicotine-containing e-liquid solution and its pharmacokinetics. Liquid nicotine refills contain nicotine in varying concentrations, which vary widely between and within products. The pharmacokinetics of nicotine are dependent on the route of administration, renal/hepatic clearance and urinary pH. The dose is another essential determinant of nicotine exposure. There is a considerable discrepancy between the generally accepted lethal dose and symptoms reported in case studies. Ingested doses correlate poorly to clinical symptoms. Symptoms of liquid nicotine toxicity vary from mild to severe between patients and are the result of overstimulation of nicotinic acetylcholine receptors, which may lead to fatal respiratory failure and cardiovascular collapse.

EXPERT OPINION

The literature on nicotine-containing e-liquid intoxications originating from vaping device refills are mainly case reports. Based on these case reports, we propose a treatment plan which is primarily symptomatic. Research should focus on providing insight on its toxicity, based on oral and transdermal pharmacokinetics and on toxicodynamics.

Shared Decision-Making: A Cross-Sectional Study Assessing Patients Awareness and Preferences in Saudi Arabia

BACKGROUND AND AIM

Shared decision-making (SDM) has become broadly accepted during the consultation, especially when there are many options of treatment. This study aims to assess patients' levels of awareness and preferences of SDM in Saudi Arabia.

METHODS

This is a cross-sectional study targeting patients in Saudi Arabia. Two validated questionnaires were used, the first validated questionnaire focuses on measuring knowledge, attitude and experiences of shared-decision making. The second questionnaire is the the Autonomy-Preference-Index focusing on patients' preferences for being involved in SDM. Relevant items to the study aim were chosen and translated into Arabic. Psychometric testing was conducted for Arabic and English versions and tested for content and face validity. The questionnaire administered online via social media channels, between February 2021 and May 2021. A total of 411 respondents completed the questionnaire.

RESULTS

The findings showed a positive association between awareness and preferences of SDM among patients in Saudi Arabia. In the awareness of the SDM domain, females reported higher scores than male participants (t = -4.504, P < 0.001). Saudis reported higher scores in their awareness of SDM than non-Saudis (t = 2.569, P = 0.011). Participants without health insurance reported higher scores in their awareness of SDM than those insured (t = -2.130, P = 0.034). Participants with degree have higher knowledge levels than participants with no degree (f = 10.034, P < 0.001). Females reported higher scores in their preferences of SDM than the male (t = -2.099, P = 0.036). Participants who visited private health-care settings in their last clinical encounter reported higher preferences of SDM than participants who received care in other settings (f = 2.653, P = 0.048).

CONCLUSION

The study concludes that the more aware a patient is, the more likely they prefer SDM practice. This finding can support health-care policymakers in developing SDM policies that enhance patient-centered care.

Overall Treatment Strategy for Patients With Metastatic NSCLC With Activating EGFR Mutations

Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (EGFR-TKIs) are standard of care in the first-line (1L) setting for patients with metastatic non-small cell lung cancer (mNSCLC) with activating EGFR mutations. EGFR-activating mutations are a predictive factor for response to EGFR-TKIs. Meta-analyses have shown that patients with exon 21_L858R mutations exhibit reduced sensitivity to EGFR-TKIs, resulting in inferior patient outcomes compared to those with exon 19 deletion mutations, with worse overall survival, progression-free survival, objective response, and disease control rates. Clinical activity observed with 1L therapy with first-generation (1G), second-generation (2G), and third-generation (3G) EGFR-TKIs is not permanent, and resistance inevitably develops in all cases, supporting the importance of overall treatment planning. The introduction of the 3G EGFR-TKI, osimertinib, provides an opportunity to overcome T790M-mediated resistance to 1G, and 2G EGFR-TKIs. Additionally, with the use of osimertinib, fewer T790M mutations are being detected as T790M is not a reported resistance mechanism to 3G EGFR-TKIs. However, there are currently no approved targeted therapies after 3G EGFR-TKIs. In order to further improve patient outcomes, there is a need to explore additional options for the overall treatment strategy for patients, including 1L and beyond. Combination of vascular endothelial growth factor (VEGF) inhibitors and EGFR-TKIs or chemotherapy and EGFR-TKIs may be a potential therapeutic approach in the 1L setting. This review discusses current treatment options for mNSCLC with activating EGFR mutations based on tumor, patient, and treatment characteristics and how an overall treatment plan may be developed.

Interaction of therapeutic12C ions with bone-like targets: physical characterization and dosimetric effect at material interfaces

Carbon therapy is a promising treatment option for cancer. The physical and biological properties of carbon ions can theoretically allow for the delivery of curative doses to the tumor, while simultaneously limiting risks of toxicity to adjacent healthy structures. The treatment effectiveness can be further improved by decreasing the uncertainties stemming from several sources, including the modeling of tissue heterogeneity. Current treatment plans employ density-based conversion methods to translate patient-specific anatomy into a water system, where dose distribution is calculated. This approach neglects differences in nuclear interactions stemming from the elemental composition of each tissue. In this work, we investigated the interaction of therapeutic carbon ions with bone-like materials. The study concentrated on nuclear interactions and included attenuation curves of 200 and 400 AMeV beams in different types of bones, as well as kinetic energy spectra of all charged fragments produced up to 29 degrees from the beam direction. The comparison between measurements and calculations of the treatment planning system TRiP98 indicated that bone tissue causes less fragmentation of carbon ions than water. Overall, hydrogen and helium particles were found to be the most abundant species, while heavier fragments were mostly detected within 5 degrees from the beam direction. We also investigated how the presence of a soft tissue-bone interface could affect the depth-dose profile. The results revealed a dose spike in the transition region, that extended from the entry channel to the target volume. The findings of this work indicated that the tissue-to-water conversion method based only on density considerations can result in dose inaccuracies. Tissue heterogeneity regions containing bones can potentially produce dose spikes, whose magnitude will depend on the patient anatomy. Dose uncertainties can be decreased by modeling nuclear interactions directly in bones, without applying the tissue-to-water conversion.

Telemonitoring in the Covid-19 Era: The Tuscany Region Experience

Covid-19 has brought many difficulties in the management of infected and high-risk patients. Telemedicine platforms can really help in this situation, since they allow remotely monitoring Covid-19 patients, reducing the risk for the doctors, without decreasing the efficiency of the therapies and while alleviating patients’ mental issues. In this paper, we present the entire architecture and the experience of using the Tel.Te.Covid19 telemedicine platform. Projected for the treatment of chronic diseases, it has been technologically updated for the management of Covid-19 patients with the support of a group of doctors in the territory when the pandemic arrived, introducing new sensors and functionalities (e.g., the familiar use and video calls). In Tuscany (Central Italy), during the first wave of outbreak, a model for enrolling patients was created and tested. Because of the positive results, the latter has been then adopted in the second current wave. The Tel.Te.Covid19 platform has been used by 40 among general practitioners and doctors of continuity care and about 180 symptomatic patients since March 2020. Both patients and doctors have good opinion of the platform, and no hospitalisations or deaths occurred for the monitored patients, reducing also the impact on the National Healthcare System.

Surgical oncology in the elderly

Poor cancer-specific outcomes in the elderly group are primarily a surgical failure. Surgeons are insufficiently trained to draw a line between fit and frail patients; this results in over-treatment of the frail patient, as well as under-treatment of the fit one. Communication skills should be improved to better understand the patient's requests. The timing of the surgical procedure is crucially important; all efforts should be put in place to optimize the patient's conditions before the surgery takes place.

Self-Management Plans in Patients with Hereditary Angioedema: Strategies, Outcomes and Integration into Clinical Care

Chronic conditions, whether genetic or acquired, impose a significant burden on health care systems with high utilisation of hospital and emergency department resources. Self-management is increasingly recognised as one of the pillars in models of care for those with long-term medical conditions. Hereditary angioedema (HAE) is a rare genetic disorder inherited in an autosomal dominant fashion. It is characterised by the occurrence of unpredictable attacks of swelling (angioedema) affecting many body parts including subcutaneous tissues, the gut mucosa and the upper airway. For those affected, it is associated with a high burden of illness and poor quality of life as a result of its unpredictability and the threat of asphyxiation from upper airway oedema or severe pain from abdominal involvement. Prompt recognition and appropriate treatment are necessary to avoid the pain and suffering associated with attacks and to manage life-threatening laryngeal swellings that around 50% of HAE patients will experience in their lifetime. Since the early 2000s, a number of very effective, albeit expensive, treatment options have become available, at least in some countries. Utilisation of these options within a written patient self-management plan provides the most satisfactory treatment outcomes and improves patient quality of life. Successful self-management depends on a productive partnership between patient and health care professional, with patient education the cornerstone of a successful outcome. This is a dynamic process, particularly in a condition such as HAE where frequency and severity of attacks may vary given different life circumstances.

Dosimetric assessment of patient-specific breath-hold reproducibility on liver motion for SBRT planning

PURPOSE

To investigate the impact of breath-hold reproducibility on liver motion using a respiratory motion management device.

METHODS

Forty-four patients with hepatic tumors, treated with SBRT with breath-hold, were randomly selected for this study. All patients underwent three consecutive computed tomography (CT) scans using active breath-hold coordinator (ABC) with three repeated single breath-hold during simulation. The three CT scans were labeled as ABC1-CT, ABC2-CT, and ABC3-CT. Displacements of centroids of the entire livers among the three ABC-CTs were measured as a surrogate for intrafractional motion. For each patient, two different treatment plans were prepared: (a) a clinical plan using a 5-mm expansion of an ITV that encompassed all three GTVs from each of the three ABC-CTs, and (b) a research plan using a 5-mm expansion of the GTV from only ABC1-CT to create PTV. The clinical plan acceptance criteria were that 95% of the PTV and 99% of the GTV received 100% of the prescription dose. Dosimetric endpoints were analyzed and compared for the two plans.

RESULTS

All shifts in the medial-lateral direction (range: -3.9 to 2.0 mm) were within 5 mm while 7% of shifts in the anterior-posterior direction (range: -10.5 to 16.7 mm) and 11% of shifts in the superior-inferior direction (range: -17.0 to 8.7 mm) exceeded 5 mm. Six patients (14%) had an intrafraction motion greater than 5 mm in any direction. For these six patients, if a plan was created based on a PTV from a single CT (ex. ABC1-CT), 5 of 12 GTVs captured from other ABC-CTs would fail to meet the clinical acceptance criteria due to poor breath-hold reproducibility.

CONCLUSIONS

Non-negligible intrafractional motion occurs in patients with poor breath-hold reproducibility. To identify this subgroup of patients, acquiring three CTs with active breath-hold during simulation is a feasible practical method.

PROA concept: prosthetic restoration with orthodontic appliance

This paper describes an alternative computer-aided design/computer-aided manufacturing (CAD/CAM) technique for the creation of a combined prosthetic restoration with orthodontic appliance (PROA). This concept allows the use of orthodontic appliances such as brackets, attachments, or any other type of appliance over different types of prosthetic restorations. The PROA concept aims to mitigate problems associated with performing restorative treatment when orthodontic treatment is necessary. This proposed concept provides the clinicians with proper control and planning of the interdisciplinary treatment that will lead to the final tooth shape, form, and proportions while performing orthodontic tooth movements.

Successful combination of endoscopic and laparoscopic removal of multiple ingested needles: A case report

RATIONALE

Foreign body (FB) ingestion is a relatively common clinical situation in the emergency department. However, multiple sharply pointed foreign bodies located in different organs are rare conditions and no definite treatment guidelines has been established.

PATIENT CONCERNS

A 31-year-old amateur magician visited the outpatient clinic with a chief complaint of epigastric discomfort. He might have accidentally swallowed some needles while practicing a magic trick 2 days before.

DIAGNOSIS

Imaging tests revealed 1 needle was stuck in the left liver lobe through the stomach wall, 1 was in the third portion of the duodenum, 3 were in the ascending colon, and 2 were in the transverse colon.

INTERVENTIONS

A needle in the duodenum and 5 in the colon were removed by endoscopy. The needle stuck in the liver from the stomach was not visible inside the stomach and was successfully removed by laparoscopy a few days later.

OUTCOMES

The patient was able to tolerate an oral diet and was discharged on postoperative day 4 without any complications.

LESSONS

Developing a treatment plan in cases of multiple sharp FB may be difficult. A multidisciplinary team of endoscopists and surgeons is needed to determine the best possible treatment plan. This experience illustrates the importance of the planning of the sequence and method of removal of multiple foreign bodies from the gastrointestinal tract.

Implant-assisted removable prosthetic rehabilitation after distraction osteogenesis in a patient with ameloblastoma recurrence: A case report

INTRODUCTION

A resected mandibular edentulous ridge resulting from an ameloblastoma and marginal mandibulectomy is a restorative challenge. To maintain oral hygiene, recurrent examinations, and for long-term maintenance, a removable dental prosthesis is preferred to an implant-supported fixed dental prosthesis.

PATIENT CONCERNS

A 28-year-old Asian man was referred for evaluation of a radiolucent area on the right side of the mandible. The right mandibular area had increasingly enlarged over a period of ≥5 months. Marginal resection and inferior alveolar nerve repositioning of the mandible were performed by oral surgeons, followed by reconstruction of the resected mandible with distraction osteogenesis. After 6 years, the patient presented with swelling of the same area.

DIAGNOSIS

Histopathological examination revealed recurrence of benign ameloblastoma in the mandible. After mass excision of the recurrent benign tumor, dental implants were installed. To aid with recurrent examinations and oral hygiene maintenance, a treatment plan using implant-assisted removable dental prosthesis, instead of a fixed prosthesis, was formulated.

INTERVENTIONS

The edentulous area was rehabilitated with a tooth- and implant-assisted removable partial denture. Due to the insufficient intermaxillary clearance, the removable prosthesis was designed in such a manner that retention, support, and stability could be ensured by separate components.

OUTCOMES

The tooth- and implant-assisted removable partial denture showed satisfactory function and esthetics. No complications were observed in the dental prosthesis and supporting tissues during the 3-year follow-up period.

CONCLUSION

In recurrent ameloblastoma cases, a removable dental prosthesis may be an effective treatment option for oral rehabilitation. The type of denture design used in this study is novel for implant-assisted removable partial denture rehabilitation.

4-Dimensional computed tomography analysis of clinical target volume displacement in adjuvant radiation of patients with gastric cancer and its implication on radiotherapy

The present study aimed to accurately measure the displacement magnitude of the radiotherapy subsite target due to respiration, and to evaluate its implication on 4-dimensional computed tomography (4D-CT) in adjuvant radiation of gastric cancer. To investigate this, 10 patients with gastric cancer receiving adjuvant radiotherapy were enrolled. 4D-CT scans were performed on all patients and respiratory signals were recorded simultaneously. The clinical target volume (CTV) and 7 regions of interest (ROIs) were delineated in all phases of the CT imaging. The displacements of all ROIs in the cephalic-caudal, anterior-posterior and left-right directions were measured and analyzed. Two sets of plans based on planning target volume 3D (PTV_3D) and PTV_4D, were generated for each patient and PTV_3Dcal was calculated by expanding the non-uniform margin on CTV_3D according to the displacement analysis data. The dosimetric parameters and target volumes of the 3 radiotherapy treatment plans were compared. The displacement of the various ROIs varied widely. The mean PTV_4D was smaller than the PTV_3D and PTV_3Dcal. Compared with Plan_3D, Plan_4D reduced the mean dose of radiation to the liver and left kidney by 23.2 and 43.5%, respectively. The liver volume receiving ≥30 Gy and the left kidney volume receiving ≥20 Gy were decreased by 10.8 and 29.7%, respectively. No differences were observed in the PTV coverage and protection of organs at risk (OARs) between Plan_3Dcal and Plan_4D. In conclusion, the breathing-induced displacement patterns of the subsite targets in patients with gastric cancer vary. The individualized CTV margins of expansion based on 4D-CT lead to a decrease PTV and radiation dose to OARs. The non-uniform margins in various directions should be considered as areas for further investigation.

Ultrasonographic changes in the liver tumors as indicators of adequate tumor coverage with electric field for effective electrochemotherapy

Background

The aim of the study was to characterize ultrasonographic (US) findings during and after electrochem-otherapy of liver tumors to determine the actual ablation zone and to verify the coverage of the treated tumor with a sufficiently strong electric field for effective electrochemotherapy.

Patients and methods

US findings from two representative patients that describe immediate and delayed tumor changes after electrochemotherapy of colorectal liver metastases are presented.

Results

The US findings were interrelated with magnetic resonance imaging (MRI). Electrochemotherapy-treated tumors were exposed to electric pulses based on computational treatment planning. The US findings indicate immediate appearance of hyperechogenic microbubbles along the electrode tracks. Within minutes, the tumors became evenly hyperechogenic, and simultaneously, an oedematous rim was formed presenting as a hypoechogenic formation which persisted for several hours after treatment. The US findings overlapped with computed electric field distribution in the treated tissue, indicating adequate coverage of tumors with sufficiently strong electric field, which may predict an effective treatment outcome.

Conclusions

US provides a tool for assessment of appropriate electrode insertion for intraoperative electrochemo-therapy of liver tumors and assessment of the appropriate coverage of a tumor with a sufficiently strong electric field and can serve as predictor of the response of tumors.

Root Development of Permanent Incisors and Mandibular Molars in Correlation with Treatment Plan

BACKGROUND

The incisors and molars play a major role in the formation and function of permanent dentition. Much research has been devoted to investigating the eruption of teeth and their root development.

AIM

To study the root development of permanent incisors and mandibular molars in correlation with treatment plan and proper treatment protocols.

MATERIALS AND METHODS

The Demirjian's method was used to assess the root development of incisors and mandibular molars in children between 7 and 12 years old.

RESULTS

In 7-year-old children most of the lower first mandibular molars (76%) had complete root length, but open apices. Eighty-two percent of the roots of the first mandibular molars of the 8-year-old children and 54% of these molars of the 9-year-old children were with open apices. The first mandibular molars had incomplete roots in the 10-year-olds (6%) and even in the 11-year-old children (4%). We detected Stage E in 32% of the 10-year-olds and in 24% of the 11-year-old children. Even in 12-year-old children we found Stage E in 4% of them from their panoramic X-rays. We detected complete root development in all of the children at the age of 12.

CONCLUSIONS

Dental practitioners have to wait until the age of 10, 11 and even 12 to extract the first molars, when the furcation is formed. Proper clinical examination and diagnostic radiographs should be done before the beginning of the treatment of molars and incisors at the age between 7 and 12.

Periodontal Diagnosis and Treatment Planning Among Indiana Dental Faculty, Periodontists, and General Practice Dentists: A Multi-Group Comparison

Diagnosis and treatment planning for periodontal disease are fraught with challenges because of the complex and multifactorial nature of the disease as well as the inherent variability in interpretation of clinical findings. It is important for all practitioners to be accurate and consistent in formulating diagnoses based on the American Academy of Periodontology classification guidelines and to implement treatment plans to adequately address patients' needs. The aim of this study was to compare diagnoses and treatment plans among four groups of participants: full-time and part-time periodontology faculty at Indiana University School of Dentistry (IUSD), full-time and part-time IUSD general practice faculty, full-time periodontists in private practice, and full-time general practitioners in private practice. The study, conducted September 2016 to February 2017, also sought to determine if the calibrated participants had more correct diagnoses and treatment plans than those who had not received calibration training. Each of the four groups had 20 participants each. Participants evaluated ten de-identified case records and selected a diagnosis and treatment plan for each case. In the results, the 20 IUSD periodontal faculty members, most of whom had participated in calibration sessions, had overall better agreement and more correct responses for diagnoses and treatment plans than the IUSD general practice faculty members, private practice general practitioners, and private practice periodontists (only one of those 60 participants had participated in calibration sessions). The results supported the notion that periodic calibration is needed to standardize faculty criteria, facilitate better agreement and accuracy, and enhance consistency in the use of clinical criteria during training for dental students and in practice.

Evaluation of Hybrid Arc and Volumetric-Modulated Arc Therapy Treatment Plans for Fractionated Stereotactic Intracranial Radiotherapy

Purpose:

The study was aimed to compare hybrid arc and volumetric-modulated arc therapy treatment plans for fractionated stereotactic radiotherapy of brain tumors.

Methods:

Treatment plans of 22 patients were studied. Hybrid arc and volumetric-modulated arc therapy plans were generated using Brainlab iPlanDose and Varian Eclipse treatment planning systems, respectively, with 6 MV photon beams on a Varian TrueBeam STx linear accelerator (Palo Alto, CA). Prescription dose was 54 Gy. The fractionation was 1.8 Gy per fraction and 30 fractions in total, or 2 Gy per fraction and 27 fractions in total. Planning target volume ranged from 2.4 to 28.6 cm³. Dose conformity index, gradient index, homogeneity index, and maximum doses in organs at risk were compared. Wilcoxon signed rank test was used to determine statistical significance in paired comparison.

Results:

Conformity indexes of hybrid arc and volumetric-modulated arc therapy plans are 1.10 ± 0.10 and 1.14 ± 0.07, respectively (P = .4); gradient indexes are 5.02 ± 1.20 and 5.64 ± 1.28, respectively (P = .0001); homogeneity indexes are 1.02 ± 0.01 and 1.05 ± 0.01, respectively (P = .0001); brainstem maximum doses are 53.87 ± 1.63 Gy and 54.06 ± 3.17 Gy, respectively (P = .1); and optic chiasm maximum doses are 53.86 ± 1.28 Gy and 53.95 ± 1.81, respectively (P = .4). The monitor unit efficiencies of hybrid arc and volumetric-modulated arc therapy plans are 2.57 ± 0.25 MU/cGy and 2.68 ± 0.24 MU/cGy, respectively (P = .2). The differences of conformity index, gradient index, and homogeneity index between hybrid arc and volumetric-modulated arc therapy plans are small: 0.08 ± 0.05, 0.65 ± 0.46, and 0.02 ± 0.01, respectively. The maximum doses in organs at risks are similar between hybrid arc and volumetric-modulated arc therapy plans. Hybrid arc and volumetric-modulated arc therapy plans, which have similar monitor unit efficiencies, present similar dosimetric results in the fractionated intracranial radiotherapy.

Racial disparities in family-provider interactions for pediatric asthma care

OBJECTIVE

Black and Latino children experience significantly worse asthma morbidity than their white peers for multifactorial reasons. This study investigated differences in family-provider interactions for pediatric asthma, based on race/ethnicity.

METHODS

This was a cross-sectional study of parent surveys of asthmatic children within the Population-Based Effectiveness in Asthma and Lung Diseases Network. Our study population comprised 647 parents with survey response data. Data on self-reported race/ethnicity of the child were collected from parents of the children with asthma. Outcomes studied were responses to the questions about family-provider interactions in the previous 12 months: (1) number of visits with asthma provider; (2) number of times provider reviewed asthma medications with patient/family; (3) review of a written asthma treatment plan with provider; and (4) preferences about making asthma decisions.

RESULTS

In multivariate adjusted analyses controlling for asthma control and other co-morbidities, black children had fewer visits in the previous 12 months for asthma than white children: OR 0.63 (95% CI 0.40, 0.99). Additionally, black children were less likely to have a written asthma treatment plan given/reviewed by a provider than their white peers, OR 0.44 (95% CI 0.26, 0.75). There were no significant differences by race in preferences about asthma decision-making nor in the frequency of asthma medication review.

CONCLUSION

Black children with asthma have fewer visits with their providers and are less likely to have a written asthma treatment plan than white children. Asthma providers could focus on improving these specific family-provider interactions in minority children.

Dosimetric differences in flattened and flattening filter-free beam treatment plans

This study investigated the dosimetric differences in treatment plans from flattened and flattening filter-free (FFF) beams from the TrueBeam System. A total of 104 treatment plans with static (sliding window) intensity-modulated radiotherapy beams and volumetric-modulated arc therapy (VMAT) beams were generated for 15 patients involving three cancer sites. In general, the FFF beam provides similar target coverage as the flattened beam with improved dose sparing to organ-at-risk (OAR). Among all three cancer sites, the head and neck showed more important differences between the flattened beam and FFF beam. The maximum reduction of the FFF beam in the mean dose reached up to 2.82 Gy for larynx in head and neck case. Compared to the 6 MV flattened beam, the 10 MV FFF beam provided improved dose sparing to certain OARs, especially for VMAT cases. Thus, 10 MV FFF beam could be used to improve the treatment plan.

An evaluation of patient's decisions regarding dental prosthetic treatment

Introduction:

For fabricating dental prostheses that meet patients' demands and have good longevity and function, appropriate treatment planning and decision-making are required. Therefore, not only technical skills and clinical judgment of the dentist are needed, but also patients' attitude toward treatment plays a critical role in posttreatment satisfaction.

Aim:

The aim of this study is to investigate the factors affecting decision-making and the selection of dental prosthesis by the patients.

Materials and Methods:

A cross-sectional survey to determine patients' attitudes about replacement of teeth was conducted. This survey was performed with the help of a prevalidated questionnaire, which contained the demographic data of every patient, whether or not they accept the treatment plan proposed by the dentist, and a close-ended multiple choice question stating the reasons cited by them if they decline the proposed treatment plan.

Results:

The data were subjected to statistical analysis by Chi-square test at a significance level of P < 0.05. A relationship between the demographical information such as age, gender, educational status, marital status, and monthly income of each patient and the single best reason opted by them to not undergo the proposed treatment plan was established.

Conclusions:

In the sample of population studied, most of the patients declined the proposed treatment plan and accepted the alternate one. High expenditure is the most common reason for this rejection.

Communication Skills and Decision Making for Elderly Patients With Advanced Kidney Disease: A Guide for Nephrologists

Elderly patients comprise the most rapidly growing population initiating dialysis therapy and may derive particular benefit from comprehensive assessment of geriatric syndromes, coexisting comorbid conditions, and overall prognosis. Palliative care is a philosophy that aims to improve quality of life and assist with treatment decision making for patients with serious illness such as kidney disease. Palliative skills for the nephrology provider can aid in the care of these patients. This review provides nephrology providers with 4 primary palliative care skills to guide treatment decision making: (1) use prognostic tools to identify patients who may benefit from conservative management, (2) disclose prognostic information to patients who may not do well with dialysis therapy, (3) incorporate patient goals and values to outline a treatment plan, and (4) prepare patients and families for transitions and end of life.

Forensic focused treatment planning: a new standard for forensic mental health systems

Almost no literature addresses treatment planning for the forensic psychiatric patient. In the absence of such guidance, recovery-oriented multifocal treatment planning has been imported into forensic mental health systems from community psychiatric settings, despite the fact that conditions of admission and discharge are vastly different for forensic psychiatry inpatients. We propose that instead of focusing on recovery, forensic treatment planning should prioritize forensic outcomes, such as restoration of trial competence or mitigation of violence risk, as the first steps in a continuum of care that eventually leads to the patient's ability to resolve forensic issues and return to the community for recovery-oriented care. Here we offer a model for treatment planning in the forensic setting.

Assessment of the calibration of periodontal diagnosis and treatment planning among dental students at three dental schools

Calibration in diagnosis and treatment planning is difficult to achieve due to variations that exist in clinical interpretation. To determine if dental faculty members are consistent in teaching how to diagnose and treat periodontal disease, variations among dental students can be evaluated. A previous study reported high variability in diagnoses and treatment plans of periodontal cases at Indiana University School of Dentistry. This study aimed to build on that one by extending the research to two additional schools: Marquette University School of Dentistry and West Virginia University School of Dentistry. Diagnosis and treatment planning by 40 third- and fourth-year dental students were assessed at each of the schools. Students were asked to select the diagnosis and treatment plans on a questionnaire pertaining to 11 cases. Their responses were compared using chi-square tests, and multirater kappa statistics were used to assess agreement between classes and between schools. Logistic regression models were used to evaluate the effects of school, class year, prior experience, and GPA/class rank on correct responses. One case had a statistically significant difference in responses between third- and fourth-year dental students. Kappas for school agreement and class agreement were low. The students from Indiana University had higher diagnosis and treatment agreements than the Marquette University students, and the Marquette students fared better than the West Virginia University students. This study can help restructure future periodontal courses for a better understanding of periodontal diagnosis and treatment planning.

Changes in treatment plan for carpal tunnel syndrome based on electrodiagnostic test results

This study evaluated how often the treatment plan for carpal tunnel syndrome (CTS) changed based on electrodiagnostic test results. Secondly, we assessed factors associated with a change in the treatment plan for CTS. One-hundred-and-thirty English-speaking adult patients underwent electrodiagnostic testing in a prospective cohort study. Treatment plan was recorded before and after testing. Treatment plan changed in 25 patients (19%) based on electrodiagnostic test results. The plan for operative treatment before testing decreased significantly after testing (83% versus 72%). The best logistic regression model for no change in treatment plan included a prolonged or non-recordable median distal sensory latency (normal, prolonged, or non-recordable), and explained 24% of the variation. For surgeons that manage CTS on the basis of objective pathophysiology rather than symptoms, electrodiagnostic test results often lead to changes in recommended treatment.

Prosthetic restoration in the single-tooth gap: patient preferences and analysis of the WTP index

OBJECTIVE

The objective of this study was to evaluate the preference of a patients' population, according to the index of willingness to pay (WTP), against two treatments to restore a single-tooth gap: the implant-supported crown (ISC) and the 3-unit fixed partial denture prosthesis (FPDP) on natural teeth.

MATERIALS AND METHODS

Willingness to pay values were recorded on 107 subjects by asking the WTP from a starting bid of €2000 modifiable through monetary increases or decreases (€100). Data were collected through an individually delivered questionnaire. The characteristics of the population and choices made, the median values and WTP associations with socio-demographic parameters (Mann-Whitney and Kruskal-Wallis tests), correlations between variables (chi-square test in contingency tables) and significant parameters for predicting WTP values obtained in a multiple linear regression model were revealed.

RESULTS

The 64% of patients expressed a preference for ISC, while the remaining 36% of the population chose the FPDP. The current therapeutic choice and those carried out in the past were generally in agreement (>70% of cases, P = 0.0001); a relationship was discovered between the anterior and posterior area to the same method of rehabilitation (101 of 107 cases, 94.4%). The WTP median values for ISC were of €3000 and of €2500 in the anterior and posterior areas, respectively. The smallest amount of money has been allocated for FPDP in posterior region (median of €1500). The "importance of oral care" for the patient was a significant predictor, in the regression model analysis, for the estimation of both anterior (P = 0.0003) and posterior (P < 0.0001) WTP values. The "previous therapy" variable reached and was just close to significance in anterior (P = 0.0367) and posterior (P = 0.0511) analyses, respectively.

CONCLUSIONS

Within the limitations of this study, most of the population (64%) surveyed indicated the ISC as a therapeutic solution for the replacement of a single missing tooth, showing a higher WTP index in the anterior area. Among investigated socio-demographic variables, the importance assigned by the patient to oral care appeared to influence WTP values of the rehabilitation, regardless the location of the single gap in the mouth.

Treatment planning in conservative dentistry

A patient attending for treatment of a restorative nature may present for a variety of reasons. The success is built upon careful history taking coupled with a logical progression to diagnosis of the problem that has been presented. Each stage follows on from the preceding one. A fitting treatment plan should be formulated and should involve a holistic approach to what is required.

The quality of life of persons with TBI in the process of a comprehensive rehabilitation program

BACKGROUND

The aim of the research was to evaluate the effectiveness of the phased rehabilitation program in patients after traumatic brain injury, one developed by the authors and controlled by the strategic plan, pertaining to their quality of life compared to patients treated according to a standard, phased rehabilitation program.

MATERIAL/METHODS

The study included 40 patients of post traumatic brain injury treated at the Rehabilitation Clinic of the L. Rydygier Academy of Medical Sciences in Bydgoszcz and the Department of Medical Rehabilitation of the Cracow Rehabilitation Centre. An experimental group included 20 patients rehabilitated by a strategic approach and a control group consisted of 20 patients treated before the introduction of this approach. In assessing the effectiveness of rehabilitation, a structured interview was used with clinical observation and the Battery of Quality of Life Assessment. The study was conducted twice: before and after eight weeks of rehabilitation.

RESULTS

The quality of life of people after brain injury is affected by self-service difficulties, difficulties in meeting the physiological needs and loss of psychophysical comfort, decreased mobility, impaired cognitive functions and executive and social functions. There is no consistency between the stated (subjective) level of quality of life of the patient, and the depth of objectively measured disability resulting from the injury sustained.

CONCLUSIONS

A rehabilitation program controlled by a strategic plan, in collaboration with the patient treated subjectively is more effective in improving the quality of life, since the cooperating patient is more motivated to carry out individually designed goals. A rehabilitation program based on a strategic plan is worthy of recommendation for the treatment and improvement of patients after cranio-cerebral trauma.

Treatment planning study of the 3D dosimetric differences between Co-60 and Ir-192 sources in high dose rate (HDR) brachytherapy for cervix cancer

Purpose

To evaluate whether Co-60 is equivalent to Ir-192 for HDR cervical brachytherapy, through 3D-DVH dose comparisons in standard and optimised plans. Previous studies have only considered 2D dosimetry, point dose comparisons or identical loading. Typical treatment times and economics are considered.

Material and methods

Plans were produced for eight cervix patients using Co-60 and Ir-192 sources, CT imaging and IU/two-channel-ring applicator (Eckert Ziegler BEBIG). The comparison was made under two conditions: (A) identical dwell positions and loading, prescribed to Point A and (B) optimised source dwells, prescribed to HR-CTV. This provided a direct comparison of inherent differences and residual differences under typical clinical plan optimisation. The DVH (target and OAR), ICRU reference points and isodose distributions were compared. Typical treatment times and source replacement costs were compared.

Results

Small differences (p < 0.01) in 3D dosimetry exist when using Co-60 compared to Ir-192, prescribed to Point A with identical loading patterns, particularly 3.3% increase in rectum D2cc. No significant difference was observed in this parameter when prescribing to the HR-CTV using dwell-time optimisation. There was no statistically significant difference in D90 between the two isotopes. Co-60 plans delivered consistently higher V150% (mean +4.4%, p = 0.03) and V400% (mean +11.6%, p < 0.01) compared to Ir-192 in optimised plans. Differences in physical source properties were overwhelmed by geometric effects.

Conclusions

Co-60 may be used as an effective alternative to Ir-192 for HDR cervix brachytherapy, producing similar plans of equivalent D90, but with logistical benefits. There is a small dose increase along the extension of the source axis when using Co-60 compared to Ir-192, leading to small rectal dose increases for identical loading patterns. This can be eliminated by planning optimisation techniques. Such optimisation may also be associated with increases in the overdose volume (V150-V400) with Co-60 compared to Ir-192.

The value of a CT scan compared to plain radiographs for the classification and treatment plan in tibial plateau fractures

This study aimed to evaluate the intra- and interobserver agreement for both fracture classification according to Schatzker and treatment plan of tibial plateau fractures using plain radiographs alone and with computed tomography (CT) scans. The study was carried out prospectively to assess the impact of an advanced radiographic study on the agreement of treatment plan and fracture classification of tibial plateau fractures. Eight experienced observers (six surgeons and two radiologists) classified 15 tibial plateau fractures with plain radiographs and CT scans and set up a treatment plan. Agreement was measured using kappa coefficients. Using plain radiographs alone, the mean interobserver kappa coefficient for classification was 0.47, which decreased to 0.46 after addition of CT scans. Using plain films alone for formulating a treatment plan, the mean interobserver kappa coefficient was 0.40, which decreased to 0.30 after addition of CT scans. The mean intraobserver kappa coefficient for fracture classification using plain radiographs was 0.60, which decreased to 0.57 with addition of CT scans. The mean intraobserver kappa coefficient for treatment plan based on plain radiographs alone was 0.53, which decreased to 0.45 after addition of CT scans. In contrast with other recent publications, there is no increase in inter- and intra-agreement of a CT scan compared to plain radiographs for the classification and treatment plan in tibial plateau fractures. Routine CT scanning of the knee for tibial plateau fractures is not supported by this study.

Radiobiologically based treatment plan evaluation for prostate seed implants

Purpose

Accurate prostate low dose-rate brachytherapy treatment plan evaluation is important for future care decisions. Presently, an evaluation is based on dosimetric quantifiers for the tumor and organs at risk. However, these do not account for effects of varying dose-rate, tumor repopulation and other biological effects. In this work, incorporation of the biological response is used to obtain more clinically relevant treatment plan evaluation.

Material and methods

Eleven patients were evaluated. Each patient received a 145 Gy implant. Iodine-125 seeds were used and the treatment plans were created on the Prowess system. Based on CT images the post-implant plan was created. In the post-plan, the tumor, urethra, bladder and rectum were contoured. The biologically effective dose was used to determine the tumor control probability and the normal tissue complication probabilities for the urethra, bladder, rectum and surrounding tissue.

Results

The average tumor control probability and complication probabilities for the urethra, bladder, rectum and surrounding tissue were 99%, 29%, 0%, 12% and 6%, respectively. These measures provide a simpler means for evaluation and since they include radiobiological factors, they provide more reliable estimation of the treatment outcome. 

Conclusions

The goal of this work was to create more clinically relevant prostate seed-implant evaluation by incorporating radiobiological measures. This resulted in a simpler descriptor of treatment plan quality and was consistent with patient outcomes.

Nanoparticle based cancer treatment: can delivered dose and biological dose be reliably modeled and quantified?

Essential developments in the reliable and effective use of heat in medicine include: 1) the ability to model energy deposition and the resulting thermal distribution and tissue damage (Arrhenius models) over time in 3D, 2) the development of non-invasive thermometry and imaging for tissue damage monitoring, and 3) the development of clinically relevant algorithms for accurate prediction of the biological effect resulting from a delivered thermal dose in mammalian cells, tissues, and organs. The accuracy and usefulness of this information varies with the type of thermal treatment, sensitivity and accuracy of tissue assessment, and volume, shape, and heterogeneity of the tumor target and normal tissue. That said, without the development of an algorithm that has allowed the comparison and prediction of the effects of hyperthermia in a wide variety of tumor and normal tissues and settings (cumulative equivalent minutes/ CEM), hyperthermia would never have achieved clinical relevance. A new hyperthermia technology, magnetic nanoparticle-based hyperthermia (mNPH), has distinct advantages over the previous techniques: the ability to target the heat to individual cancer cells (with a nontoxic nanoparticle), and to excite the nanoparticles noninvasively with a non-injurious magnetic field, thus sparing associated normal cells and greatly improving the therapeutic ratio. As such, this modality has great potential as a primary and adjuvant cancer therapy. Although the targeted and safe nature of the noninvasive external activation (hysteretic heating) are a tremendous asset, the large number of therapy based variables and the lack of an accurate and useful method for predicting, assessing and quantifying mNP dose and treatment effect is a major obstacle to moving the technology into routine clinical practice. Among other parameters, mNPH will require the accurate determination of specific nanoparticle heating capability, the total nanoparticle content and biodistribution in the target cells/tissue, and an effective and matching alternating magnetic field (AMF) for optimal and safe excitation of the nanoparticles. Our initial studies have shown that appropriately delivered and targeted nanoparticles are capable of achieving effective tumor cytotoxicity at measured thermal doses significantly less than the understood thermal dose values necessary to achieve equivalent treatment effects using conventional heat delivery techniques. Therefore conventional CEM based thermal dose - tissues effect relationships will not hold for mNPH. The goal of this effort is to provide a platform for determining the biological and physical parameters that will be necessary for accurately planning and performing safe and effective mNPH, creating a new, viable primary or adjuvant cancer therapy.

Dosimetric analysis of modulated and hybrid arcs in stereotactic radiosurgery

PURPOSE

Forward-planned conformal arcs (termed dynamic arcs in the BrainLab iPlan system) have been routinely used in cranial stereotactic radiosurgery (SRS) for many yeras. This study compares dosimetric parameters of the newer, inversely-planned volumetric modulated arc therapy (VMAT) and VMAT-conformal hybrid plans with conformal arc plans. In the hybrid plans, various numbers of conformal arcs in a conformal plan are replaced with VMAT arcs.

METHODS

Ten brain cancer cases previously treated on a Novalis accelerator for frameless cranial stereotactic radiosurgery using conformal arcs generated by BrainLab iPlan treatment planning system were retrospectively studied with various numbers of VMAT arcs replacing the conformal arcs. Pure VMAT plans of different numbers of arcs were also generated using the same angle and arc length setup for all or part of the conformal arcs and compared with both the original and hybrid plans. Pinnacle version 9.0 was used for treatment plan generation. SmartArc was used for the VMAT planning for a Novalis accelerator. The conformity index (CI), defined as the ratio of the isodose volume to the isodose covered target volume, gradient index (GI), defined as the ratio of the 50% isodose volume (V₅₀) to the 100% isodose volume, volume covered by 12 Gy isodose (V₁₂), mean dose and standard deviation of dose in target were studied.

RESULTS

With one of the conformal arcs replaced with a VMAT arc of the same weighting and geometric setup, the average CI with one standard deviation was improved from 1.35 ± 0.18 to 1.29 ± 0.15 (p-value 0.03), while the average GI degraded from 3.8 ± 1.0 to 4.9 ± 1.5 (p-value < 0.01). The degraded GI in the VMAT plans is due to the absence of beam margin limit in SmartArc planning. Pure VMAT plans usually demonstrated better CI values than the hybrid and conformal arc plans when the number of arcs was greater than 2. The GI value was improved with increasing number of arcs in VMAT plans. For target volumes greater than 1 cc, VMAT plans demonstrated improved CI and smaller V₅₀ and V₁₂ than that in conformal arc plans. Better dose fall-off in normal tissue in VMAT plans is accompanied with higher dose heterogeneity in the target volume.

CONCLUSION

VMAT and conformal-VMAT hybrid plans usually offer better target conformity. The dose fall-off in normal tissue is also better in VMAT plans when the number of arcs is greater than 3 and target volume is greater than 1 cc, but compromise the dose homogeneity in target volumes. VMAT plans are the best option for targets that are greater than 1 cc for cranial radiosurgery treatments, while for very small targets, conformal arc technique may still be the better choice based on data of dose fall-off in normal tissues.

Radiobiological evaluation of the influence of dwell time modulation restriction in HIPO optimized HDR prostate brachytherapy implants

Purpose

One of the issues that a planner is often facing in HDR brachytherapy is the selective existence of high dose volumes around some few dominating dwell positions. If there is no information available about its necessity (e.g. location of a GTV), then it is reasonable to investigate whether this can be avoided. This effect can be eliminated by limiting the free modulation of the dwell times. HIPO, an inverse treatment plan optimization algorithm, offers this option. In treatment plan optimization there are various methods that try to regularize the variation of dose non-uniformity using purely dosimetric measures. However, although these methods can help in finding a good dose distribution they do not provide any information regarding the expected treatment outcome as described by radiobiology based indices.

Material and methods

The quality of 12 clinical HDR brachytherapy implants for prostate utilizing HIPO and modulation restriction (MR) has been compared to alternative plans with HIPO and free modulation (without MR). All common dose-volume indices for the prostate and the organs at risk have been considered together with radiobiological measures. The clinical effectiveness of the different dose distributions was investigated by calculating the response probabilities of the tumors and organs-at-risk (OARs) involved in these prostate cancer cases. The radiobiological models used are the Poisson and the relative seriality models. Furthermore, the complication-free tumor control probability, P₊ and the biologically effective uniform dose (D¯¯) were used for treatment plan evaluation and comparison.

Results

Our results demonstrate that HIPO with a modulation restriction value of 0.1-0.2 delivers high quality plans which are practically equivalent to those achieved with free modulation regarding the clinically used dosimetric indices. In the comparison, many of the dosimetric and radiobiological indices showed significantly different results. The modulation restricted clinical plans demonstrated a lower total dwell time by a mean of 1.4% that was proved to be statistically significant (p = 0.002). The HIPO with MR treatment plans produced a higher P₊ by 0.5%, which stemmed from a better sparing of the OARs by 1.0%.

Conclusions

Both the dosimetric and radiobiological comparison shows that the modulation restricted optimization gives on average similar results with the optimization without modulation restriction in the examined clinical cases. Concluding, based on our results, it appears that the applied dwell time regularization technique is expected to introduce a minor improvement in the effectiveness of the optimized HDR dose distributions.

An approach to difficult clinical problems

Often physicians use an intuitive approach to treatment, based on years of clinical experience and discussion with colleagues. However, some complex clinical problems in family practice require a formal, structured, rational apprach to decision making. This article describes how clinical decision analysis was used in a family practice unit, for a patient with a suspected loose hip prosthesis. The use of probabilities and working through a 'decision tree' assisted in the formation of a successful treatment plan.