Treatment Planning Delivery Research Articles

PHSOR06 Presentation Time: 12:55 PM: Medical Physics Residents Have Spoken: They Want More Brachytherapy Training Opportunities

<h3>Purpose</h3> To evaluate the current status of brachytherapy (BT) training received by medical physics residents (MPR) in North America by surveying residents currently enrolled in, and recently graduated from CAMPEP-accredited residency programs. The documented decline in the use of BT may result in reduced training opportunities. This survey aims to identify the current strengths and areas for improvement in MPR BT training. <h3>Materials and Methods</h3> A survey consisting of 26 questions was developed to collect data in five areas: (1) training program demographics; (2) didactic and practical training methods; (3) caseload and confidence levels of residents for various treatment modalities (including HDR, LDR, IORT, TARE, and Radiopharm), disease sites, and clinical tasks (including treatment planning, plan checks, and treatment delivery); (4) level of interest in performing BT post-residency; and (5) level of interest in receiving additional BT training opportunities. The survey was reviewed by several AAPM committees and was approved by the Executive Committee. The survey was distributed to residents currently enrolled in, and graduates within 5 years of residency training. <h3>Results</h3> The response rate was 23% (186 responses / 796 recipients). 60% of respondents had completed their training and 40% were currently enrolled in a program. Only 53% of currently enrolled residents had completed the BT training required by their program's curriculum. Therefore, to accurately depict the BT training experience of MPR, data is presented only from those having completed training. The majority of residents (94%) received three months or more of dedicated BT training and 96% believed it was important to learn BT during residency. Further, MPR (88%) believed their program director valued their BT education. A very notable finding was that only 49% of residents felt confident enough to perform BT for all sites treated at their training institution upon completion of their training program. HDR gynecological procedures were the only modality and disease site combination out of 14 modality and site combinations with more than 50% of individuals reporting feeling "very confident" at the completion of their training. MPR indicated an increase in caseload (29%) would most improve their confidence level followed closely by increased case involvement (25%). Few (11%) believed additional didactic training would improve their confidence level. The majority (73%) of MPR enjoyed their BT rotation more than other rotations. Most wanted to (72%) and would be (67%) performing BT at their first position post-residency. Additional training opportunities were desired by the majority (64%) of MPR and 10% were unsure. This subset of individuals reported interest in selecting BT as an elective rotation (66%), performing a BT rotation at another institution with a higher caseload (76%), and completing a BT fellowship post-residency (63%, Figure 1). The interest level of MPR in pursuing a fellowship was greater than the 2% reported by Marcrom et al. (IJROBP, 2018) for radiation oncology residents. <h3>Conclusions</h3> MPR believe BT training during residency is important and the majority of MPR did not achieve their desired level of confidence in performing BT procedures at the completion of their residency training. Caseload was identified as the primary factor contributing to low confidence levels. The majority indicated they wanted to (and would be) performing BT post-residency, and desired additional training opportunities. Strong interest was expressed in pursuing (1) an additional rotation, (2) rotations through outside training facilities, and (3) optional fellowships. These opportunities are available to radiation oncology residents through the ABS-sponsored 300-in-10 program. There is a demonstrated need and interest for an equivalent program for medical physicists.

Chemotherapy-Induced Toxicities and Their Associations with Clinical and Non-Clinical Factors among Breast Cancer Patients in Vietnam.

Understanding the burden and factors related to chemotherapy-induced toxicity is important in treatment planning for breast cancer patients. We conducted a prospective study among 396 newly diagnosed and chemotherapy-treated breast cancer patients recruited in two major cancer hospitals in northern Vietnam. Toxicities were captured through medical chart reviews and patient self-reports and graded using NCI CTCAE classification. Associations for sociodemographic and clinical factors with chemotherapy-induced toxicities during first-line chemotherapy were evaluated via multivariable logistic regression. Severe (i.e., grade ≥ 3) hematological (38.6%), and gastrointestinal (12.9%) toxicities were common. A pre-existing nephrological condition was significantly associated with the risk of severe hematological toxicity with adjusted odds ratios (OR) and 95% confidence intervals (CIs) of 2.30 (1.32-4.01). Patients living in rural areas had a lower risk of severe hematological toxicity (OR = 0.48; 95% CI, 0.30-0.77). Patients diagnosed with stage II and stage III-IV had a lower risk of severe gastrointestinal toxicity with ORs and 95% CIs of 0.26 (0.12-0.59) and 0.47 (0.20-1.10), respectively. Triple-negative/basal-like subtype was associated with a higher risk of severe hematological (OR = 3.15; 95% CI, 1.56-6.34) and gastrointestinal toxicities (OR = 3.60; 95% CI, 1.45-8.95) comparing to hormone receptor (HR)-positive HER2-negative subtype. Further research investigating underlying mechanisms would facilitate the development and delivery of personalized treatment and care plans.

Proton Beam Therapy for Pancreas Cancer: PTCOG Consensus Recommendations for Simulation, Treatment Planning and Treatment Delivery

<h3>Purpose/Objective(s)</h3> The proximity of gastrointestinal (GI) luminal organs-at-risk (OAR) poses a challenge to radiotherapy (RT) for pancreas cancer (PC). Proton beam therapy (PBT) may reduce toxicities compared to photon therapy by avoiding radiation exposure to large volumes of the abdomen while enabling safe dose escalation. The purpose of this study is to create recommendations for the safe treatment of PC with PBT. <h3>Materials/Methods</h3> The Particle Therapy Co-Operative Group (PTCOG) Gastrointestinal Subcommittee consisting of radiation oncologists and medical physicists with extensive clinical experience using PBT for GI cancers developed expert consensus recommendations for PC describing simulation, treatment planning, and treatment delivery through their collective experience and systematic review of the literature. <h3>Results</h3> The following general recommendations were established: <i>Simulation</i>: Indexed immobilization is recommended to reduce patient setup variability. Patients should be supine with arms above the head. Additional imaging such as PET/CT and/or MRI should be considered for target delineation. Contrast CT is recommended but should be performed subsequent to the planning CT at simulation to avoid the need to override Hounsfield Units. Dual-energy CT should be used, if available, to reduce CT-related proton range uncertainties. Motion management strategies are imperative, including 4DCT for motion accounting and breath-hold, or other techniques for motion mitigation. Patients should also have an empty stomach. <i>Treatment planning</i>: Beam angle selection is critical. Posterior and lateral beam angles are preferred to minimize the dosimetric impact of variable anatomy such as bowel. Robust optimization should be used for pencil beam scanning (PBS) techniques. When treating with PBS, single-field optimization (SFO) is often preferrable to increase robustness. If OAR constraints cannot be met with SFO, then multi-field optimization may be used. Higher linear energy transfer (LET) at the end of range should be considered in the context of sparing distal OARs. Increased beam angle separation should be used to reduce skin dose and mitigate the impact of higher LET. <i>Treatment delivery</i>: Volumetric image guidance, where available, should be used daily. Verification CT scans should be acquired <i>ad-hoc</i> as deemed necessary, or at least every other week, to assess the dosimetric impact of changes in anatomy, such as weight changes and variation in bowel gas and gastric filling. Adaptive re-planning should be performed as required. <h3>Conclusion</h3> The PTCOG Gastrointestinal Subcommittee has developed PBT expert consensus recommendations for PC. These recommendations enable PBT facilities to develop protocols for safe dose escalation studies.

Clinical Outcomes of Stereotactic Body Radiation Therapy across Treatment Platforms Employing Varied Approaches to Respiratory Management at a Single Institution

<h3>Purpose/Objective(s)</h3> Stereotactic Body Radiation Therapy (SBRT) has been the standard of care for early-stage non-small cell lung cancer patients who do not undergo surgery since soon after the publication of RTOG 0236. Since then, various linear accelerator platforms have been employed with a variety of approaches to respiratory management, treatment planning and treatment delivery. Comparisons of local control and survival end points using a variety of treatment platforms in addition to respiratory management techniques have not been reported. Here, we present the results of our analysis of clinical outcomes at a single institution across multiple treatment platforms representative of the available technology since the widespread adoption of SBRT for early-stage lung cancer. <h3>Materials/Methods</h3> Consecutive patients who underwent SBRT for early-stage lung cancer between 2011 and 2018 at a single institution were retrospectively analyzed. Treatments were planned and delivered with standardized simulation, dose and fractionation per institutional guidelines. Overall Survival (OS), Local Control (LC), Distant Metastasis Free Survival (DMFS), and Progression Free Survival (PFS) were calculated for the entire cohort. Log rank comparisons of all survival endpoints were then calculated by treatment platform: stereoscopic orthogonal kV x-ray localization with conventional Linac (Linac1), volumetric cone beam CT localization with conventional Linac (Linac2), and megavoltage CT with helical tomotherapy (Linac3). Comparisons were also performed by respiratory management technique: free breath (FB), breath hold (BH) or end expiration respiratory gating (RG). <h3>Results</h3> A total of 240 patients were included in the analysis. Treatment platform utilization was well balanced in the group: 28% on Linac1, 32% on Linac2, and 40% on Linac3. The majority of patients were treated with FB, 72%. Median OS for the entire cohort was 50 months. The crude rate of local recurrence was 7%. Kaplan-Meier estimate of LC for the entire cohort was 94% at 3 years. The median time to local recurrence was not reached. LC was not impacted by treatment platform, p = 0.897, or respiratory management technique, p = 0.623. Comparisons by treatment platform and respiratory management technique revealed no significant differences in OS, DMFS, and PFS. <h3>Conclusion</h3> Irrespective of treatment platform or approach to respiratory management, SBRT remains highly effective at providing durable LC in patients with early-stage lung cancer. Differences in treatment delivery platform and respiratory management do not significantly influence other disease control and survival outcomes.

IMRT and SBRT Treatment Planning Study for the First Clinical Biology-Guided Radiotherapy System

<h3>Purpose/Objective(s)</h3> The first clinical biology-guided radiation therapy (BgRT) system – RefleXion^TM X1 - was installed and commissioned for clinical use at our institution. This study aimed at evaluating the treatment plan quality and delivery efficiency for IMRT/SBRT cases without PET-guidance. <h3>Materials/Methods</h3> Forty-two patient plans across six cancer sites (conventionally-fractionated lung, head and neck, anus, prostate, brain, and lung SBRT) planned with the Eclipse^TM treatment planning system (TPS) and treated with either a TrueBeam® or Trilogy® were selected for this retrospective study. For each Eclipse VMAT plan, two corresponding plans were generated on the X1 TPS with 10 mm jaws (X1 10mm) and 20 mm jaws (X1 20mm) using our institutional planning constraints. All clinically relevant metrics in this study, including PTV D95%, PTV D2%, Conformity Index (CI), R50, organs- at-risk (OAR) constraints, and beam-on time were analyzed and compared between 126 VMAT and RefleXion plans using paired t-tests. <h3>Results</h3> All but three planning metrics were either equivalent or superior for the X1 10mm plans as compared to the Eclipse VMAT plans across all planning sites investigated. The Eclipse VMAT and X1 10mm plans generally achieved superior plan quality and sharper dose fall-off superior/inferior to targets as compared to the X1 20mm plans, however, the X1 20mm plans were still considered acceptable for treatment. Strong correlation was observed between the TPS-calculated beam-on time and PTV length in the superior-inferior direction for the X1 10mm (<i>R</i>² = 0<i>.</i>87) and X1 20mm (<i>R</i>² = 0<i>.</i>85) plans. On average, the required beam-on time increased by a factor of 1.6 across all sites for X1 10mm compared to X1 20mm plans. <h3>Conclusion</h3> Clinically acceptable IMRT/SBRT treatment plans were generated with the X1 TPS for both the 10 mm and 20 mm jaw settings. The X1 10mm plans were equivalent or superior to the Eclipse VMAT plans, however the beam-on times were longer.

70 Gy? IC RU Sure?

<h3>Purpose/Objective(s)</h3> Radiation dose prescription reporting standards are defined in ICRU 83. However, individual centers worldwide may have variable interpretations of this standard. Here, we assess head and neck prescription implementation in multiple large H&N cancer centers. <h3>Materials/Methods</h3> All oropharyngeal cancer patients receiving curative radiotherapy from Jan 2017 to Dec 2019 were included. The prescription dose for each patient was scaled to 70Gy to ensure direct compatibilities of dosimetric data. GTV, CTV, PTV DVH data from two centers in Europe and one center in North America were evaluated using graphical visualization and DVH statistics. <h3>Results</h3> A total of 707 patients from the three centers were evaluated. Mean dose varied by 1.32Gy,1.30Gy, 1.01 Gy between the centers for GTV, CTV, and PTV respectively and these differences were statistically significant (p<0.001). The near-minimum dose (D98%) varied by 1.31Gy, 1.50Gy, 1.26 Gy between the centers for GTV, CTV, and PTV respectively (p<0.001). The scatter plot of the individual patients' mean and near-minimum dose showed distinct clusters linked directly to the three centers local interpretation of dose prescription. <h3>Conclusion</h3> The current interpretation of prescription definition standards results in statistically significant systematic dose variations between large centers treating the same class of patients. Systematic variations in delivered dose complicates interpretation of individual center's outcomes as well as interpretation of multicenter trials addressing important dose-related questions (e.g., dose de-escalation). The current technical capabilities both in treatment planning and dose delivery could allow for a more constrained dose prescription to help improve the radiotherapy quality and conformity.

Understanding factors that affect older people’s capacity to manage the workload associated with living with cancer

Background Many older people who are living with cancer do so with concurrent complex health and social issues. Assessment and treatment planning for cancer often focus primarily on the disease, missing opportunities to identify and address these significant wider concerns.Aim To gain an understanding of the factors that can increase or reduce older people’s capacity to manage the workload associated with the self-management of cancer and other conditions.Method Secondary analysis of questionnaire data comprising 224 responses to 19 structured items covering health and daily living issues and analysis of free-text responses, focusing on factors affecting an individual’s capacity to manage their workload associated with living with cancer.Results Reduced physical function affected many respondents’ capacity to manage their health and other responsibilities and to live their everyday lives. Many respondents were concerned about continuing to care for those dependent on them and identified factors that enhanced their capacity in their social network and from healthcare professionals. Organisational factors such as scheduled appointments, transport and availability of parking further affected respondents’ capacity.Conclusion There is an implicit need to identify and address the main factors that can increase an individual’s capacity to manage their health and to support the delivery of person-centred cancer treatment and care plans.

Insensitivity of machine log files to MLC leaf backlash and effect of MLC backlash on clinical dynamic MLC motion: An experimental investigation.

PurposeMulti‐leaf‐collimator (MLC) leaf position accuracy is important for accurate dynamic radiotherapy treatment plan delivery. Machine log files have become widely utilized for quality assurance (QA) of such dynamic treatments. The primary aim is to test the sensitivity of machine log files in comparison to electronic portal imaging device (EPID)‐based measurements to MLC position errors caused by leaf backlash. The secondary aim is to investigate the effect of MLC leaf backlash on MLC leaf motion during clinical dynamic plan delivery.MethodsThe sensitivity of machine log files and two EPID‐based measurements were assessed via a controlled experiment, whereby the length of the “T” section of a series of 12 MLC leaf T‐nuts in a Varian Millennium MLC for a Trilogy C‐series type linac was reduced by sandpapering the top of the “T” to introduce backlash. The built‐in machine MLC leaf backlash test as well as measurements for two EPID‐based dynamic MLC positional tests along with log files were recorded pre‐ and post‐T‐nut modification. All methods were investigated for sensitivity to the T‐nut change by assessing the effect on measured MLC leaf positions. A reduced version of the experiment was repeated on a TrueBeam type linac with Millennium MLC.ResultsNo significant differences before and after T‐nut modification were detected in any of the log file data. Both EPID methods demonstrated sensitivity to the introduced change at approximately the expected magnitude with a strong dependence observed with gantry angle. EPID‐based data showed MLC positional error in agreement with the micrometer measured T‐nut length change to 0.07 ± 0.05 mm (1 SD) using the departmental routine QA test. Backlash results were consistent between linac types.ConclusionMachine log files appear insensitive to MLC position errors caused by MLC leaf backlash introduced via the T‐nut. The effect of backlash on clinical MLC motions is heavily gantry angle dependent.

Identifying risk characteristics using failure mode and effect analysis for risk management in online magnetic resonance-guided adaptive radiation therapy.

Online magnetic resonance-guided adaptive radiotherapy (MRgART) is a new technology of radiotherapy and requires a new quality control program in many aspects. This study aimed to gain a deeper understanding of risks in online MRgART through the application of failure mode and effect analysis (FMEA) for more enhanced and effective quality assurance (QA) programs. We present an FMEA conducted by a multidisciplinary team with more than two years of experience. A process map describing the whole process of online MRgART was developed and potential failure modes were identified. High-risk failure modes and their potential causes and corrective measures were also identified. Failure modes were classified into three categories, MRgRT, online ART, and conventional RT, to investigate their features. A comparison with previous studies was also conducted to gain a general perspective. In total, 153 failure modes and 49 high risks were identified. Among all failure modes, 51, 63, and 66 were related to MRgRT, online ART, and conventional RT, respectively. The hazardous processes were structure segmentation, treatment planning, and treatment beam delivery. Lists of failure modes identified in this study and previous studies were presented. Based on the results, characteristics and general aspects of the risks were discussed. Exploring the results of the FMEA enhanced our understanding of risk characteristics to improve QA program of online MRgART.

Syntaxin 18 regulates the DNA damage response and epithelial-to-mesenchymal transition to promote radiation resistance of lung cancer

Radiotherapy is an important modality in lung cancer treatment. Despite advances in treatment planning and dose delivery, patient benefit is still limited by in-field relapse and metastatic recurrence. Simultaneous application of cisplatinum-based chemotherapy leads to moderately improved outcomes, thus providing proof-of-concept for radiosensitization strategies in lung cancer. In an unbiased functional genetic screen for radiosensitization targets in lung cancer, we identified syntaxin 18, a protein involved in retrograde vesicular transport between the Golgi apparatus and endoplasmic reticulum, as mediator of radioresistance. Downregulation of endogenous syntaxin 18 specifically reduced clonogenic survival of radioresistant and radiosensitive lung cancer cells following X-radiation. Gene expression programs regulating DNA repair, mitotic checkpoints and mitosis were altered in isogenic cells with reduced syntaxin 18 expression. Functionally, this translated into impaired DNA damage-induced cell cycle checkpoints leading to cell death by mitotic catastrophe. Interestingly, downregulation of syntaxin 18 in lung cancer cells also impaired expression of markers of epithelial-mesenchymal-transition, and reduced migration and invasion capacity. These findings suggest that syntaxin 18 is a key player regulating genes responsible for controlling the growth of the primary tumor as well as metastases upon radiotherapy of lung cancer. They provide a promising lead for biologically rational radiosensitization strategies impacting on radiation-induced cell death as well as metastasis.

Dosimetric feasibility of hippocampal avoidance whole brain radiotherapy with an MRI-guided linear accelerator.

Purpose/Objective(s)Whole brain radiotherapy with hippocampal avoidance (HA‐WBRT) is a technique utilized to treat metastatic brain disease while preserving memory and neurocognitive function. We hypothesized that the treatment planning and delivery of HA‐WBRT plans is feasible with an MRI‐guided linear accelerator (linac) and compared plan results with clinical non‐MRI‐guided C‐Arm linac plans.Materials/MethodsTwelve HA‐WBRT patients treated on a non‐MRI‐guided C‐Arm linac were selected for retrospective analysis. Treatment plans were developed using a 0.35T MRI‐guided linac system for comparison to clinical plans. Treatment planning goals were defined as provided in the Phase II Trial NRG CC001. MRI‐guided radiotherapy (MRgRT) treatment plans were developed by a dosimetrist and compared with clinical plans. quality assurance (QA) plans were generated and delivered on the MRI‐guided linac to a cylindrical diode detector array. Planning target volume (PTV) coverage was normalized to ∼95% to provide a control point for comparison of dose to the organs at risk.ResultsMRgRT plans were deliverable and met all clinical goals. Mean values demonstrated that the clinical plans were less heterogeneous than MRgRT plans with mean PTV V37.5 Gy of 0.00% and 0.03% (p = 0.013), respectively. Average hippocampi maximum doses were 14.19 ± 1.29 Gy and 15.00 ± 1.51 Gy, respectively. The gamma analysis comparing planned and measured doses resulted in a mean of 99.9% ± 0.12% of passing points (3%/2mm criteria). MRgRT plans had an average of 38.33 beams with average total delivery time and beam‐on time of 13.7 (11.2–17.5) min and 4.1 (3.2–5.4) min, respectively. Clinical plan delivery times ranged from 3 to 7 min depending on the number of noncoplanar arcs. Planning time between the clinical and MRgRT plans was comparable.ConclusionThis study demonstrates that HA‐WBRT can be treated using an MRI‐guided linear accelerator with comparable treatment plan quality and delivery accuracy.

Positron Emission Tomography-based Dose Painting Radiation Therapy in a Glioblastoma Rat Model using the Small Animal Radiation Research Platform.

A rat glioblastoma model to mimic chemo-radiation treatment of human glioblastoma in the clinic was previously established. Similar to the clinical treatment, computed tomography (CT) and magnetic resonance imaging (MRI) were combined during the treatment-planning process. Positron emission tomography (PET) imaging was subsequently added to implement sub-volume boosting using a micro-irradiation system. However, combining three imaging modalities (CT, MRI, and PET) using a micro-irradiation system proved to be labor-intensive because multimodal imaging, treatment planning, and dose delivery have to be completed sequentially in the preclinical setting. This also results in a workflow that is more prone to human error. Therefore, a user-friendly algorithm to further optimize preclinical multimodal imaging-based radiation treatment planning was implemented. This software tool was used to evaluate the accuracy and efficiency of dose painting radiation therapy with micro-irradiation by using an in silico study design. The new methodology for dose painting radiation therapy is superior to the previously described method in terms of accuracy, time efficiency, and intra- and inter-user variability. It is also an important step towards the implementation of inverse treatment planning on micro-irradiators, where forward planning is still commonly used, in contrast to clinical systems.

Determination of commissioning criteria for multileaf-collimator, stereotactic radiosurgery treatments on Varian TrueBeam and Edge machines using a novel anthropomorphic phantom.

An anthropomorphic phantom has been developed by Varian Medical Systems for commissioning multileaf‐collimator (MLC), stereotactic radiosurgery (SRS) treatments on Varian TrueBeam and Edge linear accelerators. Northwest Medical Physics Center (NMPC) has collected end‐to‐end data on these machines, at six independent clinical sites, to establish baseline dosimetric and geometric commissioning criteria for SRS measurements with this phantom. The Varian phantom is designed to accommodate four interchangeable target cassettes, each designed for a specific quality assurance function. End‐to‐end measurements utilized the phantom to verify the coincidence of treatment isocenter with a hidden target in a Winston‐Lutz cassette after localization using cone‐beam computed tomography (CBCT). Dose delivery to single target (2 cm) and single‐isocenter, multitarget (2 and 1 cm) geometries was verified using ionization chamber and EBT3 film cassettes. A nominal dose of 16 Gy was prescribed for each plan using a site's standard beam geometry for SRS cases. Measurements were performed with three Millennium and three high‐definition MLC machines at beam energies of 6‐MV and 10‐MV flattening‐filter‐free energies. Each clinical site followed a standardized procedure for phantom simulation, treatment planning, quality assurance, and treatment delivery. All treatment planning and delivery was performed using ARIA oncology information system and Eclipse treatment planning software. The isocenter measurements and irradiated film were analyzed using DoseLab quality assurance software; gamma criteria of 3%/1 mm, 3%/0.5 mm, and 2%/1 mm were applied for film analysis. Based on the data acquired in this work, the recommended commissioning criteria for end‐to‐end SRS measurements with the Varian phantom are as follows: coincidence of treatment isocenter and CBCT‐aligned hidden target < 1 mm, agreement of measured chamber dose with calculated dose ≤ 5%, and film gamma passing > 90% for gamma criteria of 3%/1 mm after DoseLab auto‐registration shifts ≤ 1 mm in any direction.

The role for MRI-guided transurethral ultrasound ablation in the continuum of prostate cancer care.

Prostate cancer continues to have a negative impact on the duration and quality of life for males and their families. MRI is transforming the pathway of prostate cancer detection, diagnosis, staging, and surveillance, backed by multiple Level 1 studies and robust reporting standards. This evolving paradigm of MRI-directed care is now being expanded to include in-bore MRI-guided prostate tissue ablation techniques, which reduce the burden of genitourinary complications associated with standard-of-care treatments, without sacrificing cancer control. The workflow for MRI-guided transurethral ultrasound ablation relies on intraprocedural MRI guidance for treatment planning, automated and physician-monitored treatment delivery, and post-treatment assessment at both immediate and long-term time points. Our early experience has identified several procedure refinements, and aligns with early evidence from prospective clinical studies using transurethral ultrasound ablation for treatment of patients with either primary or recurrent disease. Driven by quantitative real-time imaging, MRI-guided ablative interventions provide rich datasets for developing technical refinements and predictive models that will progressively improve patient outcomes as these novel techniques become part of a new standard-of-care.

Proton Therapy for Prostate Cancer: Challenges and Opportunities.

Simple SummaryReported clinical outcomes of proton therapy (PT) for localized prostate cancer are similar to photon-based external beam radiotherapy. Apparently, the dosimetric advantages of PT have yet to be translated to clinical benefits. The suboptimal clinical outcomes of PT might be attributable to inadequate dose prescription, as indicated by the ASCENDE-RT trial. Moreover, uncertainties involved in the treatment planning and delivery processes, as well as technological limitations in PT treatment systems, may lead to discrepancies between planned doses and actual doses delivered to patients. In this article, we reviewed the current status of PT for prostate cancer and discussed different clinical implementations that could potentially improve the clinical outcome of PT for prostate cancer. Various technological advancements under which uncertainties in dose calculations can be minimized, including MRI-guided PT, dual-energy photon-counting CT and high-resolution Monte Carlo-based treatment planning systems, are highlighted.The dosimetric advantages of proton therapy (PT) treatment plans are demonstrably superior to photon-based external beam radiotherapy (EBRT) for localized prostate cancer, but the reported clinical outcomes are similar. This may be due to inadequate dose prescription, especially in high-risk disease, as indicated by the ASCENDE-RT trial. Alternatively, the lack of clinical benefits with PT may be attributable to improper dose delivery, mainly due to geometric and dosimetric uncertainties during treatment planning, as well as delivery procedures that compromise the dose conformity of treatments. Advanced high-precision PT technologies, and treatment planning and beam delivery techniques are being developed to address these uncertainties. For instance, external magnetic resonance imaging (MRI)-guided patient setup rooms are being developed to improve the accuracy of patient positioning for treatment. In-room MRI-guided patient positioning systems are also being investigated to improve the geometric accuracy of PT. Soon, high-dose rate beam delivery systems will shorten beam delivery time to within one breath hold, minimizing the effects of organ motion and patient movements. Dual-energy photon-counting computed tomography and high-resolution Monte Carlo-based treatment planning systems are available to minimize uncertainties in dose planning calculations. Advanced in-room treatment verification tools such as prompt gamma detector systems will be used to verify the depth of PT. Clinical implementation of these new technologies is expected to improve the accuracy and dose conformity of PT in the treatment of localized prostate cancers, and lead to better clinical outcomes. Improvement in dose conformity may also facilitate dose escalation, improving local control and implementation of hypofractionation treatment schemes to improve patient throughput and make PT more cost effective.

Three discipline collaborative radiation therapy (3DCRT) special debate: FLASH radiotherapy needs ongoing basic and animal research before implementing it to a large clinical scale.

Three discipline collaborative radiation therapy (3DCRT) special debate: FLASH radiotherapy needs ongoing basic and animal research before implementing it to a large clinical scale.

IMRT and SBRT Treatment Planning Study for the First Clinical Biology-Guided Radiotherapy System.

Purpose: The first clinical biology-guided radiation therapy (BgRT) system—RefleXionTM X1—was installed and commissioned for clinical use at our institution. This study aimed at evaluating the treatment plan quality and delivery efficiency for IMRT/SBRT cases without PET guidance. Methods: A total of 42 patient plans across 6 cancer sites (conventionally fractionated lung, head, and neck, anus, prostate, brain, and lung SBRT) planned with the EclipseTM treatment planning system (TPS) and treated with either a TrueBeam® or Trilogy® were selected for this retrospective study. For each Eclipse VMAT plan, 2 corresponding plans were generated on the X1 TPS with 10 mm jaws (X1-10mm) and 20 mm jaws (X1-20mm) using our institutional planning constraints. All clinically relevant metrics in this study, including PTV D95%, PTV D2%, Conformity Index (CI), R50, organs-at-risk (OAR) constraints, and beam-on time were analyzed and compared between 126 VMAT and RefleXion plans using paired t-tests. Results: All but 3 planning metrics were either equivalent or superior for the X1-10mm plans as compared to the Eclipse VMAT plans across all planning sites investigated. The Eclipse VMAT and X1-10mm plans generally achieved superior plan quality and sharper dose fall-off superior/inferior to targets as compared to the X1-20mm plans, however, the X1-20mm plans were still considered acceptable for treatment. On average, the required beam-on time increased by a factor of 1.6 across all sites for X1-10mm compared to X1-20mm plans. Conclusions: Clinically acceptable IMRT/SBRT treatment plans were generated with the X1 TPS for both the 10 mm and 20 mm jaw settings.

Probabilistic risk assessment of radiotherapy application

The recent rapid development and increasing complexity of radiotherapy devices and applications has increased the importance of correct and safe treatment. Risk management is very important in radiotherapy (RT), because incorrect treatment can have serious consequences in terms of mortality or morbidity. However, there are currently few studies on risk analysis in RT. This quantitative and qualitative study of the radiotherapy system (all radiotherapy process) uses the fault tree method, one of the probabilistic risk assessment methods in radiotherapy applications, which is used to devise accident preventive actions. First of all, RT applications were divided into simulation, treatment planning and treatment delivery. For each, work flow charts were determined, and fault trees were created in SAPHIRE (Systems Analysis Programs for Hands-on Integrated Reliability Evaluations) software. Fault probabilities were determined using the expert judgment method. This analysis allowed the identification of the weak points of the system, both qualitatively and quantitatively. The analyzes also revealed that there was a 0.5% occurrence probability of a top event, determined as an incorrect dose or dose distribution in RT. It was determined that the greatest contribution to this probability value was matching error with image guidance, 7.88%. Fault tree analysis (FTA) was found to facilitate a detailed examination of the radiotherapy system. After the risk analysis, the appropriate quality control method for weak points should be determined and implemented for safety management in radiotherapy.

Radiological and nonradiological methods of dental and skeletal age assessment: A narrative review

Age is one of the essential factors which play an important role in every aspect of life. Importance of age determination is related to many fields including treatment planning and drug delivery in pediatric dentistry, orthodontics, forensic sciences, and also in individuals who provide inaccurate details of age as in cases of illegal immigrants and in the corpse of unknown identity. The age estimation methods at different stages of life consist of a physical examination, radiographic examination of the hand bones and cervical vertebrae, and dental examination using two-dimensional and three-dimensional imaging. The different dental age estimation methods used are morphological, biochemical, and radiological methods. These methods have inborn advantages and disadvantages. Other than dental age, skeletal age has also been used to determine a child's development as skeletal maturity is closely related to the craniofacial growth. Correlation of the dental and skeletal ages with the chronological age of children helps clinicians to estimate the growth left in the child and the possible treatment that can be carried out utilizing it. This article critically reviews various dental and skeletal aspects of age estimation from infancy to adulthood with its scope and limitation.

Cancer patients presenting to the emergency department in northwest syria

Emergency departments face a high density of patients as they address many patient groups. Cancer patients constitute a significant proportion of the population presenting to the emergency department for many reasons, including new symptoms, exacerbation of existing problems, treatment complications, and disease progression. This study can be helpful in determining treatment approach, planning, and service delivery. All cancer patients admitted to the emergency department between 1 January 2022 and 31 March 2022 were included in the study. Medical records were retrospectively analyzed from hospital records. A total of 90 patients were included in the study. Data were collected from the patient records by examining the reasons for admission, demographic and clinical data, diagnoses, and laboratory tests. The most common cancers were breast (43.3%), colon (20.0%), lung (12.2%). In the last 1 month, 73.3% of patients visited the emergency department 1 time, 24.4% 2 times, and 2.2% 3 times. The association between the number of visits to the emergency department in the last 1 month and the ECOG groups was statistically significant (p=0.020). Patients presented to the emergency department mainly with pain (66.7%) and nausea/vomiting (57.8%). The most common cancers in patients admitted to the emergency department in our study are similar to the literature. It has been reported in the literature that the symptoms detected in our study are potentially less severe, and emergency room visits can be reduced if patients are encouraged to self-manage similar symptoms through education. From this point of view, to reduce the number of cancer patients applying to the emergency service in regions of internal turmoil and conflict such as Syria, it is very important to identify the reasons for patient admission and to provide training emphasizing the self-management of their symptoms.