Denoising proton reference dosimetry spectrum using a large area ionization chamber - physical basis and type A uncertainty.

Reference dosimetry measurement in a pencil beam scanning system can exhibit dose fluctuation due to intra-spill spot positional drift. This results in a noisy reference dosimetry measurement against energy which could introduce errors in monitor unit calibration. The aim of this study is to investigate the impact of smoothing the reference dosimetry measurements on the type A uncertainty.

A treatment-site-specific evaluation of commercial synthetic computed tomography solutions for proton therapy.

Background And Purpose: Despite the superior dose conformity of proton therapy, the dose distribution is sensitive to daily anatomical changes, which can affect treatment accuracy. This study evaluated the dose recalculation accuracy of two synthetic computed tomography (sCT) generation algorithms in a commercial treatment planning system.

Materials And Methods: The evaluation was conducted for head-and-neck, thorax-and-abdomen, and pelvis sites treated with proton therapy.

Descriptions of Scientific Evidence and Uncertainty of Unproven COVID-19 Therapies in US News: Content Analysis Study.

Background: Politicization and misinformation or disinformation of unproven COVID-19 therapies have resulted in communication challenges in presenting science to the public, especially in times of heightened public trepidation and uncertainty.

Objective: This study aims to examine how scientific evidence and uncertainty were portrayed in US news on 3 unproven COVID-19 therapeutics, prior to the development of proven therapeutics and vaccines.

Methods: We conducted a media analysis of unproven COVID-19 therapeutics in early 2020.

Proton Beam Range and Charge Verification Using Multilayer Faraday Collector.

Purpose: A daily quality assurance (QA) check in proton therapy is ensuring that the range of each proton beam energy in water is accurate to 1 mm. This is important for ensuring that the tumor is adequately irradiated while minimizing damage to surrounding healthy tissue. It is also important to verify the total charge collected against the beam model.

Real-time gated proton therapy with a reduced source to imager distance: Commissioning and quality assurance.

Introduction: Real-time gated proton therapy (RGPT) is a motion management technique unique to the Hitachi particle therapy system. It uses pulsed fluoroscopy to track an implanted fiducial marker. There are currently no published guidelines on how to conduct the commissioning and quality assurance.

Repurposing DailyQA3 for an efficient and spot position sensitive daily quality assurance tool for proton therapy.

Introduction: Daily quality assurance is an integral part of a radiotherapy workflow to ensure the dose is delivered safely and accurately to the patient. It is performed before the first treatment of the day and needs to be time and cost efficient for a multiple gantries proton center. In this study, we introduced an efficient method to perform QA for output constancy, range verification, spot positioning accuracy and imaging and proton beam isocenter coincidence with DailyQA3.

First clinical experience following the consensus guide for calibrating a proton stopping power ratio curve in a new proton centre.

Background And Purpose: This work introduces the first assessment of CT calibration following the ESTRO's consensus guidelines and validating the HLUT through the irradiation of biological material.

Methods: Two electron density phantoms were scanned with two CT scanners using two CT scan energies. The stopping power ratio (SPR) and mass density (MD) HLUTs for different CT scan energies were derived using Schneider's and ESTRO's methods.

Pulsed low-dose rate radiotherapy for recurrent bone sarcomas: case reports and brief review.

Purpose: Re-irradiation for bulky recurrent sarcoma carries significant risks. Pulsed low-dose rate radiotherapy (PLDR) is an attractive option for re-irradiation due to inherent radiobiological advantages.

Materials And Methods: We present two patients who underwent reirradiation using PLDR technique, followed by a literature review.

Effects of modern aesthetic dental fillings on proton therapy.

Background And Purpose: High-density dental fillings pose a non-negligible impact on head and neck cancer treatment. For proton therapy, stopping power ratio (SPR) prediction will be significantly impaired by the associated image artifacts. Dose perturbation is also inevitable, compromising the treatment plan quality.

US state laws on medical freedom and investigational stem cell procedures: a call to focus on state-based legislation.

The premature marketing of investigational stem cell interventions (SCIs) is a growing market in the US. Several US states have passed legislation to permit and promote unproven and experimental SCIs for individuals with terminal or chronic diseases. These SCI medical freedom laws, which are largely based on right-to-try legislation, increase access to experimental SCIs with little to no oversight.

Implementing dispersion measurement as part of scanning proton therapy commissioning and quality assurance.

. Dispersion in an accelerator quantifies the deviation of the proton trajectory when there is a momentum deviation. We present for the first time a safe method of measuring dispersion in the clinic, using a scintillator detector and the momentum deviations within a spill.

The effect of spill change on reliable absolute dosimetry in a synchrotron proton spot scanning system.

Background: Absolute dosimetry measurement is an integral part of Treatment Planning System (TPS) commissioning and it involves measuring the integrated absorbed dose to water for all energies in a pencil beam scanning delivery system. During the commissioning of Singapore's first proton therapy center, a uniform scanned field with an Advanced Markus chamber method was employed for this measurement, and a large dose fluctuation of at least 5% was observed for 10% of the energy layers during repeated measurements.

Purpose: This study aims to understand the root cause of this fluctuation by relating the actual delivered spot information in the log file with the charge measurement by the ion chambers.

ISSCR Education Committee syllabus and learning guide for enhancing stem cell literacy.

The rapidly evolving stem cell field puts much stress on developing educational resources. The ISSCR Education Committee has created a flexible stem cell syllabus rooted in core concepts to facilitate stem cell literacy. The free syllabus will be updated regularly to maintain accuracy and relevance.

Prescribing unproven cancer drugs: physician perspectives on expanded access and right to try.

Background: For gravely ill patients who have no treatment options and who are ineligible for clinical trials, the US Food and Drug Administration (FDA) established the Expanded Access Program (EAP). Motivated by efforts to weaken FDA regulation and sold as providing greater access to experimental drugs, the federal Right to Try Act (RTT) was passed in 2017. It reduces FDA oversight by not requiring physicians to report safety data and foregoes approval of protocols by local institutional review boards.

The two-bucket problem of unproven stem cell interventions.

The two-bucket problem of unproven stem cell interventions (SCIs) continues to bifurcate good (ethical) from bad (unethical) practices in the translation of stem cell medicine in ways that divert attention from other salient and challenging questions. It causes scholars to focus narrowly on reprimanding bad actors through legal and regulatory approaches and distracts from other important considerations such as how best to balance evidence with unmet patient needs and address misinformation about unproven stem cell interventions potentially changing patient behavior. The stem cell science community needs to consider a range of ethical practices and aim to address important questions that have yet not received sufficient consideration.

The Direct to Consumer Stem Cell Market and the Role of Primary Care Providers in Correcting Misinformation.

Introduction: Direct to consumer stem cell and regenerative interventions (SCRIs) for various medical conditions have increased in popularity due to unmet medical needs and the promise of SCRIs to meet those needs. These interventions may have varying levels of safety and efficacy data and many lack sufficient scientific data to be marketed. The direct to consumer SCRI industry has received significant attention due to potential physical, economic, and emotional harms to patients.

Modern-era radiotherapy and ischaemic heart disease-related mortality outcomes in Asian breast-cancer patients.

Introduction: Left-sided breast-cancer patients treated with adjuvant radiotherapy (RT) before the 1990s were associated with increased risk of cardiac mortality. Modern RT techniques have since improved, resulting in lower radiation doses to the heart. However, concerns regarding cardiac toxicity remain.

Patients seeking stem cell therapies-a prospective qualitative analysis from a Regenerative Medicine Consult Service.

Despite patient demand for stem cell therapies (SCTs) for musculoskeletal conditions, there remains limited research on why patients seek SCTs or their sources of information. We employ three questions into a consult intake form: (1) Why are you interested in stem cell treatment for your condition? (2) How did you find out about stem cell treatment for your condition? (3) Have you contacted a stem cell clinic? Responses analyzed, using a qualitative content analysis approach to identify themes reveal many patients seek SCTs to treat pain or delay surgery which may align with some current clinical evidence while other patients express motivations as expected outcomes (e.g.

Opinion: Patient reported motivations for seeking stem cell therapy and considerations for counseling.

Stem cell therapies occupy a unique place in the American public's consciousness which has led to excessive enthusiasm over their potential to cure orthopedic conditions. Much has been written about direct-to-consumer marketing of cell therapies for a myriad of medical conditions. Far less has been studied on the attitudes that drive many patients to seek stem cell and orthobiologic therapies for musculoskeletal conditions.

Oncologists' reflections on patient rights and access to compassionate use drugs: A qualitative interview study from an academic cancer center.

The U.S. Food and Drug Administration (FDA) allows patients with serious illnesses to access investigational drugs for "compassionate use" outside of clinical trials through expanded access (EA) Programs.