Definition of medical event is to be based on the total source strength for evaluation of permanent prostate brachytherapy: A report from the American Society for Radiation Oncology

AbstractPurposeThe Nuclear Regulatory Commission deems it to be a medical event (ME) if the total dose delivered differs from the prescribed dose by 20% or more. A dose-based definition of ME is not appropriate for permanent prostate brachytherapy as it generates too many spurious MEs and thereby creates unnecessary apprehension in patients, and ties up regulatory bodies and the licensees in unnecessary and burdensome investigations. A more suitable definition of ME is required for permanent prostate brachytherapy.Methods and MaterialsThe American Society for Radiation Oncology (ASTRO) formed a working group of experienced clinicians to review the literature, assess the validity of current regulations, and make specific recommendations about the definition of an ME in permanent prostate brachytherapy.ResultsThe working group found that the current definition of ME in §35.3045 as “the total dose delivered differs from the prescribed dose by 20 percent or more” was not suitable for permanent prostate brachytherapy since the prostate volume (and hence the resultant calculated prostate dose) is dependent on the timing of the imaging, the imaging modality used, the observer variability in prostate contouring, the planning margins used, inadequacies of brachytherapy treatment planning systems to calculate tissue doses, and seed migration within and outside the prostate. If a dose-based definition for permanent implants is applied strictly, many properly executed implants would be improperly classified as an ME leading to a detrimental effect on brachytherapy. The working group found that a source strength-based criterion, of >20% of source strength prescribed in the post-procedure written directive being implanted outside the planning target volume is more appropriate for defining ME in permanent prostate brachytherapy.ConclusionsASTRO recommends that the definition of ME for permanent prostate brachytherapy should not be dose based but should be based upon the source strength (air-kerma strength) administered

Report of AAPM Therapy Physics Committee Task Group 74: Inâ air output ratio, Sc, for megavoltage photon beams

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134830/1/mp7367.pd

Principles in Positioning Cross-Projecting Lasers

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A quality management program in intravascular brachytherapy

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Detector design for surgical guidance

WOS:000880289400007Occult, non-palpable tumor localization has always been a challenge for surgeons due to the difficulty of identifying the margins of the tumor, is indistinguishable from normal tissue, leading to situations requiring a re-excision. The conventional localization techniques rely heavily on preoperative imaging. The large size and long acquisition time associated with preoperative-imaging devices make them infeasible for intraoperative use. Registering preoperative imaging information with the anatomy of the patient real time in the operating room often is difficult and inaccurate. To provide a real-time guidance and let the surgeon track tumor and anatomy of the patient simultaneously requires a radiotracer taken up by the tumor and a hand-held or robotic-arm supported detection device. The radiotracer could be a material such as 123I-labeled CLR1404 that deposits in most tumors but not in normal tissues, and 99mTc-labeled nanoparticles injected to locate Sentinel Lymph Nodes (SLNs). This detector needs characteristics such as: a high energy resolution to distinguish the gamma emissions from the tumor-seeking agent (159 keV) from that from the SLNs (140 keV); a fine spatial resolution to resolve deeply seated nodes from each other and identify the margins of the tumor; a sufficient sensitivity to image the structures live-time in the OR; and a light weight to be handled easily. Hence, the detector selection, in terms of both its components (detector type, collimation type, and front-end electronics) and its characteristics (detector thickness, width, energy resolution, detection efficiency, sensitivity, and decay time), is very important. If the selected crystal is a scintillator, selection of the photon multiplication device is another important component as part of a compact and efficient photomultiplier device. The collimation of the detector affects most aspects of the detector and requires careful optimization. This chapter discusses design characteristics and development of an inorganic scintillator-based lanthanum bromide (LaBr3) detector unit based on the performance characteristics needed to accomplish the goal of radio-guided surgery

Evaluation of Water-Equivalent Plastics as Phantom Material for Electron-Beam Dosimetry

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The AAPM should develop protocols generically, and avoid documents that are too strict and prescriptive, to facilitate their adoption by regulatory agencies like the Nuclear Regulatory Commission and States

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The water-equivalence of phantom materials for Sr-90-Y-90 beta particles

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