Establishment of national diagnostic reference levels (DRLs) for radiotherapy localisation computer tomography of the head and neck.

AIM: The aim of this research is to establish if variation exists in the dose delivered for head and neck (HN) localisation computed tomography (CT) imaging in radiation therapy (RT); to propose a national diagnostic reference levels (DRLs) for this procedure and to make a comparison between the national DRL and a DRL of a European sample. BACKGROUND: CT has become an indispensable tool in radiotherapy (RT) treatment planning. It is a requirement of legislation in many countries that doses of ionising radiation for medical exposures be kept 'As Low As Reasonably Achievable'. There are currently no dose guidelines for RT localisation CT of the HN. MATERIALS AND METHODS: All RT departments in Ireland and a sample of European departments were surveyed. Dose data on CT dose length product (DLP); dose index volume (CTDIvol); current time product; tube voltage and scan length was acquired for ten average-sized HN patients from each department. DRLs were proposed for DLP and CTDIvol using the rounded 75th percentile of the distribution of the means. RESULTS: 42% of Irish departments and one European department completed the survey. Significant variation was found in the mean DLP, CTDIvol and scan lengths across the Irish departments. The proposed Irish DRL is 882 mGy cm and 21 mGy and the European department DRL is 816 mGy cm and 21 mGy, for DLP and CTDIvol, respectively. CONCLUSIONS: Variation exists in doses used for HN RT localisation CT. DRLs have been proposed for comparison purposes with the aim of dose optimisation.

A review of dosimetric and toxicity modeling of proton versus photon craniospinal irradiation for pediatrics medulloblastoma.

BACKGROUND: Craniospinal irradiation (CSI) is the standard radiation therapy treatment for medulloblastoma. Conventional CSI photon therapy (Photon-CSI) delivers significant dose to surrounding normal tissue (NT). Research into pediatric CSI with proton therapy (Proton-CSI) has increased, with the aim of exploiting the potential to reduce NT dose and associated post-treatment complications. This review aims to compare treatment outcomes of pediatric medulloblastoma patients between Proton- and Photon-CSI treatments. MATERIAL AND METHODS: A search and review of studies published between 1990 and 2016 comparing pediatric (2-18 years) medulloblastoma Proton- and Photon-CSI in three aspects - normal organ sparing and target coverage; normal organ dysfunction and second malignancy risks - was completed. RESULTS: Fifteen studies were selected for review and the results were directly compared. Proton-CSI reported improved out-of-field organ sparing while target coverage improvements were inconsistent. Normal organ dysfunction risks were predicted to be lower following Proton-CSI. Secondary malignancy risks (SMRs) were generally lower with Proton-CSI based on several different risk models. CONCLUSIONS: Proton-CSI conferred better treatment outcomes than Photon-CSI for pediatric medulloblastoma patients. This review serves to compare the current literature in the absence of long-term data from prospective studies.

A randomized trial comparing bladder volume consistency during fractionated prostate radiation therapy.

PURPOSE: Organ motion is a contributory factor to the variation in location of the prostate and organs at risk during a course of fractionated prostate radiation therapy (RT). A prospective randomized controlled trial was designed with the primary endpoint to provide evidence-based bladder-filling instructions to achieve a consistent bladder volume (BV) and thus reduce the bladder-related organ motion. The secondary endpoints were to assess the incidence of acute and late genitourinary (GU) and gastrointestinal (GI) toxicity for patients and patients' satisfaction with the bladder-filling instructions. METHODS AND MATERIALS: One hundred ten patients were randomly assigned to 1 of 2 bladder-filling protocols; 540 mL (3 cups) of water or 1080 mL (6 cups) of water, in a single institution trial. A portable ultrasound device, BladderScan BVI 6400 (Verathon Inc, Bothell, WA), measured BVs at treatment planning computed tomography (TPCT) scan and 3 times per week during RT. Maximum bladder dose and BV receiving ≥ 50, 60, and 70 Gy were recorded. Acute and late GU and GI toxicity were evaluated, as were patients' comfort, perception of urinary symptoms, and quality of life (QoL). RESULTS: There was significantly less BV variation in the 540 mL arm when compared with 1080 mL (median: 76 mL vs 105 mL, P = .003). Larger BVs on initial TPCT correlated with larger BV variations during RT (P < .0005). There were no statistically significant associations between arm and GU/GI toxicity, dose median comfort scores, or median QoL scores. CONCLUSIONS: The 540 mL bladder-filling arm resulted in reproducible BVs throughout a course of RT, without any deterioration in QoL or increase in toxicities for prostate patients.