Comparing four volumetric modulated arc therapy beam arrangements for the treatment of early-stage prostate cancer.

INTRODUCTION: This study compared four different volumetric modulated arc therapy (VMAT) beam arrangements for the treatment of early-stage prostate cancer examining plan quality and the impact on a radiotherapy department's resources. METHODS: Twenty prostate cases were retrospectively planned using four VMAT beam arrangements (1) a partial arc (PA), (2) one arc (1A), (3) one arc plus a partial arc (1A + PA) and (4) two arcs (2A). The quality of the dose distributions generated were compared by examining the overall plan quality, the homogeneity and conformity to the planning target volume (PTV), the number of monitor units and the dose delivered to the organs at risk. Departmental resources were considered by recording the planning time and beam delivery time. RESULTS: Each technique produced a plan of similar quality that was considered adequate for treatment; though some differences were noted. The 1A, 1A + PA and 2A plans demonstrated a better conformity to the PTV which correlated to improved sparing of the rectum in the 60-70 Gy range for the 1A + PA and 2A techniques. The time needed to generate the plans was different for each technique ranging from 13.1 min for 1A + PA to 17.8 min for 1A. The PA beam delivery time was fastest with a mean time of 0.9 min. Beam-on times then increased with an increase in the number of arcs up to an average of 2.2 min for the 2A technique. CONCLUSION: Which VMAT technique is best suited for clinical implementation for the treatment of prostate cancer may be dictated by the individual patient and the availability of departmental resources.

The quality assurance of volumetric modulated arc therapy (VMAT) plans for early stage prostate cancer: a technical note.

As radiation therapy transitions from intensity modulated radiation therapy (IMRT) to volumetric modulated arc therapy (VMAT) it is important to consider the quality assurance (QA) of VMAT plans in light of what has previously been learned and developed in IMRT QA. This technical note assesses if IMRT based plan QA software, which has reduced the need in IMRT for phantom dose measurements on the linear accelerator, can be incorporated into VMAT QA processes. Twenty prostate cases were retrospectively planned using VMAT with one arc to deliver a prescription of 74 Gy in 37 fractions. A plan QA was performed using both IMSure (version 3.3), a software-based IMRT QA program, and ArcCHECK (version 6.2.3.5713), a phantom-based VMAT QA tool. Outcomes assessed included the time needed to perform the QA of both the IMSure and ArcCHECK QA methods, and agreement between planned dose and QA measured dose. On average per case, the ArcCHECK technique needed 31.5 min to perform the VMAT plan QA, while IMSure required 3.5 min to perform the same QA. All 20 cases passed dosimetric QA using ArcCHECK. However, using IMSure, three cases failed dosimetric QA using the departments existing IMRT QA criteria. This research has demonstrated that the IMRT QA software IMSure may be incorporated into the QA of VMAT plans, however the criteria to assess the dosimetry of the VMAT plans may need to be different to that for IMRT cases. The implication of this research for radiation therapists is to be critically aware of the differences between the plan QA requirements and methods for IMRT and those required for VMAT.

A Retrospective Planning Analysis Comparing Volumetric-Modulated Arc Therapy (VMAT) to Intensity-Modulated Radiation Therapy (IMRT) for Radiotherapy Treatment of Prostate Cancer.

PURPOSE: This study aims to compare intensity-modulated radiation therapy (IMRT) to volumetric-modulated arc therapy (VMAT) for the treatment of prostate cancer. Particular focus was placed on the impact IMRT and VMAT have on departmental planning and treatment resources. MATERIALS AND METHODS: Twenty prostate cancer cases were retrospectively planned to compare 5-field IMRT to VMAT using a single arc (VMAT-1A) and 2 arcs (VMAT-2A). The impact on departmental resources was assessed by comparing the time needed to generate the dose distributions and to deliver the treatment plan. A comparison of plan quality was also performed by comparing homogeneity, conformity, the number of monitor units (MUs), and dose to the organs at risk. RESULTS: IMRT and VMAT-2A were able to produce adequate plans for all cases. Using VMAT-1A, planning guidelines were achieved in 8 of the 20 cases. IMRT provided an improved dose distribution and the best homogeneity to the planning target volume. Also, the IMRT plans were generated significantly faster than both VMAT techniques. VMAT planning provided significantly improved conformity and used significantly fewer monitor units than IMRT. VMAT-1A treatments were significantly faster than both IMRT and VMAT-2A. VMAT plans delivered lower dose to the bladder and heads of femur, and an increased dose to the rectum in the low dose region. CONCLUSION: IMRT may have an advantage over VMAT for the treatment of prostate cancers. This is primarily due to the uncertainty of achieving planning guidelines using VMAT and the extended time needed to generate the VMAT plans.

A retrospective planning analysis comparing intensity modulated radiation therapy (IMRT) to volumetric modulated arc therapy (VMAT) using two optimization algorithms for the treatment of early-stage prostate cancer.

INTRODUCTION: The primary aim of this study is to compare intensity modulated radiation therapy (IMRT) to volumetric modulated arc therapy (VMAT) for the radical treatment of prostate cancer using version 10.0 (v10.0) of Varian Medical Systems, RapidArc radiation oncology system. Particular focus was placed on plan quality and the implications on departmental resources. The secondary objective was to compare the results in v10.0 to the preceding version 8.6 (v8.6). METHODS: Twenty prostate cancer cases were retrospectively planned using v10.0 of Varian's Eclipse and RapidArc software. Three planning techniques were performed: a 5-field IMRT, VMAT using one arc (VMAT-1A), and VMAT with two arcs (VMAT-2A). Plan quality was assessed by examining homogeneity, conformity, the number of monitor units (MUs) utilized, and dose to the organs at risk (OAR). Resource implications were assessed by examining planning and treatment times. The results obtained using v10.0 were also compared to those previously reported by our group for v8.6. RESULTS: In v10.0, each technique was able to produce a dose distribution that achieved the departmental planning guidelines. The IMRT plans were produced faster than VMAT plans and displayed improved homogeneity. The VMAT plans provided better conformity to the target volume, improved dose to the OAR, and required fewer MUs. Treatments using VMAT-1A were significantly faster than both IMRT and VMAT-2A. Comparison between versions 8.6 and 10.0 revealed that in the newer version, VMAT planning was significantly faster and the quality of the VMAT dose distributions produced were of a better quality. CONCLUSION: VMAT (v10.0) using one or two arcs provides an acceptable alternative to IMRT for the treatment of prostate cancer. VMAT-1A has the greatest impact on reducing treatment time.

An Introduction to the Intensity-modulated Radiation Therapy (IMRT) Techniques, Tomotherapy, and VMAT.

The goal of radiation therapy is to administer a therapeutic dose of radiation to a target while limiting the side effects caused by delivering the dose to surrounding tissues and vital organs. The ongoing pursuit to achieve an optimal dose distribution has prompted the radiation therapy profession to develop new techniques that incorporate advances in technology. In radiation therapy today, modern techniques that include three-dimensional conformal radiation therapy (3D-CRT) and intensity-modulated radiation therapy (IMRT) are routinely used in the treatment of cancers. Compared with 3D-CRT, IMRT is capable of producing dose distributions that conform to the planning treatment volume and deliver a reduced dose to surrounding tissues and vital organs. This has come with the cost of increased treatment time and a larger volume of normal tissue receiving low radiation doses. Most recently, there has been considerable interest in the rotating gantry IMRT techniques, tomotherapy and volumetric-modulated arc therapy (VMAT). Tomotherapy is a dedicated treatment system that is best described as a combination of a computed tomography scanner and a linear accelerator. In tomotherapy, treatment is delivered using a rotating fan beam. A therapeutic dose is delivered when a patient is translated smoothly through the bore of the machine as its gantry continuously rotates. Tomotherapy is capable of producing high-quality plans that increasingly spare dose to surrounding organs at risk. In VMAT, treatment is delivered on a linear accelerator using a cone beam that rotates around the patient. The cone beam is modulated by dynamic multileaf collimation, variable dose rate and variable gantry speed to generate IMRT-quality dose distributions in a single optimized arc around the patient. VMAT treatments can significantly reduce the time and monitor units required to deliver a patient's treatment. Conventional IMRT, tomotherapy and VMAT typically produce dose distributions of similar quality. Which technique is most suited to treat a patient will depend on considerations such as the availability of the specific treatment type and its impact on the utilization of departmental planning and treatment resources.

Assessment of personal qualities in selection of medical radiation science students.

UNLABELLED: It is increasingly acknowledged that, in addition to prior academic achievement, there is a need to seek evidence for the abilities and personal qualities of applicants to health professional programs at a university. The aim of this study was to determine the specific abilities and personal qualities required for excellence in practice in the relevant professional domains of medical radiation science (MRS). METHODS: A focus group, consisting of MRS academic staff, developed a questionnaire. The questionnaire was sent to senior MRS practitioners throughout Australia and 213 were returned for analysis. Respondents were asked to rate 40 specific abilities and qualities (referred to as "elements") on a 5-point scale. RESULTS: Two hundred thirteen completed questionnaires were returned, a 53% response rate. One hundred twelve respondents (52%) indicated they currently worked in diagnostic radiography (DR), 57 (27%) worked in radiation therapy (RT), and 44 (21%) worked in nuclear medicine (NM). The duration (mean +/- SD) of the respondents' professional practice in MRS was 14.5 +/- 10 y, with durations ranging from 1 to 43 y. Raw scores and mean scores were examined for any influence of the variable "Number of Years in Practice." DISCUSSION: No major differences were found between the ratings provided by the practitioners from the 3 different MRS professional domains of NM, RT, and DR. Factor analysis indicated the existence of 3 orthogonal factors in the questionnaire data: (a) treat others professionally and ethically, (b) engage with and be open to others, and (c) problem-solving ability. Qualitative analysis of the respondents' comments provided similar themes: (a) the need for professional competence (knowledge and abilities), (b) ethical behavior, (c) the need for a technology and a people orientation, and (d) MRS should be the first choice of MRS students and not a second choice to other professional degrees. CONCLUSION: Senior medical radiation scientists identified professionalism, ethical behavior, engagement with and openness to others, intrinsic specific motivation, and an orientation to people and technology as nonacademic qualities required for excellence in the practice of the professions embraced by MRS.