Treatment Planning Study of Volumetric Modulated Arc Therapy for Same-Day Planning and Treatment of Vertebral Bone Metastases Within a Rapid-Access Palliative Radiation Therapy Program

Framework Development: Standardizing Definition of Advanced Practice Radiation Therapy Activities for Clinical Workload Quantification

Purpose

Advanced practice (AP) in radiation therapy (RT) is being implemented around the globe. In an effort to advance the understanding of the similarities and differences in APRT roles in Ontario, Canada, a community of practice (CoP) sought ways to provide quantitative data on the nature of APRT clinical activities and the frequency with which these activities were being executed.

Methods

In 2017, a consensus building project involving 20 APRTs and 14 radiation therapy (RT) department managers in Ontario was completed to establish a mechanism to quantify APRTs' clinical impact. In Round 1 & 2, expert feedback was gathered to generate an Advanced Practice (AP) Activity List. In Round 3: 20 APRTs completed an online survey to assess the importance and applicability of each AP Activity to their role using Likert scale (0-5). A final AP Activity List & Definitions was generated.

Results & discussion

Round 1: Forty-seven AP activities were identified. Round 2: 3/14 RT managers provided 145 feedback statements on Round 1 AP Activity List. The working group used RT managers' feedback to clarify AP activities and definitions, specifically merging 33 unique AP activities to create 11 inclusive AP activities and eliminating 8 activities identified from Round 1. The most inclusive AP activity created was #1 New Patient Consultation, this AP Activity is merged from 7 unique AP activities. Incorporating RT managers' feedback with the internal AP clinical workload lists from 2 Ontario cancer centres resulted in a revised AP Activity List with 20 AP inclusive activities. Round 3: 14/20 APRTs provided Likert scores on this revised list. The most applicable AP activities (mean score) were #16 Technical Consultation (4.0), #15 Contouring Target Volume (3.8) and #2 Planning Consultation (3.8); the least applicable was #18 MR Applicator Assessment (0.9).

Conclusions

This is the first systematic attempt to build consensus on AP clinical activities. Non-clinical APRT activities related to research, education, innovation, and program development were not in the scope of this project. The Final AP Activity List & Definitions serves as a framework that allows standardized and continuous monitoring of AP clinical activities and impact.

Comparison of Rapid to Standard Volumetric Modulated Arc Therapy for Palliative Radiotherapy in Lung Cancer Patients

Patients with incurable lung cancer often present with debilitating symptoms that require urgent palliative radiotherapy. Volumetric modulated arc therapy (VMAT) provides several dosimetric advantages compared to basic non-conformal techniques, but involves complex planning resulting in a slower turn-around time for treatment. A simplified planning technique known as 'rapid VMAT' was developed with an aim to deliver palliative treatment to patients within 48 hours. The purpose of this study was to prospectively compare the dosimetric quality of rapid VMAT plans to standard VMAT plans. Fourteen consecutive rapid VMAT cases were re-planned de novo as per standard VMAT planning guidelines. Planning target volume (PTV) and organs at risk (OARs) were then compared. PTV coverage and dose to OARs including the spinal canal, lung, heart, and esophagus were similar between rapid and standard VMAT. Each plan was ready for treatment within 48 hours of the CT simulation. This study describes an expedited process for which palliative radiotherapy can be delivered to lung tumors with a similar robust quality that is provided for curative intent VMAT radiotherapy plans.

Advanced Radiation Therapy Technology Use in the Treatment of Bone Metastases in a Public, Salary-Funded, Non-Incentivized Health Care System

PURPOSE

There is limited evidence to support the routine use of conformal radiotherapy (RT) techniques in the treatment of bone metastases. This study evaluated trends in advanced technique use within the province of British Columbia.

MATERIALS AND METHODS

Data on patients who received RT for bone metastases between 2009 and 2016 (with the exception of 2012) at 6 regional cancer centers were reviewed. Descriptive statistics summarized radiation technique patterns. Logistic regression assessed the influence of patient, treatment, and provider variables on receipt of RT technique.

RESULTS

A total of 24,215 RT courses were identified; 97% were planned by simple RT and 3% by advanced techniques (3-dimensional conformal radiotherapy, intensity-modulated radiotherapy, and stereotactic body radiotherapy). The use of advanced techniques was significantly higher in recent years compared with in 2009 (odds ratios [ORs], 2.2, 4.2, 4.2, and 6.3, respectively, for the years 2013 to 2016; P < .001). Patients with thyroid, sarcoma, and neuroendocrine malignancies (ORs, 10.3, 5.5, and 5.2, respectively; P < .005) were more likely to be treated with advanced techniques, as were skull, sternum, rib, and pelvic metastases (ORs, 8.0, 5.2, 2.2, and 2.2, respectively; P < .001). Advanced techniques were most commonly used in the setting of re-irradiation (38%). They were associated with slightly higher incompletion rates (3.0% v 1.5%, P < .005) and less use within 30 days of death (6% v 15%, P < .001).

CONCLUSION

Within our publicly funded, salary-based provincial health care system, we found that the majority of bone metastases are still being treated by simple RT; however, the use of advanced techniques is increasing, and we identified select patterns in which they are being prescribed. Additional study into clinical benefit is required.

Can Conformity-Based Volumetric Modulated Arc Therapy Improve Dosimetry and Speed of Delivery in Radiation Therapy to Lumbosacral Spine Compared with Conventional Techniques?

PURPOSE

Volumetric modulated arc therapy (VMAT) has generally been perceived as too time and resource intensive for palliative radiation therapy mainly because of the need for extensive organs at risk contouring. Dose-limiting conformity-based objectives can be automatically generated and are commonly used to conform isodoses closely around the target volumes during inverse planning. The aim of this study was to determine if conformity-based objectives can be used to create VMAT plans for lumbosacral spine palliative radiation therapy without organs at risk contours, which will improve conformity, dose homogeneity, and speed of delivery compared with standard forward planning approaches.

METHODS

A total of 25 patients were retrospectively replanned using three different planning techniques: (1) anterior-posterior parallel opposed pair (POP); (2) single isocenter anterior-posterior half-beam block junctioned to three fields, posterior and two laterals (JUNC); and (3) VMAT single arc. Treatment volume included L1-S5 vertebrae prescribed to 20 Gy in five fractions. Conformality index, homogeneity index, contour, planning, and treatment time were compared for each technique.

RESULTS

Planning target volume V95 ≥95% was maintained for all 75 replans. VMAT was superior to POP and JUNC in terms of conformality (POP 2.0 vs. JUNC 1.8 vs. VMAT 1.2; P < .01) and homogeneity (POP 1.1 vs. JUNC 1.1 vs. VMAT 1.0; P < .01). Planning times for POP were the lowest (3.2 minutes). VMAT and POP had similar delivery times (1.5 minutes), which were approximately half the JUNC delivery time (3.2 minutes).

CONCLUSIONS

Conformity-based VMAT was dosimetrically superior to conventional field-based planning and reduced delivery time. This reduction in normal tissue dose as well as reduced time spent on the treatment couch can potentially improve the quality of life in palliative patients receiving radiotherapy to the lumbosacral spine.