Date Approved


Graduate Degree Type


Degree Name

Medical Dosimetry (M.S.)

Degree Program

Allied Health Sciences

First Advisor

Kristen Vu

Academic Year



Spatially fractionated radiation therapy (SFRT) often has a radiological advantage in the management of bulky tumors over traditional radiation treatment regimes. Implementation of SFRT into linear accelerator-based clinics can give radiation oncology departments another tool to increase the quality of life in patients undergoing treatment for large and bulky tumors. MLC-based static fields and external grid compensators offer clinicians simple routes to introduce SFRT into their program.


A total of 10 patients, all of whom had bulky thoracic tumors and were previously treated with conventional radiotherapy, were chosen for this retrospective SFRT study. The researcher created three plans for each patient, consisting of one static anterior gantry angle. One plan was created with an external grid compensator, one with standard-definition Multi-Leaf Collimators (MLCs), and one with high-definition MLCs. The dosimetric quality was compared for each planning type. Results Statistical analysis was performed on the collected data utilizing SAS 9.4. In order to examine treatment differences, a one-way repeated measures ANOVA test was used, along with a post hoc proc mixed with paired sampled T-test analysis. The resulting P-Value between the three treatment techniques was


Delivery of SFRT utilizing either an external grid or an MLC-based approach has shown feasibility in a linear accelerator-based clinic. The treatment plans generated in the TPS utilizing an external grid, standard definition MLCs, and high definition MLCs all produced consistent dosimetric quality with peaks and valleys that align with the goal of an SFRT plan. The largest difference was seen in the PVDR. The PVDR were as follows: external GRID plan =5.30, MLC-HD = 8.98, and MLC-SD = 8.62