The treatment of locally advanced rectal cancer (LARC) is undergoing significant advancements, especially with the integration of innovative radiation therapy techniques. A recent study has delved deep, comparing the dosimetric performance of volumetric modulated arc therapy (VMAT) plans used for preoperative short-course radiation therapy (SCRT) employing two distinct linear accelerator platforms: Halcyon and Infinity. Each system presents unique advantages, but optimizing patient outcomes hinges on identifying which approach delivers effective radiation doses with minimal adverse effects.
The study, conducted at Sir Run Run Shaw Hospital, assessed thirty patients diagnosed with clinical stage T3a-T4a rectal cancer who underwent preoperative SCRT. With the median age of participants around 61 years, their treatment plans were analyzed post-application of VMAT techniques using the Halcyon and Infinity machines, both recognized for their efficiency and precision. The results not only affirm the effectiveness of both platforms but also paint a clearer picture for clinicians striving for optimal treatment protocols.
Existing protocols for treating LARC often combine concurrent chemoradiation followed by total mesorectal excision. This dual approach, known as total neoadjuvant therapy (TNT), aims to address the aggressiveness of the cancerous growth effectively. SCRT has gained traction among healthcare professionals due to its fewer treatment sessions coupled with high patient compliance, making it favorable for achieving targeted outcomes.
One primary finding of the study indicated comparable plan quality concerning the target volume and organ at risk (OAR) dose distribution between the two platforms. Significantly, it was noted, ‘Overall plan quality concerning target volume and OARs was comparable for plans delivered on Halcyon and Infinity Agility machines, with each platform having advantages.’ Such insights are invaluable as they suggest both platforms deliver effective and reliable treatment outcomes.
The methodology employed was rigorous, with researchers utilizing advanced planning tools and computer simulations to devise treatment protocols. Treatment plans were generated using the RayStation planning system, focused on ensuring precise dose distribution across different target areas without overexposing healthy tissues. This aspect is particularly pivotal, as rectal cancer treatments often necessitate minimizing radiation exposure to surrounding organs to mitigate side effects like gastrointestinal toxicity and myelosuppression.
Results revealed quantifiable differences between the Halcyon and Infinity plans, especially concerning dosimetric metrics. The Infinity VMAT plans showcased superiority concerning PTV coverage and controlling target hotspots, with reduced radiation leakage and enhanced modulation options, which contributed to its effectiveness. The report stated, ‘Plans based on the Infinity + RayStation platform performed equally or even demonstrated superior control over target hotspots compared to Halcyon VMAT plans.’ This nuanced performance evaluation offers clinical teams insights on equipment selection based on specific treatment needs.
The study's findings hold practical significance, especially when translating the data to clinical settings where patient outcomes are the priority. Clinicians can rely on comparative metrics such as the mean dose distribution and the volume of organs exposed to radiation when deciding between platforms. With treatment efficiency being equally important, the analysis pointed out, the higher modulation capability of the Infinity system may lead to lower beam-on time, improving overall delivery efficiency.
While the Halcyon system demonstrated certain challenges, primarily associated with treatment time due to the number of monitor units required for its plans, it also allows for unique treatment setups which contribute to operational efforts, indicating no one-size-fits-all solution exists. The ability to involve image-guided therapy (IGRT) with the Halcyon linear accelerator has also been shown to mitigate some challenges, ensuring accuracy during complex treatment plans.
To conclude, the comparative dosimetric analysis of VMAT plans for preoperative SCRT concerning LARC highlights the strengths of both Halcyon and Infinity linear accelerators. Both systems stand as valid treatment modalities with their unique benefits, confirming their role within clinical frameworks for administering radiation therapy. Continuing to explore the nuances of these technologies promises to optimize patient care and therapeutic effectiveness as more insights from such studies illuminate the path forward.
