Academic Courses > DOS 522 > MU Second Checks
DOS 522 - Week 4 Discussion
Writing Prompt
Many radiation therapy departments utilize third party software (e.g. MU Check, RadCalc, etc.) for performing monitor unit second checks; as opposed to pen and paper with a calculator. What does your department use for verifying proper MU/dose from the treatment planning system? What are the advantages and disadvantages of using such software?
Initial Post: Computerized MU Checks vs Hand Calculations
At Loyola University Health System, we use RadCalc as our MU second check tool. Once we have completed a plan in Eclipse, we will export a copy of the plan to RadCalc. RadCalc is able to read the beam parameters, MLC positions, and calc point location. If the edges of the beam flash into the air around the patient, we have to manually try to create a region inside the MLC opening that represents air rather than tissue. This method is somewhat crude, but if the calc point is not near the surface, the results are fairly accurate. We look for differences in calculated MUs of 3% or less between what Eclipse determined and what RadCalc suggests. Anything more than that and we will stop to try to figure out what is causing the discrepancy.
The pros of having RadCalc are that it is a vastly faster way to do a second check than hand-calculation. Some techniques such as IMRT would be take a prohibitively long time to hand-calc, and techniques such as VMAT would be nearly impossible to hand-calculate. Software like RadCalc also produces reports that can be included in the patient's records. By using a different calculation algorithm than the planning system, the second check allows one algorithm to audit the other, leading to more confidence in the accuracy of the result.
One of the cons of software like RadCalc is high cost. This is an extremely specialized tool, so the publisher can not sell it cheaply if they want to stay in business. Another con is that the algorithm is less robust than the algorithm that Eclipse uses. There are three choices in RadCalc, and we choose the most accurate one, but it is still working with a limited set of inputs. One could also say that the fact that we always use a computer to perform second-checks might eventually make physics and dosimetry staff complacent, to the point that they never question data coming from the computer. If both computer systems fail to take into account some unusual factor that can not easily be modeled, such as a metal implant, then both systems will give wrong answers, whereas a trained human can make reasonable accommodations.
Software like RadCalc is a valuable addition to a radiation oncology department. That being said, it is important to have a firm grasp on what the software is doing, so that errors can be detected easily if they occur.
The pros of having RadCalc are that it is a vastly faster way to do a second check than hand-calculation. Some techniques such as IMRT would be take a prohibitively long time to hand-calc, and techniques such as VMAT would be nearly impossible to hand-calculate. Software like RadCalc also produces reports that can be included in the patient's records. By using a different calculation algorithm than the planning system, the second check allows one algorithm to audit the other, leading to more confidence in the accuracy of the result.
One of the cons of software like RadCalc is high cost. This is an extremely specialized tool, so the publisher can not sell it cheaply if they want to stay in business. Another con is that the algorithm is less robust than the algorithm that Eclipse uses. There are three choices in RadCalc, and we choose the most accurate one, but it is still working with a limited set of inputs. One could also say that the fact that we always use a computer to perform second-checks might eventually make physics and dosimetry staff complacent, to the point that they never question data coming from the computer. If both computer systems fail to take into account some unusual factor that can not easily be modeled, such as a metal implant, then both systems will give wrong answers, whereas a trained human can make reasonable accommodations.
Software like RadCalc is a valuable addition to a radiation oncology department. That being said, it is important to have a firm grasp on what the software is doing, so that errors can be detected easily if they occur.
Academic Courses > DOS 522 > MU Second Checks
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Written February 11, 2015
Second Semester, 1 Month into Internship |