## 2 Materials and Methods
### Specific Parameter Adjustment  
The personalized planning engine implemented in Pinnacle has several critical parameters, including the constrained leaf motion (CLM) and the minimum segment area (MSA), among others included in the \"Advanced Parameters\" window. The CLM is the limit imposed on the magnitude of subsequent changes in the aperture shape, defined as  
\[CLM\left(\frac{cm}{deg}\right)=\frac{LeafSpeed\left(\frac{cm}{s}\right)}{GantryRate \left(\frac{deg}{s}\right)} \tag{1}\]  
In the previous Pinnacle version (Pinnacle 16.2), CLM was set to 0.46 cm/deg, as a violation of the maximum leaf speed was allowed for some control points for Elekta machines. On the contrary, in Pinnacle v. 16.4.3, the CLM significantly restricts MLC  
Figure 1: Study design. leaf motion, so higher values (up to 0.8 cm/deg) were recommended to improve plan quality significantly. The Pinnacle application notes [31] suggested a CLM range of 0.8 to 1. So, we decided to enlarge the range investigated for CLM to assess the algorithm's behavior and the feasibility of accurate dose delivery based on the LINAC performance. The minimum segment area (MSA) represents the minimum area value allowed for segments in the plan and was estimated as  
\[MSA=\pi\left(\frac{3\cdot V}{4\ \pi}\right)^{\frac{3}{3}} \tag{2}\]  
as suggested by the Pinnacle user manual. Regarding MSA, the initial indication was based on empirical recommendations related to the volume of PTV (i.e., the square of the higher volume), while in the subsequent application note \"Pinnacle3 Evolution Personalized Planning Strategies and Tips--Pinnacle3 16.4.3--DHF368901 Rev E\", the indication was to use from 9 to 16 for PCa and higher values for HNCa to reduce MUs. Thus, we investigated MSA in the range from 6 to 30. A similar approach was adopted for the other advanced option parameters. Regarding the other advanced option settings, a summary of the above parameters, their description, and the investigated values are reported in Supplementary Materials Table S1. The resulting absorbed dose distributions were evaluated according to scorecards, total MUs, and plan delivery accuracy, which were assessed with the \(\gamma\)-passing criteria. For each investigated case, a treatment template (referred to as \"treatment technique\" in Pinnacle) was developed and used in the subsequent calculations. The VMAT technique was implemented for both cases using two arcs of 6 MV and a control point spacing of 4\({}^{\circ}\). Each collimator angle was set to 15\({}^{\circ}\) and 345\({}^{\circ}\) to minimize the tongue-and-groove cumulative effect. The dose computation algorithm was the collapsed cone convolution (CCC), as thoroughly described by [PERSON] [32]. More in depth, the prostate plans were developed using two complete VMAT arcs with an isocenter placed at the total PTV (i.e., PTV 68 + prostate bed + PTV 56) choosing the \"mandatory constraints\" listed in Table 1 as optimization goals, with \"priority\" set according to fDVHs: priority equal to \"very high\" was chosen for constraints resulting in the \"difficult\" area, priority equal to \"high\" was selected for constrains resulting in the \"challenging\" area, and priority equal to \"medium\" was chosen for constrains resulting in the \"easy\" area. The feasibility module was used to assess the fDVHs and to evaluate the real achievability of the required constraints, indicated as \"Optimal Objectives\" in Table 1.  
The obtained results demonstrated the non-achievability of three requirements for the PCa case concerning the maximum dosage on the rectum, the percentage volume of the rectum receiving 40 Gy, and the percentage volume of the bladder receiving 65 Gy. Based on the suggested fDVH, new \"mandatory objectives\" (Table 1) were defined by choosing constraints in the \"difficult\" area, considered as \"sufficient\" in accordance with the reference documents.