Applied tube voltage (kilovolts, kV) and tube current (milliampere seconds, mAs) affect CT radiation dose and image quality and should be optimised for the individual patient. CARE kV determines the kV and mAs providing the lowest dose to the patient, whilst maintaining user-defined reference image quality. Given that kV changes affect CT values which are used to obtain attenuation maps, the aim was to evaluate the effect of kV changes on PET quantification and CT radiation dose using phantoms. Four phantoms (‘Lungman’, ‘Lungman plus fat’, ‘Esser’ and ‘NEMA image quality’ (NEMA IQ)) containing F-18 sources underwent 1 PET and 5 CT scans, with CARE kV on (automatic kV selection and mAs modulation) and in semi mode with specified tube voltages of 140, 120, 100 and 80 kV (mAs modulation only). A CARE kV image quality reference of 120 kV/50 mAs was used. Impact on PET quantification was determined by comparing measured activity concentrations for PET reconstructions from different CT scans with the reconstruction using the 120 kV reference, and dose (DLP, CTDIvol) differences calculated by comparing doses from all kV settings with the 120 kV reference. CARE kV-determined optimal tube voltage and CARE kV ‘on’ dose (DLP) savings compared with the 120 kV reference were: Lungman, 100 kV, 2.0%; Lungman plus fat, 120 kV, 0%; Esser, 100 kV, 9.3%; NEMA IQ, 100 kV, 3.4%. Using tube voltages in CARE kV ‘semi’ mode which were not advised by CARE kV ‘on’ resulted in dose increases ≤ 65% compared with the 120 kV reference (greatest difference Lungman plus fat, 80 kV). Clinically insignificant differences in PET activity quantification of up to 0.7% (Lungman, 100 kV, mean measured activity concentration) were observed when using the optimal tube voltage advised by CARE kV. Differences in PET quantification of up to 4.0% (Lungman, 140 kV, maximum measured activity concentration) were found over the full selection of tube voltages in semi mode, with the greatest differences seen at the most suboptimal kV for each phantom. However, most differences were within 1%. CARE kV on can provide CT radiation dose savings without concern over changes in PET quantification.

中文翻译：

---

验证PET-CT的CARE kV自动管电压选择：幻像中的PET量化和CT辐射剂量减少

施加的电子管电压（千伏，kV）和电子管电流（毫安秒，mAs）会影响CT辐射剂量和图像质量，应针对每个患者进行优化。CARE kV确定提供患者最低剂量的kV和mAs，同时保持用户定义的参考图像质量。考虑到kV的变化会影响用于获得衰减图的CT值，目的是使用幻像来评估kV的变化对PET定量和CT辐射剂量的影响。对包含F-18光源的四个体模（“肺脏”，“肺脏加脂肪”，“ Esser”和“ NEMA图像质量”（NEMA IQ））进行了1次PET和5次CT扫描，并启用了CARE kV（自动kV选择和mAs调制）和半模模式，并具有140、120、100和80 kV的指定灯管电压（仅限mAs调制）。使用120 kV / 50 mAs的CARE kV图像质量参考。通过将来自不同CT扫描的PET重建物的测量活性浓度与使用120 kV参考物的重建物进行比较，并比较所有kV设置中的剂量与120 kV参考物的剂量（DLP，CTDIvol）差异，从而确定对PET定量的影响。与120 kV参考电压相比，CARE kV确定的最佳管电压和CARE kV“接通”剂量（DLP）节省如下：Lungman，100 kV，2.0％； Lungman，100 kV，2.0％； Lungman，100 kV，2.0％。Lungman加脂肪，120 kV，0％; Esser，100 kV，9.3％; NEMA IQ，100 kV，3.4％。使用CARE kV“半”模式不建议的CARE kV“半”模式的管电压，与120 kV参考电压（最大差值Lungman加脂肪为80 kV）相比，剂量增加≤65％。PET活性定量的临床差异不明显，最高为0。当使用CARE kV建议的最佳管电压时，观察到7％（肺曼，100 kV，平均测得的活性浓度）。在半模态的整个管电压选择中，发现PET定量的差异高达4.0％（Lungman，140 kV，最大测得的活性浓度），对于每个体模，在最大次佳kV处观察到最大差异。但是，大多数差异在1％以内。开启CARE kV可以节省CT辐射剂量，而无需担心PET定量的变化。每个体模在最次优kV处看到的差异最大。但是，大多数差异在1％以内。开启CARE kV可以节省CT辐射剂量，而无需担心PET定量的变化。每个体模在最次优kV处看到的差异最大。但是，大多数差异在1％以内。开启CARE kV可以节省CT辐射剂量，而无需担心PET定量的变化。