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Competing Interests: The authors have no potential conflicts of interest to disclose.

Thermal ablation is a good alternative treatment in patients who are unable to undergo adrenalectomy. Even though the Asian Conference on Tumor Ablation (ACTA) has been held for many years, adrenal ablation guidelines have not been established. No guidelines for adrenal ablation are established in American and European countries, either. The aim of this review was to introduce the first version of ACTA guidelines for adrenal tumor ablation.

Objective: To compare oncological and functional mid-term outcomes following robotic partial nephrectomy (RPN) and radiofrequency ablation (RFA) for treating T1a renal cell carcinoma (RCC) using propensity score-matching., Methods: Between December 2008-April 2016, 63 patients from each treatment group were propensity score-matched for age, sex, American Society of Anesthesiologists score, tumour size, tumour laterality, tumour histology, R.E.N.A.L. nephrometry score and preoperative estimated glomerular filtration rate (eGFR). Post-treatment follow-up periods for RPN and RFA ranged from 1-90 months (median, 24.6) and 1-65 months (21), respectively. Tumour location, percentage of eGFR preservation and 2-year recurrence-free survival rate were compared between groups., Results: Exophytic and endophytic RCC occurred in 73.0 % (46/63) and 27.0 % (17/63) of the RPN group, and 52.4 % (33/63) and 47.6 % (30/63) of the RFA group, respectively (p=0.017). There was 91.7 % preservation of eGFR in the RPN group and 86.8 % in the RFA group (p=0.088). Two-year recurrence-free survival rate was 100 % in the RPN and 95.2 % in the RFA group (p=0.029)., Conclusions: RPN provides a higher recurrence-free survival rate than RFA. However, RFA is a better treatment option for an endophytic or recurrent RCC that is difficult to treat with RPN., Key Points: • RPN provides a higher recurrence-free survival rate than RFA. • Unlike RPN, repeat RFA is easy to perform for recurrent RCC. • Endophytic RCC could be better treated with RFA.

Purpose: Percutaneous radiofrequency ablation is so painful that this treatment requires pain control such as conscious sedation or general anesthesia. It is still unclear which type of anesthesia is better for treatment outcomes of renal cell carcinoma. This study aimed to compare general anesthesia and conscious sedation in treating patients with renal cell carcinoma with radiofrequency ablation., Methods: Between 2010 and 2015, 51 patients with biopsy-proven renal cell carcinomas (<4 cm) were treated with computed tomography-guided radiofrequency ablation. General anesthesia was performed in 41 and conscious sedation was performed in 10 patients. Tumour size, local tumour progression, metastasis, major complication, effective dose, glomerular filtration rate difference, and recurrence-free survival rate were compared between these groups., Results: The mean tumour size was 2.1 cm in both groups (P = .673). Local tumour progression occurred in 0% (0 of 41) of the general anesthesia group, but in 40% (4 of 10) of the conscious sedation group (P = .001). Metastases in these groups occurred in 2.4% (1 of 41) of the general anesthesia group and 20% (2 of 10) of the conscious sedation group (P = .094). No major complications developed in either group after the first radiofrequency ablation session. The mean effective doses in these groups were 21.7 mSv and 21.2 mSv, respectively (P = .868). The mean glomerular filtration rate differences in the general anesthesia and conscious sedation groups were -13.5 mL/min/1.73 m 2 and -19.1 mL/min/1.73 m 2 , respectively (P = .575). Three-year recurrence-free survival rates in these groups were 97.6% and 60.0%, respectively (P = .001)., Conclusions: General anesthesia may provide better intermediate outcomes than conscious sedation in treating small renal cell carcinomas with radiofrequency ablation., (Copyright © 2017 Canadian Association of Radiologists. Published by Elsevier Inc. All rights reserved.)

Objective: To evaluate the mid-term outcomes of percutaneous radiofrequency ablation (RFA) treatment in patients with small (< 4 cm) renal cell carcinoma (RCC) in Korea., Materials and Methods: Between 2010 and 2015, 51 patients (40 men and 11 women; median age, 57 years) with biopsyproven 51 RCC were treated using CT-guided RFA. All patients were clinically staged T1aN0M0 prior to RFA. The median tumor size and follow-up period were 2.1 cm (range, 1.0-3.9 cm) and 26 months (4-60 months), respectively. Local tumor progression, distant metastasis, primary and secondary effectiveness rates, and major complication rates were recorded. Estimated glomerular filtration rates (GFRs) between pre-RFA and last follow-up were compared using paired t tests. The 2-year recurrence-free survival rate was calculated using Kaplan-Meier survival analysis., Results: Of the 51 patients, 2 (3.9%) experienced local tumor progression, and 1 (2.0%) had lymph node metastasis after the first RFA session. Primary and secondary effectiveness rates were 96.1% (49/51) and 100% (1/1), respectively. Only 1 patient experienced a major complication (uretero-pelvic stricture) after the second RFA session for treating a local tumor progression, and the major complication rate was 1.9% (1/52). The median pre-RFA and last follow-up GFRs were 87.1 mL/ min/1.73 m(2) (14.2-142.7 mL/min/1.73 m(2)) and 72.0 mL/min/1.73 m(2) (7.2-112.6 mL/min/1.73 m(2)), respectively (p < 0.0001). The 2-year recurrence-free survival rate was 96.0%., Conclusion: CT-guided RFA is a safe and effective treatment in Korean patients with T1a RCC because of excellent mid-term outcomes.

Adrenalectomy is a treatment of choice for functioning adrenocortical adenoma. We experienced a case of unresected aldosteronoma after right adrenalectomy. Computed tomography-guided transhepatic radiofrequency ablation was carried out to treat the unresected functioning adenoma. The purpose of our case report was to show the clinical findings, computed tomography imaging features and computed tomography-guided transhepatic ablation techniques for adrenocortical adenoma arising from adrenohepatic fusion., (© 2015 The Japanese Urological Association.)

Purpose: To evaluate retrospectively the techniques and outcomes of percutaneous radiofrequency (RF) ablation for treatment of Bosniak III or IV lesions., Materials and Methods: Between August 2006 and August 2013, 30 patients (25 men and 5 women; mean age, 57 y; range, 22-77 y) with 35 nonhereditary Bosniak III (n = 15) or IV (n = 20) lesions underwent computed tomography-guided RF ablation. The mean size of the lesions was 2.8 cm ± 0.9 (range, 1.1-4.3 cm). The mean follow-up period was 24 months ± 16 (range, 6-70 mo). Duration of ablation, number of sessions and electrode repositions, primary and secondary effectiveness rates, major complication rate, reduction rate of lesion size, estimated glomerular filtration rate (GFR), and local tumor progression were recorded. Wilcoxon signed rank test was used for statistical analysis., Results: Mean duration of ablation was 18 minutes ± 14 (range, 2-65 min), and median number of sessions was one. Median number of electrode repositions was 1.0 ± 1.6 (range, 0-6). Primary and secondary effectiveness rates were 97.1% (34 of 35) and 100% (1 of 1), respectively. Mean reduction rate of lesion size was significantly greater from before RF ablation to 1 month after RF ablation (7.1 mm/mo ± 4.5) compared with from 1 month after RF ablation to the last month of follow-up (0.2 mm/mo ± 0.2; P < .0001). Mean GFR after RF ablation (65.4 mL/min/1.73 m(2) ± 26.1) was minimally reduced but significantly different from mean GFR before RF ablation (76.0 mL/min/1.73 m(2) ± 28.4; P < .0001). Major complications occurred in 2 of 35 RF ablation sessions for a rate of 5.7%, resulting from pneumothorax. Of 30 patients, 29 (96.7%) did not have local tumor progression or metastasis for 2 years., Conclusions: Percutaneous RF ablation is technically feasible and yields excellent short-term outcomes in treating sporadic Bosniak III or IV lesions., (Copyright © 2015 SIR. Published by Elsevier Inc. All rights reserved.)

Purpose: To investigate the utility of dual-energy (DE) CT using virtual noncontrast (VNC) and iodine overlay (IO) images to assess therapeutic response to radiofrequency ablation (RFA) for renal cell carcinomas (RCCs)., Materials and Methods: In this institutional review board-approved study (with waiver of informed consent), 47 patients with RCCs that underwent DECT after RFA were enrolled in this study. DECT protocols included true noncontrast (TNC), linearly blended DE corticomedullary and late nephrographic phase imaging. Two types of VNC and IO images were derived from corticomedullary and late nephrographic phases, respectively. To predict local tumor progression at RFA site, linearly blended and IO images were analyzed both qualitatively and quantitatively. Contrast-to-noise ratios (CNR) of renal cortex-to-RFA zones were calculated. The overall imaging quality of VNC images was compared with TNC images., Results: The IO images from corticomedullary and late nephrographic phases showed excellent diagnostic performance (each sensitivity 100% and each specificity 91.5%) for predicting local tumor progression. The degree of enhancement of local tumor progression was not significantly different between linearly blended and IO images (P>0.05). The mean CT numbers were not significantly different between TNC and VNC images (P>0.05). In renal cortex-to-RFA site, CNR between linearly blended and IO images was not significantly different (P>0.05). The VNC imaging quality from the two phases was given a good rating., Conclusion: VNC and IO images from DECT may allow acceptable diagnostic performance with less radiation exposure as a follow-up imaging tool after RFA for RCC, compared to the linearly blended CT images., (Crown Copyright © 2013. Published by Elsevier Ireland Ltd. All rights reserved.)

Renal cell carcinoma (RCC) in patients with von Hippel Lindau (VHL) disease tends to be multifocal, bilateral, and recur or develop new tumors after removal. These characteristics make treating hereditary RCCs difficult for urologists or radiologists compared to treating a sporadic RCC. Radiofrequency ablation (RFA) is a minimally-invasive treatment for small hereditary RCCs associated with a low complication rate and a minimal decrease in renal function. No RFA guidelines have been established about what to treat and when and how to ablate RCCs in patients with VHL disease. Besides, reports on complications and treatment outcomes in this patient group are rare. The purpose of this review is to discuss the indications, techniques, complications, and outcomes of RFA in treating RCC in patients with VHL disease., (© 2013 The Foundation Acta Radiologica.)

Purpose: To estimate effective dose during CT-guided cryoablation of liver tumors, and to assess which procedural factors contribute most to dose., Materials and Methods: Our institutional review board approved this retrospective, HIPAA-compliant study. A total of 20 CT-guided percutaneous liver tumor cryoablation procedures were performed in 18 patients. Effective dose was determined by multiplying the dose length product for each CT scan obtained during the procedure by a conversion factor (0.015mSv/mGy-cm), and calculating the sum for each phase of the procedure: planning, targeting, monitoring, and post-ablation survey. Effective dose of each phase was compared using a repeated measures analysis. Using Spearman correlation coefficients, effective doses were correlated with procedural factors including number of scans, ratio of targeting distance to tumor size, anesthesia type, number of applicators, performance of ancillary procedures (hydrodissection and biopsy), and use of CT fluoroscopy., Results: Effective dose per procedure was 72±18mSv. The effective dose of targeting (37.5±12.5mSv) was the largest component compared to the effective dose of the planning phase (4.8±2.2mSv), the monitoring phase (25.5±6.8mSv), and the post-ablation survey (4.1±1.9mSv) phase (p<0.05). Effective dose correlated positively only with the number of scans (p<0.01)., Conclusions: The effective dose of CT-guided percutaneous cryoablation of liver tumors can be substantial. Reducing the number of scans during the procedure is likely to have the greatest effect on lowering dose., (Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.)

Purpose: To compare percutaneous radiofrequency ablation (RFA) and open partial nephrectomy (OPN) for the treatment of renal cell carcinoma (RCC) with respect to renal function and mid-term oncological outcome., Materials and Methods: From January 2006 to December 2008, 40 (RFA group) and 110 (OPN group) patients underwent RFA and OPN for sporadic RCC, respectively. The sizes and locations of RCCs were matched between the two groups. To determine the lesion size, the maximum transverse diameter was measured. Estimated glomerular filtration rates (eGFR) before and after treatment and overall three-year recurrence-free survival rates were calculated and compared., Results: Tumours in the RFA and OPN groups ranged from 9-76 mm (24.4 ± 13.1 mm) and from 6-60 mm (22.3 ± 10.2 mm), respectively (p = 0.962). The locations of RCCs were not significantly different (p = 0.101-0.508). The mean reductions of eGFR in the RFA and OPN groups were 2.3 ± 8.6 mL/min/1.73 m² (range, -23 to +17.5 mL/min/1.73 m²) and 7.4 ± 10.9 mL/min/1.73 m² (-23.6 to +42.8 mL/min/1.73 m², respectively (p = 0.013). Overall three-year recurrence-free survival rates in the RFA and OPN groups were 94.7% and 98.9%, respectively (p = 0.266)., Conclusion: For treating size- and location-matched RCCs, RFA is superior to OPN with respect to the preservation of renal function. Furthermore, RFA can achieve excellent mid-term outcomes that are equivalent to those of OPN.

Background: Radiofrequency ablation (RFA) is accepted as a minimally invasive treatment of renal cell carcinoma (RCC). However, RFA is not fully evaluated for treating RCC in patients with von Hippel Lindau (VHL) disease who cannot undergo surgery due to serious postoperative morbidity or mortality., Purpose: To evaluate the role of RFA of RCC in patients with VHL disease previously undergoing renal surgery., Material and Methods: Percutaneous RFA was performed for treating 14 RCCs in six patients who had undergone radical nephrectomy (n = 3) or repeated nephron-sparing surgery (n = 3). Treatment feasibility, complications, outcome, and the change of renal function were evaluated., Results: To completely ablate 14 RCCs, 23 ablations during 12 sessions were necessary. Of 14 RCCs, nine were in proximity (<5 mm) to one or more following organs: bowel (n = 4), ureteropelvic junction or pelvis (n = 2), psoas muscle (n = 2), vascular pedicle (n = 1), and pancreas (n = 1). Of 12 sessions, one major complication (pneumothorax) developed in one session (8%). No residual or recurrent tumors were identified at the ablation areas. However, new three solid tumors less than 1 cm in diameter developed during the follow-up period but ablation was withheld until these tumors had grown to more than 1 cm in size. The mean level of serum creatinine increased with 6.4% and the mean estimated glomerular filtration rate decreased by 12.8% after the last ablation compared to those before the initial ablation (P < 0.05)., Conclusion: Despite technical difficulties, percutaneous RFA is a promising treatment for VHL patients who cannot undergo surgery because of excellent treatment outcome and minimal change of renal function.

Purpose: To evaluate which factor is involved in limiting ultrasound (US)-guided radiofrequency (RF) ablation of small renal masses., Materials and Methods: Twenty-five patients with 31 renal masses underwent image-guided RF ablation. If a lesion was visible on US, US-guided RF ablation was performed. If a lesion was invisible on US or if the lesion was incompletely ablated or recurred following US-guided RF ablation, CT-guided RF ablation was performed. We analyzed the various factors which were involved in US-guided RF ablation., Results: Of 31 masses, thirteen were US-visible lesions and underwent US-guided RF ablation whereas thirteen were US-invisible lesions and thus underwent CT-guided RF ablation. The remaining five lesions were US-visible but needed additional CT-guided RF ablation, due to incomplete ablation (n=4) or recurrence (n=1); these renal masses (3.1+/-1.0 cm) were significantly larger than those (1.8+/-0.6 cm) ablated with US alone (p<0.05). Steam bubbles (4.4 cm+/-0.7 cm) of the masses requiring additional CT-guided RF ablation were significantly larger than those (2.9 cm+/-0.7 cm) of the tumors completely ablated with US alone in size (p<0.05)., Conclusions: US-invisibility, lesion size, and steam bubbles may limit to perform US-guided RF ablation of small renal masses., (Copyright (c) 2009 Elsevier Ireland Ltd. All rights reserved.)

Purpose: We investigated the preliminary results of percutaneous radio frequency ablation for renal tumors in patients with von Hippel-Lindau disease., Materials and Methods: Between October 2005 and April 2009 image guided radio frequency ablation was performed to ablate a total of 48 renal tumors in 11 patients with von Hippel-Lindau disease. Six of the 11 patients had undergone radical or partial nephrectomy for renal cell carcinomas. We recorded whether tumors were successfully ablated, major complications, and changes in serum creatinine and the estimated glomerular filtration rate., Results: A total of 29 sessions (70 ablations) were done. Of 48 tumors 42 (88%) were successfully ablated at 1 (41) or 3 (1) sessions and 6 (12%) had residual or recurrent lesions. Two residual tumors were treated with nephrectomy, 2 were too small to be ablated and 1 was treated with chemotherapy due to pulmonary metastasis. The remaining residual tumor was completely ablated at 2 sessions but recurred. Overall 8 of 11 patients (73%) were successfully treated with radio frequency ablation but 3 (27%) had residual or recurrent tumors. Two major complications (6.9%) developed at a total of 29 sessions, including arteriovenous fistula and ureteral perforation. Mean serum creatinine increased 11.2% and the mean estimated glomerular filtration rate decreased 9.4% after the last ablation., Conclusions: Percutaneous radio frequency ablation may be a treatment option for multifocal renal tumors in patients with von Hippel-Lindau disease but preliminary results were not satisfactory due to technical failure., (2010 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.)

Radiofrequency (RF) ablation is an alternative treatment for renal cell carcinoma (RCC) in patients unable to undergo surgery. Although RF ablation has a low complication rate because of its minimally invasive nature, unintended heat may be conducted by several critical organs during ablation procedures, leading to a variety of complications. Major complications that usually require treatment include bowel injury, ureteral injury, massive bleeding and residual or recurrent tumour. Minor complications that may require only observation include pain, haematoma, haematuria, neuromuscular injury, pneumothorax, infarction and inflammatory tract mass. The most common cause of complications is the tumour's proximity to neighbouring organs. In addition, careless electrode manipulation and the patient's comorbidities may also lead to complications. To avoid many of these complications, the distance between the tumour and neighbouring organs should be widened using methods such as changing the patient's position, using the RF electrode as a lever and hydrodissection. Furthermore, carefully manipulating the RF electrode and assessing the patient's general condition help to prevent complications. In this review, we discuss the complications resulting from RF ablation of RCC with an emphasis on causes, imaging features and prevention methods.

Radiofrequency ablation is accepted as a minimally invasive treatment for renal tumors in patients who are poor candidates for surgery. However, ablation of tumors that abut large vessels is likely to be incomplete due to the heat-sink effect or may result in vascular injury. We report a case of a renal tumor abutting the inferior vena cava, which was successfully treated with radiofrequency ablation, with an emphasis on the technical aspects required to avoid both incomplete ablation and vascular injury by using a radiofrequency electrode as a lever.

Percutaneous radiofrequency ablation of renal tumors is known to be an effective treatment in patients with marginal renal function. Recently, this treatment was used in a patient with a renal tumor that arose in a single kidney. The tumor was completely ablated, but renal infarction developed because of a thermally injured segmental artery during ablation. We report the computed tomography imaging features, with an emphasis on the technical aspects of the ablation procedure.

The spontaneous regression of metastatic lesions from renal cell carcinoma (RCC) is extremely rare, but may be encountered following cytoreductive treatments. We report a case of a recurrent RCC with multiple metastatic lesions which spontaneously regressed after undergoing radiofrequency ablation of the renal tumor.

The purpose of this study was to assess the efficacy of image-guided radiofrequency (RF) ablation of cystic renal tumors. Between November 2005 and August 2007, computed tomography (CT) or ultrasound-guided RF ablation was performed in nine patients with 14 Bosniak category III (n = 5) or IV (n = 9) cystic renal tumors using an internally cooled RF ablation system. We evaluated the number of sessions, cycles and duration of energy application, treatment results, lesion size change, and complications. Together the cystic renal tumors required 15 sessions and 23 cycles of energy application. The duration of energy application per one tumor ablation ranged from 1 to 12 min (mean 6 min). The last follow-up CT indicated complete coagulation of 14/14 (100%) lesions. None of these tumors had recurred within 1-19 months (mean 8 months). The maximum diameter of the cystic renal tumors was significantly reduced from 2.5 +/- 0.6 cm before ablation to 1.7 +/- 0.7 cm at the last follow-up CT (P < 0.01). Complications were pneumothorax (n = 2), inguinal paresthesia (n = 1), and arteriovenous fistula (n = 1). Image-guided RF ablation is an effective treatment for Bosniak category III or IV cystic renal tumors, which might need relatively shorter duration of energy application than purely solid renal tumors of the same size.

Purpose: To assess the positive and negative effects of computed tomographic (CT)-guided instillation of 5% dextrose in water (D5W) into the anterior pararenal space before renal radiofrequency (RF) ablation in a porcine model., Materials and Methods: Under CT guidance, D5W was instilled into the right anterior pararenal space of 10 pigs and RF ablation performed in the right kidney. For the control lesions, RF ablation was performed in the left kidney of the same pigs without pretreatment with D5W. Approximately 1 week after RF ablation, bowel adhesion to both kidneys was compared by using a 5-point scale at open laparotomy, as follows: grade 0=no adhesion, grade 1=detachable adhesion, grade 2=grade 1 adhesion plus other adhesion to organs, grade 3=undetachable adhesion, and grade 4=bowel perforation. The areas of coagulation necrosis in both kidneys were compared at pathologic examination., Results: Bowel adhesions to the right kidneys were classified as grade 0 in nine pigs and as grade 1 in one pig, whereas those to the left kidneys were classified as grade 2 in two pigs and as grade 3 in eight (P<.05). The mean areas of coagulation necrosis in right and left kidneys were 0.58 cm2+/-0.5 and 1.53 cm2+/-1.3, respectively (P<.05)., Conclusions: CT-guided D5W instillation has a positive effect in reducing the amount of bowel adhesion injury during RF ablation. However, this technique may limit the area of coagulation necrosis in a swine model. Longer term pathologic evaluation is necessary to fully understand the effects of D5W instillation.

Radiofrequency (RF) ablation has been accepted as a safe minimally invasive treatment for renal cell carcinoma but may cause minor complications in a small number of cases. The present report describes the occurrence of an arteriovenous fistula after RF ablation of a renal tumor located within the renal sinus that subsequently required interventional therapy.

Purpose: This study aimed to compare functional and oncological outcomes between partial nephrectomy (PN) and radiofrequency ablation (RFA) for a small renal mass (SRM, ≤4 cm) in patients with chronic kidney disease (CKD). Materials and Methods: Patients with CKD who underwent either PN or RFA for SRM between 2005 and 2019 were included. Patients were stratified into two categories: CKD stage 2 and CKD stage 3 or higher. We performed propensity score matching (PSM) analysis in patients with CKD stage 2 and CKD stage 3 or higher. We compared the functional and oncological outcomes between two groups according to CKD stage before and after PSM. Results: Among 1332 patients, 1195 patients were CKD stage 2 and 137 patients were CKD stage 3 or higher. After PSM analysis using age, pre-treatment eGFR, and clinical tumor size as matching variables, the PN and RFA groups had 270 and 135 CKD stage 2 patients, respectively, and both had 53 patients each with CKD stage 3 or higher. There were no significant differences in percent change in eGFR at 1 year post-operation between groups in patients with CKD stage 2 and stage 3 or higher. Among all patients with tissue-proven malignancy, the 5-year recurrence-free survival (RFS), cancer-specific survival, and overall survival were significantly higher in the PN group. However, only the 5-year RFS was significantly higher in the PN group after matching. Conclusion: Mortality is low in patients with SRM, and functional outcomes were not significantly different between the two treatments. RFA could be an alternative treatment modality in patients who are poor candidates for surgery. [ABSTRACT FROM AUTHOR]

Objective: Computed tomography (CT)-guided radiofrequency ablation (RFA) results in a high radiation dose. This study aimed to assess low-dose CT protocols for guiding RFA and oncologic outcomes for the treatment of small renal cell carcinoma (RCC). Materials and methods: Between December 2011 and December 2014, CT-guided RFA was performed in 31 patients with 31 biopsy-proven RCCs (median, 2.1 cm). RFA included planning, targeting, monitoring and survey phases. The dose length product (DLP), CT dose index volume (CTDIvol), effective dose, number of scans, scan range, tube current and exposure time of RFA phases were compared. The 3-year recurrence-free survival rate was recorded. Nonparametric or parametric repeated-measures ANOVA with Dunn’s or Tukey-Kramer multiple comparisons and Kaplan-Meier analysis were used for statistical analysis. Results: The median total DLP, CTDIvol and effective dose of CT-guided RFA procedures per session were 1238.8 mGy (range 517.4-3391.7 mGy), 259.7 mGy (10.7-67.9 mGy) and 18.6 mSv (7.8-50.9 mSv), respectively. The median DLP, CTDIvol, effective dose, number of scans, tube current and exposure time during the targeting phase were higher than those during the other phases (p < 0.001). The scan range in the targeting phase was the same as that in the monitoring phase (p > 0.05) but smaller than those in the planning and survey phases (p < 0.001). The 3-year recurrence-free survival rate was 96.7%. Conclusions: Low-dose CT protocols for guiding RFA may reduce radiation dose without compromising oncologic outcomes. Reducing the number of scans during the targeting phase contributes to dose reduction. [ABSTRACT FROM AUTHOR]