Comparative dosimetry of radiography device, MSCT device and two CBCT devices in the elbow region.

The aim of the study was to estimate and to compare effective doses in the elbow region resulting from four different x-ray imaging modalities. Absorbed organ doses were measured using 11 metal oxide field effect transistor (MOSFET) dosimeters that were placed in a custom-made anthropomorphic elbow RANDO phantom. Examinations were performed using Shimadzu FH-21 HR radiography device, Siemens Sensation Open 24-slice MSCT-device, NewTom 5G CBCT device, and Planmed Verity CBCT device, and the effective doses were calculated according to ICRP 103 recommendations. The effective dose for the conventional radiographic device was 1.5 µSv. The effective dose for the NewTom 5G CBCT ranged between 2.0 and 6.7 µSv, for the Planmed Verity CBCT device 2.6 µSv and for the Siemens Sensation MSCT device 37.4 µSv. Compared with conventional 2D radiography, this study demonstrated a 1.4-4.6 fold increase in effective dose for CBCT and 25-fold dose for standard MSCT protocols. When compared with 3D CBCT protocols, the study showed a 6-19 fold increase in effective dose using a standard MSCT protocol. CBCT devices offer a feasible low-dose alternative for elbow 3D imaging when compared to MSCT.

Third-line treatment and 177Lu-PSMA radioligand therapy of metastatic castration-resistant prostate cancer: a systematic review.

AIMS: There is a controversy as to the relative efficacy of 177Lu prostate specific membrane antigen (PSMA) radioligand therapy (RLT) and third-line treatment for patients with metastatic castration-resistant prostate cancer (mCRPC). The aim of our systematic review was to elucidate whether 177Lu-PSMA RLT and third-line treatment have similar effects and adverse effects (PROSPERO ID CRD42017067743). METHODS: The review followed Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. Searches in Pubmed and Embase selected articles up to September 2017. A search in ClinicalTrials.gov indicated ongoing studies. The meta-analysis used the random-effects model. RESULTS: Twelve studies including 669 patients reported 177Lu-PSMA RLT. Overall, 43% of the patients had a maximum decline of PSA of ≥50% following treatment with 177Lu-PSMA RLT. The treatment with 177Lu-PSMA-617 and 177Lu-PSMA for imaging and therapy (I&T) had mainly transient adverse effects. Sixteen studies including 1338 patients reported third-line treatment. Overall, 21% of the patients had a best decline of PSA of ≥50% following third-line treatment. After third-line treatment with enzalutamide and cabazitaxel, adverse effects caused discontinuation of treatment for 10% to 23% of the patients. 177Lu-PSMA RLT gave a best PSA decline ≥50% more often than third-line treatment (mean 44% versus 22%, p = 0.0002, t test). 177Lu-PSMA RLT gave objective remission more often than third-line treatment (overall 31 of 109 patients versus 43 of 275 patients, p = 0.004, χ2 test). Median survival was longer after 177Lu-PSMA RLT than after third-line treatment, but the difference was not statistically significant (mean 14 months versus 12 months, p = 0.32, t test). Adverse effects caused discontinuation of treatment more often for third-line treatment than for 177Lu-PSMA RLT (22 of 66 patients versus 0 of 469 patients, p < 0.001, χ2 test). CONCLUSIONS: As for patients with mCRPC, treatment with 177Lu-PSMA-617 RTL and 177Lu-PSMA I&T gave better effects and caused fewer adverse effects than third-line treatment.

Dose monitoring in pediatric and young adult head and cervical spine CT studies at two emergency duty departments.

PURPOSE: As the number of pediatric computed tomography (CT) imaging is increasing, there is a need for real-time radiation dose monitoring and evaluation of the imaging protocols. The aim of this study was to present the imaging data, patient doses, and observations of pediatric and young adult trauma-and routine head CT and cervical spine CT collected by a dose monitoring software. METHODS: Patient age, study date, imaging parameters, and patient dose as volume CT dose index (CTDIvol) and dose length product (DLP) were collected from two emergency departments' CT scanners for 2-year period. The patients were divided into four age groups (0-5, 6-10, 11-15, and 16-20 years) for statistical analysis and effective dose determination. The 75th percentile doses were evaluated to be used as local diagnostic reference levels (DRLs). RESULTS: Six hundred fifteen trauma head, 318 routine head, and 592 trauma cervical spine CT studies were assessed. All mean CTDIvol values were statistically lower in hospital B (40.3 ± 12.3, 30.03 ± 11.1, and 6.9 ± 3.1 mGy, respectively) than in hospital A (53.0 ± 12.9, 43.2 ± 8.7, and 18.3 ± 7.3 mGy, respectively). Statistically significant differences were observed on scanning length between hospitals and between CTDIvol values when protocol was updated. The 75th percentiles of trauma cervical spine in hospital B can be used as local DRL. Non-optimized protocols were also revealed in hospital A. CONCLUSION: Dose monitoring software offers a valuable tool for evaluating the imaging practices and finding non-optimized protocols.

VMAT technique enables concomitant radiotherapy of prostate cancer and pelvic bone metastases.

BACKGROUND: Prostate cancer (PCa) patients with metastatic disease often suffer from skeletal pain and urinary retention impairing their quality of life. Prophylactic radiotherapy to bone metastases planned concomitantly with primary PCa radiotherapy could enable more precise control of combined dose in healthy tissues when compared to sequential palliative treatment. MATERIALS AND METHODS: Volumetric modulated arc therapy (VMAT) was planned for 14 PCa patients with primary bone metastases. The bone planning target volume (PTVbone) was contoured together with the PTVs of prostate (pr), pelvic lymph nodes (ln) and seminal vesicles (sv). Another virtual plan was calculated excluding PTVbone for dose volume histogram (DVH) comparison. DVHs were additionally compared to a set of actual VMAT treatment plans of a control cohort of 13 high risk PCa patients treated with PTVpr, PTVsv and PTVln. The prescribed doses varied between 42 and 76 Gy for PTVbone. RESULTS: Recommended healthy tissue tolerances (Quantec) were not exceeded except for one patient's rectum V50Gy value. Rectum doses did not increase significantly due to the inclusion of PTVbone. For bladder, there was a slight increase for V65Gy and V50Gy (2.7% and 7.4%). The DVHs of metastatic and non-metastatic patients were comparable. There were no differences in the PTVpr DVH parameters, while mean PTVln dose increased by 3.7 Gy-4.4 Gy due to the increased treatment volume related to PTVbone. All side effects were

Characterization of MOSFET dosimeters for low-dose measurements in maxillofacial anthropomorphic phantoms.

The aims of this study were to characterize reinforced metal-oxide-semiconductor field-effect transistor (MOSFET) dosimeters to assess the measurement uncertainty, single exposure low-dose limit with acceptable accuracy, and the number of exposures required to attain the corresponding limit of the thermoluminescent dosimeters (TLD). The second aim was to characterize MOSFET dosimeter sensitivities for two dental photon energy ranges, dose dependency, dose rate dependency, and accumulated dose dependency. A further aim was to compare the performance of MOSFETs with those of TLDs in an anthropomorphic phantom head using a dentomaxillofacial CBCT device. The uncertainty was assessed by exposing 20 MOSFETs and a Barracuda MPD reference dosimeter. The MOSFET dosimeter sensitivities were evaluated for two photon energy ranges (50-90 kVp) using a constant dose and polymethylmethacrylate backscatter material. MOSFET and TLD comparative point-dose measurements were performed on an anthropomorphic phantom that was exposed with a clinical CBCT protocol. The MOSFET single exposure low dose limit (25% uncertainty, k = 2) was 1.69 mGy. An averaging of eight MOSFET exposures was required to attain the corresponding TLD (0.3 mGy) low-dose limit. The sensitivity was 3.09 ± 0.13 mV/mGy independently of the photon energy used. The MOSFET dosimeters did not present dose or dose rate sensitivity but, however, presented a 1% decrease of sensitivity per 1000 mV for accumulated threshold voltages between 8300 mV and 17500 mV. The point doses in an anthropomorphic phantom ranged for MOSFETs between 0.24 mGy and 2.29 mGy and for TLDs between 0.25 and 2.09 mGy, respectively. The mean difference was -8%. The MOSFET dosimeters presented statistically insignificant energy dependency. By averaging multiple exposures, the MOSFET dosimeters can achieve a TLD-comparable low-dose limit and constitute a feasible method for diagnostic dosimetry using anthropomorphic phantoms. However, for single in vivo measurements (<1.7 mGy) the sensitivity is too low.

A Deep Learning-Based Automated CT Segmentation of Prostate Cancer Anatomy for Radiation Therapy Planning-A Retrospective Multicenter Study.

A commercial deep learning (DL)-based automated segmentation tool (AST) for computed tomography (CT) is evaluated for accuracy and efficiency gain within prostate cancer patients. Thirty patients from six clinics were reviewed with manual- (MC), automated- (AC) and automated and edited (AEC) contouring methods. In the AEC group, created contours (prostate, seminal vesicles, bladder, rectum, femoral heads and penile bulb) were edited, whereas the MC group included empty datasets for MC. In one clinic, lymph node CTV delineations were evaluated for interobserver variability. Compared to MC, the mean time saved using the AST was 12 min for the whole data set (46%) and 12 min for the lymph node CTV (60%), respectively. The delineation consistency between MC and AEC groups according to the Dice similarity coefficient (DSC) improved from 0.78 to 0.94 for the whole data set and from 0.76 to 0.91 for the lymph nodes. The mean DSCs between MC and AC for all six clinics were 0.82 for prostate, 0.72 for seminal vesicles, 0.93 for bladder, 0.84 for rectum, 0.69 for femoral heads and 0.51 for penile bulb. This study proves that using a general DL-based AST for CT images saves time and improves consistency.

Effective Radiation Dose in the Wrist Resulting from a Radiographic Device, Two CBCT Devices and One MSCT Device: A Comparative Study.

The objective of the present study was to assess and compare the effective doses in the wrist region resulting from conventional radiography device, multislice computed tomography (MSCT) device and two cone beam computed tomography (CBCT) devices using MOSFET dosemeters and a custom made anthropomorphic RANDO phantom according to the ICRP 103 recommendation. The effective dose for the conventional radiography was 1.0 µSv. The effective doses for the NewTom 5 G CBCT ranged between 0.7 µSv and 1.6 µSv, for the Planmed Verity CBCT 2.4 µSv and for the MSCT 8.6 µSv. When compared with the effective dose for AP- and LAT projections of a conventional radiographic device, this study showed an 8.6-fold effective dose for standard MSCT protocol and between 0.7 and 2.4-fold effective dose for standard CBCT protocols. When compared to the MSCT device, the CBCT devices offer a 3D view of the wrist at significantly lower effective doses.

LOW-DOSE CT PROTOCOL OPTIMIZATION FOR THE ASSESSMENT OF ACUTE APPENDICITIS: THE OPTICAP PHANTOM STUDY.

The aim was to evaluate effects of voltage, noise input (NI) and iterative reconstruction (IR) on radiation dose and image quality in order to establish a contrast enhanced low-dose protocol for assessment of acute appendicitis. An anthropomorphic abdominal phantom mimicking contrast enhanced abdomen was scanned with 80, 100 and 120 kV, standard and strong IR and 11 NIs (66 protocols). A total of 14 test tubes of increasing iodine dilutions and one tube with an appendicolith were evaluated within the phantom. The dose, HUs, noise, contrast-to-noise ratio (CNR) and figure of merit (FOM) were determined. Visual quality scores were assessed by two readers. A clinically used voltage-IR combination (120 kV, standard IR) was used as a reference. Overall, 100 kV with standard IR (p = 0.002) and 80 kV with both IRs (p < 0.001) showed higher CNR than the reference, but noise was most pronounced at 80 kV (p < 0.001). The highest FOM was found in the 100 kV protocols (p < 0.001). The reference and 100 kV with standard IR had highest image quality scores, where the 100 kV protocol enabled a distinct dose reduction. Lowering the voltage seems to be a more favorable tool than IR changes in optimizing the dose in contrast enhanced abdominal CT. TRIAL REGISTRATION: ClinicalTrials.gov number, NCT01022567.

Comparison of Effective Dose and Image Quality for Newborn Imaging on Seven Commonly Used CT Scanners.

This study compares the image quality and the patient doses on seven different computed tomography (CT) scanners for newborn chest imaging. The dose was measured by using an anthropomorphic newborn phantom and thermoluminescence dosemeters (TLDs). The effective dose was estimated separately based on a dose-length-product display, TLD measurements and the ImPACT CT dose calculation software. The image quality was assessed using a signal-to-noise ratio and a contrast-to-noise ratio (CNR). In order to compare the different scanners, a figure of merit (FOM) based on the rate of CNR2 and computed tomography dose index (CTDIvol) was calculated. The organ doses within the scan area ranged between 0.3 and 2.9 mGy and they depended on the organ and used scanner. The highest effective dose (1.1 mSv) was observed on Aquilion 32 and the lowest effective dose was observed on the Aquilion One (0.22 mSv). The lowest organ doses and highest FOM were observed on the Optima 660. With the Aquilion One and the Definition Dual Flash the examination was 71-90% faster when compared with other scanners. Newer devices equipped with novel dose-saving methods provide a lower dose, as well as take better advantage of the radiation in the image formation.

177Lu-PSMA-617 radioligand therapy for a patient with lymph node metastatic prostate cancer.

Prostate specific membrane antigen (PSMA) is expressed in unfavorable prostate cancer. PSMA is basis for new diagnostics and theranostics. PET/CT using PSMA is more sensitive than choline PET/CT. 177Lu-PSMA radioligand therapy is mainly used for patients with end-stage prostate cancer. This report describes a patient with a third recurrence in lymph nodes. The recurrence was treated with 177Lu-PSMA radioligand therapy instead of chemotherapy with docetaxel. The effect was in part evaluated relative to that of two established salvage treatments. Prior salvage radiotherapy and abiraterone of the first and second recurrence in lymph nodes had given only a partial reduction of PSA. Nevertheless within five months of follow-up, 177Lu-PSMA radioligand therapy of the third recurrence in lymph nodes reduced PSA for a period to unmeasurable levels. 177Lu-PSMA radioligand therapy gave only mild adverse effects. In conclusion, for a patient with lymph node metastatic prostate cancer, 177Lu-PSMA-617 radioligand therapy had an attractive therapeutic profile. A follow-up study of similar patients is being planned.

Radiotherapy Boost for the Dominant Intraprostatic Cancer Lesion-A Systematic Review and Meta-Analysis.

External beam radiotherapy (EBRT) for prostate cancer can be performed with a high dose of 86 Gy; however, one-tenth or more of the patients will develop recurrence. Prostate cancer is mainly multifocal, but a dominant intraprostatic lesion (DIL) is often the site of local recurrence after EBRT. We undertook a systematic review and meta-analysis to clarify whether functional imaging might identify the DIL and whether a RT boost to the DIL might be increased to an ultrahigh dose level of ≥ 90 Gy without increased toxicity. Of 62 selected studies, 13 reported the size of the DIL. The mean of the median DIL volumes was 2.4 cm(3) (95% confidence interval, 0.9-4.4 cm(3)). Eighteen diagnostic studies with 1205 patients evaluated the diagnostic accuracy using multiparametric magnetic resonance imaging for intraprostatic cancer lesions. Evaluating 14,654 prostate segments, the diagnostic accuracy was 77%. Eleven therapeutic studies with 988 patients reported a RT boost for the DIL. The summary boost dose for the DIL was a mean of 89 Gy in 5 studies using intensity modulated RT (calculated as the equivalent dose in 2-Gy fractions) and a mean of 141 Gy in 4 studies using a combination of EBRT and brachytherapy (P = .018, t test). In 1 therapeutic study, 239 patients had a 98% 10-year disease-free survival rate. Many of our therapeutic studies used a boost dose to the DIL of > 90 Gy. The reported boost for DIL is effective and safe.

Multimodal Primary Treatment of Metastatic Prostate Cancer with Androgen Deprivation and Radiation.

AIM: We combined anti-androgen therapy with radiotherapy in a first-line setting for metastatic prostate cancer aiming to cause maximal cancer-cell death to delay the emergence of castration-resistant disease. MATERIALS AND METHODS: In this non-randomized retrospective series of 46 patients, the initial median prostate-specific antigen (PSA) was 98.5 µg/l (range=6.7-15,500), median Gleason score 9 and most men had at least T3N1M1 disease. All patients received luteinizing hormone releasing hormone analog or degarelix with bicalutamide. If PSA remained above 1 µg/l, docetaxel was initiated. At PSA nadir, all patients received radical radiotherapy of the prostate. RESULTS: The median follow-up time was 4.38 years (range=0.36-11.24). Most radiotherapy-related adverse events were grade 1 and transient. There were no grade 4 events. Overall survival (OS) at 5 years was 81.3%. CONCLUSION: The feasibility and safety of aggressive multimodality treatment were good resulting in an excellent median OS of 8.35 years.

Dental cone beam CT: A review.

For the maxillofacial region, there are various indications that cannot be interpreted from 2D images and will benefit from multiplanar viewing. Dental cone beam CT (CBCT) utilises a cone- or pyramid-shaped X-ray beam using mostly flat-panel detectors for 3D image reconstruction with high spatial resolution. The vast increase in availability and amount of these CBCT devices offers many clinical benefits, and their ongoing development has potential to bring various new clinical applications for medical imaging. Additionally, there is also a need for high quality research and education. European guidelines promote the use of a medical physics expert for advice on radiation protection, patient dose optimisation, and equipment testing. In this review article, we perform a comparison of technical equipment based on manufacturer data, including scanner specific X-ray spectra, and describe issues concerning CBCT image reconstruction and image quality, and also address radiation dose issues, dosimetry, and optimisation. We also discuss clinical needs and what type of education users should have in order to operate CBCT systems safely. We will also take a look into the future and discuss the issues that still need to be solved.

Evaluation of Alpha-Therapy with Radium-223-Dichloride in Castration Resistant Metastatic Prostate Cancer-the Role of Gamma Scintigraphy in Dosimetry and Pharmacokinetics.

Radium-223-dichloride ((223)RaCl2) is a new bone-seeking calcium analogue alpha-emitter, which has obtained marketing authorization for the treatment skeletal metastases of hormone-refractory prostate cancer. The current treatment regimen is based on six consecutive doses of (223)RaCl2 at 4 week intervals and the administered activity dose, 50 kBq/kg per cycle is based on patient weight. We analyzed two patients using quantitative serial gamma imaging to estimate dosimetry in tumors and see possible pharmacokinetic differences in the treatment cycles. The lesions were rather well visualized in gamma scintigraphy in spite of low gamma activity (<1.1% gamma radiation) at 0, 7 and 28 days using 30-60 min acquisition times. Both our patients analyzed in serial gamma imagings, had two lesions in the gamma imaging field, the mean counts of the relative intensity varied from 27.8 to 36.5 (patient 1), and from 37.4 to 82.2 (patient 2). The half-lives varied from 1.8 days to 4.5 days during the six cycles (patient 1), and from 1.5 days to 3.6 days (patient 2), respectively. In the lesion half-lives calculated from the imaging the maximum difference between the treatment cycles in the same lesion was 2.0-fold (1.8 vs. 3.6). Of these patients, patient 1 demonstrated a serum PSA response, whereas there was no PSA response in patient 2. From our data, there were maximally up to 4.0-fold differences (62.1 vs. 246.6 ) between the relative absorbed radiation doses between patients as calculated from the quantitative standardized imaging to be delivered in only two lesions, and in the same lesion the maximum difference in the cycles was up to 2.3-fold (107.4 vs. 246.6). Our recommendation based on statistical simulation analysis, is serial measurement at days 0-8 at least 3 times, this improve the accuracy significantly to study the lesion activities, half-lives or calculated relative absorbed radiation doses as calculated from the imaging. Both our patients had originally two metastatic sites in the imaging field; the former patient demonstrated a serum PSA response and the latter demonstrated no PSA response. In these two patients there was no significant difference in the lesion activities, half-lives or calculated relative absorbed radiation doses as calculated from the quantitative imaging. Our results, although preliminary, suggest that dose monitoring can be included as a part of this treatment modality. On the other hand, from the absorbed radiation doses, the response cannot be predicted because with very similar doses, only the former patient responded.

Effective radiation dose of a MSCT, two CBCT and one conventional radiography device in the ankle region.

BACKGROUND: The aim of this study was to assess and compare the effective doses (ICRP 103) in the ankle region of X-ray imaging resulting from a multi slice computed tomography (MSCT) device, two cone beam CT (CBCT) devices and one conventional x-ray device. METHODS: Organ dose measurements were performed using 20 metal oxide field effect transistor (MOSFET) dosimeters that were placed in a custom made anthropomorphic RANDO ankle phantom. The following scanners were assessed in this study: Siemens Sensation Open 24-slice MSCT-scanner (120 kVp, 54 mAs), NewTom 5G CBCT scanner (110 kVp, 2.3 - 59 mAs), Planmed Verity CBCT-scanner (90 kVp, 48 mAs), Shimadzu FH-21 HR direct radiography equipment (AP + LAT), (57 kVp, 16 mAs). RESULTS: Measurements of the MSCT device resulted in 21.4 µSv effective dose. The effective doses of CBCTs were between 1.9 µSv and 14.3 µSv for NewTom 5G and 6.0 µSv for Planmed Verity. Effective doses for the Shimadzu FH-21 HR conventional radiography were 1.0 µSv (LAT) and 0.5 µSv (AP), respectively. CONCLUSIONS: Compared with a conventional 2D radiographic device, this study showed a 14-fold effective dose for standard MSCT and 1.3 -10 fold effective dose for standard CBCT protocols. CBCT devices offers a 3D view of ankle imaging and exhibited lower effective doses compared with MSCT.

Planning of External Beam Radiotherapy for Prostate Cancer Guided by PET/CT.

In this paper, we give an overview of articles on non-choline tracers for PET/CT for patients with prostate cancer and planning of radiotherapy guided by PET/CT. Nineteen articles described (11)C-Acetate PET/CT. Of 629 patients 483 (77%, 95% CI 74% - 80%) had positive (11)C-Acetate PET/CT scans. Five articles described (18)F-FACBC PET/CT. Of 174 patients, 127 (73%, 95% CI 68% - 78%) had positive scans. Both tracers detected local lesions, lesions in regional lymph nodes, and distant organs. Ten articles described (18)F-NaF PET/CT and found that 1289 of 3918 patients (33%) had positive reactive lesions in bones. PET/CT scan can guide external beam radiotherapy (EBRT) planning for patients with loco-regional prostate cancer. In six studies with 178 patients with localized prostate cancer, PET/CT pointed out dominant intraprostatic lesions (DIL). Oncologists gave EBRT to the whole prostate and a simultaneously integrated boost to the DIL. Four studies with 254 patients described planning of EBRT for patients with PETpositive lymph nodes. After the EBRT, 15 of 29 node-positive patients remained in remission for median 28 months (range 14 to 50 months). Most articles describe (11)C- and (18)F-Choline PET/CT. However, (11)C-Acetate and (18)F-FACBC may also be useful tracers for PET/CT. Planning of radiotherapy guided by MRI or PET/CT is an investigational method for localized prostate cancer. Current clinical controlled trials evaluate whether the method improves overall survival.

PET/CT Dose Planning for Volumetric Modulated Arc Radiation Therapy (VMAT) -Comparison with Conventional Approach in Advanced Prostate Cancer Patients.

Molecular imaging is the only way of defining biological target volume (BTV) for externalbeam radiation therapy (EBRT) and may be used for advanced targeting in dose planning and dose painting. There are, however, no reports about the EBRT response when dose planning is based on BTV target definition in advanced prostate cancer. Clinical and biochemical results of two clinically equal group of patients with advanced prostate cancer patients were compared. Both groups were treated with volumetric modulated arc therapy (VMAT) based on target definition by PET/CT (1(st) group) or conventional imaging (2(nd) group). Biochemical relapse occurred in 16.6% (in 1 out of 6) of the patients in the first group and 50% (3 out of 6) patients in the second group during the follow up period. Clinical manifestation of disease occurred in 33% (2 out of 6) patients of the first group and in 5 out of 6 (83,3%) patients in the second one. 4 patients in the first group had no biochemical relapse and no clinical manifestation during the follow up period. The difference in the duration of progression free period was statistically significant between the groups (p<0.010) being in the first group 16.5±5.4 (10-24) months and 4.6±2.9 (2-10) months in the second one. Because patients with PET/CT based VMAT had lower incidence of biochemical relapse, less clinical manifestations and longer, statistically significant duration of progression free period as compared to patients treated with VMAT based on conventional imaging, our preliminary results suggest introducing BTV definition based on PET imaging for VMAT in the EBRT of prostate cancer.

Volumetric-modulated arc therapy for a pelvic lymph node metastasis from prostate cancer: a case report.

A 50-year-old patient had an early biochemical recurrence after radical prostatectomy and androgen deprivation therapy and castration. An anti-1-amino-3-[¹8F] fluorocyclobutane-1-carboxylic acid positron emission tomography/computed tomography scan showed a single pelvic lymph node metastasis. The patient was given volume-modulated arc therapy with a cumulative dose of 50 Gy for the volume with pelvic lymph nodes and 78 Gy to the boost volume for the lymph node metastasis. He experienced only a transitory mild toxicity from the rectum and the urinary bladder and had a partial remission for 16 months.