| Home | E-Submission | Sitemap | Contact Us |  
Radiation Oncology Journal > Volume 42(1); 2024 > Article
Wong, Master, Pang, Yang, and Looi: Pulsed low-dose rate radiotherapy for recurrent bone sarcomas: case reports and brief review



Re-irradiation for bulky recurrent sarcoma carries significant risks. Pulsed low-dose rate radiotherapy (PLDR) is an attractive option for re-irradiation due to inherent radiobiological advantages.

Materials and Methods

We present two patients who underwent re-irradiation using PLDR technique, followed by a literature review.


The first case is that of a 76-year-old male who developed an in-field recurrence of a bulky pelvic bone high-grade chondrosarcoma after he was treated with definitive radiotherapy using helical TomoTherapy with a total dose of 66 Gy. The patient was re-irradiated using PLDR with a shrinking field technique; 50 Gy in 2 Gy fractions followed by a boost of 20 Gy in 2 Gy fractions. The patient remains disease-free without significant toxicity 60 months post-irradiation. The second case is that of an 82-year-old female who was treated with a definitive irradiation of 66 Gy in 33 fractions for a right shoulder grade II chondrosarcoma. She developed an in-field recurrence 28 months later and presented with bulky disease causing brachial plexopathy and lymphedema. The patient was re-irradiated with a palliative intent to a total dose of 50 Gy in 2 Gy fractions over 5 weeks using PLDR. Brachial plexopathy resolved shortly after re-irradiation, but local progression near the surface was evident 8 months later. She passed away from unrelated causes 11 months later.


We present two cases highlighting our early experience with PLDR, which was effective in the re-irradiation of recurrent bony sarcoma. Our study highlights PLDR as an option for re-irradiation in recurrent unresectable tumors.


Pulsed low-dose rate radiotherapy (PLDR) refers to radiation therapy delivered in a series of low-dose pulses separated by time intervals. The therapeutic benefits are two-fold: firstly, tumor response to radiation may be improved by a hyper-radiosensitivity phenomenon whereby improved oxygenation between pulses enhances sensitivity at doses below 0.3 Gy [1,2]. Secondly, the intrafraction time interval between each pulse may allow for an improved toxicity profile due to improved repair of sublethal DNA damage [1]. In an opinion article, Ma et al. [3] argued that the radiobiological advantages of PLDR will allow it to become the treatment modality of choice for the re-irradiation of recurrent cancers. Despite the radiobiological advantages, the adoption of this technique has been modest as a low-dose rate necessarily implies a longer treatment time. However, there is both preclinical and clinical evidence supporting the use of PLDR for re-irradiation, and PLDR has been adopted as routine clinical practice for re-irradiation in some centers [3]. Common indications include locally recurrent central nervous system (CNS) tumors, as well as unresectable recurrent esophageal, head neck, and breast tumors. Notably, there exists a paucity of data for re-irradiation of sarcoma, and as such we undertook to describe our experience with the use of PLDR for re-irradiation of two cases of unresectable locally recurrent bony sarcomas, which had received definitive irradiation previously. Additionally, we conducted a literature review of PLDR re-irradiation.

Case Report

Patient consent and ethics approval was obtained for this study (Singhealth cIRB Ref No. 2018/2020). We delivered PLDR using volumetric modulated arc therapy (VMAT). For both cases, we employed a 2-arc plan, utilizing each arc as one pulse. The pair of arcs was delivered five3 times, resulting in 10 pulses delivered over 30 minutes for each fraction. We selected VMAT over intensity-modulated radiotherapy as the inherent rotational pattern of delivery allowed for more degrees-of-freedom and better dose homogeneity for each pulse [4,5]. The dose rate used was 100 MU/min, which was suitably selected to allow the multi-leaf collimator to deliver the required dose modulation. In line with radiobiological studies, the maximum dose per pulse was less than 40–50 cGy.

1. Case presentations

Appendicular chondrosarcomas are radioresistant, hence surgery is the preferred treatment modality. However, when non-morbid complete resection is impossible, local control has been achieved with the use of high-dose radiotherapy. We describe two elderly patients who received PLDR re-irradiation for local control in this scenario.

Patient 1

The first patient was a 76-year-old male who had a 12-cm bulky high-grade chondrosarcoma of ilium. Complete resection would have required a hemipelvectomy, the morbidity of which was unacceptable to the patient. He was thus treated with definitive radiotherapy using helical TomoTherapy with a total dose of 66 Gy in 2 Gy fractions. Surveillance imaging demonstrated a stable treated lesion for 31 months until an F-fluorodeoxyglucose (FDG)-avid 4 cm nodule of the right ischium was demonstrated within the prior radiotherapy treatment volume without any evidence of systemic disease (Fig. 1). Subsequently, a biopsy confirmed the recurrence of high-grade chondrosarcoma. The patient declined surgery due to the expected morbidity with a complete resection, which would entail a hemipelvectomy. Particle therapy was not available within our treatment network at that time, and travel to an overseas center for particle therapy was financially and logistically prohibitive. The patient was re-irradiated using PLDR with a shrinking field technique. In the first phase, 50 Gy in 2 Gy fractions was delivered to the original tumor bed plus the recurrent disease, as we considered the entire original tumor bed to be at risk. This was followed by a boost of 20 Gy in 2 Gy fractions, resulting in a total dose of 70 Gy to the gross residual disease (Fig. 2). Daily megavoltage computed tomography imaging was performed to ascertain that the bowel was out of the target volume. The patient tolerated the re-irradiation well with minimal acute toxicities. Notably, there was complete resolution of the previously FDG-avid nodule 3 months after PLDR re-irradiation on computed tomography (CT) imaging. It has been 60 months since he received PLDR re-irradiation and he continues to remain disease-free without significant toxicity at 81 years of age. In terms of late toxicity, he has developed grade 2 fibrosis and mild telangiectatic skin changes, although functionally he is well with the European Cooperative Oncology Group performance status of 0.

Patient 2

The second case is that of an 82-year-old female with a grade II chondrosarcoma of the right proximal humerus, which had previously been treated with definitive irradiation as she was not able to accept the morbidity of a forequarter amputation that would be necessary for complete resection. She was treated with a total dose of 66 Gy in 33 fractions using three-dimensional conformal radiotherapy (3DCRT). She developed a bulky in-field recurrence 28 months later with lymphoedema, as well as brachial plexopathy due to tumor compression. Sequelae of late toxicity from prior radiotherapy treatment were also evident—i.e., skin fibrosis, skin atrophy, and telangiectasia were observed. She was restaged with CT imaging, which demonstrated bulky disease in the right proximal humerus with compression of the brachial plexus without any evidence of systemic disease (Fig. 3). The patient was re-irradiated with a palliative intent to a total dose of 50 Gy in 2 Gy fractions over 5 weeks using PLDR (Fig. 4). In terms of acute toxicity, she developed grade 2 dermatitis in the form of dry desquamation. There was a resolution of brachial plexopathy shortly after re-irradiation; lymphoedema resolved with physiotherapy as well. Six months post-re-irradiation, the tumor was stable on plain X-ray imaging; she was without motor weakness and the desquamation had resolved. There was significant fibrosis and telangiectasias, which were present prior to re-irradiation. However, at the 8th-month mark, a superficial component of the tumor had progressed and caused focal skin ulceration (Fig. 5). This was due to the underdosing of the superficial tumor from the skin-sparing effect of photons. The rest of the tumor remained stable. Otherwise, she did not exhibit overt normal tissue toxicities. Eleven months post-radiotherapy, she succumbed to a respiratory infection unrelated to the tumor.


With certain exceptions, surgical resection with complete margins is ideal for most recurrent tumors with prior irradiation. Unfortunately, management can be challenging as surgical resection may not always be feasible due to potential morbidity. Radiotherapy is often considered for definitive treatment as an alternative, but the cumulative dose and subsequent late toxicities often prohibit the delivery of curative doses. Re-irradiation with PLDR is an attractive option in this setting. Although the mechanisms are incompletely understood, pre-clinical studies have demonstrated low-dose hyper-radiosensitivity of tumor cells, a phenomenon also known as the “inverse dose rate effect” [6]. This phenomenon provides the potential for potentiating anti-tumor effects while minimizing normal tissue toxicity. The rationale behind this method lies in exploiting differences in radiation response between tumor cells and normal cells. As the radiation doses are delivered in pulses, allowing healthy cells to repair and recover between treatments. On the other hand, tumor cells are selectively damaged due to their reduced ability to repair DNA damage, thereby enhancing the therapeutic ratio in re-irradiation. There is also murine evidence that PLDR has better synergism with anti-programmed death-1 antibody than conventional radiotherapy [7].
Clinical studies on PLDR are limited mainly to single-institution retrospective studies and are mostly concerned with intra-cranial tumors, which likely reflects the limited treatment options in locally recurrent brain malignancies [8].
In a more recent report on novel unconventional radiotherapy techniques by Tubin et al. [9], PLDR was noted as a novel technique to overcome radio-resistance and mitigate normal organ toxicities in re-irradiation. However, the authors noted that although retrospective studies and even a single-arm prospective trial have been published, comparative studies with conventional delivery are lacking [9]. Additionally, many reports have limited follow-up. Thus, questions remain regarding the long-term effects of PLDR.
In this study, we contribute to the body of evidence that PLDR should be considered as an option for patients with prior irradiation presenting with bulky recurrences when an oncological resection is not possible. We report on two patients with locally recurrent chondrosarcoma who were not surgical candidates and thus underwent re-irradiation with PLDR. The first patient received re-irradiation with a total dose of 66 Gy and had a robust response with a 5-year survival with remarkably little toxicities. Our report therefore provides evidence, albeit anecdotal, that PLDR may mitigate the late toxicity associated with high cumulative doses after re-irradiation. In the second patient, we did not deliver a high dose due to significant pre-existing late toxicity from the initial course of definitive radiotherapy. Although there was an initial clinical response with improvement in brachial plexopathy, she eventually developed in-field progression of the superficial aspect of the tumor that caused skin ulceration 8 months later which we hypothesized was due to the skin-sparing effect of photons leading to under-dosing. She eventually succumbed to an unrelated condition.
Other novel techniques for delivering re-irradiation have been explored. These include spatially fractionated radiotherapy with either microbeams or specialized lead collimators; particle therapy with protons or carbon ions; or stereotactic radiotherapy. Each of these techniques exploits different radiobiological or dose-distribution mechanisms to improve tumor cell killing while minimizing normal organ toxicities. Spatially fractionated radiotherapy creates radiation low dose troughs and is hypothesized to improve immunological upregulation. Unfortunately, this technique requires additional resources in the form of training and equipment, and expertise may not be readily available. Particle therapy has a benefit over conventional radiotherapy through reduced low and intermediate-dose splash because of the inherent lack of an exit beam. Particle therapy is an attractive option for re-irradiation but is not always available within treatment networks; logistic and financial cost issues can also be prohibitive. Stereotactic body radiotherapy utilizes steep dose gradients to deliver high ablative doses and is an attractive option for small tumors. However, there can be significant toxicity for larger tumors, which may limit its utility for bulky recurrences. Compared to these modalities, PLDR is technologically easy to implement and requires no significant expense in equipment or training.
CNS tumors have been the focus of several PLDR re-irradiation studies [8,10-12]. In a study of 103 patients with recurrent gliomas, Adkison et al. [8] reported a median survival of 11.4 months for low-grade, 5.6 months for grade 3, and 5.1 months for grade 4 tumors. The median PLDR re-irradiation dose was 50 Gy and the average cumulative dose was 106.8 Gy. Patients with grade 4 disease who had a longer disease-free interval (<14 months vs. ≥14 months) before PLDR re-irradiation were found to have a longer median survival of 21 weeks versus 28 weeks, respectively. The mean treatment volume was 403 cm3. Four patients were found to have necrosis on autopsy. However, only 15 of the 103 patients underwent autopsy and the true rate is likely higher. The authors concluded that PLDR is safe and allows for the retreatment of larger volumes [8]. Murphy et al. [10] reported the outcomes of 24 patients with a variety of CNS tumors who received PLDR re-irradiation for recurrent disease. The median dose for PLDR re-irradiation was 54 Gy, while the median target volume was 369.1 cm3. With a median follow-up of 5.2 months, the median overall survival (OS) and 6-month OS after PLDR treatment was 8.7 months and 71%, respectively. The rate of grade 3 toxicity after PLDR re-irradiation was 18.1%, which was similar to the rate of 20.7% after initial therapy. There was no recorded event of necrosis, which is reassuring, considering that the group was heavily pretreated, with 50% or more having undergone 4 or more lines of systemic therapy. Bovi et al. [12] investigated the addition of PLDR re-irradiation to bevacizumab in patients with recurrent high-grade gliomas. In this retrospective study of 80 patients, 47 patients were treated with bevacizumab alone, while 33 received additional PLDR re-irradiation. There were statistically significant improvements to the progression-free survival (PFS; 12 months vs. 4 months) and OS (16 months vs. 9 months) in the PLDR group. In a study of recurrent ependymoma (ages 3–31, with 8 lesions; 2 brains and 6 spinal cord) requiring large field re-irradiation post initial resection and adjuvant radiotherapy, patients received a median cumulative dose of 105 Gy after a median interval between radiotherapy of 58 months. The 4-year OS rate was 60% and no patients developed necrosis on serial magnetic resonance imaging scans, although one patient developed radiculopathy [11]. The median portal volume for patients treated with 2D-planning techniques was 348 cm2, while the median volume encompassed by the prescribed dose was 82.9 cm3 for those treated with 3DCRT. With a notable median follow-up of 64 months, the estimated 4-year OS and PFS were 60% and 35.7%, respectively. In a recent publication, Kutuk et al. [13] reported on their experience with PLDR re-irradiation in 18 patients with recurrent primary CNS malignancies. At a median follow-up of 8.7 months, the median PFS and OS were 5.7 months and 6.7 months, respectively. The median cumulative prescription dose was 102.7 Gy and symptomatic radiation necrosis occurred in three patients. The conclusion was that despite the high-cumulative dose to organs at risk, the tumor control and toxicity outcomes were within expectations. These studies suggest that in patients with CNS recurrences who have undergone previous radiotherapy, PLDR is an option that warrants consideration, especially when large-volume treatment is required. This is particularly useful when other options such as surgical resection or stereotactic radiosurgery are not feasible.
Richards et al. [14] reported outcomes of 17 patients with breast cancer re-irradiation with PLDR with a median prior radiation dose of 60 Gy and median PLDR dose of 54 Gy. All patients exhibited a response—15 patients had a complete response, and two had a partial response. After a median follow-up of 18 months, two failed in-field. The estimated 2-year local control rate was 92%. Four patients had grade 3 acute skin toxicity. The median cumulative dose was 110 Gy. Two patients developed non-healing ulcers as late toxicity; both had complicated surgical histories with wound healing issues before PLDR. This outcome measures favorably against other data from conventional re-irradiation.
Limited data exists for PLDR in head and neck cancers. A case report described a patient with recurrent nasopharyngeal carcinoma who received PLDR as a third course of radiotherapy resulting in a total of 190 Gy delivered cumulatively [15]. A complete response was achieved. However, the long-term follow-up outcomes of this patient were not described.
For gastrointestinal cancers, Yang et al. [16] published a phase 2 study of 14 patients who received 50–54 Gy abdominal PLDR. Eleven of them exhibited partial responses, and three demonstrated disease stability. No serious adverse effects were observed. A later study by the same authors [17] demonstrated that the combination of capecitabine and oxaliplatin, immunotherapy, and PLDR for gastric cancers with peritoneal dissemination was tolerable and efficacious with an objective response rate of 70.8%.
There is a paucity of data for sarcomas. PLDR for chondrosarcoma was briefly reported in a case series by Yan et al. [18] in which a middle-aged patient with locally recurrent indolent chondrosarcoma received 54 Gy/27 fractions palliative re-irradiation after initial 50 Gy and the conclusion was that PLDR was safe and effective. Our case reports contribute to the scant literature on PLDR for sarcomas.
Lee et al. [19] reported the outcomes of 39 patients who received PLDR re-irradiation using forward-planning techniques to targets in the thorax, abdomen, and pelvic region. With a median dose of 50.4 Gy and 50 Gy for first and re-irradiation and a median follow-up of 8 months, 79% experienced symptomatic improvement. Although 23% of patients experienced grade 2 or more toxicities, none developed grade 4 or 5 toxicities. In a study of 13 patients with recurrent cancer (head and neck, lung, and pelvis sites), Tong et al. [20] reported responses in all patients—partial and complete responses in 10 and three patients, respectively. The previous dose received was ≥50 Gy in all patients, while the re-irradiation dose ranged from 10 Gy to 60 Gy. With a median follow-up of 27 months, all toxicities were grade 2 or lower, with only one patient developing grade 3 toxicity in the form of skin fibrosis.
In conclusion, PLDR is a novel radiotherapy technique that exploits the radiobiological phenomenon of low-dose hyper-radiosensitivity to maximize tumor killing in tumors while minimizing normal organ toxicities by encouraging sublethal repair. Compared to alternative re-irradiation modalities, PLDR is relatively simple to implement and can be used for large, bulky tumors. However, the low dose rate requires a longer time on couch. Our two cases highlight our early experience with PLDR irradiation for bulky recurrences of recurrent bony sarcoma. Notably, one patient has remained in long-term remission for 5 years without significant treatment sequelae. We also conducted a literature review of PLDR in re-irradiation and our findings recapitulate the safety and efficacy of PLDR as an option in the setting of re-irradiation of recurrent tumors where resection is not feasible. Although the data is encouraging, more prospective studies are required, particularly to compare its efficacy against conventional photons.


Statement of Ethics

Patient consent and ethics approval was obtained for this study (Singhealth cIRB Ref No. 2018/2020).

Conflict of Interest

No potential conflict of interest relevant to this article was reported.


We would like to thank the various therapists, physicists and physicians in the National Cancer Center of Singapore for evaluating, implementing and delivering pulsed low dose rate radiotherapy in patients.



Author Contributions

Conceptualization, Wong RX, Master Z, Pang E; Data curation, Wong RX; Formal analysis, Wong RX; Investigation, Wong RX; Methodology, Wong RX; Validation, Wong RX, Looi WS; Visualization, Wong RX, Master Z, Pang E; Writing–original draft, Wong RX; Writing-review & editing, Wong RX, Yang VSW, Looi WS, Master Z, Pang E.

Data Availability Statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.

Fig. 1.
(A) Axial CT image demonstrating recurrent soft tissue centered within the ischium and hemi-sacrum at diagnosis for patient #1. (B) FDG-avid biopsy-proven recurrence after definitive radiotherapy. (C) Axial CT image at the same level 50 months after post PLDR re-irradiation demonstrated radiotherapy showed complete resolution of the soft tissue recurrence. CT, computed tomography; FDG, F-fluorodeoxyglucose; PLDR, pulsed low-dose rate radiotherapy.
Fig. 2.
(A) PLDR VMAT (superior) and (B) initial TomoTherapy RT (inferior) plans for patient #1 show a 90% isodose line in pink. PLDR, pulsed low-dose rate radiotherapy; VMAT, volumetric modulated arc therapy; RT, radiotherapy.
Fig. 3.
Coronal CT images of the right shoulder chondrosarcoma for patient #2: (A) before first radiotherapy and (B) 28 months later. Before re-irradiation, it demonstrated skin involvement and tumor growth at the superior aspect, compression of neurovascular structures, and distortion of the chest wall at the medial aspect.
Fig. 4.
(A) PLDR VMAT (superior) and (B) initial 3DCRT (inferior) plans for patient #2. PLDR, pulsed low-dose rate radiotherapy; VMAT, volumetric modulated arc therapy; 3DCRT, three-dimensional conformal radiotherapy.
Fig. 5.
A skin ulceration due to tumor invasion (patient #2) was evident over the superficial component of the tumor which grew 8 months post-re-irradiation.


1. Joiner MC, Marples B, Lambin P, Short SC, Turesson I. Low-dose hypersensitivity: current status and possible mechanisms. Int J Radiat Oncol Biol Phys 2001;49:379–89.
crossref pmid
2. Tome WA, Howard SP. On the possible increase in local tumour control probability for gliomas exhibiting low dose hyper-radiosensitivity using a pulsed schedule. Br J Radiol 2007;80:32–7.
crossref pmid
3. Ma CM, Luxton G, Orton CG. Point/counterpoint: pulsed reduced dose rate radiation therapy is likely to become the treatment modality of choice for recurrent cancers. Med Phys 2011;38:4909–11.
crossref pmid pdf
4. Kang S, Lang J, Wang P, et al. Optimization strategies for pulsed low-dose-rate IMRT of recurrent lung and head and neck cancers. J Appl Clin Med Phys 2014;15:4661.
crossref pmid pdf
5. Lin MH, Price RA, Li J, Kang S, Li J, Ma CM. Investigation of pulsed IMRT and VMAT for re-irradiation treatments: dosimetric and delivery feasibilities. Phys Med Biol 2013;58:8179–96.
crossref pmid
6. Leonard BE. Thresholds and transitions for activation of cellular radioprotective mechanisms: correlations between HRS/IRR and the 'inverse' dose-rate effect. Int J Radiat Biol 2007;83:479–89.
crossref pmid pmc
7. Zhang P, Yin S. Impacts of combining pulsed low dose rate radiotherapy (PLDR) and anti-PD-1 antibody on tumor growth and its mechanism for lung cancer in mice. Int J Radiat Oncol Biol Phys 2023;117(2 Suppl):E278.
8. Adkison JB, Tome W, Seo S, et al. Reirradiation of large-volume recurrent glioma with pulsed reduced-dose-rate radiotherapy. Int J Radiat Oncol Biol Phys 2011;79:835–41.
crossref pmid
9. Tubin S, Vozenin MC, Prezado Y, et al. Novel unconventional radiotherapy techniques: current status and future perspectives - report from the 2nd international radiation oncology online seminar. Clin Transl Radiat Oncol 2023;40:100605.
crossref pmid pmc
10. Murphy ES, Rogacki K, Godley A, et al. Intensity modulated radiation therapy with pulsed reduced dose rate as a reirradiation strategy for recurrent central nervous system tumors: an institutional series and literature review. Pract Radiat Oncol 2017;7:e391–9.
crossref pmid
11. Mohindra P, Robins HI, Tome WA, Hayes L, Howard SP. Wide-field pulsed reduced dose rate radiotherapy (PRDR) for recurrent ependymoma in pediatric and young adult patients. Anticancer Res 2013;33:2611–8.
12. Bovi JA, Prah MA, Retzlaff AA, et al. Pulsed reduced dose rate radiotherapy in conjunction with bevacizumab or bevacizumab alone in recurrent high-grade glioma: survival outcomes. Int J Radiat Oncol Biol Phys 2020;108:979–86.
crossref pmid pmc
13. Kutuk T, Tolakanahalli R, McAllister NC, et al. Pulsed-reduced dose rate (PRDR) radiotherapy for recurrent primary central nervous system malignancies: dosimetric and clinical results. Cancers (Basel) 2022;14:2946.
crossref pmid pmc
14. Richards GM, Tome WA, Robins HI, et al. Pulsed reduced dose-rate radiotherapy: a novel locoregional retreatment strategy for breast cancer recurrence in the previously irradiated chest wall, axilla, or supraclavicular region. Breast Cancer Res Treat 2009;114:307–13.
crossref pmid pdf
15. Li GH, Zhu B, Yang F, Ma CK, Yang DQ. Use of cetuximab in combination with pulsed reduced dose-rate radiotherapy in a patient with recurrence of nasopharyngeal carcinoma in the neck. Exp Ther Med 2012;3:869–72.
crossref pmid pmc
16. Yang Y, Yan J, Liu J, et al. Phase 2 study of pulsed low dose rate radiation therapy for gastric cancer patients with peritoneal metastasis. Int J Radiat Oncol Biol Phys 2017;99(2 Suppl):E201.
17. Yang Y, Yan J, Liu J, et al. Phase II study of combining immunotherapy and pulsed low dose rate radiotherapy for abdominal metastasis of gastric cancer. J Clin Oncol 2021;39(15_suppl):e16099.
18. Yan J, Yang J, Yang Y, et al. Use of pulsed low-dose rate radiotherapy in refractory malignancies. Transl Oncol 2018;11:175–81.
crossref pmid pmc
19. Lee CT, Dong Y, Li T, et al. Local control and toxicity of external beam reirradiation with a pulsed low-dose-rate technique. Int J Radiat Oncol Biol Phys 2018;100:959–64.
crossref pmid
20. Tong X, Luo FS, Yang GR, et al. A clinical study on pulsed low dose rate radiation therapy for recurrent cancers. Mathews J Cancer Sci 2021;6:28.
Editorial Office
Department of Radiation Oncology, Samsung Medical Center,
Proton Therapy Center, B2, 81, Irwon-ro, Gangnam-gu, Seoul 06351, Republic of Korea
Tel : +82-2-3410-3617
E-mail: rojeditor@gmail.com, roj@kosro.or.kr
Copyright © The Korean Society for Radiation Oncology.                      Developed in M2PI
Close layer
prev next