Advances in laser therapies for the scar. / ç˜¢ç—•çš„æ¿€å ‰æ²»ç–—è¿›å±•.

Scars are classified into 5 types: Superficial scars, hypertrophic scars, atrophic scars, depressed scars, and keloid. These types are primarily characterized by abnormal production of fibroblasts and collagen, as well as the disorderly arrangement of connective tissue. Laser treatment for scars involves the coordinated activation of various signaling pathways and cytokines. However, the exact pathological mechanism for scar formation remains unclear, leading to a lack of radical treatment. Recently, laser treatment has gained popularity as a new minimally invasive approach for scar treatment. The emergence of new theories such as fractional, picosecond laser, and laser-assisted drug delivery has led to continuous advance in laser treatment. Up to now, it has been developed numerous novel treatments, including combined with drug, physical, and other treatments, which have shown superior therapeutic effects. In order to optimize laser treatment in the future, it is crucial to combine new materials with postoperative care. This will help clinicians develop more comprehensive treatment strategies. Therefore, it is important to explore treatment options that have broader applicability.

[Clinical study of ear keloids with surgical excision and intraoperative low-energy X-ray irradiation therapy].

Objective:To explore the clinical efficacy of surgical excision combined with low-energy X-ray irradiation in the treatment of ear keloids. Methods:Clinical data of 32 cases of ear keloid lesions that received surgical treatment alone or surgery combined with radiotherapy from March 2019 to November 2022 in the Department of Otorhinolaryngology Head and Neck Surgery of the Tianjin First Central Hospital were retrospectively analyzed. Among them, 10 cases received radiotherapy and 22 cases did not receive radiotherapy. The radiotherapy group received irradiation with a large divided dose of 50 kV low-energy X-rays. The mode of fractionation radiotherapy was as follows: the first was 10 Gy of intraoperative radiation therapy and the second was 8 Gy on the 3rd postoperative day for a total of 18 Gy. The local efficacy and skin radiation reaction were observed at a follow-up of 8-52 months. Results:The median follow-up was 26 months, and as of the date of the last follow-up, 9 cases were cured and 1 case was ineffective in the radiotherapy group, with an effective rate of 90.0%, while 9 cases were cured and 13 cases were ineffective in the no-radiotherapy group, with an effective rate of 40.9%. The recurrence of ear keloids was not related to the side, site, or etiology of the patient's onset（P>0.05）. Recurrence was related to whether or not the patients received radiotherapy（χ²=4.885, P<0.05）, and the recurrence rate in the radiotherapy group（10.0%） was significantly lower than that in the non-radiotherapy group（59.1%）. Conclusion:Surgical excision combined with low-energy X-ray irradiation therapy is an effective method of treating keloids in the ear, especially with intraoperative radiation therapy can achieve more satisfactory results.

A Single-Institution Review of the Use of Radiation in the Adjuvant and Definitive Management of Keloids.

AIMS: Many individuals suffer from keloids that are refractory to standard treatment modalities, including surgical excision alone. Radiation therapy can be used to reduce the risk of recurrent keloids post-operatively, as well as be used as primary treatment for keloids not amenable to surgical resection. The purpose of this study was to review our institutional experience of radiation therapy for keloid management. MATERIALS AND METHODS: A retrospective review of patients treated with radiation therapy for keloids between 2014 and 2020 at our institution was performed. RESULTS: A total of 70 keloids in 41 patients were treated. For the 55 keloids treated with post-operative radiation therapy (16Gy delivered in 2 fractions), 82.5% (33/40) of evaluable lesions did not recur. Among the 15 keloids treated with definitive radiation therapy (24Gy delivered in 3 fractions), 78.6% (11/14) of evaluable keloids showed complete flattening, and 14.3% (2/14) had partial flattening. Both acute and late toxicities were mild, with only a single instance of grade 3 toxicity (dermatitis). CONCLUSION: Our study confirms that radiation therapy has a role in reducing the risk of keloid recurrence post-operatively, and plays an important role in the definitive management of unresectable keloids.

Effective keloid management using a combinatorial continuous-wave and repeat fractionated ablative CO2 laser regimen.

BACKGROUND: Keloids are benign proliferative scars that form as a result of dysregulated growth and collagen deposition in response to cutaneous injury. Laser therapies have emerged as promising options for the treatment of keloids, with performance varying by laser type and lesion characteristics. PURPOSE: To assess the combined continuous wave and repetitive fractionated CO2 laser treatment of keloids. METHODS: A retrospective chart review of 22 cases of keloid scars treated with combined CO2 laser modes. A single session of continuous wave followed by five sessions of fractional delivery. Efficacy was assessed using the Patient and Observer Scar Assessment Scale (POSAS) and the Vancouver Scar Scale. The Numeric Rating Scale was used to assess patient satisfaction and pain. RESULTS: Most patients were female (77.3%) with skin type IV (72.7%), age was 24.3 ± 9.3 years, most keloids were located on the earlobe (56.5%) or arm or hand (17.4%), size ranged from 5 to 10 cm, and time since injury ranged from 3 months to 35 years. No serious adverse events were reported. At 6 months, significant improvements from baseline occurred in all characteristics, scar color (4.8 ± 2.8 to 1.9 ± 1.1), rigidity (5.0 ± 2.8 vs. 5.4 ± 2.8), thickness (5.4 ± 2.8 vs. 2.0 ± 1.1), and irregularity (5.9 ± 2.4 vs. 1.9 ± 0.9). The Vancouver scores followed a similar trend. Patient-rated overall improvement from 37 ± 17.6 at baseline to 16.1 ± 8.5 at 6 months, and improvement in associated pain and pruritus. CONCLUSION: Combination of two ablative laser delivery modes within a single laser platform provided for effective and safe keloid management and left patients highly satisfied.

Risk factors for local recurrence of keloids and hypertrophic scars after postoperative electron beam radiotherapy.

OBJECTIVE: Keloids and hypertrophic scars are benign fibroproliferative lesions that occur as a result of skin injury. Postoperative radiation therapy is used to reduce the recurrence rate because of the high recurrence rate with surgical treatment alone. This study aimed to identify the risk factors for recurrence after postoperative electron beam radiotherapy. MATERIALS AND METHODS: Patients with keloid or hypertrophic scars with at least one lesion and who underwent postoperative electron beam radiotherapy at our institution from June 2013 to March 2022 were included in the study, while patients with a follow-up period of fewer than three months were excluded. RESULTS: A retrospective analysis was performed on 94 lesions in 81 patients. Exactly two years after the treatment, the actuarial local control rate was 86.4%. The chest wall, shoulder, and suprapubic area were identified as high-risk recurrence sites. Compared to other body sites, these sites had significantly lower local control rates (two-year local control rates: 75.5% vs. 95.2%, P = 0.005). After multivariate analysis, treatment site (P = 0.014), male gender (P = 0.019), and younger age (P = 0.029) were revealed to be statistically significant risk factors for local recurrence. Risk factors for keloid recurrence after postoperative electron beam radiotherapy were therefore identified. CONCLUSION: This result could be used for follow-up and as a determinant for the optimal dose/fractionation of postoperative radiotherapy.

Application of fractional carbon dioxide laser monotherapy in keloids: A meta-analysis.

BACKGROUND: There is no evidence-based guidance on the use of fractional CO2 laser in the excision of scars. AIM: To explore the effectiveness and safety of fractional CO2 laser in the treatment of keloids. METHODS: In this meta-analysis, we searched the PubMed, Embase, and Cochrane databases from inception to April 2023. We only included studies reporting fractional CO2 laser treatment of keloids. We excluded duplicate published studies, incomplete studies, those with incomplete data, animal experiments, literature reviews, and systematic studies. RESULTS: The pooled results showed that the Vancouver Scar Scale (VSS) parameters of height weighted mean difference (WMD) = -1.10, 95% confidence interval (CI): -1.46 to -0.74), pigmentation (WMD = -0.61, 95% CI: -1.00 to -0.21), and pliability (WMD = -0.90, 95% CI: -1.17 to -0.63) were significantly improved after fractional CO2 laser treatment of keloids. However, vascularity did not significantly change. Additionally, the total VSS was significantly improved after treatment (WMD = -4.01, 95% CI: -6.22 to -1.79). The Patient Scars Assessment Scale was significantly improved after treatment (WMD = -15.31, 95% CI: -18.31 to -12.31). Regarding safety, the incidences of hyperpigmentation, hypopigmentation, pain, telangiectasia, and atrophy were 5%, 0%, 11%, 2% (95% CI: 0%-6%), and 0% (95% CI: 0%-4%), respectively. CONCLUSIONS: Fractional CO2 laser is effective in the treatment of keloids and can effectively improve the height, pigmentation, and pliability of scars, and patients are satisfied with this treatment. Further studies should explore the role of combination therapy.

Post-operative KEloids iRradiation (POKER): does the surgery/high-dose interventional radiotherapy association make a winning hand?

PURPOSE: To report the results involving post-operative interventional radiotherapy (POIRT) in a homogenous cohort of patients affected by keloid and treated at a single institution with the same fractionation schedule. PATIENTS AND METHODS: Inclusion criteria were: surgery with a histopathological diagnosis of keloid, subsequent high-dose rate interventional radiotherapy (HDR-IRT)-12 Gy in 4 fractions (3 Gy/fr) twice a day-and follow-up period ≥ 24 months. RESULTS: One-hundred and two patients and a total of 135 keloids were eligible for the analyses. Median follow-up was 64 [IQR: 25-103] months. Thirty-six (26.7%) recurrences were observed, 12-months and 36-months cumulative incidence of recurrence were 20.7% (95% CI 12.2-28.5) and 23.8% (95% CI 14.9-31.7) respectively. History of spontaneous keloids (HR = 7.00, 95% CI 2.79-17.6, p < 0.001), spontaneous cheloid as keloid cause (HR = 6.97, 95% CI 2.05-23.7, p = 0.002) and sternal (HR = 10.6, 95% CI 3.08-36.8, p < 0.001), ear (HR = 6.03, 95% CI 1.71-21.3, p = 0.005) or limb (HR = 18.8, 95% CI 5.14-68.7, p < 0.001) keloid sites were significantly associated to a higher risk of recurrence. CONCLUSIONS: The findings support the use of surgery and POIRT as an effective strategy for controlling keloid relapses. Further studies should focus on determining the optimal Biologically Effective Dose and on establishing a scoring system for patient selection.

Efficacy and safety of surgical excision and reconstruction combined with radiotherapy for huge keloids: A 13-year experience.

BACKGROUND: Surgical excision combined with radiotherapy is considered an effective treatment for keloids, while the efficacy and safety of this regimen for huge keloids in patients who need reconstruction after excision is still unclear. Therefore, this study aimed to evaluate the efficacy and safety of surgical excision and reconstruction combined with radiotherapy for huge keloids in a single center with 13 years of experience. METHODS: All consecutive patients with huge keloids who underwent surgical excision and reconstruction combined with radiotherapy were identified. Demographic information, prior interventions for keloids, parameters and complications, and recurrence rates were documented. RESULTS: Twenty-one patients (10 males; mean age, 43.19 ± 18.15 years) were included, 14 patients reconstructed with z-plasties, 5 with skin grafts, and 2 with skin flaps. During a mean follow-up of 75 months, one patient developed local necrosis without the need for revision surgery and two patients developed temporary hyperpigmentation. Two patients with the z-plasties suffered partial keloids recurrence, which was healed with corticosteroid injection. No wound infection, hematoma, telangiectasia, or new keloids at donor sites were observed. The overall appearance of reconstructed defects was aesthetically acceptable. CONCLUSION: Surgical excision and reconstruction combined with radiotherapy may be safe and effective for huge keloids.

Outcomes of omega variant keystone flap in conjunction with single fraction radiotherapy for helical keloids: A comprehensive one-year follow-up study.

BACKGROUND: Achieving esthetically pleasing results for helical keloids can be challenging. This study aims to share the results of a treatment approach for helical keloids, which involves complete excision and reconstruction using an omega variant keystone flap, followed by a single fractional radiotherapy. METHODS: The current study is a retrospective review of 25 helical keloids in 21 patients from May 2021 to March 2023. All keloid cases were excised entirely. We covered the defect with an omega variant keystone flap followed by a single fraction of 9.5 or 10 Gy radiotherapy within 24 h after surgery. The mean follow-up period was 12 months. The primary outcome was recorded as recurrence versus non-recurrence. The secondary outcome was scores assessed by the Patient and Observer Scar Assessment Scale. RESULTS: All 25 keloids in 21 patients completed the treatment protocol, with a follow-up interval of 12 months. Of these patients, 100% had successful treatment of their keloids without any keloid recurrence. The postoperative course was uneventful except for one case of early postoperative flap congestion, which was spontaneously healed without any interventions. Scores obtained from the Patient and Observer Scar Assessment Scale showed that pain, itchiness, color, stiffness, thickness, irregularity, vascularity, pigmentation, thickness, relief, and pliability significantly improved. (p < 0.001). CONCLUSIONS: We successfully reconstructed helical keloids using an omega variant keystone flap after keloid removal followed by 9.5 or 10 Gy single fractional radiotherapy without any keloid recurrence in one-year follow-ups.

Inhibition of keloid by 32P isotope radiotherapy through suppressing TGF-ß/Smad signaling pathway.

BACKGROUND: Keloid seriously affects the appearance, and is accompanied by some symptoms including pain, burning, itching. Radioactive nuclides such as 32P have been proved to be effective in inhibiting the formation of keloid, but the mechanism remains unclear. METHODS: The keloid animal model was established through keloid tissues implantation. Hematoxylin-Eosin (HE) and Masson staining were performed to investigate histological changes and collagen deposition. The mRNA and protein expression were assessed using RT-PCR and western blotting, respectively. Cell apoptosis and cycle were evaluated through flow cytometry. RESULTS: Both 32P isotope injection and skin path significantly reduced the size of keloid, and inhibited TGF-ß/Smad signaling pathway. SRI-011381, the agonist of TGF-ß/Smad signaling pathway, markedly reversed the influence of 32P isotope on cell proliferation, cell apoptosis, cell cycle of LNCaP cells and TGF-ß/Smad signaling pathway. CONCLUSIONS: 32P isotope injection and skin path greatly reduced the size of keloid, and the TGF-ß/Smad signaling pathway was remarkably inhibited by 32P isotope treatment. The regulation of dermal fibroblast by 32P isotope was reversed by SRI-011381. 32P isotope might inhibit keloid through suppressing TGF-ß/Smad signaling pathway. Our study provides a novel therapeutic strategy for the treatment of keloid.

Efficacy of a multimodal approach of laser therapy for earlobe keloids management in dark population.

BACKGROUND: Patients with keloids are often younger than 30 years old and have darker skin. AIM: To evaluate the efficacy and safety of CO2 laser therapy in the management of earlobe and helix keloids in dark subjects. METHODS: A total of 21 dark patients (five men and 16 women) presented with the earlobe and ear helix keloids, with a mean age of 30.5 (±6.7) years and with phototype between III-VI, were enrolled. In order to improve their earlobe and helix keloids, all patients underwent a single session of CO2 laser therapy immediately followed by a pulsed Dye laser procedure. A single well-experienced doctor performed all treatment sessions and the response to treatment. Patients were followed-up for 6 months after termination of therapy. Clinical images were examined and collected: all patients were examined clinically and with Dermoscopy. RESULTS: The majority of the patients treated show complete remission of keloid lesions. Clinical photographs show a visible aesthetic improvement of several types of keloids in dark subjects. CONCLUSIONS: Our data demonstrate that this combined laser therapeutic protocol appears to be effective and well tolerated for the management of earlobe and helix keloids in dark subjects, with no high recurrence rate and avoiding the adverse effects and lengthy recovery time.

Risk factors for recurrence after keloid surgery with electron radiotherapy.

The aim of this study was to investigate the effect of postoperative electron radiotherapy (RT) on local control for keloids and to identify risk factors for recurrence. The clinical data of 82 patients treated at our institution from January 2015 to October 2019 were collected. The data included the general condition of the patients, clinical characteristics of the keloids, treatment plan, local control, and treatment side effects. A total of 82 patients (129 keloids) were included. The study included 23 men (28%) and 59 females (72%). The median patient age was 32 years (range, 18-67 years). Twenty-six recurrences were observed, and the 1-, 3-, and 5-year local control rates were 93%, 81%, and 73%, respectively. Univariate analysis revealed that age (P = .03), hypertension (P = .04), scar shape (P < .001), primary site (P = .02), maximum lesion diameter (P < .001), pain and itching (P = .005), local tension (P = .005), and infection (P < .001) were risk factors for local recurrence. Multivariable analysis revealed that maximum lesion diameter (P < .001), infection (P < .001), interval between surgery and RT (P = .02), and previous treatment (P = .02) were independent risk factors. Complete excision of keloids combined with electron RT is safe and seemingly effective. For keloids with a high risk of recurrence, more aggressive treatment should be chosen, and further prospective studies are needed to explore the optimal treatment.

Quantitative study on dose distribution of Freiburg flap for keloid high-dose-rate brachytherapy based on MatriXX.

PURPOSE: To quantify the dose distribution effect of insufficient scattering conditions in keloid HDR brachytherapy with Freiburg fFlap (FF) applicator. MATERIALS AND METHODS: A phantom composed of FF applicator, MatriXX and solid water slices was designed and scanned for treatment planning. Bolus with different thicknesses were covered to offer different scatter conditions. Planar dose distributions were measured by MatriXX. The maximum value (Max), average value (Avg) and γ passing rate (3 mm/3%) were evaluated by the software MyQA Platform. RESULTS: The maximum and average doses measured by MatriXX were lower than the calculated values. The difference increased as field size decreased. The Max value, found at 0.86 cm level in the two tube case, was -20.0%, and the avg value was -11.9%. All the γ values were less than 95%. This difference gradually decreased with increasing bolus thickness and the γ values were significantly improved. CONCLUSION: MatriXX could be used for dose verification of HDR brachytherapy with an FF applicator. When the FF applicator was applied for keloid, insufficient scattering conditions would cause an insufficient target dose. This difference could be reduced by covering the bolus with different thicknesses on the applicator. The smaller the field, the thicker the bolus required.

Surgical Treatment for Chest "Lock" Keloid Using Autologous Split-Thickness Skin Grafting and Postoperative Radiotherapy.

BACKGROUND: The treatment of chest "lock" keloids is challenging due to skin defects and a high recurrence rate. OBJECTIVE: Evaluation of the effectiveness of autologous split-thickness skin graft with local radiotherapy for treating chest "lock" keloids. METHODSAND MATERIALS: Fifty-seven patients with chest "lock" keloids were treated from July 2018 to September 2020. The skin defects were closed with an autologous split-thickness skin graft (STSG) and vacuum sealing drainage. The donor and the recipient sites received the first session of radiotherapy 72 hours postoperation for 3 consecutive days. Patients underwent follow-up examinations 12 months after surgery. The Patient and Observer Scar Assessment Scale (POSAS) was used to assess the treatment outcome. RESULTS: Except for the complaints of pain, which did not improve in the patients' assessments (p = .368), POSAS improved significantly after treatment (p < .0001). The cure rate (including cured and partially cured scars) was 100%. No keloid recurrence was observed during the follow-up period. CONCLUSION: The procedure of treating chest "lock" keloid by keloid debulking and autologous STSG followed by postoperational radiotherapy is a novel combined methodology for treating keloids.

Surgical Core Excision With Tongue Flap Closure in Combination With Electron Beam Radiotherapy in the Treatment of Ear Keloids.

BACKGROUND: Ear keloids are disfiguring disorders resistant to various treatments. OBJECTIVE: The authors aimed to assess the efficacy of surgical treatment of ear keloids in a Chinese population using a tongue flap with electron beam radiotherapy. METHODS: The authors conducted a retrospective analysis of 41 patients treated at the Affiliated Hospital of Nantong University between January 2018 and May 2021. Core excision with a tongue flap was performed, followed by 3 days of electron beam radiotherapy and 3 to 6 months of pressure clip application. The Vancouver Scar Scale (VSS) and the Visual Analog Scale (VAS) were used to assess the results. RESULTS: The mean age of the patients was 28.10 years (9-61 years). Postoperative follow-up ranged from 5 to 32 months (mean:12.07). The patients underwent 3 days of postoperative radiotherapy followed by pressure clips for 2 to 6 months. Thirty-seven patients had no recurrence, whereas 4 had a mild recurrence (<3 mm in height) with redness and itchiness. The VSS and VASscores significantly decreased. (p < .05). CONCLUSION: Excision with a tongue flap and radiotherapy can be used as the primary treatment for ear keloids considering the good outcome and long-term management.

Laser Combined with Radiotherapy for Keloid Treatment: A Novel and Efficient Comprehensive Therapy with a Lower Recurrence Rate.

BACKGROUND: Keloids are a fibroproliferative skin disorder with a high recurrence rate. Combined therapies are often used in clinical treatment, but, in addition to the relatively high risk of relapse and complexity of the treatment process, side effects remain unknown for combination therapies. METHODS: A total of 99 patients with keloids in 131 positions were included in this retrospective study. Fractional CO 2 laser therapy was first applied with energy ranging from 360 to 1008 mJ; then, 6-Mev, 900-cGy electron beam irradiation was applied twice. The first pass was initiated within 24 hours after the laser therapy, and the second pass was performed on the seventh day after laser therapy. The Patient and Observer Scar Scale evaluated the lesions before the treatment and at 6, 12, and 18 months after treatment. At each follow-up visit, the patients filled out a questionnaire on recurrence, side effects, and satisfaction. RESULTS: The authors found a significant decrease in total Patient and Observer Scar Scale score [29 (23, 39) versus 61.2 ± 13.4; P < 0.001] at the 18-month follow-up compared with the baseline value (before the therapy). A total of 12.1% of the patients had recurrences during the 18-month follow-up period (11.1% partial recurrence and 1.0% complete recurrence). The total satisfaction rate was 97.0%. No severe adverse effects were observed during the follow-up period. CONCLUSIONS: Laser combined with radiotherapy is a new comprehensive therapy comprising ablative lasers and radiotherapy for keloids. It had excellent clinical efficacy, low recurrence rate, and no serious adverse effects. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.

Validation of HDR brachytherapy doses in the treatment of keloid scars using the egs_brachy Monte Carlo application.

Objective. Radiotherapy is a well-known alternative in the treatment of keloid scars to reduce the recurrence of scars. The purpose of this study was to investigate the feasibility and accuracy of dose delivered from a high-dose-rate (HDR) afterloaders in keloid scar brachytherapy using Monte Carlo (MC) simulations and measurements.Approach. Treatment doses and central axis dose profiles were measured using radiophotoluminescence dosimeters and radiochromic films, respectively, with two HDR afterloaders, both using an Ir-192 source, in a phantom made of solid water and polycarbonate sheets. The nominal treatment dose calculated by the AAPM Task Group No. 43 (TG-43) dose model was set to 8.5 Gy at a distance of 0.5 cm laterally from the middle of the source line located in a plastic applicator simulating a 15 cm long surgically removed scar treatment with 30 equally spaced (0.5 cm) source positions. The dose profiles were measured at three different distances from the applicator and the absolute doses at four points at different distances. MC simulations were performed using the egs_brachy, which is based on EGSnrc code system.Main results. The measured and simulated dose profiles match well, especially at 10.0 mm (difference <1%) and 15.0 mm depths (difference <4%), and with a small dose difference at 5.0 mm depth (difference <4%). Point dose measurements agreed well in the dose maximum area (difference <7%) with the simulated dose profiles, although the largest difference near the edge of the profile was <30%. The dose differences between the TG-43 dose model and the MC simulation were small (differences <4%).Significance. Simulated and measured dose levels at a depth of 0.5 cm showed that the nominal treatment dose can be achieved with the utilized setup. The measurement results of the absolute dose agree well with the corresponding simulation results.

Double enhancement effect of a surface dose with tungsten rubber bolus in photon radiotherapy for keloids and superficial tumors.

To clarify the dosimetric characteristics of a real-time variable shape rubber-containing tungsten (STR) bolus in a clinical plan and investigate the efficacy of the STR bolus in photon radiotherapy for keloids and other superficial tumors. A 5 mm gel bolus or 1 mm STR bolus was placed on a solid water phantom. Tangential irradiation was performed using a TomoTherapy Radixact-X9 and 6 MV X-ray flattening-filter-free beam, and the surface dose was measured with radiochromic film. Clinical-like plans (TomoDirect; TD and TomoHelical; TH) were applied with the same geometry and the dose distributions were measured. The increase in surface dose by the build-up effect and backscatter was 37.7% and 8.0% for the gel bolus, and 40.5% and 26.4% for the STR bolus, respectively. In the TD and TH plans, the increase in surface dose was 27.4% and 48.3% for the gel bolus, and 39.0% and 63.2% for the STR bolus. Similary, changes in the sagittal plane dose were - 3.9% and 6.1% for the gel bolus, and - 6.3% and 6.9% for the STR bolus. The STR bolus effectively increased the surface dose by the build-up effect and backscatter in photon radiotherapy for keloids and other superficial tumors.