Citation Nr: 21002989 Decision Date: 01/19/21 Archive Date: 01/19/21 DOCKET NO. 16-18 373 DATE: January 19, 2021 ORDER Service connection for polycythemia vera (a blood cancer) due to exposure to ionizing radiation is denied. FINDING OF FACT The Veteran’s polycythemia vera (a blood cancer) was not caused by his verified in-service exposure to ionizing radiation during a training course in the Navy from 1952 to 1956. CONCLUSION OF LAW The criteria have not been met for entitlement to service connection for polycythemia vera (a blood cancer) based on in-service exposure to ionizing radiation. 38 U.S.C. §§ 1101, 1110, 1112, 1113, 1154(a), 5107; 38 C.F.R. §§ 3.102, 3.303, 3.307, 3.309. REASONS AND BASES FOR FINDING AND CONCLUSION The Veteran served on active duty from December 1952 to November 1956 in the U.S. Navy. This matter comes to the Board of Veterans’ Appeals (Board) on appeal from a September 2015 rating decision issued by an Agency of Original Jurisdiction (AOJ) of the Department of Veterans Affairs (VA). This appeal has been advanced on the Board’s docket. 38 U.S.C. § 7107(b) (effective February 19, 2019); 38 C.F.R. § 20.800(c) (2019). In October 2016, the Veteran and his spouse testified at a hearing before a Decision Review Officer (DRO hearing). In June 2018, the Veteran and his son and a friend presented testimony at a Travel Board hearing before the undersigned Veterans Law Judge. Transcripts of both hearings are associated with the claims file. In July 2018, the Board remanded the appeal for further development. This case has since been returned to the Board for appellate review, after the AOJ substantially complied with the Board’s remand orders. Stegall v. West, 11 Vet. App. 268, 271 (1998). Finally, in January 2021, the Veteran’s representative submitted additional medical treatise evidence, after certification of the Veteran’s appeal. On this issue, under the provisions of 38 U.S.C. § 7105(e) (2018) for Legacy appeals, a waiver of AOJ consideration of new, pertinent evidence submitted by the Veteran or his representative after the appeal has been transferred to the Board is no longer required. In other words, under this statute, a waiver of AOJ consideration is presumed, absent a written request from the Veteran that the AOJ review the new evidence first. While the Veterans Appeals Improvement and Modernization Act of 2017 (AMA) deleted the provisions of 38 U.S.C. § 7105(e) (2018), the Public Law specified that Legacy appeals (such as the current appeal) were to be treated differently than appeals under the AMA. See Pub. L. 115-55 § 2(x)(1). In any event, in a December 2020 statement from the Veteran’s representative, the Veteran explicitly waived his right to have the AOJ initially consider any additional evidence submitted. Therefore, the Board accepts this additional medical treatise evidence for inclusion in the record and consideration by the Board at this time, with or without a waiver. See 38 C.F.R. §§ 20.901, 20.1305(c) (2019). I. VA’s Duty to Notify and Assist The Veterans Claims Assistance Act of 2000 (VCAA), in part, describes VA’s duties to notify and assist claimants in substantiating a claim for VA benefits. 38 U.S.C. §§ 5100, 5102, 5103, 5103A, 5106, 5107, 5126 (2012); Honoring America’s Veterans and Caring for Camp Lejeune Families Act of 2012, Pub. L. No. 112-154, §§ 504, 505, 126 Stat. 1165, 1191-93; 38 C.F.R. §§ 3.102, 3.156(a), 3.159, 3.326(a) (2019). As to the duty to notify, the Veteran was provided adequate notice for his service connection claim due to ionizing radiation in notice letters from the AOJ dated in May 2015, June 2015, July 2015, June 2016, and May 2019. Several of these notice letters discussed the specific information required to establish a service connection claim under the unique provisions pertinent to ionizing radiation. See e.g., 38 C.F.R. §§ 3.309(d), 3.311 (2019). Subsequent to the most recent ameliorative July 2018 Board remand, neither the Veteran nor his representative has raised any issues with the duty to notify or duty to assist. See Scott v. McDonald, 789 F.3d 1375, 1381 (Fed. Cir. 2015) (holding that the Board has an obligation to read filings in a liberal manner, but that obligation does not require the Board to “search the record and address procedural arguments when the veteran fails to raise them before the Board.”); Dickens v. McDonald, 814 F.3d 1359, 1361 (Fed. Cir. 2016) (applying Scott to a duty to assist argument). II. Service Connection Service connection may be granted for disability resulting from disease or injury incurred in or aggravated by active service. 38 U.S.C. §§ 1110, 1131, 5107; 38 C.F.R. § 3.303. The three-element test for service connection requires evidence of: (1) the existence of a current disability; (2) in-service incurrence or aggravation of a disease or injury; and (3) a causal relationship between the current disability and the disease or injury incurred or aggravated during service — the “nexus” requirement. Holton v. Shinseki, 557 F.3d 1363, 1366 (Fed. Cir. 2009) (quoting Shedden v. Principi, 381 F.3d 1163, 1167 (Fed. Cir. 2004)). Under 38 C.F.R. § 3.303(d), disorders diagnosed after discharge may also still be service connected if all the evidence, including pertinent service records, establishes the disorder was incurred in service. See Combee v. Brown, 34 F.3d 1039, 1043 (Fed. Cir. 1994). VA is to give "due consideration" to "all pertinent medical and lay evidence" in evaluating a claim for disability benefits. 38 U.S.C. § 1154(a). Thus, there is no categorical rule that medical evidence is required when the determinative issue is either medical etiology or a medical nexus. Davidson v. Shinseki, 581 F.3d 1313, 1316 (Fed. Cir. 2009). The Board should make explicit findings regarding the competency and, if necessary, the credibility of the lay evidence of record. Miller v Wilkie, 32 Vet. App. 249, 257-262 (2020). Lay testimony is competent to describe the presence of readily observable features or symptoms of injury or illness that are not medical in nature, such as varicose veins, tinnitus, and flat feet. See 38 C.F.R. § 3.159(a)(2); Barr v. Nicholson, 21 Vet. App. 303, 307-310 (2007). The Federal Circuit has also clarified that lay evidence can be competent for the medical diagnosis or etiology of a condition if: (1) the layperson is competent to identify the medical condition, (2) the layperson is reporting a contemporaneous medical diagnosis, or (3) lay testimony describing symptoms at the time supports a later diagnosis by a medical professional. Jandreau v. Nicholson, 492 F.3d 1372, 1376-77 (Fed. Cir. 2007). And if the disability is of the type for which lay evidence is competent, the Board must weigh the probative value of that lay evidence against other evidence of record in making its determination regarding the award of service connection. Buchanan v. Nicholson, 451 F.3d 1331, 1334-37 (Fed. Cir. 2006). In determining whether service connection is warranted, the Board shall consider the benefit-of-the-doubt doctrine. 38 U.S.C. § 5107(b); 38 C.F.R. § 3.102; Alemany v. Brown, 9 Vet. App. 518 (1996); Gilbert v. Derwinski, 1 Vet. App. 49 (1991). The Veteran contends that he was exposed to ionizing radiation in 1954 during his active service in the Navy. He reports being exposed to ionizing radiation during a one to two week training course in Hawaii in March 1954. The name of the course was “RAD Safe #425.” The focus of the course was how to handle radioactive materials and the use of Geiger counters to locate radioactive materials. The Veteran also stated that during the training he was taught how to use Cobalt-60 to make a “Dirty Hydrogen Bomb.” There were 10 radiation tests over a 10-day period. During the training, the Veteran says his Navy instructor advised the trainees that each time they opened a load box (called a “pig”) they were each exposed to half the lethal dose of radiation per session. The source of the radiation was Cobalt-60 according to the Veteran. Cobalt-60 was the size of a matchhead, kept in a solid lead chest three feet square, with a pocket in the top about the size of a shoe box. The Veteran sat approximately 2-3 feet from the box from which the instructor removed a container of Cobalt-60 granules. Then, the Cobalt-60 granules were hidden in a field for the Veteran to locate with Geiger counters. In the 1950s, the Veteran asserts that the dangers of ionizing radiation were unknown and underappreciated at that time. As such, he was not provided with a dosimeter to quantify the amount of ionizing radiation he was exposed to. The Navy did not acknowledge or quantify the amount of ionizing radiation exposure for the Veteran during this training, as no paperwork addressing same was maintained as part of his service records. The Veteran also reports that he was exposed to ionizing radiation sometime from 1952 to 1956 during his active service in the Navy when his plane briefly stopped to refuel in Nagasaki or Hiroshima, Japan, “about 5 years after the bomb”. See September 2015 VA telemedicine and social work telephone encounter notes; June 2015 and June 2019 Radiation Risk Activity Information Sheets (RRAISs); October 2016 DRO hearing testimony. Post-service, the Veteran says he first noticed the symptoms of polycythemia vera in the early 1970s, which is at least 14 years after discharge from active duty. He has pointed out that medical research states that the symptoms of ionizing radiation exposure can take 30-50 years to appear. Also, polycythemia vera can take decades to present itself. His symptoms of polycythemia vera included fatigue, exhaustion, headaches, intense itches, rashes on his arms and legs, bruising, a high red blood cell count seen on testing, and skin cancer on his face. However, the Veteran asserts that the only possible cause of the development of his polycythemia vera was his in-service ionizing radiation exposure in 1954 during the training course or during his brief stay in Japan. He states he had no post-service exposure to ionizing radiation either occupationally or recreationally. He reports working post-service as an aircraft mechanic and a crop duster. In addition, none of his family members have developed polycythemia vera. See February 2015, June 2015, December 2015, April 2018, September 2018, June 2019, and February 2020 Veteran statements; June 2015 and June 2019 Radiation Risk Activity Information Sheets (RRAISs); November 2015 NOD (VA Form 21-0958) and accompanying statement; October 2016 DRO hearing; June 2018 Travel Board hearing; December 2020 representative statements; and January 2021 Brief from the American Legion. Polycythemia vera is “a myeloproliferative disorder of unknown etiology characterized by abnormal proliferation of all hematopoietic bone marrow elements and an absolute increase in red cell mass and total blood volume." See Dorland's Illustrated Medical Dictionary 1488 (32nd ed. 2012). According to internet medical treatise evidence cited and discussed by the Veteran’s representative in January 2021, polycythemia vera is a rare, chronic disorder involving the overproduction of blood cells in the bone marrow (myeloproliferation). It is classified as a “blood cancer.” It is caused by a malignant change in the genetic material (DNA) within a single cell of the bone marrow (clonal disorder). The underlying reason for why this malignant change occurs is unknown. A variety of symptoms can occur in individuals with polycythemia vera including nonspecific symptoms such as headaches, fatigue, weakness, dizziness or itchy skin; an enlarged spleen (splenomegaly); a variety of gastrointestinal issues; and the risk of blood clot formation, which may prevent blood flow to vital organs. More than 90 percent of individuals with polycythemia vera have a variation (mutation) in the JAK2 gene. The exact role that this variation plays in the development of polycythemia vera is not yet known. The symptoms of polycythemia vera usually develop slowly over many years. See https://rarediseases.org/rare-diseases/polycythemia-vera/. Upon review of the evidence of record, service connection for polycythemia vera (a blood cancer) due to exposure to ionizing radiation is denied. The first and perhaps most fundamental requirement for any service-connection claim is proof the Veteran has a current disability. See 38 U.S.C. § 1110; 38 C.F.R. § 3.303(a); Degmetich v. Brown, 104 F. 3d 1328, 1332 (1997). In the absence of proof of a current disability, there can be no valid claim. Boyer v. West, 210 F.3d 1351, 1353 (Fed. Cir. 2000). In the present case, there is probative evidence that the Veteran meets the threshold criterion for service connection of a current disability. See 38 U.S.C. § 1110; 38 C.F.R. § 3.303(a). Specifically, according to a February 2015 VA hematology / oncology clinic note, the Veteran was noted to be JAK2 mutation positive, with a diagnosis of polycythemia vera. The first explicit diagnosis of polycythemia vera was from a February 2014 VA treatment record. The Veteran was prescribed Hydroxyurea 1000mg daily for his polycythemia vera. As such, the first element of service connection (existence of a current disability) is met. The remaining question is whether the Veteran’s current polycythemia vera first manifested in service in the Navy from 1952 to 1956, within one year of service (as a blood cancer), or is otherwise related thereto due to in-service exposure to ionizing radiation. Initially, in the present case, the Veteran’s polycythemia vera (identified as a blood cancer or malignant tumor) is an enumerated “chronic disease” listed under 38 C.F.R. § 3.309(a); therefore, 38 C.F.R. § 3.303(b) applies. Walker v. Shinseki, 708 F.3d 1331, 1338-39 (Fed. Cir. 2013). Under 38 C.F.R. § 3.303(b), where the evidence shows an enumerated “chronic disease” in service such as a malignant tumor (or within the presumptive period under § 3.307), or “continuity of symptoms” of such a disease after service, the disease shall be presumed to have been incurred in service. Walker, 708 F.3d 1335-1337. Service connection for an enumerated “chronic disease” such as a malignant tumor under 38 C.F.R. § 3.309(a) can also be also be established on a presumptive basis by showing that it manifested itself to a degree of 10 percent or more within one year from the date of separation from service. 38 U.S.C. §§ 1101, 1112, 1113; 38 C.F.R. §§ 3.307(a)(3), 3.309(a). Service treatment records (STRs) dated from 1952 to 1956 are negative for any complaint, treatment, or diagnosis of polycythemia vera. At his November 1956 STR discharge examination, no disabilities were noted for the Veteran. Laboratory testing, blood tests, and a urinalysis were all negative for any abnormalities in November 1956. In addition, post-service, there is no probative, credible evidence of polycythemia vera within one year of separation from the Navy in 1956 or 1957. Thus, the Veteran is not entitled to service connection for polycythemia vera on a presumptive basis, either as a chronic disease during service or within one year of service. 38 U.S.C. §§ 1101, 1112, 1113; 38 C.F.R. §§ 3.307(a)(3), 3.309(a); Walker, 708 F.3d 1335-37. In fact, with regard to chronicity and continuity of symptomology, the first post-service evidence of possible symptoms of polycythemia vera is from the 1970s. That is, the Veteran testified that he first experienced skin symptoms such as bleeding of the skin due to skin cancer or polycythemia vera in the early 1970s. See June 2018 Travel Board hearing testimony. This is approximately 14 years after the Veteran’s discharge from his service in the Navy in 1956. This was not supported by any contemporary clinical evidence from the 1970s. In this regard, a September 1972 medical certificate for a commercial pilot’s license determined the Veteran met all medical standards, with no mention of any abnormal medical findings at that time. Contemporaneous evidence has greater probative value than history as reported by the veteran. Curry v. Brown, 7 Vet. App. 59, 68 (1994). In fact, the earliest clinical evidence of record in the claims file of skin symptoms possibly the result of polycythemia vera is from VA treatment records dated from 1999 to 2004, which is 43 years after the Veteran’s discharge from service. Beginning in 1999, VA treatment records began to record lumps that come and go under the Veteran’s armpits, ecchymotic rashes, and itchy skin on the ears, elbows, arms, legs, and feet. This was treated with hydrocortisone cream and clotrimazole 1% topical cream. Most importantly, there is no lay allegation from the Veteran that he had any symptoms of polycythemia vera until 14 years or so after his service in the Navy. See e.g., January 2017 Veteran statement - polycythemia vera takes decades to present itself; June 2018 Travel Board hearing testimony. Thus, the legal concepts of chronicity and continuity of symptomology do not assist the Veteran in the present case with his claim for service connection for polycythemia vera. 38 C.F.R. § 3.303(b). See also Walker, 708 F.3d at 1339-40. The Board now turns to the central question in the present case - whether the development of the Veteran’s polycythemia vera was caused by in-service exposure to ionizing radiation from his training in 1954 or from his brief stop in Hiroshima or Nagasaki (Japan) sometime between 1952 to 1956. Service connection for a condition, which is claimed to be attributable to ionizing radiation exposure during service, may be established in one of three different ways. Davis v. Brown, 10 Vet. App. 209, 211 (1997); Rucker v. Brown, 10 Vet. App. 67, 71 (1997). First, presumptive service connection under 38 U.S.C. § 1112(c) and 38 C.F.R. § 3.309(d) is warranted for certain diseases present in a “radiation-exposed veteran.” Second, a "radiogenic disease" may be service-connected on a direct basis after specified developmental procedures are conducted under the special framework of 38 C.F.R. § 3.311. Third, even if the claimed disability cannot be awarded under 38 C.F.R. § 3.309(d) or under 38 C.F.R. § 3.311, direct service connection can be established by showing that the disease was incurred during or aggravated by service, including presumptive service connection for chronic diseases. See 38 U.S.C. § 1110; 38 C.F.R. §§ 3.303, 3.307, 3.309. Combee v. Brown, 34 F.3d 1039, 1043 (Fed. Cir. 1994). The Board has conducted a careful analysis of both the evidence of record and the legal provisions of 38 C.F.R. § 3.309(d) and 38 C.F.R. § 3.311. In light of the particular facts of this Veteran’s case, neither of the ionizing radiation regulations (38 C.F.R. § 3.309(d) or 38 C.F.R. § 3.311) provides a basis to award service connection for the Veteran’s polycythemia vera as the result of in-service exposure to ionizing radiation from 1952 to 1956. In addition, as will be discussed below, the general provisions for service connection governing the awards of VA compensation provide no basis to award service connection for his polycythemia vera. The first inquiry must focus on whether the Veteran may be entitled to service connection for his polycythemia vera (blood cancer) on a presumptive basis under 38 C.F.R. § 3.309(d). That is, if the Veteran has (1) one of the diseases listed under 38 U.S.C. § 1112(c) and 38 C.F.R. § 3.309(d); and (2) was a “radiation-exposed veteran” who was involved in a “radiation-risk activity” during active duty, then it will be presumed that the disease was incurred in service. In that case, service connection would be established for the disease, provided the rebuttable presumptions of 38 C.F.R. § 3.307 are also satisfied. In the present case, the Veteran has polycythemia vera (blood cancer), which is not listed as a disease specific to “radiation-exposed veterans” for the purpose of presumptive service connection. See 38 C.F.R. § 3.309(d)(2). What’s more, the Veteran did not participate in a “radiation-risk activity” as defined in 38 C.F.R. § 3.309(d)(3)(ii). There are six (6) types of “radiation risk activity” for purposes of awarding presumptive service connection under 38 C.F.R. § 3.309(d). They are as follows: Onsite participation in a test involving the atmospheric detonation of a nuclear device; participation in the occupation of Hiroshima or Nagasaki, Japan between August 6, 1945 and July 1, 1946; internment as a prisoner of war (POW) in Japan (or service in Japan immediately after internment) with the opportunity for radiation exposure comparable to occupation forces in Hiroshima or Nagasaki; service for at least 250 days before February 1, 1992 at a gaseous diffusion plant in Paducah, Kentucky, or Portsmouth, Ohio, or at the K25 area at Oak Ridge, Tennessee; service before January 1, 1974 on Amchitka Island, “if exposed to ionizing radiation” during duty related to Long Shot (1965), Milrow (1969), or Cannikin (1971) underground nuclear tests; and finally service equivalent to an employee of the Department of Energy member of Special Exposure Cohort. See 38 C.F.R. § 3.309(d)(3)(ii)(A)-(E). In the present case, the evidence of record clearly shows the Veteran did not engage in a “radiation-risk activity” as defined above by 38 C.F.R. § 3.309(d)(3)(ii). In this regard, the Board will assume the Veteran is credible in his allegation that during his active service in the Navy from 1952 to 1956 his plane briefly stopped to refuel in Nagasaki or Hiroshima, Japan, “about 5 years after the bomb”. See September 2015 VA telemedicine and social work telephone encounter notes; June 2015 and June 2019 Radiation Risk Activity Information Sheets (RRAISs); and October 2016 DRO hearing. However, under VA regulation, only participation in the occupation of Hiroshima or Nagasaki, Japan between August 6, 1945 and July 1, 1946 qualifies as “radiation risk activity” for purposes of awarding presumptive service connection. See 38 C.F.R. § 3.309(d)(3)(ii)(B), vi. Here, the Veteran’s brief visit to Nagasaki or Hiroshima, Japan, sometime between 1952 and 1956 was at least 6 years after the timeframe specified in the VA regulation. Thus, his visit to Japan sometime between 1952-1956 did not constitute a “radiation risk activity” listed under 38 C.F.R. § 3.309(d)(3)(ii)(A)-(E). Moreover, it is undisputed he was not a POW in Japan during the required timeframe. See 38 C.F.R. § 3.309(d)(3)(ii)(C). Furthermore, the Veteran does not describe any other type of exposure to ionizing radiation that would encompass a “radiation risk activity” listed above under 38 C.F.R. § 3.309(d)(3)(ii)(A)-(E). Therefore, service connection for his polycythemia vera (blood cancer) cannot be presumed as a disease incurred in service because the Veteran was not a “radiation-exposed veteran” as defined under 38 C.F.R. § 3.309(d)(3)(i). In other words, the Board finds that the presumptive provisions of 38 C.F.R. § 3.309(d) are not applicable here. The second inquiry will focus on whether the Veteran may be entitled to service connection for his polycythemia vera (blood cancer) on a direct basis for a “radiogenic disease,” after specified developmental procedures are conducted under the special framework of 38 C.F.R. § 3.311. On this issue, 38 C.F.R. § 3.311 does not provide presumptive service connection for a radiogenic disease but provides special procedures to help a veteran or his survivors prove his or her claim on a direct basis. Ramey v. Gober, 120 F.3d 1239, 1244 (Fed. Cir. 1997). The governing regulation states that, if a “radiogenic disease” (i) first became manifest after service, (ii) cannot be granted under the presumptive provisions of 38 C.F.R. § 3.307 or 38 C.F.R. § 3.309, and (iii) it is contended the “radiogenic disease” is the result of exposure to ionizing radiation in service, a dose assessment is necessary / must be made prior to adjudication of the claim. 38 C.F.R. § 3.311(a)(1)-(2). Depending on the date and location of the claimed ionizing radiation exposure, the dose assessment is obtained from one of two federal agencies: (1) the Department of Defense, specifically the Defense Threat Reduction Agency (DTRA) for atmospheric nuclear weapons test participation claims and Japanese occupation claims; or (2) VA’s Under Secretary for Health for “all other exposure claims.” See 38 C.F.R. § 3.311(a)(2)(i)-(iii). (The current Veteran’s factual situation involving radiation training in March 1954 would fall under “all other exposure claims.”) In the present case, the Veteran contends that his polycythemia vera (blood cancer) was the result of exposure to ionizing radiation during service at a March 1954 training on ionizing radiation. As discussed above, clinical evidence of record confirms the Veteran developed polycythemia vera (blood cancer) years after his discharge from service in 1956. Polycythemia vera is not listed as a “radiogenic disease” under 38 C.F.R. § 3.311(b)(2)(i)-(xxiv). However, under 38 C.F.R. § 3.311(b)(3), it is specifically noted that Public Law 98-542 requires VA to determine whether sound medical and scientific evidence supports establishing a rule identifying polycythemia vera as a radiogenic disease. VA has determined that sound medical and scientific evidence does not support including polycythemia vera on the list of known radiogenic diseases in this regulation. Even so, VA is instructed to consider a claim based on any assertion that polycythemia vera is a radiogenic disease under the provisions of 38 C.F.R. § 3.311(b)(4). In this respect, although polycythemia vera is specifically excluded by VA regulation as a radiogenic disease, VA will still consider a claim for same if the Veteran cites or submits competent scientific or medical evidence that polycythemia vera is a radiogenic disease. See 38 C.F.R. § 3.311(b)(3); VAOPGCPREC 15-99 (Nov. 16, 1999). In the instant case, the Veteran has in fact submitted medical and scientific evidence that polycythemia vera qualifies as a “radiogenic disease.” See 38 C.F.R. § 3.311(b)(4). In particular, a September 2015 private medical opinion from Dr. H.R.H., MD., a family medicine doctor, assessed that the bone marrow tract is “especially sensitive” to radiation injury. An October 2015 private medical opinion from Dr. R.C.R., MD., a medical oncologist and hematologist, provided that as a class of diseases, and as a specific subtype of polycythemia vera, there has been a causal link identified with disease formation and prior exposure to ionizing radiation. He added that other than exposure to benzene products, there are really no other known causes of this type of blood disorder. A January 2016 VA physician statement from Dr. J.K.S., MD., a VA staff physician and oncologist, determined that an increased incidence of polycythemia vera has been seen in a few medical studies of people with radiation exposures. Thus, Dr. J.K.S. surmised that the Veteran’s in-service radiation exposure “may have” played a role in the development of his blood problems. It follows that a dose assessment (as to the size and nature of the radiation dose) was warranted in the present case from VA’s Under Secretary for Health under “all other exposure claims.” See 38 C.F.R. § 3.311(a)(1), (2)(iii). In fact, in light of the above findings, in the Board’s earlier July 2018 Board remand, the Board instructed the AOJ to follow the correct developmental procedures for the Veteran’s alleged ionizing radiation exposure, as required under 38 C.F.R. § 3.311. This included obtaining a dose assessment. For “other exposure claims” such as the claim of the current Veteran, when the AOJ submits the request for a dose assessment to the appropriate entity, a request will be made for any available records concerning a veteran’s exposure to ionizing radiation. These records normally include but may not be limited to the veteran's Record of Occupational Exposure to Ionizing Radiation (DD Form 1141), if maintained, STRs, and other records which may contain information pertaining to the veteran's radiation dose in service. All such records will be forwarded to the Under Secretary for Health, who will be responsible for preparation of a dose estimate, to the extent feasible, based on available methodologies. See 38 C.F.R. § 3.311(a)(2)(iii). In determining whether a veteran was exposed to ionizing radiation during service, according to the Court, VA has the duty to gather “all relevant evidence” from various sources of information. Earle v. Brown, 6 Vet. App. 558, 562 (1994). That is, all relevant evidence of record must be considered and addressed. This could include unit records, temporary duty orders, a DD Form 1141 (Record of Occupational Exposure to Ionizing Radiation), service personnel records (SPRs), STRs, and statements or letters from the Veteran, his family, friends, or buddy statements from fellow service members. Notably, with regard to lay evidence, the Court has held that a veteran is competent to describe the general circumstances of an in-service “injury” due to radiation exposure. Rucker v. Brown, 10 Vet. App. 67, 74 (1997). With regard to in-service evidence of radiation exposure and a dose assessment, there is probative medical and lay evidence of in-service exposure to ionizing radiation for the Veteran in 1953 / 1954. This evidence establishes an in-service event or injury for the Veteran. See 38 C.F.R. § 3.303(a). The Veteran’s DD Form 214 verifies that he attended a training course called “RAD Safe 425.” A December 1953 SPR Administrative Remarks document indicates that for seven days in December 1953 the Veteran underwent training, including “radiological safety.” The Veteran has submitted a copy of an old letter from himself addressed to his spouse dated in March 1954. In this letter contemporary to his in-service radiation training, the Veteran told his wife that he was learning about radioactive material in training school and finding the radioactive material with a Geiger counter. He discussed alpha, beta, and gamma ray work pertinent to dealing with a nuclear atomic blast. Therefore, the Veteran’s lay description (in various statements and hearing testimony discussed above) of his exposure to ionizing radiation during a one to two week training course in Hawaii in March 1954 is consistent with the places, types, and circumstances of the Veteran’s service in the U.S. Navy at that time. See 38 U.S.C. § 1154(a); 38 C.F.R. § 3.303(a). Service records did not include a DD Form 1141, Record of Occupational Exposure to Ionizing Radiation, or its equivalent. Despite extensive development, the Board was unable to secure such evidence as it received multiple negative responses. See e.g., July 20, 2020 response from Naval History and Heritage Command Archives Branch; March 2020 JSRRC Radiation DRO email; August 2015 and February 2020 Department of Navy letters from the Naval Dosimetry Center; December 2014 PIES response from the National Personnel Records Center (NPRC). With regard to in-service evidence of radiation exposure and a dose assessment, most importantly, the Board has reviewed the November 2020 medical opinion from the office of the VA Undersecretary for Health. This dose assessment was prepared and reviewed by D.K.M., BS, RRPT, AMAAHP, Health Physicist, and Dr. E.S., MD, MPH, FAAFP, Director of the Post-9/11 Era Environmental Health Program. D.K.M. wrote that a radiation dose is “the prime factor” to consider when determining the causation of radiation induced disease. Being in the vicinity of a radiation source does not necessarily mean a significant exposure occurred. Where the presumption does not exist under 38 C.F.R. § 3.309(d), the radiation dose must be determined through direct measurement or reconstruction methodology. Once the radiation dose is determined, the issue of disease causation can be addressed. In the present Veteran’s case, there was no record of a radiation dose provided by the military. Therefore, the VA Undersecretary for Health designee assigned a radiation dose itself based on the Veteran’s description and the other evidence of record. This dose assessment explained that regarding the Veterans’ claim of being exposed to half a lethal dose of Cobalt-60, the lethal dose of ionizing radiation is expressed several ways but most commonly as LD 50/30, which means at a dose of 450 rem, ½ of the exposed population will die within 30 days without supportive medical care. (In making this assessment, a link was provided to an internet article from the U.S Nuclear Regulatory Commission (NRC)). The VA Undersecretary for Health designee did not believe that the Veteran was exposed to 200 rem or more during a training course. Such an act of cavalier disregard, for what was already known about the effects of radiation, would not be tolerated in the Department of Defense. The Veteran attended this training course in 1954. At this time, the annual dose limit for occupational exposure was changed to 5 rem per year. See US Nuclear Regulatory Commission, 10 C.F.R. § 20.1201(a) - Occupational Dose Limits for Adults. The VA Undersecretary for Health designee assigned a dose of 5 rem for the Veteran’s time in question of training in the Navy “RAD Safe #425,” with the professional knowledge that even this dose is too high. In fact, the Veterans’ dose was likely to have been less than 1 rem according to these clinicians. Following receipt of the dose assessment from the designee of the Under Secretary of Health, if the Veteran provides a separate dose estimate from a “credible source” that represents a “material difference” from the Under Secretary of Health dose estimate, the claim must be referred to an independent expert (selected by the Director of the National Institute of Health (NIH)) for a separate radiation dose estimate. 38 C.F.R. § 3.311(a)(3). A “material difference” ordinarily exists where one estimate is at least double the other estimate. 38 C.F.R. § 3.311(a)(3)(i). The regulations define a “credible source” as a dose estimate, “prepared by a person or persons certified by an appropriate professional body in the field of health physics, nuclear medicine, or radiology and if based on the facts and circumstances of the particular claim. 38 C.F.R. § 3.311(a)(3)(ii). In the present case, no separate, concrete dose estimate from a “credible source” is of record. A September 2015 private medical opinion from Dr. H.R.H., MD., a family medicine doctor, remarked that the risk of cancer depends on the dose and begins to build up even with very low doses. There is no "minimum threshold." Dr. H.R.H. noted the severity of symptoms and illness depends on the type and the amount of radiation the person was exposed to. In the Veteran’s case, “[b]ecause it is difficult to determine the amount of radiation exposure, the best signs of the severity of the exposure are: the length of time between the exposure and the onset of symptoms, the severity of symptoms, and severity of changes in white blood cells causing, for example, polycythemia vera.” An October 19, 2015 private medical opinion from Dr. M.J., MD, a primary care doctor, noted the Veteran had a “past history of being exposed to significant radiation in the 1950s.” No further detail on the size and nature of the radiation dose was proffered by Dr. M.J. An October 2015 private medical opinion was offered by Dr. R.C.R., MD., a medical oncologist and hematologist. The Veteran reported to Dr. R.C.R. that he had a “fairly extensive radiation exposure history” during his military service. However, Dr. R.C.R. emphasized that “[t]he amount and duration of radiation exposure cannot be easily quantified and may not even be pertinent. The studies looking at the causal relationship between the exposure and the disease development have not been able to define a minimum dose necessary to cause the disease.” Thus, Dr. R.C.R provided no further details on the size and nature of the radiation dose. A January 2016 VA physician statement from Dr. J.K.S., MD., a VA staff physician and oncologist, noted the Veteran’s report that “he had significant radiation exposure in the military and feels that this may have played a role in the development of his blood problems.” Dr. J.K.S. provided no further details on the size and nature of the radiation dose, including in a subsequent December 2017 VA medical opinion. In light of the above evidence, in the present case there exists no separate dose estimate from a “credible source” that represents a “material difference” from the Under Secretary of Health dose estimate. A “material difference” ordinarily exists where one estimate is at least double the other estimate. 38 C.F.R. § 3.311(a)(3)(i). As such, it was unnecessary to refer the claim to an independent expert (selected by the Director of the National Institute of Health (NIH)) for a separate radiation dose estimate. See 38 C.F.R. § 3.311(a)(3). The above November 2020 dose assessment from the designee of the VA Undersecretary for Health of “5 rem” for the Veteran’s training in the Navy suffices in the present case. When (1) a dose assessment (greater than zero) or other records are secured that confirm that the veteran was exposed to ionizing radiation during active duty; and (2) there is a determination he subsequently developed a “radiogenic disease”; and (3) this “radiogenic disease” became manifest within a certain specified period after exposure to radiation in service, VA will refer the claim to the Under Secretary for Benefits to consider the claim and request an advisory opinion. See 38 C.F.R. § 3.311(b)(1). However, if any of the foregoing three requirements are not met, it shall not be determined that a disease has resulted from exposure to ionizing radiation under such circumstances under the provisions of 38 C.F.R. § 3.311. For example, if the dose estimate is zero, or there is no competent evidence the Veteran was exposed to ionizing radiation during service, VA is not required to forward the claim to the Under Secretary for Benefits for an advisory opinion. See Wandel v. West, 11 Vet. App. 200, 205 (1998). In the present case, since the Veteran has submitted medical and scientific evidence that polycythemia vera qualifies as a “radiogenic disease” and a dose assessment was secured, the final pre-adjudicatory step under § 3.311 was to refer the claim to the Under Secretary for Benefits for further consideration. 38 C.F.R. § 3.311(b)(1)(iii). As with the entities above, the Under Secretary for Benefits may designate a party to respond on the Under Secretary’s behalf. See Parrish v. Shinseki, 24 Vet. App. 391 (2011) (holding that express designation of responsibility to the VA Under Secretary for Benefits (USB) stated in regulation governing disability claims based on in-service radiation exposure does not limit the USB’s authority to designate the Compensation and Pension Service Director to render the opinion regarding service connection required by the regulation); see also 38 C.F.R. § 3.100; 38 C.F.R. § 2.6(b)(1) (authorizing the Under Secretary of Benefits “to authorize supervisory or adjudicative personnel within his/her jurisdiction to perform such functions as may be assigned.”). When the ionizing radiation claim is forwarded for review, the Under Secretary for Benefits (or designee) shall consider the claim with reference to the six factors specified in paragraph (e) of 38 C.F.R. § 3.311 and may request an advisory medical opinion from the Under Secretary for Health. See 38 C.F.R. § 3.311(c)(1). Under 38 C.F.R. § 3.311(e), the factors to be considered in determining whether a veteran's disease resulted from exposure to ionizing radiation in service include: (1) The probable dose, in terms of dose type, rate and duration as a factor in inducing the disease, taking into account any known limitations in the dosimetry devices employed in its measurement or the methodologies employed in its estimation; (2) The relative sensitivity of the involved tissue to induction, by ionizing radiation, of the specific pathology; (3) The veteran's gender and pertinent family history; (4) The veteran's age at time of exposure; (5) The time-lapse between exposure and onset of the disease; and (6) The extent to which exposure to radiation, or other carcinogens, outside of service may have contributed to development of the disease. The Under Secretary for Benefits (or designee) need not specifically discuss each the six factors in its advisory opinion. See Hilkert v. West, 12 Vet. App. 145, 149-50 (1998). However, the Board cannot rely on a “cursory” opinion of the Under Secretary for Benefits which simply repeats the opinion from the Under Secretary for Health. Stone v. Gober, 14 Vet. App. 116, 121 (2000). After referring to these factors, the Under Secretary for Benefits (or designee) must determine the likelihood that the Veteran’s exposure to radiation in service resulted in his radiogenic disease. Pursuant to 38 C.F.R. § 3.311(c)(1), the Under Secretary for Benefits may conclude: (1) That “sound scientific and medical evidence” supports the conclusion that “it is at least as likely as not” that the Veteran’s disease resulted from exposure to radiation in service. In such instance, the AOJ must be advised of the determination and rationale in writing. 38 C.F.R. § 3.311(c)(1)(i). (2) That there is “no reasonable possibility” that the Veteran’s disease resulted from radiation exposure during service. In such instance, the AOJ must be advised of the determination and rationale in writing. 38 C.F.R. § 3.311(c)(1)(ii). (3) That he or she “is unable to conclude” whether “it is at least as likely as not,” or that there is “no reasonable possibility” that the Veteran’s disease resulted from radiation exposure during service. In which case, the Under Secretary for Benefits shall refer the matter to an outside consultant. 38 C.F.R. § 3.311(c)(2). For purposes of paragraph (c)(1) of this section above, “sound scientific evidence” means observations, findings, or conclusions which are statistically and epidemiologically valid, are statistically significant, are capable of replication, and withstand peer review. “Sound medical evidence” means observations, findings, or conclusions which are consistent with current medical knowledge and are so reasonable and logical as to serve as the basis of management of a medical condition. See 38 C.F.R. § 3.311(c)(3). When adjudicating the ionizing radiation claim, the determination of service connection will be made by VA under the generally applicable provisions of this part, giving due consideration to all evidence of record, including any opinion provided by the Under Secretary for Health or an outside consultant, and to the evaluations published pursuant to §1.17 of this title. With regard to any issue material to consideration of a claim, the provisions of §3.102 of this title (benefit-of-the-doubt doctrine) apply. See 38 C.F.R. § 3.311(f). With regard to the central question of whether the Veteran’s current polycythemia vera (blood cancer) was caused by his in-service exposure to ionizing radiation from his training in 1954, given the results of his dose assessment, the Board has considered the specified developmental procedures under the special framework of 38 C.F.R. § 3.311. On this issue, the claims file contains a mix of favorable and unfavorable medical opinions. The Board has a duty to analyze the credibility and probative value of the evidence of record. Madden v. Gober, 125 F.3d 1477, 1481 (Fed. Cir. 1997). That is, the Board must determine, as a question of fact, both the weight and credibility of the evidence. Equal weight is not accorded to each piece of evidence contained in a record; every item does not have the same probative value. The Board must analyze the credibility and probative value of all material evidence submitted by and on behalf of a claimant, account for the evidence that it finds to be persuasive or unpersuasive and provide the reasons for its rejection of any material evidence favorable to the claimant. See Struck v. Brown, 9 Vet. App. 145, 152 (1996); Caluza v. Brown, 7 Vet. App. 498, 506 (1995). The probative value of medical opinion evidence is based on the medical expert’s personal examination of the patient, the physician’s knowledge and skill in analyzing the data, and the medical conclusion that the physician reaches. Guerrieri v. Brown, 4 Vet. App. 467, 470-71 (1993). Whether a physician provides a basis for his or her medical opinion goes to the weight or credibility of the evidence in the adjudication of the merits. See Hernandez-Toyens v. West, 11 Vet. App. 379, 382 (1998). Other factors for assessing the probative value of a medical opinion are the physician’s access to the claims folder and the thoroughness and detail of the opinion. See Prejean v. West, 13 Vet. App. 444, 448-9 (2000); Nieves-Rodriguez, 22 Vet. App. 295 (2008). Also, a VA examiner must consider the Veteran’s relevant lay statements regarding in-service incurrence and whether they are consistent or inconsistent with medical knowledge. Miller v Wilkie, 32 Vet. App. 249, 258-60 (2020). It is not error for the Board to favor the opinion of one competent medical expert over that of another when the Board gives an adequate statement of reasons or bases. See Owens v. Brown, 7 Vet. App. 429, 433 (1995). With regard to favorable evidence for a nexus, in a September 2015 private medical opinion, Dr. H.R.H., MD., a family medicine doctor, appeared to opine that the Veteran’s polycythemia vera was due to the effects of radiation exposure. In the Veteran’s case, “[b]ecause it is difficult to determine the amount of radiation exposure, the best signs of the severity of the exposure are: the length of time between the exposure and the onset of symptoms, the severity of symptoms, and severity of changes in white blood cells causing, for example, polycythemia vera.” However, Dr. H.R.H. provided no probative analysis of these signs of severity in the Veteran’s particular case in terms of reaching his favorable conclusion. Also, the size and nature of the radiation dose was not offered. The probative value of a medical professional’s statement is dependent, in part, upon the extent to which it reflects “clinical data or other rationale to support his opinion.” Bloom v. West, 12 Vet. App. 185, 187 (1999). A bare conclusion, even one reached by a health care professional, is not probative without a factual predicate in the record. Miller v. West, 11 Vet. App. 18, 22 (2007). A mere conclusion by a medical doctor is insufficient to allow the Board to make an informed decision. Stefl v. Nicholson, 21 Vet. App. 120, 125 (2007). A medical opinion must support its conclusions with analysis. Id. at 124. Whether a physician provides a basis for his or her medical opinion goes to the weight or credibility of the evidence in the adjudication of the merits. See Hernandez-Toyens v. West, 11 Vet. App. 379, 382 (1998). A review of the claims file does not substitute for a lack of a reasoned analysis. Nieves-Rodriguez v. Peake, 22 Vet. App. 295, 304 (2008). For these reasons, the above favorable private medical opinion is quite limited in its probative value. With regard to favorable evidence for a nexus, in an October 2015 private medical opinion from Dr. M.J., MD, a primary care doctor, the Veteran was noted to have a past history of being exposed to “significant radiation” in the 1950s. Certainly radiation exposure is known to lead to multiple medical problems. The Veteran also has polycythemia vera. Dr. M.J. assessed this should be considered in determining if he is disabled based on his service in the military in the 1950s. No further analysis was forthcoming from Dr. M.J. Also, the size and nature of the radiation dose was not offered, except that it was “significant.” In fact, no actual conclusive medical opinion was proffered by Dr. M.J. In this regard, the probative value of medical opinion evidence is based in part on the medical conclusion that the physician reaches. Guerrieri, 4 Vet. App. at 470-71. With regard to favorable evidence for a nexus, in an October 2015 private medical opinion, Dr. R.C.R., MD., a medical oncologist and hematologist, noted the Veteran’s report of a “fairly extensive radiation exposure history” during his military service. However, Dr. R.C.R. emphasized that “[t]he amount and duration of radiation exposure cannot be easily quantified and may not even be pertinent. The studies looking at the causal relationship between the exposure and the disease development have not been able to define a minimum dose necessary to cause the disease.” Thus, Dr. R.C.R. provided no further details on the size and nature of the radiation dose. Ultimately, Dr. R.C.R. opined that if the Veteran was exposed to radiation as he describes, then he has greater than a 50 percent likelihood of having developed his polycythemia from his radiation exposure. Dr. R.C.R. reasoned that as a class of diseases, and as a specific subtype of polycythemia vera, there has been a causal link identified with disease formation and prior exposure to ionizing radiation. Other than exposure to benzene products, there are really no other known causes of the Veteran’s type of blood disorder. Since the Veteran has one of the known exposures as a risk factor (radiation), it was more likely than not the cause of his disease. The probative value of this favorable opinion is stronger than the above favorable opinions because it was written by a medical oncologist and hematologist specialist and provides a more detailed explanation. However, under 38 C.F.R. § 3.311(e), this opinion did not assess the probable in-service dose of radiation the Veteran was exposed to. This factor is most important under a 38 C.F.R. § 3.311 analysis. With regard to favorable evidence for a nexus, in January 2016 and December 2017 VA physician statements, Dr. J.K.S., MD., a VA staff physician and oncologist, noted the Veteran’s report that “he had significant radiation exposure in the military and feels that this may have played a role in the development of his blood problems.” Dr. J.K.S. added that the Veteran’s radiation exposure was “well documented.” Dr. J.K.S. provided no further details on the size and nature of the radiation dose. However, Dr. J.K.S. cited medical treatise evidence in that an increased incidence of polycythemia vera has been seen in a few studies of people with radiation exposures. Dr. J.K.S. also mentioned considering the Veteran’s “health condition over time,” but provided little detail as to how this was pertinent in the Veteran’s particular case. In conclusion, Dr. J.K.S. opined it is more likely than not that the Veteran’s polycythemia vera is related to his in-service radiation exposure. He added that the Veteran’s polycythemia vera “has been chronic since that time” (i.e., since the time of discharge from the Navy in 1956). However, the Veteran has not alleged that his polycythemia vera was present in 1956, and STR discharge blood tests in 1956 did not reveal it to be present. Thus, Dr. J.K.S.’s statement of chronicity is unsupported by the medical and lay evidence of record. The Board is not required to accept a medical opinion that is unsupported by clinical findings. Godfrey v. Brown, 8 Vet. App. 113, 121 (1995). Again, Dr. J.K.S. supported his favorable opinion by citing to medical treatise studies showing polycythemia vera among nuclear weapons test participants. On this point, medical treatise evidence can provide important support when combined with an opinion of a medical professional. Mattern v. West, 12 Vet. App. 222, 228 (1999). With regard to favorable evidence for a nexus, over the course of the appeal, the Veteran and his representative have submitted various medical treatise articles from the Internet providing a description of polycythemia vera and also a Cobalt bomb. See e.g., February 2015 Mayo Clinic internet article; June 2016 and May 2018 and June 2019 Wikipedia articles received about Cobalt Bomb; January 2021 Brief from the American Legion with links to separate and unrelated medical treatise articles on polycythemia vera and radiation generally. The most relevant evidence was a November 2015 medical treatise article noting that polycythemia vera may have many contributing factors, including gender, age, and environment. This article added that exposure to “intense” radiation “may” increase the risk for polycythemia vera. Therefore, this medical treatise evidence provides some limited support for the Veteran’s claim. However, this particular medical treatise evidence did not discuss the specific facts and circumstances of the present Veteran’s case. Bailey v. O’Rourke, 30 Vet. App. 54, 60 (2018). This lessens the probative weight of the above medical treatise evidence. In general, an attempt to establish a medical nexus between service and a disease or injury solely by generic information in a medical journal or treatise “is too general and inclusive.” Sacks v. West, 11 Vet. App. 314, 317 (1998). The weight to be given medical treatise or article evidence is a matter within the sound discretion of the fact finder. See e.g., In re Joint E. & S. Dist. Asbestos Litig., 52 F.3d 1124, 1137 (2d Cir. 1995). Conversely, with regard to the unfavorable evidence against a nexus, the Board has considered the unfavorable November 2020 medical advisory opinion from the office of the VA Undersecretary for Health. This dose assessment was prepared and reviewed by D.K.M., BS, RRPT, AMAAHP, Health Physicist, and Dr. E.S., MD, MPH, FAAFP, the Director of Post-9/11 Era Environmental Health Program. D.K.M. wrote that once the radiation dose is determined, the issue of disease causation can be addressed. After a detailed discussion already addressed above, the VA Undersecretary for Health designee assigned a dose of 5 rem for the Veteran’s time in question of training in the Navy “RAD Safe #425,” with the professional knowledge that even this dose is too high. In fact, the Veterans’ dose was likely to have been less than 1 rem. The November 2020 clinicians discussed the circumstances of the Veteran’s in-service exposure to ionizing radiation in detail when he was 20 years of age. The Veteran is a Caucasian male and a former smoker, having quit in 1968 after smoking for 20 years. He has a positive family history of cancer with three brothers having prostate cancer. Following service, the Veteran worked as an airplane mechanic and crop duster. The November 2020 clinicians discussed the post-service history of the Veteran’s polycythemia vera. The Veteran was first diagnosed with polycythemia vera decades after service. The November 2020 clinicians reviewed and addressed three of the favorable medical opinions of record. Importantly, the November 2020 clinicians determined that the favorable medical opinions included in the claims file did not use “sound scientific and medical evidence” because they did not discuss the Veteran’s actual radiation dose during service and how that radiation dose was causative for the claimed disease. Crucially, the November 2020 clinicians emphasized that a radiation dose is “the prime factor” to consider when determining the causation of radiation induced disease. Being in the vicinity of a radiation source does not necessarily mean a “significant” exposure occurred. The radiation dose must be determined through direct measurement or reconstruction methodology. As such, the favorable opinions were speculative and of no medical value according to the November 2020 clinicians. They observed that several studies of atomic bomb survivors concerning the potential long-term effects of radiation exposure on granulocyte behavior have been performed.... there was no relationship of either aplastic anemia or polycythemia vera with radiation dose in the atomic bomb survivors. See Mettler and Upton - Medical Effects of Ionizing Radiation, 3rd Edition. Elsevier, 2008. The November 2020 clinicians focused upon this medical treatise evidence which showed that the kinetic pattern of postradiation events in hematopoietic tissue has been described by a large number of authors. Due to the short life span of neutrophils (7 to 17 hours) and of platelets (about 10 days), there is “rather rapid development of granulocytopenia and thrombocytopenia after radiation-induced injury of a major proportion of the hemopoietic system.” Lymphocytic depletion may be seen within hours of irradiation, whereas platelets and granulocytes are depleted over days, and depletion of red cells (erythrocytes) occurs over weeks. Late changes of aplastic anemia that are reported in the literature can occur as a result of vascular compromise and fibrosis. Under these circumstances all cell lines are equally affected. Such changes are not seen with acute marrow doses of less than 10 to 20 Gy [1000 to 2000 rads] in a relatively acute regimen. Marrow depression usually does not occur with chronic exposure unless doses exceed 0.4 Sv [40 rem] per year.” (The assigned radiation dose was 5 rem for the Veteran). The November 2020 clinicians opined that based on the above analysis, and the assigned radiation dose of 5 rem for the Veteran, it is “unlikely” that the Veteran’s polycythemia vera was caused by exposure to ionizing radiation during his military service. In light of the above unfavorable November 2020 medical advisory opinion from the office of the Undersecretary for Health, the designee of the Under Secretary for Benefits considered the claim in November 2020 with reference to the six factors specified in 38 C.F.R. § 3.311(e). See November 5, 2020 Memorandum from the Director of Compensation Service. This November 5, 2020 Memorandum from the Director of Compensation Service agreed with the conclusions of the office of the Undersecretary for Health. Her reasoning was similar to the November 2020 clinician advisory opinion from the office of the Undersecretary for Health. Therefore, a detailed discussion of its contents would be unnecessary and repetitive. In short, the Director of Compensation Service as designee of the Under Secretary for Benefits offered the same unfavorable conclusion for the Veteran’s radiation claim. See 38 C.F.R. § 3.311(c)(1). The Board finds that the unfavorable November 2020 medical advisory opinion from the office of the Undersecretary for Health holds greater probative weight than the favorable VA and private medical opinions of record on the following central question: whether the Veteran’s current polycythemia vera (blood cancer) was caused by his in-service exposure to ionizing radiation from his training in 1954. First, the common thread running through all the favorable nexus opinions is that they failed to consider the probable dose, in terms of dose type, rate and duration as a factor in inducing the Veteran’s polycythemia vera. It is difficult to envision granting a claim under the special developmental provisions of 38 C.F.R. § 3.311(a) without securing a dose estimate. Establishing the probable radiation dose is listed as the first factor a clinician should consider according to 38 C.F.R. § 3.311(e), in determining whether a veteran’s disease resulted from exposure to ionizing radiation in service. Instead, the favorable medical opinions in the present vaguely referred to “significant” or “extensive” radiation exposure during service without quantifying the radiation dose based on “sound medical and scientific evidence.” See 38 C.F.R. § 3.311(c)(1)-(3). There was no separate dose estimate from a “credible source” that represented a “material difference” from the Under Secretary of Health dose estimate. See 38 C.F.R. § 3.311(a)(3). As relevant to this point, the Court recently held that 38 C.F.R. § 3.311(c) requires that VA determine whether the dose estimate constitutes “sound medical and scientific evidence,” in order to provide an adequate statement of reasons or bases. Skaar v. Wilkie, No. 17-2574, 2020 U.S. App. Vet. Claims LEXIS 1295 (Dec. 17, 2020). In the present case, the November 2020 medical advisory opinion from the office of the Undersecretary for Health addressed in great detail the methodology the clinicians used to measure the dose of the Veteran’s radiation exposure (5 rem) during active duty. In contrast, the favorable private and VA medical opinions were unable to statistically quantify the Veteran’s dose assessment even though the Veteran described the nature of his in-service radiation exposure in detail. This limits the probative value of the favorable VA and private opinions. The Court has held that a medical examiner’s conclusions were of “questionable probative value” when the examiner failed to consider certain relevant information. Mariano v. Principi, 17, Vet. App. 305, 312 (2003). Second, the November 2020 medical advisory opinion from the office of the Undersecretary for Health addressed several of the other factors a clinician should consider according to 38 C.F.R. § 3.311(e), in determining whether a veteran’s disease resulted from exposure to ionizing radiation in service. These factors included the veteran’s gender and pertinent family history; the veteran’s age at time of exposure; and the time-lapse between exposure and onset of the disease. That is, the November 2020 medical advisory opinion from the office of the Undersecretary for Health contained greater detail and statistical analysis than any of the favorable VA and private medical opinions. The November 2020 medical advisory opinion was thorough and supported by detailed explanations. It also considered the Veteran’s reported history and lay statements in the context of the entire evidentiary record. The November 2020 medical advisory opinion contained an extensive analysis concerning the factual basis underlying its rationale with a citation to relevant medical treatise evidence. In this regard, the probative value of a medical professional’s statement is dependent, in part, upon the extent to which it reflects “clinical data or other rationale to support his opinion.” Bloom v. West, 12 Vet. App. 185, 187 (1999); see also Black v. Brown, 5 Vet. App. 177, 180 (1995). The Court has stated that an examination or opinion is adequate when it sufficiently informs the Board of a medical expert’s judgment on a medical question and the essential rationale for that opinion. Monzingo v. Shinseki, 26 Vet. App. 97, 105 (2012). The November 2020 medical advisory opinion from the office of the Undersecretary for Health accomplishes this task. Therefore, although the favorable private and VA medical opinions and medical treatise evidence above provide some support for the Veteran’s ionizing radiation claim, their probative weight is also limited by their analytical flaws discussed above. With regard to lay evidence, the Court has held that a veteran is competent to describe the general circumstances of an in-service “injury” due to radiation exposure. Rucker v. Brown, 10 Vet. App. 67, 74 (1997). However, neither the Veteran nor his representative has the medical training or expertise for offering a medical nexus opinion that his current polycythemia vera (blood cancer) is related to in-service ionizing radiation exposure. See 38 C.F.R. § 3.159(a)(1)-(2); Jandreau, 492 F.3d at 1377. That is, “[a]lthough lay persons are competent to provide opinions on some medical issues, see Kahana v. Shinseki, 24 Vet. App. 428, 435 (2011), as to the specific issue in this case, the development of polycythemia vera (blood cancer) years after in-service ionizing radiation exposure in the Navy, falls outside the realm of common knowledge of a lay person. See again Jandreau, 492 F.3d at 1377 n.4 (lay persons are not competent to diagnose cancer).” Also, the Veteran as a layperson is not competent to render a dose assessment or dose estimate. In summary, service connection for the Veteran’s polycythemia vera (blood cancer) cannot be awarded under the special framework of 38 C.F.R. § 3.311. Finally, the Board will consider whether direct service connection for polycythemia vera (blood cancer) can be established by showing that the disease was incurred during service. See 38 U.S.C. § 1110; 38 C.F.R. § 3.303; Combee v. Brown, 34 F.3d 1039, 1043 (Fed. Cir. 1994). In other words, the Board will consider the Veteran’s service connection claim under the general provisions governing the awards of VA compensation. STRs dated from 1952 to 1956 are negative for any complaint, treatment, or diagnosis of polycythemia vera. At his November 1956 STR discharge examination, no disabilities were noted for the Veteran. Laboratory testing, blood tests, and a urinalysis were all negative for any abnormalities in November 1956. In addition, post-service, there is no probative, credible evidence of polycythemia vera within one year of separation from the Navy in 1956 or 1957. Thus, the Veteran is not entitled to service connection for polycythemia vera on a presumptive basis, either as a chronic disease during service or within one year of service. 38 U.S.C. §§ 1101, 1112, 1113; 38 C.F.R. §§ 3.307(a)(3), 3.309(a); Walker, 708 F.3d 1335-37. Furthermore, there is no lay assertion from the Veteran or from the clinical evidence of record suggesting or demonstrating continuous, ongoing symptomatology for his polycythemia vera subsequent to his discharge from the Navy in 1956. See 38 C.F.R. § 3.303(b); Walker, 708 F.3d 1335-1337. A prolonged period without a complaint can be considered, along with other factors concerning a claimant's health and medical treatment during and after military service, as evidence of whether an injury or a disease was incurred in service which resulted in any chronic or persistent disability. See Maxson v. Gober, 230 F.3d 1330, 1333 (Fed. Cir. 2000). Finally, with regard to a nexus, outside of the context of his in-service radiation exposure, there is no other medical opinion of record linking his current polycythemia vera to any event, incident, or injury from his active naval service. Holton, 557 F.3d at 1366. See also 38 C.F.R. § 3.303(a), (d). Accordingly, the preponderance of the evidence is against service connection for polycythemia vera (a blood cancer), to include as due to exposure to ionizing radiation during service. 38 U.S.C. § 5107; 38 C.F.R. § 3.102; Gilbert v. Derwinski, 1 Vet. App. 49 (1990). The claim is denied. DAVID L. WIGHT Veterans Law Judge Board of Veterans’ Appeals Attorney for the Board P.S. Rubin, Counsel The Board’s decision in this case is binding only with respect to the instant matter decided. This decision is not precedential and does not establish VA policies or interpretations of general applicability. 38 C.F.R. § 20.1303.